WunderBlog Archive » Category 6™

Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.

Stan about to leave the Yucatan

By: Dr. Jeff Masters, 1:29 AM GMT on October 03, 2005

Tropical Storm Stan
Tropical Storm Stan is holding together as it moves has weakened during its passage across the Yucatan Peninsula, and is probably a tropical depression. There is very little deep convection surrounding the system, although the upper level ouflow is still good on all sides except the west.

Stan will have to re-organize once it pops out into the Gulf of Mexico Monday, and will have 36 hours or so to intensify over the warm 29 - 30C waters of the Gulf as it tracks westward. Wind shear is expected to remain very low, under 5 knots, and Stan could be a Category 1 hurricane as it approaches the Mexican coast on Tuesday. The latest model runs are still split on whether of not Stan will make it ashore on Tuesday. Two reliable models--the GFDL and Canadian--take Stan across Mexico and redevelop him as a tropical storm in the Pacific. However, the other models aren't so sure, and weaken the ridge that is driving Stan westward, allowing Stan to stall, loop back, or even turn northwards and threaten the U.S. later in the week. If Stan does stall and head northwards towards the U.S., he will have to contend with a large upper-level low pressure system forecast to form in the Gulf of Mexico by Thursday that would bring significant wind shear and weaken him.

Complicating the long range forecast is the fact that most of the computer models expect a second tropical storm to form nearby late in the week. The formation location varies depending upon which model one looks at. Two models indicate a storm will form off the east coast of Florida and scrape the Carolina coast (GFS and NOGAPS). The UKMET forms a storm near New Orleans and tracks it south into the Bay of Campeche; and the GFDL sees a new storm forming in the Yucatan Channel by the western tip of Cuba. We also need to keep an eye on the large area of thunderstorms approaching the Bahamas from the east, which could develop into a tropical storm later in the week.

Suffice to say, the waters surrounding the U.S. are expected to be very unsettled over the coming week, and this is a dangerous period of hurricane season for us. Ocean temperatures are still very warm, and the forecast is for very light wind shear over much of the hurricane breeding grounds.

Tropical Storm Otis
Tropical Storm Otis has decayed to a 45-mph tropical storm, and is forecast to continue to weaken and dissipate over the next three days. If Otis comes ashore in the Baja Peninsula, flooding and wind damage will be minimal. Otis's remains will probably not affect Arizona's weather.

Taiwan and China
Typhoon Langwang (Chinese for Dragon King), made landfall on Taiwan at dawn Sunday as a Category 3 typhoon with 120 mph winds. Passage over the 10000 foot high mountains of Taiwan significantly weakened Longwang, which struck mainland China today as a Category 1 hurricane. Longwang did heavy damage on Taiwan, killing 2,and injuring 46 people. In a freakish double-whammy, a magnitude 5.4 earthquake hit the island as Longwang came ashore, but did little damage.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

acronym/abbrevation/contraction guide :)

http://www.srh.noaa.gov/srh/jetstream/append/acronyms_a.htm
and the glossary of terms.
Oops here we go.

http://www.srh.noaa.gov/srh/jetstream/append/glossary_a.htm
Looks like things are going to pick up around here again this week. I hope nothing forms that will threaten the US.
Dr. Masters' post is very, very, very unsettling. Not that it's anything that we didn't know, but to have it coming from the expert's head...
StSimonsIslandGaGuy....thanks for the info on subtropical/hybrid systems.
Trouble is a brewin in the Atlantic waters....
tnx again st simons when tropics cool down i am going to online weather school!
I agree...the clouds east of Florida/Bahamas appear to be organizing.
I agree, 79, this is from the last blog if you didn't catch it:

Posted By: aquak9 at 9:14 PM EDT on October 02, 2005.
stsimons, yes I remember your posts as well, I suppose we just might still be cussing and dis-cussing the weather long after hurricane season is over. And I was thinking earlier how these female storms have been beee- otches this year, hope we are wrong about Tammy. Anyway, the weather here in jax has made a complete change starting Sat 3pm...something's going on out there, the pine trees are wiggling thier fingers, the clouds are practicing exploding into the sky...yes something's going on out there..
Does anyone know where exactly in the NE GUlf? I think I remember reading near Cedar Key?
aqua

that allowed a colorado team to finally win in Florida! the Buffalos nor Broncos cant stand the heat and humidity

lol
I said Citrus County yesterday, and it (the GFS) is still calling for a system to landfall there. The question is, tropical storm, hurricane, or subtropical storm, if any?
Yeah aquak, weather seems like a tropical system is developing. I live in Central Florida and we are getting rain daily now, after not getting any for an entire month. In addition, almost all models show a low pressure system affecting Florida late this week.
jld-yeah I know, gators and jags both went down the pipe this weekend...
Torn or Hurricane79, at this point, what do you predict will happen in the next couple of weeks with the favorability in the Atlantic?
jldfish where in the upstate are you we are in the clemson area
At the risk of losing all credibility, I think we may see 6-8 named systems in the next two weeks, but 4-6 is more likely. It's going to get scary...
clemson

I am actually in Florence..."northern midlands"

Trouper, a good chance for tropical development for the next 6 or 7 days, then things may quiet down as a large trough should sweep through by next Sunday or Monday.
We aren't really going to know any more than we do now about Tammy (?) until Wednesday.
tornadoty you think that may be we get up to TD 30 or may up to TD 40?
tornadoty- Thanks! Let's hope it's none of the above! Is this a separate storm than the one Dr. Masters is talking about in the GFS models forming off of the east coast? There are so many different ones predicted, I can't keep them all straight. I know nothing about weather except from what I have learned reading this blog for the past year.
TD 30 possibly, TD 40, in a word, no.
Thats true StSimons, something may not consolidate until Wednesday, possibly as early as Tuesday night. This new system should come from the vorticity we can see in the satellite images near 25N 69W
torn, FYI there have NEVER been 8 systems form in a 2 week period in the Atlantic, or even in the whole month of October. 6 in two weeks has happened twice, in Sept 1933 and Aug/Sept 1995. The record for September is 10, and for August, 8. I am trying to find what the record for October is.
aquak9

sent u a message
Yes, cTampa, that is a different storm than the one froming off the E coast, I actually think that one has a much greater chance of hitting New England then hitting Florida.
tornadoty may be n more then TD 35 and would this be in the Greek Alphabet by then and how far down will it go
hey dos any one like to send me some mail on her some time
I know, StSimons. That is the worst case scenario (if everything were to develop). Like I said 4-6 is much more likely, and, with all the activity (a new low in the Caribbean, the system shown as forming off the West Coast of Florida, the system(s) E of the Bahamas, and the impressive waves coming off the coast of Africa), I think those numbers are plausible.
I'm sticking with a total of 6 more storms as my official prediction for this season, meaning we'll have 24 storms and reach the name Gamma.
Remember too, StSimons, that this is 2005, and climotology means diddily squat. The NHC has even come out and said that the pattern is much more like September then October.
wow, guys. Seems like it was years ago, we were watching TD10 die...anyway, please post links tomorow, as I'll be in view-only mode during the day...by wed or thurs I think things are gonna get hairy..."a change is in the air-I can feel it"

goodnite, ya'll
gamma waves!!

sorry, had to throw that in! :)
Good night, aquak9.
Talk to ya mid week aquak
hey dos any one like to send me some mail on her some time
Well--climatology actually does mean diddly squat and more :) October is an active month, but it is in third place behind August and September. I am looking through the yearly records now, and not finding and Oct with more than 4 storms yet. Records are made to be broken though :)
StSimons, what was the old record for July storms?
That thunderstorm activity southeast of Puerto Rico is getting pretting intense.
before this year it was 4 in 1966 and 1995.
Well, thi past summer we saw a ridge that was not in its normal place for the most part, with a break near 60W persisting, and the ridge axis across the NE gulf. This was not normal for summer, and resulted in much below normal rains for Florida. We all know what else resulted from this scenario.

Now, we see a ridge/ trough pattern setup which we should have seen during the summer, but now are seeing in early fall. This is disturbing, mainly because it drives any area of weather in the Atlantic that is South of 30N, across warm waters and towards the US. This pattern seems to be in place through the next 6 to 7 days.

Any comments?
I need to take a break from this bbl.
I think your right on 79. I have noticed the exact same thing. As if we are a month and a half behind schedule.
hey 79

yeah the gfs has had a storm form over the atlantic and possibly make it to the us. so the next 7-12 days will be very active for the tropics if the gfs storm forms sooner and moves faster, all possible, it could get more west than the last run showed, mor elike the scenarion the run at 8pm yesterday showed. i think we will see a landfall in the next 10 days somewhere from one of the 3 or so systems the models form in the next 10 days. season is far from over
when is the new up date on stan?
30 minutes
that system se of pr was under 20kt shear and that shear has relaxed to 5-10kts and with the explosion of t-storms i could see possible development if it can continue with its convection.
We definitely did not get our normal afternoon thunder showers this summer in central Florida. However, we had them today. 79- I would like to think we are near the end of hurricane season and Florida dodged the bullet this year, but your last post has me thinking and wondering...What in the world will November be like if you're right?
53. dcw
We did over near Lakeland, cTampa. The difference is that they were unusually intence and early in the day.

And we can officially refer to climatology as "that unreliable history stuff" this year.
November is strange--most years have nothing at all, but some Novembers have had 2 hurricanes, in fact more Novembers have had 2 hurricanes than 1. I cannot recall if a November ever had 3 hurricanes but I don't think so. In the 20th century four hurricanes have made landfall in the US--all were in Florida and none were major. Florida has had close calls with major landfalling hurricanes in November in 1985 and 1932.
when we get to Nov 30th are we done or it keep going in to Dec too any one no this ? let me no
My favorite track for a November hurricane making landfall is this one :

http://www.wunderground.com/hurricane/at193506.asp
I think the middle of the state, unfortunately everyone that was recovering from last year that didn't need it, got all of the rain this summer. Afternoon thunderstorms are usually like clock work at the beach and in Tampa.
stsimons - This is my personal favorite for November: Link
And this is the latest a hurricane has hit--in my book it has it making landfall as a cat 1 not as a tropical storm as on this track. This track is wierd, it has the storm reintensifying to hurricane status while still over Central FL.
oops forgot the link http://www.wunderground.com/hurricane/at192502.asp
I always thought Gordon's track looked like a treble clef :)
I was in a band in those days. I was SURE of it!
subtropic this to tell you that that did not make landfall has a hurricane i made landfall has a TD and is it me or was that hurricane a the G storm for Nov what??? that new a G storm in Nov
David. I am aware of that. Gordon turned away from the coast suddenly right after reaching hurricane status.
we now have TD stan
66. iyou
subtropic - I was involved in a lawsuit in 1994 - it looks like a dollar sign to me !! heheh
stsimons- are you just trying to get a rise out of me? ha. I have been debating on whether (weather...lol) or not to call about flood insurance this year. That track at least dies it out before making landfall in Tampa Bay. TWC said the next costliest storm to hit the US would be the Tampa Bay Area. I am not required to have flood insurance, but am only a mile away from the water. If we get a Cat 3 in Tampa my house will be under water. They showed a graphic that included approx. 10 sq miles under water. Unlike NO, at least the water would drain back off quickly.
That does not surprise me, Stan had a long journey across land.

5th shower of the day starting now here.
Um yep if you are in a cat 3 zone you should.
Lets just hope that summerlike ridge is a fluke and dissapears in a week!
CTampa, GET THAT INSURANCE NOW!
good evening iyou!
http://www.wunderground.com/radar/radblast.asp?zoommode=zoom&num=1&delay=15&scale=0.250&noclutter=0&ID=JAX&type=N0R&lat=31.18650055&lon=-81.37229919&label=Saint%20Simons%20Island,%20GA&showstorms=0&map.x=399&map.y=250¢erx=280¢ery=566
I guess I never paid much attention to these November storms. I was so over it by October last year.
Actually don't bother this year--flood insurance doesn't start coverage for 30 days.
76. iyou
hi subtropic - we are having perfect, gorgeous warm blue weather up here ;-)
You look at the graphics and say it will never happen here. It took this year seeing the devistation of friends' houses to realize it may not be that bad of an idea.
78. iyou
sounds boring eh??!!
I would highly recomend flood insurance for anyone living in Florida. You never know when a tropical system or local system will dump heavy rain during the rainy season. Point Fort Lauderdale had almost 14" of rain in less than 4 hours in May of 2004 damage caused by water was everywhere
iyou- where are you?
81. iyou
Toronto - our weather is benign compared to yours - if we had that amount of rain in 4 hours, we would have serious flooding!
iyou, Glad you finally got the nice weather. We are (unfortunately) watching for trouble on the horizon in the Gulf and Atlantic.
For those of you lurking that are interested:

Tropical Depression Stan Discussion Number 7

Statement as of 11:00 PM EDT on October 02, 2005

Stan has just about completed its transit of the Yucatan Peninsula. Based on a recent Quikscat pass...it is estimated that...for now...the cyclone has weakened to just below tropical storm strength. Nonetheless...the system retains a well-defined low-level circulation with some convective banding features. A prominent upper-level anticylone is situated over Stan...and vertical shear is forecast to remain light for the next couple of days. Once the center moves over the southwestern Gulf of Mexico...where surface water temperatures are almost 30 deg c...strengthening is highly likely. The official intensity forecast is very similar to the previous one...and slightly above the SHIPS guidance.
The initial motion is about 285/9. The flow south of a mid-tropospheric ridge is expected to steer the tropical cyclone on a westward to west-southwestward track over the next 48 hours or so. This would take the center near or across the coast of Mexico in 2-3 days. There is...however...a potential complication to the
track forecast. Global models indicate that an upper-level trough will dig into the northeastern Gulf of Mexico in about 48 hours...and induce the development of a mid- to low-level cyclonic circulation over the eastern and central Gulf within roughly 72 hours. This development could weaken the ridge soon enough to influence Stan's track...and delay its landfall. The track guidance models also take the tropical cyclone slower over the
southwest Gulf than the earlier runs. The official forecast is slower than the previous one...but faster than most of the guidance. Hopefully...an additional slowing of this forecast will not be required in subsequent advisories.
Forecaster Pasch

iyou it happened in oct 1954 with hurricane Hazel--Toronto got 8-15 inches of rain in 6 hours--over 90 people killed there. Population has gone up since then there, eh?
It was gone for the most part by the end of next day except for cronic low lying areas. Reason being we are at sea level and it drains quickly.
85. iyou
I hope all my dear blog associates do not have to face a single aggressive rain drop for the rest of this year..or the next 100...
It was the storm that changed Toronto
we are getting fun pouring brief showers here, just had our 5th shower of the day.
88. iyou
St.Simons-I was a teeny tadpole when Hazel came through here - I woke up once during the night - branches were whipping the window, even though there were no trees close by - the next day there was ruin - and the beach we went to on Lake Ontario was completely rearranged
Well I doubt that any of the forcasters were expecting the center of hurricane Hazel to move over Toronto 13 hours after making landfall on the NC/SC border! Center hit at midnight, which meant that people were asleep and had no warning about the flash floods.
Good night guys. Got school tomorrow. Have to wake up at 5:15.
Hazel must have had some crazy intense rain bands--set record for Raleigh, NC for rainiest 24 hr period ever--over 11 inches in less than 2 hours!
92. iyou
St.Simons - I believe there might have been warnings about flooding but they were either ignored or as you said, people were sleeping and simply did not know and that one street was washed away - there is a park there now.
Glad you made it iyou!
94. iyou
Me too!!
The forecasts in the US for Hazel had her going up the east coast to NYC--oops!

There was obviously a lot of juicy air around--Chicago set its rainfall record (not related to Hazel) of just over 9 inches on Oct 12th, just 3 days before.
ok time for bed and for me to let others talk on this board, night y'all!
72 hours...looks like this may really be something to watch. Are they just predicting a tropical depression or will it develop into something more in the eastern gulf? Our local weather just said we may have a tropical wave by mid week - more to come later.
98. iyou
I highly recommend the book 'Isaac's Storm' by Erik Larson - someone mentioned it a couple of weeks ago-got it from the library-about the Galveston hurricane of 1900- very well written, a harrowing story-some interesting things noted about the Cuban weather bureau at the time, and the Sources section is a motherlode of hurricane reading...check it out.
Night stsimons
100. iyou
Night St.Simons!
iyou, thanks for the book recommendation. Let me return the favor. Here is a link to the 1928 hurricane memorial page on the NWS website. They reference a book called "Okeechobee Hurricane" which I highly recommend (even though I have not been able to sit and read it cover to cover yet-I have read many passages. Very good book!) Ths page also has some great old pics of that storm from different cities in south east Florida. Link
So what is everyone thinking about the ULL? Looks to me like it is trying to make it to the surface. Still looks to be around 25 70.
Whats up stormj. I am thinking this is going to develope. I am seeing several circulations though and I can't quite make up my mind where it will finally form.
hey sj, that whole area from the ull to east of the lesser antiles looks like areas we might see some development
What about a 25 70 and then a 20 63 when it gets further W? I know that is unlikely, but the 25 70 area is looking pretty good right now seeing as how it was/is a ULL.
106. iyou
Thanks subtropic - I found the author's name at the bottom-I'll look for it-80 years later, devastation looks the same-I'll go back to reading the weather discussion now!
also there is an area by jamaica that could develop as well.
What's up Sub and Lefty.

Man Lefty, I made a stupid mistake. DVR's that game yesterday so I could watch it when I got home. Watched the whole thing in FF. Nearly tore my room apart watching that crap. Luckly in FF it only lasted about 20mins.lol.
stormj. sounds reasonable to me. I was looking at the San Juan radar earlier and it looked like a weak mid level circulation was trying to get going just ne of P.R. but it's looking a little less organised to me now.
lol sj. thats funny as hell. i loved the vt game yesterday and how bout those skins. 3-0 baby lol
and iyou.

Man the latest GFS looks very active to say the least. Can't even attempt to figure out what it actually means.
Lefty, What about that earlier post? those two systems?
113. iyou
hey stormj - your eyeballs must be reeling!! lol!!
well sj, i look at it like this. its saying the tropics will be active with an active itcz and low shear, so potential is for storms to form. potential is high all over the tropics right now
what post sj
wow what a hurricane year i do not think we will see this for a long time
Me 3:42 Lefty.
hey sj thats why i said this


hey sj, that whole area from the ull to east of the lesser antiles looks like areas we might see some development
After that FF?

Yeah it was complete BS. I took breaks long enough to smack the pillow a couple of times. I don't usally get angry during games, but that was a joke. May have something to do with kicking over 10 players of the team during the offseason. But we needed to get rid of the rift raft. We are already on probation. Don't need no trouble makers.
sj u feeling any halo man?
sj meet me in the lobby?
Alright I geuss I was more wondering if those two areas developing in that way. 25 70 moving WNW or NW. and 20 63 getting W of 25 70 then devloping? What would prevent that.

Hey wakeup! ...can anybody tell me why that "feeder band" on Stan's eastern flank looks like it is detaching, forming a small convection center and moving NW today from oh, say, 20.1N 85.2W to near 21N 86W....Cyclogenesis anyone? ...GFDL prediction? ...Stan turning into another Bret/Gert limping into Tampico? And a stronger system becoming dominant....just a few late nite musings.
Lefty and I were talking about that area Doc.
and three others along line to the SW with the 25 70 being the northern most of the three. All need watching.
Right on SJ, it's amazing the amount of potential development. What stands out, looking at the over all signature of the system is Stan seem s to be running past the anticyclone, while that blowup at 21N 86W is centered under it....and how "bout dem San Antonio Saint's" - the Duece was loose!
126. code1
Hey everyone,
Got to Miami 1 1/2 hours late. Plane trouble. Interesting coming into MIA though...the captain giving his usual spill about enjoying our time here said we might want to keep an eye on the weather. Never heard that on a flight before, they usually only give the current weather. Landed and had to wait before deplaning....we had a monsoon. The workers weren't able to get the ramp up to the plane. Haven't had that happen either before. Got to go to bed, work early in the morning, but I will be lurking as I can this week. Hope to get back to Ft. Walton before too much happens.
what kind of time frame are we looking at for the low east of Florida? I would think that as long as this stayed east of LA by Thursday, the cold front expected to come in would keep it away from New Orleans. How far into the gulf should it be by Thursday? (know it's hard to tell, but what does the guidance suggest?)
Hello hmfynn, ...That's a good question I think we're all wondering. A lot depends on where the forecasted low originates. Lot of possibilities - Stan's final track is uncertain, as well another cluster either spun off from it or further to the east. But, yeah, all indications are that the strong cold front will pass us in SE LA on Thu. - so between now and then, we'll just have to be alert..
take a look at this model run I was sent by a friend LINK
Does anybody see a delay in the progression of Stan's track this evening? The center looks like its changing and farther east and north. How do you see the timing of the cold front. Midland, Texas forecast discussion is apologizing for a late arrival of the cooler weather.
hey guys check this out cool

Outflow Boundary: An outward flow of air, usually from a thunderstorm, separating thunderstorm cooled air from the surrounding air. They result from the downdrafts of a convective cloud (almost always a thunderstorm). Outflow boundaries are similar in many ways to a cold front, in that their passage includes a windshift and temperature drop. Outflow boundaries can travel hundreds of miles from their point of origin, and persist for more than a day... even when the thunderstorms that created them dissipate. They also make a good trigger for additional thunderstorm development, and a line of thunderstorms will fairly often form along them if other favorable conditions are present.
LMFAO! The canadian model is nearly mocking us. Seeing that system form and then do a 180 in the Gulf seems appropriate considering this season. Poor NHC will have a hell of a time forecasting that systems if it forms. One thing is clear: every model forms something in the next week.

I also have to share that the weather coming off the Atlantic into St. Augustine this evening was/is very ominous. I was standing near the beach when a violent downdraft came in. I won't bore you, but trust me when I say it was INCREDIBLY POWERFUL, and that I will never forget it.
really wil what mph do you think it was
Hard to say, I would guess it was about 55-60 mph. It came ahead of this big black area over the ocean that I knew had to be a storm. I felt a few drops of rain and a couple gusts of cold air, and then the temperature dropped in a spilt second, sand blasted off the dunes and pelted me into submission. I cursed as I ran inside to tell my friends. They were already on the balcony and told me "HOLY $hit man can you believe that just happened!"

The downpour that ensued was equally remarkable. Really, no exxagerating here guys, it felt like a powerful tropical storm had suddenly spawned over us. Wish you coulda seen it guys, I tried to film it but it was too dark.
Realizing there are a lot of outflow boundaries out there generating activity in the gulf is exciting. What kind of outflow boundary will originate from the Augustine weather? Where is it going?


Going to St. Augustine radar!
Funny we had an instense gusty downpour in tampa Sunday as well. Very "tropical". Seemed different from the usual seabreeze generated storms we get.
man will thats crazy fun but crazy lol
Cirro, what are you talking aobut?
This St. Augustine downdraft appears to be a catalyst for later activity as an outflow boundary will now set up activity somewhere else. Radar is quite interesting out of Jacksonville. Numerous bands moving in like a flock of geese. I need to check satellites in the area. The weather is getting interesting!
That particular system was hauling butt eastward. There were scattered showers here yesterday, and scattered downpours all day today. I bet soon it will just become one big downpour.

Funny thing was, I only saw one lightning flash and not a single thunder in any of the systems today, despite their violence. It's just been really weird weather.
yeah ill say lol one flash for flordia unreal lol
yes, exactly Timl, that is EXACTLY what I thought. Especially due to the lack of thunder. "Very tropical" is the perfect description of the weather as of late.
theboldman, I really like that picture. If I'm not mistanken that's an anvil clould thats actually building forward into the prevailing winds aloft. Most anvils shear out in the direction of the upper level winds, but the updrafts in that storm are so strong that the anvil is building faster then the prevailing winds aloft.
yeah thought so too ill bet it was producing baseball sized hail with tat updraft lol
Yeah Jax, no thunder here as well, forgot to mention that.
what i cant believe a flordia storm had only one flash of lightining lol
Otis bringing moisture in to the Texas panhandle tonight. Outflow boundaries initiated some shower activity associated with Otis.

The primary topic of today's discussion is outflow boundaries from trade wind cumulus clouds. Shown in Fig. 1 are three (labeled here A through C) very distinct cloudy areas embedded in the northeastern Atlantic trade winds. As these areas convect they send out very distinct outflow boundaries which travel along in the flow as shown in the loop below. In the tropics, these boundaries are often associated with very dry conditions aloft. As convection proceeds upward it encounters the very dry middle levels, evaporates and becomes much colder than its environment. This negatively-buoyant air, now part of the downdraft, accelerates downward, spreading out when it encounters the ground. This is also the case in this situation, as there is a very distinct trade wind inversion present as shown in the Barbados 12Z sounding (Fig.2). The tops (determined from Channel 4 using the MCIDAS command MINMAX) of these convective systems have temperatures near 10 degrees Celsius, which according to the Barbados' sounding is approximately at the lowest portion of the inversion.

In addition to the above discussion, there is evidence of the propagation of gravity waves in this set of imagery. These waves are most easily seen in cloudy area C when the loop is run very rapidly. These waves cause the fluctuation of cloudiness as they propagate from northwest to southeast through the imagery. From the sounding temperature profile, the cloud top temperature of these cloudy areas, and fluctuation of cloudiness associated with these waves, it can be concluded that the gravity waves are propagating along the trade wind inversion.

Click here for a visible loop.
The damn trpopopause! Keeping clouds from building to 200,000 feet lol!
151. iyou
cirro - do you have that loop?
hey iyou aka weather mama lol
153. iyou
heheh - hi jeff!! great cloud pix-absolutely beautiful - saw the others on alec's blog as well!!!
yeah they are great hey want to go to the chat room iyou
Yah, that photo is incredible. Can you imagine how insane it musta been underneath of that thing! I would sit right in that spot and watch that thing grow.

Well gnight guys, must rest well to watch crazy tropics develop tomorrow. Something is about to go down, practically guaranteed IMHO.
yes will i think baseball sized hail at least and maby a twister lol or 70 mph winds lol
157. iyou
Will-that's weird what happened-scary and thrilling! good night! sure jeff-just for a few minutes-it's 3:17 a.m. here!
ok see you there lol
Barbados loop at: http://www.cira.colostate.edu/ramm/PICODAY/120897.html


Interesting story at NOAA NWS Weather Watcher of Spokane:
This event was unusual in many ways. Theweather pattern that led to this event was more typical of January rather than mid-August. A ridge of high pressure had built over the Gulf of Alaskaand amplified northward into Alaska, bringing record warm temperatures to the region. In re-sponse, the jet stream over western Canada dug tothe south, dragging a cool air mass into the North-west U.S. The hot temperatures of early Augustbegan to slowly moderate by the 10th as the Cana-dian jet gradually sagged into the area. By the af-ternoon of the 12th, a cold front was forecast tosweep south from the Canadian Rockies into north-east Washington, the northern panhandle of Idaho,and northwest Montana.A complex of thunderstorms developed ahead of the cold front by mid afternoon on the 12th, andmoved into the Spokane area after 3:30 pm, pro-ducing winds to 50 mph, dime-sized hail, and over25 fire starts from lightning and downed powerlines. The storms lost much of their strength as they passed south of the Spokane area; however the event was far from over. This thunderstorm cluster, combined with a push of cooler air from the cold front, generated what appeared to be amassive outflow boundary that affected most of eastern Washington later that afternoon.While the occurrence of outflow boundaries is notunusual, the longevity and persistent strength ofthis boundary was remarkable. This boundary wasinitially detected by the Spokane Doppler radar with speeds of 30-40 mph, which matched speeds reported from spotter reports and weather sensors. On satellite, the boundary was spotted spreadingradially west and south away from the thunder-storms. By 8 pm, the boundary had progressed allthe way to Walla Walla to the south, and Ellens-burg to the west, more than four hours after its inception with wind gusts equal to the speeds thathad moved through Spokane! Typically, an outflow boundary is formed as coolerair from the mid-levels of a thunderstorm is mixeddowntothe ground.This cooland subse-q u e n t l yheavier airmass thenspreads out ahead of the thunderstorms and can potentially spawn additional storms. As the gust front spreads out, the supply of cold outflow airbecomes increasingly shallower and its progress slows as it undergoes a mixing process with the environment and experiences friction.The boundary on August 12th did have a couple ofthings working in its favor. The pre-existing flowwas already from the northeast. So the boundarymoving to the south didn't have a head wind to"fight". Also, the topography from Spokane to theTri-Cities is a gradual down-slope, changing inelevation from about 2500' to around 400' abovesea level. Thus, gravity would have been assistingthe boundary as well.There is a problem with assigning the thunder-storm outflow as the cause of this boundary. It is due to the fact that the computer generated weather models did predict the strong cold front with gustywinds to drop through the area at that time, well before any thunderstorms has formed. Instabilityand dynamics aloft were powerful enough ahead of the front to sustain the convection under this weather pattern .There are conflicting viewpoints on the cause ofthis boundary. Was it an outflow boundary or was it a cold front? While radar and satellite maintainthe idea of an outflow boundary, there is additionalinformation to support the cold front as the bound-ary marching across the region. The jury is still outon this event, even with the forecasters. One thing is for certain, it was a unforgettable weather eventthat captured the attention of most people in the Inland Northwest. For more details, seeww.wrh.noaa.gov/otx/photo_gallery/august12_storm.php ☼
This is the html version of the file http://www.cira.colostate.edu/RAMM/PDFDOCS/Hurr_Luis.pdf.
G o o g l e automatically generates html versions of documents as we crawl the web.
To link to or bookmark this page, use the following url: http://www.google.com/search?q=cache:CowizQRdLWsJ:www.cira.colostate.edu/RAMM/PDFDOCS/Hurr_Luis.pdf+outflow+boundaries+in+hurricanes&hl=en


Google is neither affiliated with the authors of this page nor responsible for its content.
These search terms have been highlighted: outflow boundaries hurricanes



--------------------------------------------------------------------------------
Page 1
3352VOLUME128M O N T H L Y W E A T H E R R E V I E W2000 American Meteorological SocietyPICTURE OF THE MONTHA Mesoscale Low-Level Thunderstorm Outflow Boundary Associated withHurricane LuisJOHNA. KNAFFNOAA/CIRA, Colorado State University, Fort Collins, ColoradoJOHNF. WEAVERNOAA/NESDIS/RAMM Team, Fort Collins, Colorado24 January 2000 and 1 March 2000ABSTRACTA large, low-level thunderstorm outflow boundary was observed as it exited from beneath the cirrus canopyof Hurricane Luis following a period of intense convection in the storms eyewall. A description of the featureand a short summary of its behavior are presented.1. IntroductionLow-level thunderstorm outflow (LTO) boundariescan play critical roles in the life cycles of midlatitudesevere and tornadic thunderstorms (Magor 1959; Pur-dom 1976; Weaver 1979; Maddox et al. 1980; Weaverand Nelson 1982; Wilson et al. 1992; Przybylinski etal. 1993; Weaver et al. 1994; Browning et al. 1997;Markowski et al. 1998). LTO-stabilized air masses canalso have negative effects on convection, particularly ifa preexisting storm moves out over a large, stable thun-derstorm-modified air mass (e.g., Weaver et al. 1994;Weaver and Purdom 1995; Markowski et al. 1998).In tropical regions, LTO boundaries can also act tostabilize the normally unstable boundary layer, therebyweakening convection. As in midlatitudes, the tropicalprecipitation process can produce strong downdraftsthrough both precipitation loading and the evaporationof rain into a dry midlevel environment (Young et al.1995; Johnson and Nicholls 1983). Mean boundary lay-er recovery times for tropical mesoscale convective sys-tems can be 12 h or more (Saxen and Rutledge 1998;Young et al. 1995). This boundary layer stabilizationprocess most often occurs with rainband convection intropical cyclones, where the difference between the sur-face and midleveleis as much as 12 C (Barnes et al.1983). Rainband-generated downdrafts can stabilize theCorresponding author address: John Knaff, NOAA/CIRA, Colo-rado State University, Fort Collins, CO 80523.E-mail: Knaff@cira.colostate.eduboundary layer to a point that in most cases the air masscannot recover before it is ingested into the hurricaneeyewall (Powell 1990). As that author states, Anymechanism that can act to lowere, if acting on largeenough scales to modify a significant portion of theinward flowing boundary layer, should also be able toaffect storm intensity. That is to say, the central con-vection of a tropical storm might be expected to weakensomewhat following periods of strong rainband con-vection, especially if associated downdraft activity low-ers the equivalent potential temperature values of theair being ingested into the eyewall.Strong downdrafts are not limited to rainband con-vection alone. Implicit in Simpson and Riehl (1958) isthe fact that for cases of large cross-storm ventilation,where drier air intrudes all the way into the eyewall re-gion of the storm, the eyewall convection can producecooler and more intense downdrafts. The objective ofthis paper is to illustrate an unusually large LTO bound-ary associated with eyewall convection that later appearsto affect the intensification trend of Hurricane Luis.2. Hurricane Luis: 67 September 1995Hurricane Luis was a category 4 (Simpson 1974) hur-ricane that crossed the northernmost islands of the Less-er Antilles on 5 September 1995, then curved north ofPuerto Rico over the next two days. Following a shortperiod of weakening due to vertical wind shear (valuesranging from 8.8 to 9.3 m s1) and to a dry midlevel
--------------------------------------------------------------------------------
Page 2
SEPTEMBER20003353P I C T U R E O F T H E M O N T HFIG. 1. GOES 10.7- m infrared imagery of Hurricane Luis on 6 Sep 1995 at (a) 0945 and (b) 1045 UTC. Images show the rapid decayof deep convection located on the north side of the eyewall. Temperature bar wraps back to black at 70 C.FIG. 2. GOES visible imagery of Hurricane Luis on 6 Sep 1995. The images show the evolution of a large arc cloud line to the northwestof the storm associated with low-level thunderstorm outflow. Image times are (a) 1700, (b) 1900, and (c) 2100 UTC. The feature is movingoutward from its origin between 14 and 17 m s1.air intrusion into the storms center,1the hurricane de-veloped new eyewall convection on its northeasternside. The coldest cloud tops during this period occurredbetween 0945 and 1015 UTC (Fig. 1a). The new eyewallconvection did not last long. Dry environmental air atmid- and upper levels, and moderate vertical wind shear(8.8 m s1) in the environment, continued to disruptstorm intensification. Over the next hour, there was asignificant warming of the cloud tops near the center(Fig. 1b), indicating a continuation in the weakeningtrend.As the convection collapsed, a large LTO boundaryemerged from beneath the cirrus cloudiness on the1Vertical wind shear values were computed using both Aviation Modeloutput and satellite-derived cloud drift winds. The intrusion of dry mid-level air into the storms center was identified using Geostationary Op-erational Environmental Satellite (GOES) water vapor imagery.northwest side of the storm (Fig. 2). Cloud-top tem-peratures averaged 22 C over the arc cloud, which isconsistent with temperatures found near the top of thetropical cyclone boundary layer. Although first seen inthe visible imagery at 1600 UTC, the extensive spatialcoverage of this LTO boundary was not obvious until1700 UTC (Fig 2a). Throughout the day, a meso- -scalearc cloud line expanded northwestward at 1417 m s1,persisting in the visible (Fig. 2), and then in the 3.9-m channel (not shown), well into the nighttime hours.Since the storm was traveling toward the northwest atthis time, the LTO boundary, and the region of stableair associated with it, were being positioned just aheadof the storms center. When the hurricanes core crossedinto the area where this outflow air had spread, the stableair appeared to have had a strongly negative influenceon the eyewall convection.For several hours, as the center of Hurricane Luisslowly approached the LTO-stabilized air, it was still
--------------------------------------------------------------------------------
Page 3
3354VOLUME128M O N T H L Y W E A T H E R R E V I E WFIG. 3. GOES 10.7- m infrared imagery of Hurricane Luis on 7 Sep 1995 as the storm begins to encounter the low-level stable air producedthe previous day. Images show (a) 0045 UTC, a reorganizable Hurricane Luis with a ring of very cold tops surrounding the eye wall; (b)0745 UTC, eyewall convection begins to diminish; (c) 1245 UTC, eyewall convection collapses; and (d) 1715 UTC, storm begins to reintensify.Temperature bar wraps back to black at 70 C.ingesting unstable air in at least three quadrants. Thestorm actually became better organized during this pe-riod (Fig. 3a), and the vertical wind shear appeared toremain moderate to low (7.2 m s1). Eventually, how-ever, the eyewall region moved over the LTO-stabilizedboundary layer region. The convection suddenly be-came less well defined, and the area of the cold cloudtops decreased with time (Figs. 3b and 3c). Althoughthere was no significant weakening of maximum winds,or increase of mean sea level pressure, this disruptionof the eyewall structure did appear to interrupt the in-tensification trend the storm was experiencing at 0000UTC. This interruption of central deep convection andshort-term intensification is not unexpected. As Wil-loughby (1998) points out, it is the inflow above theboundary layer that is important for maintaining cir-culation outside the eyewall region. It is also interestingthat after the storm passed beyond the area of more-stabilized boundary layer air, it once again began tobecome better organized and resumed its intensification,while the vertical wind shear remained nearly constantat 7.2 m s1(Fig. 3d).The sequence of events observed in this case is con-sistent with results from several tropical cyclone bound-ary layer studies, including Powell (1990), Barnes et al.(1983), Fitzpatrick (1996), and Cione et al. (2000).Those studies imply that changes in boundary layer con-ditions outside the inner core region of the storm maynot be able to fully recover before the modified air isingested into the eyewall, potentially affecting tropicalcyclone intensity change.3. SummaryTropical cyclones produce LTO boundaries when dri-er air is present aloft. These outflows can frequently beseen in satellite imagery, but on the limited spatial scaleof the rainbands producing them. Outflow boundariesas large as the one shown in Fig. 2 are associated witheyewall convection and are much less frequently ob-
--------------------------------------------------------------------------------
Page 4
SEPTEMBER20003355P I C T U R E O F T H E M O N T Hserved. This is because eyewall convection is normallyshielded from the dry midlevel conditions of the tropicalatmosphere. This does not appear to be the case here.Based on vertical shear estimates, on 6.7- m water va-por imagery, and on published works cited in this paper,the time evolution of Hurricane Luis during the periodillustrated is assumed to be the result of the followingprocess: 1) a period of moderately intense wind shearand dry air intrusion caused the eyewall convection toingest dry midlevel air and weaken, 2) the collapsingconvection produced a very stable LTO air mass aheadof itself, 3) the convection near the center of the hur-ricane passed over this stable, low-level air mass andweakened, and 4) once out of this region, the stormreintensified. Recognition of this short-term change instorm behavior might have useful application in thenowcast time frame.Acknowledgments. The authors would like to thankDrs. Ray Zehr and Mark DeMaria for their commentson this work as well as the three anonymous reviewersfor their helpful comments. Funding for this paper wereprovided by NOAA Grant NA67RJ0152.REFERENCESBarnes, G. M., E. J. Zipser, D. P. Jorgensen, and F. D. Marks Jr.,1983: Mesoscale and convective structure of a hurricane rain-band. J. Atmos. Sci., 40, 21252137.Browning, P., J. F. Weaver, and B. Connell, 1997: The Moberly, Mis-souri, tornado of 4 July 1995. Wea. Forecasting, 12, 915927.Cione, J. J., P. G. Black, and S. H. Houston, 2000: Surface obser-vations in the hurricane environment. Mon. Wea. Rev., 128,15501561.Fitzpatrick, P. J., 1996: Understanding and forecasting tropical cy-clone intensity change. Department of Atmospheric Science Pa-per No. 598, Colorado State University, 346 pp. [Available fromDepartment of Atmospheric Science, Colorado State University,Fort Collins, CO 80523.]Johnson, R. H., and M. E. Nichols, 1983: A composite analysis ofthe boundary layer accompanying a tropical squall line. Mon.Wea. Rev., 111, 308319.Maddox, R. A., L. R. Hoxit, and C. F. Chappell, 1980: A study oftornadic thunderstorm interactions with thermal boundaries.Mon. Wea. Rev., 108, 322336.Magor, B. W., 1959: Mesoanalysis: Some operational analysis tech-niques utilized in tornado forecasting. Bull. Amer. Meteor. Soc.,40, 499511.Markowski, P. M., E. N. Rasmussen, and J. M. Straka, 1998: Theoccurrence of tornadoes in supercells interacting with boundariesduring VORTEX-95. Wea. Forecasting, 13, 852859.Powell, M. D., 1990: Boundary layer structure and dynamics in outerhurricane rainbands. Mon. Wea. Rev., 118, 918938.Przybylinski, R. W., T. J. Shea, D. L. Perry, E. H. Goetsch, R. R.Czys, and N. E. Wescott, 1993: Doppler radar observations ofhigh-precipitation supercells over the mid Mississippi Valley re-gion. Preprints, 17th Conf. on Severe Local Storms, St. Louis,MO, Amer. Meteor. Soc., 158163.Purdom, J. F. W., 1976: Some uses of high-resolution GOES imageryin the mesoscale forecasting of convection and its behavior. Mon.Wea. Rev., 104, 14741483.Saxen, T. R., and S. A. Rutledge, 1998: Surface fluxes and boundarylayer recovery in TOGA COARE: Sensitivity to convective or-ganization. J. Atmos. Sci., 55, 27632781.Simpson, R. H., 1974: The hurricane disaster potential scale. Weath-erwise, 27, 169 and 186., and H. Riehl, 1958: Mid-tropospheric ventilation as a constrainton hurricane development and maintenance. Proc. TechnicalConf. on Hurricanes, Miami Beach, FL, Amer. Meteor. Soc.,D4-1D4 -10.Weaver, J. F., 1979: Storm motion as related to boundary-layer con-vergence. Mon. Wea. Rev., 107, 612619., and S. P. Nelson, 1982: Multiscale aspects of thunderstorm gustfronts and their effects on subsequent storm development. Mon.Wea. Rev., 110, 707718., and J. F. W. Purdom, 1995: An interesting mesoscale stormenvironment interaction observed just prior to changes in severestorm behavior. Wea. Forecasting, 10, 449453.,, and E. J. Szoke, 1994: Some mesoscale aspects of the6 June 1990 Limon, Colorado, tornado case. Wea. Forecasting,9, 4561.Willoughby, H. E., 1998: Tropical cyclone eye thermodynamics. Mon.Wea. Rev., 126, 30533067.Wilson, J. W., G. B. Foote, N. A. Crook, J. C. Fankhauser, C. G.Wade, J. D. Tuttle, C. K. Mueller, and S. K. Krueger, 1992: Therole of boundary-layer convergence zones and horizontal rollsin the initiation of thunderstorms. Mon. Wea. Rev., 120, 17851815.Young, G. S., S. M. Perugini, and C. W. Fairall, 1995: Convectivewakes in the equatorial western Pacific during TOGA. Mon.Wea. Rev., 123, 110123.
Nice circular motions with Stan on satellite! Big skip on latest NOAA loop. Very interesting storm.
Stan appears health for now. Trough enters the picture later along with a cold front. Midland forecast discussion was best earlier in the evening. Front behind schedule.
Time for a radar trip at NOAA. Then a satellite trip!
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
354 AM EDT MON OCT 3 2005

.DISCUSSION...THIS WEEK`S WEATHER WILL BE QUITE COMPLICATED AND
WET TO SAY THE LEAST. A TROPICAL WAVE CURRENTLY NEAR 73W WILL MOVE
STEADILY WEST AND REACH SOUTH FLORIDA TUESDAY AFTERNOON. THE
ARRIVAL OF THIS WAVE HAS BEEN DELAYED A BIT WITH EACH NEW MODEL
RUN BUT THIS TIMING LOOKS FAIRLY GOOD. THE GFS BRINGS THE WAVE
THROUGH AS AN OPEN WAVE BUT THE ETA BRINGS IT THROUGH AS A CLOSED
1004 MB LOW. EVENTUALLY THE GFS DEVELOPS IT INTO A CLOSED LOW
LATER IN THE WEEK OVER THE NORTH CENTRAL GULF. A COLD FRONT MOVES
SOUTHEAST INTO THE GULF AND NORTH FLORIDA BY FRIDAY. A SHORT WAVE
THAT PUSHES THE COLD FRONT ALONG STARTS TO PICK UP THE LOW FRIDAY
AND DEEPENS IT TO A 1003 MB LOW OVER THE SOUTH CENTRAL GULF AND
MOVES IT TO CENTRAL FLORIDA BY SATURDAY AFTERNOON AND INTO THE
ATLANTIC NEAR DAYTONA SATURDAY NIGHT. BELIEVE THIS LOW WILL BE
EXTRA-TROPICAL AND THE WIND FIELD AND STRENGTH MAY BE OVERDONE.
THIS FRONT MAY REACH SOUTH FLORIDA LATER SUNDAY AND STALL.

EVEN SO, THIS LOOKS TO BE A VERY WET SCENARIO ESPECIALLY THURSDAY
AND FRIDAY. PWAT`S A BIT ABOVE 2" IN 00Z RAOB. GFS FCSTS THIS TO
GO DOWN A BIT AND THEN CLIMB TO 2.25" FOR TUESDAY AND WEDNESDAY AND
THEN AN IMPRESSIVE 2.4 TO 2.5" FOR THURSDAY AND FRIDAY AND THEN
DECREASING A BIT OVER THE WEEKEND. HPC QPF TOTALS THROUGH
WEDNESDAY SHOW 1.5 TO ALMOST 3 INCHES OVER THE EAST COAST TO A BIT
ABOVE 1 INCH WEST COAST. WITH THE LOW MENTIONED ABOVE MOVING FROM
THE SOUTH CENTRAL GULF TO CENTRAL FLORIDA PUTS SOUTH FLORIDA IN A
FAVORABLE SETUP FOR A FLOOD EVENT. RAIN TOTALS THURSDAY THROUGH
FRIDAY WILL PROBABLY EXCEED THE NEXT 3 DAY TOTALS. AN ESF MAY BE
NEEDED TODAY OR TONIGHT.

WILL FCST LIKELY POPS TUESDAY THROUGH FRIDAY AND MENTION HEAVY RAINFALL
THURSDAY AND FRIDAY. POPS WILL BE ABOVE MEXMOS FOR FRIDAY.

&&

.MARINE...STRONG PRESSURE GRADIENT WILL KEEP EAST WINDS UP TODAY
THROUGH THIS EVENING. WILL EXTEND THE SCA FOR THE ATLANTIC WATERS,
BISCAYNE BAY AND OUTER GULF WATERS THROUGH TONIGHT AND A SCEC FOR
THE INNER GULF WATERS. WINDS WILL DECREASE TO 10 TO 15 KNOTS BY
TUESDAY AND VEER TO THE SOUTH BY WEDNESDAY AT EVEN LESSER SPEEDS.
WINDS WILL INCREASE OUT OF THE SOUTH AND SOUTHWEST EARLY FRIDAY
IN ADVANCE OF THE LOW PRESSURE SYSTEM.

&&

.FIRE WEATHER...NO CONCERNS WITH HIGH RELATIVE HUMIDITIES
CONTINUING.

&&

.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 88 77 86 78 / 50 50 60 40
FORT LAUDERDALE 87 76 86 77 / 50 50 60 40
MIAMI 88 77 87 77 / 50 50 60 40
NAPLES 90 75 87 76 / 50 50 60 40

&&

.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
TROPICAL STORM STAN PROBABILITIES NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
4 AM CDT MON OCT 03 2005

PROBABILITIES FOR GUIDANCE IN HURRICANE PROTECTION
PLANNING BY GOVERNMENT AND DISASTER OFFICIALS

AT 4 AM CDT...0900Z...THE CENTER OF STAN WAS LOCATED NEAR
LATITUDE 20.5 NORTH...LONGITUDE 91.5 WEST

CHANCES OF CENTER OF THE STORM PASSING WITHIN 65 NAUTICAL MILES
OF LISTED LOCATIONS THROUGH 1AM CDT THU OCT 6 2005

LOCATION A B C D E LOCATION A B C D E

20.4N 94.2W 48 X X X 48 MMFR 185N 926W 4 1 2 3 10
20.2N 95.2W 31 1 X X 32 MMMD 210N 897W 7 X 1 X 8
20.0N 96.3W 15 8 1 1 25 CORPUSCHRISTI TX X X X 2 2
MMSO 238N 982W X X 5 7 12 BROWNSVILLE TX X X X 5 5
MMTM 222N 979W X 6 7 5 18 GULF 27N 96W X X X 2 2
MMTX 210N 974W 1 14 4 3 22 GULF 25N 96W X X 2 6 8
MMVR 192N 961W 16 5 1 2 24

COLUMN DEFINITION PROBABILITIES IN PERCENT
A IS PROBABILITY FROM NOW TO 1AM TUE
FOLLOWING ARE ADDITIONAL PROBABILITIES
B FROM 1AM TUE TO 1PM TUE
C FROM 1PM TUE TO 1AM WED
D FROM 1AM WED TO 1AM THU
E IS TOTAL PROBABILITY FROM NOW TO 1AM THU
X MEANS LESS THAN ONE PERCENT

FORECASTER KNABB

000
WTNT45 KNHC 030902
TCDAT5
TROPICAL STORM STAN DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT MON OCT 03 2005

THE CENTER OF STAN EMERGED OFF THE NORTHWESTERN COAST OF THE YUCATAN
PENINSULA AT ABOUT 0430Z. SHORTLY THEREAFTER AN AIR FORCE HURRICANE
HUNTER PLANE FLEW INTO THE CENTER AND MEASURED A CENTRAL PRESSURE
OF 1003 MB... THEN 1002 MB ON A MORE RECENT PENETRATION. MAXIMUM
850 MB FLIGHT LEVEL WINDS WERE 43 KT TO THE NORTHEAST OF THE
CENTER... IN THE BAND OF CONVECTION EMANATING OFFSHORE FROM THE
NORTHERN COAST OF THE PENINSULA. THIS CONVECTION APPEARS TO BE
DEEP ENOUGH TO MIX THE FLIGHT LEVEL WINDS DOWN TO THE SURFACE USING
THE 80 PERCENT REDUCTION...WHICH CORRESPONDS TO ABOUT 35 KT AT THE
SURFACE. ADDITIONALLY...CONVECTION HAS BEGUN BURSTING NEAR THE
CIRCULATION CENTER...AND TROPICAL STORM FORCE WINDS SHOULD SOON BE
OCCURRING THERE. THE ADVISORY INTENSITY IS SET TO 35 KT... MAKING
STAN A TROPICAL STORM ONCE AGAIN.

THE AIRCRAFT LOCATED THE CENTER OF CIRCULATION A BIT TO THE SOUTH OF
THE PREVIOUS ADVISORY POSITION... AND THE ESTIMATED INITIAL MOTION
IS NOW WESTWARD... 270/9. A MID LEVEL RIDGE EXTENDING FROM TEXAS
TO THE CAROLINAS SHOULD CONTINUE TO STEER STAN TOWARD THE WEST
DURING THE NEXT COUPLE OF DAYS... WITH AN EVENTUAL SLIGHT BEND SOUTH
OF WEST AND A SLOWING OF THE FORWARD SPEED. MOST OF THE MODELS
INDICATE THAT ENOUGH RIDGING WILL PERSIST TO TAKE STAN ALL THE WAY
ACROSS THE BAY OF CAMPECHE. HOWEVER... IT IS POSSIBLE THAT SOME
COMPLICATING FACTORS... INCLUDING INTERACTION WITH HIGH TERRAIN AS
STAN APPROACHES THE COAST... A DEVELOPING DISTURBANCE IN THE GULF
OF TEHUANTEPEC... AND LOW PRESSURE FORECAST TO DEVELOP OVER THE
EASTERN GULF OF MEXICO... COULD CAUSE A SLOWER MOTION THAN
INDICATED IN THE OFFICIAL FORECAST. THE NEW FORECAST IS SIMILAR TO
THE PREVIOUS ADVISORY EXCEPT FOR A SOUTHWARD ADJUSTMENT DUE TO THE
INITIAL POSITION.

STAN IS NOW OVER THE VERY WARM WATERS OF THE SOUTHWESTERN GULF OF
MEXICO... AND IS BENEATH A LARGE UPPER LEVEL ANTICYCLONE AS DEPICTED
IN GOES WATER VAPOR IMAGERY. THE COMBINATION OF THESE FACTORS WILL
LIKELY LEAD TO STRENGTHENING. AN UPPER LEVEL SHORTWAVE TROUGH
CURRENTLY OVER THE APPALACHIANS IS FORECAST BY THE DYNAMICAL MODELS
TO DIVE INTO THE EASTERN GULF OF MEXICO WITHIN 48 HOURS AND ERODE
THE UPPER LEVEL RIDGE...BUT THE SHEAR WILL PROBABLY NOT INCREASE IN
TIME TO WEAKEN STAN BEFORE FINAL LANDFALL. ACCORDINGLY THE SHIPS
GUIDANCE DIAGNOSES WEAK SHEAR AND FORECASTS A 65 KT HURRICANE
APPROACHING THE GULF COAST OF MEXICO IN ABOUT 48 HOURS. THE
OFFICIAL FORECAST IS SIMILAR TO SHIPS AND THE PREVIOUS ADVISORY.

THE NEW FORECAST REQUIRES A HURRICANE WATCH FOR PORTIONS OF THE GULF
COAST OF MEXICO.


FORECASTER KNABB


FORECAST POSITIONS AND MAX WINDS

INITIAL 03/0900Z 20.5N 91.5W 35 KT
12HR VT 03/1800Z 20.5N 92.9W 40 KT
24HR VT 04/0600Z 20.4N 94.2W 50 KT
36HR VT 04/1800Z 20.2N 95.2W 60 KT
48HR VT 05/0600Z 20.0N 96.3W 70 KT
72HR VT 06/0600Z 19.5N 97.5W 30 KT...INLAND
96HR VT 07/0600Z...DISSIPATED

hey cirro
What's up? Cold front looks to be in N. Colo. on surface analysis.
Cheyenne/Warren AFB
Last Update on Oct 3, 2:53 am MDT


Fair

41F
(5C) Humidity: 76 %
Wind Speed: N 9 MPH
Barometer: 30.01" (1009.1 mb)
Dewpoint: 34F (1C)
Wind Chill: 35F (2C)
Visibility: 10.00 mi.
More Local Wx: 3 Day History:

Overnight: Clear, with a steady temperature around 50. Northeast wind around 9 mph.

Monday: Mostly sunny, with a high near 76. Calm wind becoming south between 12 and 15 mph.

Monday Night: Partly cloudy, with a low around 45. North northwest wind between 5 and 11 mph.

Actually, The real cold front hits Cheyenne Monday night. This front is suppose to send high pressure in later.

In meteorology, a tropical cyclone (or tropical disturbance, tropical depression, tropical storm, typhoon, or hurricane, depending on strength and geographical context) is a type of low pressure system which generally forms in the tropics. While they can be highly destructive, tropical cyclones are an important part of the atmospheric circulation system, which moves heat from the equatorial region toward the higher latitudes.

It looks like fronts are going to help put a lid on the gulf! Season winding down at the continental United States!



AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AMARILLO TX
343 AM CDT MON OCT 3 2005

.DISCUSSION...
SUBTROPICAL MOISTURE CONTINUES TO STREAM NORTHEAST ACROSS NEW
MEXICO AND WEST TEXAS THIS MORNING. HAVE ADDED SOME 20 PERCENT
POPS TO THE CWA TODAY AND TONIGHT. INSTABILITY LOOKS AS GOOD AS
YESTERDAY IF NOT BETTER AND THERE WERE SOME SHOWERS AND STORMS
AROUND THEN.

MAIN STORY WILL THE LATE FALL/EARLY WINTER TYPE AIR MASS THAT IS
POISED TO MOVE SOUTH INTO THE CWA BY MID WEEK. SEE LATEST HEAVY SNOW
AND ICING DISCUSSION FROM HPC (QPFHSD). SNOWS ARE EXPECTED TO SPREAD
PRETTY FAR EAST FOR THIS TIME OF YEAR ACROSS THE NORTHERN PLAINS.
STRONG UPPER LEVEL SHORT WAVE OVER THE PACIFIC NORTHWEST COAST WILL
ROTATE EAST THROUGH THE NORTHERN ROCKIES EARLY THIS WEEK AND THEN IT
WILL HELP DRIVE A COLD FRONT SOUTHWARD ON TUESDAY. THE NAM HAS NOW
SPED THE COLD FRONT UP...WHILE THE GFS IS ABOUT 12 HOURS BEHIND. THE
CURRENT FORECAST LEANS TOWARDS THE NAM...SO IT LOOKS GOOD. THE NAM
PROBABLY HAS THE BEST HANDLE ON THE DEPTH OF THE COLD AIR AND THE
STRENGTH OF ITS ASSOCIATED SURFACE HIGH. THEREFORE...TEMPERATURES MAY
EVEN BE LOWER THAN THE "COOL" GFS NUMBERS. RIGHT NOW HAVE LOWERED
TEMPERATURES WEDNESDAY AND THURSDAY DOWN TO AROUND THE MEXMOS
NUMBERS. CURRENT POP FORECAST LOOKS GOOD AT MIDWEEK...BUT DID ADD
SOME POPS TO WEDNESDAY NIGHT AND THURSDAY AS ANOTHER UPPER LEVEL
SHORT WAVE MAY MOVE SOUTHEAST TOWARD THE PANHANDLES BEHIND VIGOROUS
SHORT WAVE LIFTING TO THE NORTHEAST ACROSS THE GREAT LAKES.

ANOTHER COLD FRONT LOOKS TO PASS THROUGH THE PANHANDLES LATE NEXT
WEEKEND AS FLOW ALOFT STAYS PROGRESSIVE.

THANK YOU FOR THE COORDINATION ABQ...PUB...DDC...OUN AND LUB.

&&
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
345 AM CDT MON OCT 3 2005

.SHORT-TERM (TODAY THROUGH TUESDAY)...CONCUR WITH THE GFS/NAM WITH
RESPECT TO THE UPPER PATTERN. ALTHOUGH THE REGION WL BE UNDER THE
INFLUENCE OF AN UPPER RIDGE DRG THE PERIOD...COPIOUS MSTR (AS
DEPICTED FROM GOES SOUNDER DATA/BRO SOUNDING) ASSOCIATED WITH
STAN...AND INSTABILITY...WL CONTRIBUTE TO CONVECTIVE ACTIVITY...WITH
THE GREATEST POPS OVR THE SRN SECTIONS. OWING TO LESS
INSOLATION...EXPECT MAX HEAT INDEX VALUES TO REMAIN BELOW 105.

&&

.AVIATION...EXPECT MVFR CEILINGS OUTSIDE OF CONVECTIVE ACTIVITY
OWING IN PART TO COPIOUS MSTR. NEAR CONVECTIVE ACTIVITY...EXPECT
IFR/MVFR CEILINGS/VSBY.

&&

.MARINE...CONCUR WITH THE WAVEWATCH SOLN WITH REGARD TO THE
WIND/SEAS DRG THE PERIOD. TODAY...INCREASING SEA HGTS FROM SWELL AND
INCREASING MOMENTUM WARRANTS AN SCA. TNGT/TUE...EXPECT SCA
CONDITIONS TO CONTINUE. BASED IN PART ON THE TRACK OF STAN...DO NOT
EXPECT SUSTAINED WIND TO EXCEED 20-25KT OVR THE COASTAL WATERS.
WATER LEVELS AT PTA/BOB HALL PIER AROUND 1FT ABV NORMAL...YET AT
LEAST 1FT BELOW MINIMUM CRITERION FOR MINOR TIDAL OVERFLOW. WL NOT
ISSUE AN CFW AT THIS TIME. HWR...WL RECONSIDER LATER GIVEN THE
LIKELIHOOD OF PERSISTENT E/NE FLOW AND WAVE ACTION FROM SWELLS. SCA
CONDITIONS LIKELY AFTER FROPA ON THURSDAY AT LEAST FOR THE GULFMEX.

&&

.LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...RAIN CHANCES AND ABOVE
NORMAL TEMPERATURES WILL CONTINUE UNTIL THE FRONTAL BOUNDARY MOVES
ACROSS EARLY THURSDAY MORNING PROBABLY BEFORE SUNRISE. MODELS
CONSISTENT IN SHOWING BEST MOISTURE FIELDS OVER THE SOUTHERN AREAS
OF THE CWFA AND WITH GOOD COASTAL CONVERGENCE DURING THE OVERNIGHT
HOURS...SHOULD SEE SOME SHOWERS AND ISOLATED THUNDER OVER THE
COASTAL SECTIONS TUESDAY NIGHT THROUGH WEDNESDAY...WITH DIURNAL
CONVECTION EXPECTED OVER INLAND AREAS. MODELS A TAD SLOWER WITH
FROPA THAN IT WAS YESTERDAY...BUT STILL FEEL FRONT WILL BE ALONG THE
COAST AT 12Z THURSDAY IF NOT SOONER. THIS WILL BE THE FIRST GOOD
FRONT OF THE YEAR AS THE PREVIOUS FRONT JUST COULD NOT HOLD UP TO
THE WELL ABOVE NORMAL/RECORD TEMPERATURES. ALTHOUGH GFS IS A BIT
SLOWER...IT ALSO APPEARS TO BE A BIT COOLER AS THE SURFACE RIDGE
DIVES SOUTHWARD INTO THE CONCHO VALLEY THURSDAY NIGHT. STILL COULD
SEE SOME SHOWERS ALONG THE FRONTAL BOUNDARY OVERNIGHT WEDNESDAY
NIGHT/THURSDAY MORNING AND ALTHOUGH CONFIDENCE IS NOT AS HIGH SINCE
THE CONVERGENCE FIELDS ARE NOT AS IMPRESSIVE. NEVERTHELESS...STILL
KEPT LOW-END CHANCE POPS FOR THE SOUTHERN SECTIONS. KEPT A SLIGHT
CHANCE FOR PRECIP OVER THE SOUTHERN SECTIONS FOR THURSDAY IN CASE
THIS FRONT CONTINUES TO BE A BIT SLOWER. AFTER THAT...DO NOT EXPECT
RAINFALL AT THIS TIME THROUGH SUNDAY ALTHOUGH WILL HAVE TO WATCH
SUNDAY NIGHT AS MOISTURE DOES TRY TO COME BACK FROM THE RIO GRANDE.
GFS IS TRYING TO BRING THE WINDS BACK TO THE SOUTHEAST/SOUTH ON
SUNDAY DIFFERENT FROM THE PREVIOUS MODEL RUN. CANADIAN AND ECMWF DO
NOT SEEM TO BRING THEM BACK AS RAPIDLY. THEREFORE JUST VEERED WINDS
A BIT FOR THE SUNDAY FORECAST RATHER THAN BUY THE GFS SOLUTION
TOTALLY. ONCE THE FRONT GOES THROUGH...WILL FINALLY SEE
TEMPERATURES MORE SEASONAL WITH OVERNIGHT LOWS NEAR OR BELOW
CLIMO...FOR A CHANGE.

173. dcw
Look at that low east of the Virgin Islands!
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT MON OCT 3 2005

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM STAN... LOCATED OVER THE SOUTHWESTERN GULF OF MEXICO ABOUT
320 MILES EAST-NORTHEAST OF VERACRUZ MEXICO.

A LARGE BUT DISORGANIZED AREA OF SHOWERS AND THUNDERSTORMS...
ASSOCIATED WITH A WESTWARD-MOVING TROPICAL WAVE AND AN UPPER-LEVEL
TROUGH...IS LOCATED A FEW HUNDRED MILES EAST OF THE CENTRAL BAHAMAS.
THUNDERSTORM ACTIVITY HAS BECOME A LITTLE MORE CONCENTRATED THIS
MORNING... AND UPPER-LEVEL WINDS ARE EXPECTED TO GRADUALLY BECOME
MORE CONDUCIVE FOR TROPICAL CYCLONE DEVELOPMENT DURING THE NEXT
COUPLE OF DAYS AS THIS SYSTEM MOVES WESTWARD.

ELSEWHERE... TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH
TUESDAY.

FORECASTER KNABB
Whoa. It looks like the wave in the mid-atlantic south of TD 19 has some spiral banding.
Have any of these waves in and around the Carribean and SE US become tropical invests yet and as such do we have early model guidance on the skeetobite site yet?
178. IKE
The area east of the bahamas appears to be coming together..."A large but disorganized area of showers and thunderstorms...
associated with a westward-moving tropical wave and an upper-level
trough...is located a few hundred miles east of the central Bahamas.
Thunderstorm activity has become a little more concentrated this
morning... and upper-level winds are expected to gradually become
more conducive for tropical cyclone development during the next
couple of days as this system moves westward."...

Per the NHC. The beginnings of Tammy..maybe a subtropical/hybrid system in the Gulf or a storm/hurricane.
179. IKE
Pressures are rather low in the Bahamas. Strong east winds. The beginnings of a storm?
180. IKE
Looking at an IR loop...definitely a low there, I think Tammy is on the prowl.
looks like another week on pins and needles watching Tammy and the cold front inch toward each other. Which one gets there first will make or break LA.
not to mention the carribean system as well, though I guess the cold front would keep that away assuming it gets there first with the blocking high pressure.
183. IKE
I think this system/Tammy will be an eastern gulf/east coast event..but Im no weatherman...so we'll see.
Just got done watching the local news here. They were very vague saying that some models develop the system in the Bahamas and some don't. He also said that it probably will move right towards us as nothing more than rain. Thats good to hear.
185. IKE
Per accuweather..."An upper-level trough of low pressure is interacting with a tropical wave east of the Bahamas and this combo is slowly moving to the west. There is plenty of northwest shear in the path of the this system so any development will be slow over the next 12-24 hours. The upper level shear will weaken east of Florida Tuesday and Wednesday as the upper trough of low pressure backs westward into the Gulf of Mexico, and this could lead to more favorable conditions for tropical development. This feature will track toward the coast of the southeastern United States over the next few days and will bring enhanced thunderstorm activity with heavy downpours to Florida starting on Tuesday and possibly lasting the rest of the workweek."
Good morning, all!

So it looks like things may have improved for the storms east of Florida. Does anyone have any opinions on wher weather patterns would steer it? Also, what about time for development. If things headed due west into Florida, would there be enough time for it to develop into anything significant?
Jupiter: my local news said something similar last night. They were keeping an eye on the stuff outside the bahamas and we would have a wet week starting tomorrow.
South Florida people: check out the front page of the sun-sentinel this morning. Big article about what could happen if the big one hit here. The accompanying maps are great.

Also, interesting to note that they said that in Broward all our inland canals and such used for water control could actually help bring the storm surge more inland. And, we would have storm surge from the ocean west AND the everglades east.
Link

Here's the link. Look to the right for the maps
They did a similar article in the Palm Beach Post about 2 weeks ago. In our area it was the Loxahatchee river which was going to cause all of the inland flooding. I am 2 miles inland and was considered to be in an area that would be completely under water because the surge would come right in the Jupiter inlet and up the Loxahatchee river. Oh well what you going to do.
Buy a boat, I guess ;)
The map showed that where my house is we shouldn't have flooding. I seriously doubt that because when we get a good rain the water pools at the bottom of my driveway. Also, a few years ago the water went all the way to my garage door.

I'm supposedly flood zone X but I bought flood insurance anyway. The whole area is a huge flood zone, in my opinion.
Concerning the disturbance east of the the Bahamas: Yesterday the westerly shear was intense and although a surface circulation was detectable, the system was unable to wrap any convection around its west side.

Today, the shear still looks strong, but there is currently a ring of convection circling a broad area centered around 24N 70W. Whether that "ring" holds together and develops (or not) depends on how fast the shear relaxes. Looks like we have at least another day before that could happen, but if the shear should suddenly relax I think the disturbance could develop rapidly since it seems there is already a low and mid-level circulation in place. Suffice to say I will be keeping a close eye on it over the next couple of days from my vantage point on the East Central FL coast.
Thanks, Guygee. Have a nice morning. Gotta take the babe to school. Bye!
The NHC mentions a new area of interest in the Carribean in it's 8 am Tropical discussion.

"AN AREA OF INTEREST HAS DEVELOPED OVER THE PAST 6 HOURS NEAR
14N38W. MID LEVEL CYCLONIC CURVATURE IS OBSERVED IN THE FIRST
VISIBLE SATELLITE IMAGES. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS WITHIN 90 NM OF LINE 12N34W-16N38W."

The gfl seems to show a westward moving tropical system moving ito the gulf snd developing then being pushed back to the NE late week. With these systems lurking and the cold front approaching this is looking possible.
the system east of the bahamas has a definite spin!!!!
ClydeFrog - Agreed! What is missing is a good upper-level high above the system. Outflow is just about non-existent on the east semi-circle due to westerly shear. This is forecast to change, the big question is when will it change?
Oops , Make that "Outflow is just about non-existent on the WEST semi-circle"

doh!
folks look at weather under archives on juan 1985 it was a late oct hybrid 85mph winds at its worst check out the track i remember it well dumped tons of rain on us here on ms coast and was devestaing to se la with coastal flooding and rain i have a hunch thats what we could have in the next week or something similar.
Well folks, Stan is not looking like the fish storm I predicted. My predictions on Tammy are still out since TD20 failed to move up the power chain.

In other news looks like fall is coming with a bang later this week up in my hood (ie classic Rochester weather. It will be 80 Tuesday and 50 Wedensday)
um, whats going on out there? I see a twisting low to my east....uh oh!
Has anyone seen the latest NAM for Thursday at 1500? Link (very ominous looking graphic, btw) It develops the Bahama disturbance moving over S Florida and into the Gulf by late Thurs as a very impressive looking 996mb cyclone. The GFS, however, wants this to move more up toward the Carolina coast then looping back NE. While I usually side with GFS, if the NAM proves true, this could be bad news for the Gulf again because it is basically the same Katrina/Rita path again.
Hallo everybuddy.

Savannah i see what you are saying but i do feel like GFS will prob be right with this. If not then we here on the coast should be ready for trouble.
morning stormy...i see that spin as well :-(
205. wpbwx
When will we feel this wave in West Palm Beach. Is it forcast to be more than a wave?
ya 65, gonna be a wet week for us....
wpb - my local news said that it may be a weak t.s. as it passes over us in FL because its moving our way...but its looking pretty wicked out there, can definately see it spinning on water vapor loop....
Stormy: Hi. did they give a location?
209. wpbwx
It is wild to watch. It just blew up in the WV loop. You could see it getting it's spin together.
Here's the miami nws statement...

.PREVIOUS DISCUSSION...THIS WEEK`S WEATHER WILL BE QUITE COMPLICATED
AND WET TO SAY THE LEAST. A TROPICAL WAVE CURRENTLY NEAR 73W WILL
MOVE STEADILY WEST AND REACH SOUTH FLORIDA TUESDAY AFTERNOON. THE
ARRIVAL OF THIS WAVE HAS BEEN DELAYED A BIT WITH EACH NEW MODEL RUN
BUT THIS TIMING LOOKS FAIRLY GOOD. THE GFS BRINGS THE WAVE THROUGH
AS AN OPEN WAVE BUT THE ETA BRINGS IT THROUGH AS A CLOSED 1004 MB
LOW. EVENTUALLY THE GFS DEVELOPS IT INTO A CLOSED LOW LATER IN THE
WEEK OVER THE NORTH CENTRAL GULF. A COLD FRONT MOVES SOUTHEAST INTO
THE GULF AND NORTH FLORIDA BY FRIDAY. A SHORT WAVE THAT PUSHES THE
COLD FRONT ALONG STARTS TO PICK UP THE LOW FRIDAY AND DEEPENS IT TO
A 1003 MB LOW OVER THE SOUTH CENTRAL GULF AND MOVES IT TO CENTRAL
FLORIDA BY SATURDAY AFTERNOON AND INTO THE ATLANTIC NEAR DAYTONA
SATURDAY NIGHT. BELIEVE THIS LOW WILL BE EXTRA-TROPICAL AND THE WIND
FIELD AND STRENGTH MAY BE OVERDONE. THIS FRONT MAY REACH SOUTH
FLORIDA LATER SUNDAY AND STALL.
Yea stormy...just what we don't need, more rain. Although I think I would like just rain as opposed to a TS or Hurricane. My kids would like to see the weather get real bad so that they can stay home from school :-)
Dr M has New Blog UP!
213. wpbwx
I am new at weather watching. A closed wave Is a tropical storm correct?
Weatherdude.. kids here in So FLA are already off pretty much the whole week! off Tues/1/2 day Thurs/off Friday..
Does anyone notice the circulation and tops of about 90degrees celcius. It is just off the Yucatan and shows moving northeast towards Florida. I'm on the southwest coast (Charley), and watching this more than Tammy thats hothin but rain.