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Tropical Storm Niala Approaching Hawaii; Heavy Rains for Gulf Coast Likely From 99L

By: Jeff Masters 3:22 PM GMT on September 26, 2015

A Tropical Storm Watch and a Flash Flood Watch are posted for Hawaii's Big Island, as Tropical Storm Niala moves northwest at 8 mph on a course that will take it about 100 miles south of the Big Island on Sunday evening. With tropical storm-force winds expected to extend out up to 80 miles from the center at that time, the Central Pacific Hurricane Center in their 11 am EDT Saturday Wind Probability Forecast gave a 26% chance for South Point on the Big Island to receive tropical storm-force winds of 39+ mph. The bigger threat from the storm will be heavy rain, which could bring 6 - 12" of rain and dangerous flash floods to the Big Island on Saturday and Sunday.


Figure 1. Latest image from the South Hawaii radar.


Figure 2. Latest satellite image of Niala.

Niala is the record 7th named storm to form in 2015 in the North Central Pacific (between 140°W and the Date Line.) According to wunderblogger Dr. Phil Klotzbach, prior to 2015, the previous record for named storms in the North Central Pacific for an entire season was four, set in 1982. The other named storms that formed in the North Central Pacific in 2015 were Malia, Halola, Ela, Iune, Kilo and Loke. This year's record activity has been due to unusually low wind shear and record-warm ocean temperatures caused by the strong El Niño event underway.

99L in Gulf of Mexico to bring heavy rain to the Gulf Coast
A trough of low pressure is moving northwestwards across Mexico's Yucatan Peninsula, and is producing a large area of disorganized showers and thunderstorms over the northwestern Caribbean Sea and portions of Central America, as seen on satellite loops. On Saturday morning, NHC designated this area of interest Invest 99L. By Sunday, this activity will push into the Gulf of Mexico, where development into a tropical or subtropical depression could occur. However, an upper-level trough of low pressure over the Western Gulf of Mexico will bring high wind shear to the Gulf, limiting the potential for 99L to strengthen, and our top three models for predicting tropical cyclone genesis are showing little development of this system. The system will get pulled northwards to affect the U.S. coast from Louisiana to the Florida Panhandle Sunday afternoon through Tuesday, bringing heavy rains of 2 - 4". In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 10% and 20%, respectively.

98L between Bermuda and the Bahamas of little concern
A non-tropical trough of low pressure (Invest 98L) is producing disorganized showers and a few thunderstorms over the western Atlantic Ocean several hundred miles south-southwest of Bermuda as the system drifts north to north-northwest at about 5 mph. With record warm ocean temperatures near 30°C (86°F) and wind shear in the moderate range, 10 - 20 knots, this disturbance may show some slow development on Saturday and Sunday. However, wind shear is predicted to rise to the high range, 20 - 30 knots, beginning on Sunday night. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 10% and 10%, respectively.

Little change to Ida
There is not much new to say about Tropical Depression Ida, which is wandering slowly over the Central Atlantic, well away from any land areas. Satellite images on Saturday morning showed Ida's center of circulation was fully exposed to view by high wind shear, and all of Ida's heavy thunderstorms were limited to the east side of the center. Ida will continue to move slowly in a region of weak steering currents for the next five days, and it is possible that high wind shear will destroy the storm by Tuesday, as suggested by Saturday morning runs of the GFS model.


Figure 3. MODIS image of Typhoon Dujuan as seen from NASA's Terra satellite on Saturday, September 26. Image credit: NASA.

Typhoon Dujuan bears down on Japan's Ryukyu Islands
Typhoon Dujuan, a Category 2 storm with 110 mph winds located about 325 miles south-southeast of Okinawa in Japan's Ryukyu Islands at 8 am EDT Saturday, is steadily intensifying as it heads northwest at 10 mph towards Taiwan. Wind shear is in the moderate range, 10 - 15 knots, and ocean temperatures are a very warm 29°C (84°F), conditions which favor intensification. Satellite loops on Saturday morning showed a large, well-organized storm with a huge 44-mile wide eye. Dujuan has taken on an annular appearance, with a large eye, thick eyewall, and very few low-level spiral bands. These type of storms are more resistant to weakening than ordinary, making Dujuan likely to maintain major typhoon status as it approaches Taiwan. The Joint Typhoon Warning Center (JTWC) projects that Dujuan will intensify to Category 4 strength by Sunday, and the storm is expected to pass near Taketomi-cho and Yonaguni-cho in Japan's Ryukyu Islands near 03 UTC Monday. The models have come into better agreement on the eventual fate of Dujuan, with a direct hit or very close pass by northern Taiwan looking increasingly likely.


Figure 4. Latest satellite image of Invest 93E (left side of image) and 92E (right side of image, close to the coast of Mexico/Central America.)

Tropical disturbances 92E and 93E a heavy rain threat to Mexico and Central America
Our three top models for predicting tropical cyclone genesis predict that an area of disturbed weather about 400 miles south of Acapulco, Mexico (Invest 93E) will develop into a tropical depression on Sunday or Monday. This system is expected to move northwards and be very near the coast close to Acapulco on Monday through Thursday, potentially bringing an extended period of dangerous flooding rains. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 90%.

Another area of disturbed weather in the Eastern Pacific along the coast near the Mexico/Guatemala border (Invest 92E) is drifting slowly to the west, and will bring heavy rains to El Salvador, southern Guatemala, and southeastern Mexico over the next few days. None of our reliable models for forecasting tropical cyclone genesis develop 92E into a tropical depression. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 30%.

Yet another area of concern is an area of low pressure that the models predict will form on Monday or Tuesday about 1000 miles southwest of the southern tip of the Baja California peninsula. Some gradual development of this system is possible later in the week while the system moves slowly northward. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave the disturbance 2-day and 5-day odds of development of 0% and 20%, respectively.

Jeff Masters

Hurricane

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

Well, there ya go.....lookin' like a bunch of dead pixels on my LCD screen again....




watch out for invest 98L


WATCHING invest 98L
By the looks of the sat pics in motion it looks like a the movement of the Yucatan low will move NE and give the the entire state of Florida a good soaking of showers and thunderstorms over the next few days, regardless of development. Wouldn't be surprised if future forecast out of NWS Miami up the chances rain later today.
looks as if we are seeing the beginning of a low level trough setting up north - south from the sw carib into se us. got your rain slicker ready?
I know one thing for sure, recon flight doesn't need to be cancelled today. Convection is on the increase near the LLC
I certainly hope the Yucatan blob brings some rain to my neck of the woods; Naples has seen below-normal precipitation for the month, the summer, and the year:



...or, if it's not going to rain, I wish the clouds and humidity would just go away already; the dewpoint is 76 right now, and there's not so much as a whisper of a breeze. Sticky, man. Sticky...





Map of Forecast Area
Last Map Update: Sun, Sep. 27, 2015 at 9:43:18 am EDT
Watches, Warnings & Advisories
National Weather Service Greer, SC National Weather Service Raleigh/Durham, NC National Weather Service Newport/Morehead, NC
National Weather Service Columbia, SC Zoom
Out

National Weather Service Charleston, SC

Flood Warning

Gale Warning

Coastal Flood Advisory

Small Craft Advisory

Rip Current Statement

Beach Hazards Statement

Hazardous Weather Outlook
Why cant I get the colors on there arrrggghhhhh......Which reminds me. Did anyone see Argo? Excellent film....true story
Quoting 511. K8eCane:

Why cant I get the colors on there arrrggghhhhh......Which reminds me. Did anyone see Argo? Excellent film....true story


Too many "true stories" movies lately, I think Hollywood is running out of ideas. The fact they are making a Tetris and Angry Birds movie proves that point.
Ida is at least trying to reorganize herself.

Quoting 472. vis0:

CREDIT:: NOAA
SUBJECT:: GoMx swirls
CORRECTION:: Its Disturbance I not II as stated in my previous comment and is part of the imgbox album's original title (just chngd URL is the same).
More FTG imgs at Sept272015_Disturbance I  at imgbox

Q:: Can i use pumice stone to erase anything written in stone?
hmmm, actually i think pumice is just like the school pencils that have the writing (unleaded lead) & erasing (cheap eraser) implement all in one, Nature ya amaze me.

That's it for this album since vis imagery will be uh, visible soon.

Enjoy the games play hard but fair.


Depends on the type of stone....and how much time you have...weather conditions could be a factor to...Morning Vis..
Quoting 512. FunnelVortex:



Too many "true stories" movies lately, I think Hollywood is running out of ideas. The fact they are making a Tetris and Angry Birds movie proves that point.


This is the story of how The american hostages were rescued from the Canadian Embassy during one of the earlier Iranian conflicts.
Oh well....waiting to hear from 98 and 99 about what their plans are....or I could get my own Magic 8 Ball, but I like Sars more...LOL
Quoting 509. GeoffreyWPB:



I believe the models will come back west a bit
Quoting 516. LargoFl:




Gee Marty do you want to come to NC? and Fla?
The Gulf is just one big mess & please no more 8 ball!!
Quoting 515. K8eCane:



This is the story of how The american hostages were rescued from the Canadian Embassy during one of the earlier Iranian conflicts.
Oh well....waiting to hear from 98 and 99 about what their plans are....or I could get my own Magic 8 Ball, but I like Sars more...LOL


For this season I prefer a chance cube.

Five red sides and one blue side. Every time I want to know if a system will progress, I roll it. And if it lands on the one blue face, then we will see progression of the system.

So there's a chance, unlikely, but a chance.
Quoting 519. gulfbreeze:

The Gulf is just one big mess & please no more 8 ball!!



Sure but im warning you that we'll have to use the models.
Quoting 509. GeoffreyWPB:





If that's where you think the llc is you're hilarious
Here's where NOAA/NWS puts the low. Remember, the surface low is not always under the strongest convection.
Quoting 521. K8eCane:




Sure but im warning you that we'll have to use the models.
Good morning Kate...The models can help with weak systems when used by experienced people. The gulf situation is at the very least complex, and may become even more so by tomorrow.


I'm a bit surprised that more people are talking about Invests 98 and 99L rather than TD Ida. I see Ida as a bigger concern, due to her being a fighter and moving into better conditions. The forecast models are also in good agreement that she will continue moving W-WSW towards the Bahamas. The shear levels have dropped significantly, so we may have a bigger threat here, than with 99L which will be a big rain storm. However Ida has the chance of being a TS or Hurricane down the road...
Quoting 526. Camerooski:

I'm a bit surprised that more people are talking about Invests 98 and 99L rather than TD Ida. I see Ida as a bigger concern, due to her being a fighter and moving into better conditions. The forecast models are also in good agreement that she will continue moving W-WSW towards the Bahamas. The shear levels have dropped significantly, so we may have a bigger threat here, than with 99L which will be a big rain storm. However Ida has the chance of being a TS or Hurricane down the road...

Could you post latest model runs of Ida
Quoting 526. Camerooski:

I'm a bit surprised that more people are talking about Invests 98 and 99L rather than TD Ida. I see Ida as a bigger concern, due to her being a fighter and moving into better conditions. The forecast models are also in good agreement that she will continue moving W-WSW towards the Bahamas. The shear levels have dropped significantly, so we may have a bigger threat here, than with 99L which will be a big rain storm. However Ida has the chance of being a TS or Hurricane down the road...


Well Ida does have more convection now (albeit disorganized) and her environment is gradually moistening. She may have a shot, but she will have to just last a little longer through this...




IDA
530. IDTH
Quoting 526. Camerooski:

I'm a bit surprised that more people are talking about Invests 98 and 99L rather than TD Ida. I see Ida as a bigger concern, due to her being a fighter and moving into better conditions. The forecast models are also in good agreement that she will continue moving W-WSW towards the Bahamas. The shear levels have dropped significantly, so we may have a bigger threat here, than with 99L which will be a big rain storm. However Ida has the chance of being a TS or Hurricane down the road...

Ida still has to overcome the dry air at the moment, it's not an immediate threat at this moment, but 99L and 98L are closer to land which is why we're talking about them. Ida could very well be something I wouldn't be shocked she's been a fighter her whole life span, but for right now she is just something to watch.
People are focusing on 99L because it is already affecting the weather in parts of the U.S. IDA on the other hand, is a long way from the U.S. and there's plenty of time to watch the system.
Quoting 522. Austin72893:

Howdy Austin..It actually is close to the " L " symbol..if one looks close. It can be hard to see sometimes with the offshore convection, especially if there is a weak meso low around.

533. IDTH
Quoting 513. FunnelVortex:

Ida is at least trying to reorganize herself.



I for the life of me can not find her center, does anyone see it?
Quoting 533. IDTH:


I for the life of me can not find her center, does anyone see it?



She no longer has one, i dont think
Quoting 533. IDTH:


I for the life of me can not find her center, does anyone see it?


It's around 25N 48W. It's not as well defined as it was before. It may become an open/remnant low for about 15-48 hours before possible regeneration and strengthening.

IDA's center could be right over you and it would be a nice day to go to the beach and fly a kite. And don't forget the sunscreen.
For a limited time only WU presents the rare cyclone at 0N, 0W........










Once WU corrects the graphics, other bloggers will wonder has NRT lost it?
Quoting 537. Sfloridacat5:

IDA's center could be right over you and it would be a nice day to go to the beach and fly a kite.
Good morning 5. Something that does concern me about Ida is she has a very large circulation. If the system were to reform, could have a dangerous storm possibly affecting someone..its wait and see..
Quoting 539. hydrus:

Good morning 5. Something that does concern me about Ida is she has a very large circulation. If the system were to reform, could have a dangerous storm possibly affecting someone..its wait and see..


Very possible. You never know with these systems. But currently, it's about as weak and disorganized as a T.D. can be.
do you guys ever read the NHC forcast i gust not

TROPICAL DEPRESSION IDA DISCUSSION NUMBER 37
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102015
1100 AM AST SUN SEP 27 2015

Ida is very disorganized this morning. Visible satellite images
indicate that the circulation of the depression is becoming
elongated from north to south, though the low-level center is
still distinct
. Deep convection is scattered and not organized,
and this system is barely classifiable using Dvorak metrics. The
initial intensity remains 25 kt.

The cyclone is embedded in a dry atmosphere, which is likely
the reason why convection is limited. In addition, the interaction
with a cold front about 350 n mi to the north of Ida is causing the
circulation to become stretched as described above. Since the
frontal boundary is expected to move closer to Ida during the next
day or so before stalling, it is possible that Ida could open up
into a trough during that time. It is also possible that Ida could
become a remnant low by then if organized deep convection does not
return. Based on the negative factors for the tropical cyclone,
prediction of when Ida becomes a remnant low and dissipates have
been moved up 24 hours from the previous advisory, and these could
occur much sooner than forecast.


ida is done
Quoting 460. Mediarologist:



I'm not going to say what that looks like to me.. it's quite amusing though.


Oh, +1
Quoting 538. nrtiwlnvragn:

For a limited time only WU presents the rare cyclone at 0N, 0W........










Once WU corrects the graphics, other bloggers will wonder has NRT lost it?


Wait... What?
Quoting 542. Tazmanian:

"do you guys ever read the NHC forcast I GUST NOT"

...........That's exactly what Ida is doing at the moment!
Not much to see in the Atlantic. Ida appears it will become a remnant low/dissipate very soon, likely sooner than the NHC forecast. 98L has not become much better organized although it still has some chance to develop. And 99L has lost organization since yesterday, and is unlikely to develop. Unless 98L starts organizing more, development prospects for the next 10 days look slim. Climatology will start to fight against activity pretty soon, especially given the El Nino. Not unreasonable to wonder if Ida may be our last named storm of the year.
Quoting 546. MAweatherboy1:

Not much to see in the Atlantic. Ida appears it will become a remnant low/dissipate very soon, likely sooner than the NHC forecast. 98L has not become much better organized although it still has some chance to develop. And 99L has lost organization since yesterday, and is unlikely to develop. Unless 98L starts organizing more, development prospects for the next 10 days look slim. Climatology will start to fight against activity pretty soon, especially given the El Nino. Not unreasonable to wonder if Ida may be our last named storm of the year.

Good News.
Meanwhile, Marty is looking stronger this morning, the center is embedded right in the middle of a nice CDO. Only thing keeping it from taking off is 15-20kts of westerly shear, which is expected to continue. So steady strengthening is more likely. Should get very close to or possibly make landfall on the Mexican coast.

Quoting 548. sporteguy03:


Good News.


Depends on who you ask...
Just sayin.
Did the models drop 99L - is it still an entity on the weather map? Although there is a lot of wind shear, and an ULL located in the W Gulf, it will be interesting to see what happens in the next 24-48hrs. Will it try to develop at the last moment? At the very least, there might be flooding rains and rough seas .. somewhere along the Gulf coast.
Typhoon Dujuan:



Will hopefully weaken before hitting Taiwan/Eastern China.
Quoting 542. Tazmanian:

do you guys ever read the NHC forcast i gust not

TROPICAL DEPRESSION IDA DISCUSSION NUMBER 37
NWS NATIONAL HURRICANE CENTER MIAMI FL AL102015
1100 AM AST SUN SEP 27 2015

Ida is very disorganized this morning. Visible satellite images
indicate that the circulation of the depression is becoming
elongated from north to south, though the low-level center is
still distinct
. Deep convection is scattered and not organized,
and this system is barely classifiable using Dvorak metrics. The
initial intensity remains 25 kt.

The cyclone is embedded in a dry atmosphere, which is likely
the reason why convection is limited. In addition, the interaction
with a cold front about 350 n mi to the north of Ida is causing the
circulation to become stretched as described above. Since the
frontal boundary is expected to move closer to Ida during the next
day or so before stalling, it is possible that Ida could open up
into a trough during that time. It is also possible that Ida could
become a remnant low by then if organized deep convection does not
return. Based on the negative factors for the tropical cyclone,
prediction of when Ida becomes a remnant low and dissipates have
been moved up 24 hours from the previous advisory, and these could
occur much sooner than forecast.


ida is done
Good...I was not fond of possible regeneration and west movement.
Quoting 550. GeoffreyWPB:




Looks like the center of 99L is now over opens water just off the northern coast of the Yucatan. It will be interesting if any convection can fire over the center with all the shear.
But plenty of rain should start to affect part of Florida and the middle Gulf Coast as we move into the late afternoon and tonight.
Good Morning from North Florida. As we were discussing on Thursday and Friday, one of the issue was whether the Yucatan low was going to actually develop into a storm this weekend when juxtaposed against the energy in the E-Pac (just on the other side of the Caribbean/Gulf) and how much "energy sharing" was going to happen between the two basins (which dominant low developed more quickly).

Seems like our answer materialized over the past 48 hours; Marty sapped some of the energy out of the Yucatan low, and sheer has dropped the chances for a storm impacting the Northern Gulf over the next few days. Good news for the Northern Gulf as we get some much needed rain without the threat of a storm or surge issues.

Will keep you all posted from Tallahassee/Big Bend region over the next few days on the ultimate rain totals but its looks for the moment like the West Coast of Florida is getting the brunt of the rain in the short term............................Have a Blessed Sunday.



%uFFFD
Shear and dry air have battered Ida for days yet the storm refuses to die.These cape verde seeds have been resistant this year.I would hate to see what would have happened if conditions were favorable.Don't expect much from 99L besides rain and 98L could be another rain maker for the east coast
Quoting 531. Sfloridacat5:

People are focusing on 99L because it is already affecting the weather in parts of the U.S. IDA on the other hand, is a long way from the U.S. and there's plenty of time to watch the system.
Nothing going to happen except rain
Quoting 557. washingtonian115:

Shear and dry air have battered Ida for days yet the storm refuses to die.These cape verde seeds have been resistant this year.I would hate to see what would have happened if conditions were favorable.Don't expect much from 99L besides rain and 98L could be another rain maker for the east coast

I have an eerie feeling the CV pattern will continue into 2016 when the el Ninio will have dropped or at least become weaker. I think we could possibly see an early forming subtropical storm next year as well, just my guesses.
99L to me looks better than last night. Bands of rain are forming in the SE Gulf and heading up over the western part of Florida
Quoting 558. Accu35blog:

Nothing going to happen except rain


Yep, but it could be a lot of rain in some areas. It's the only game in town at the moment.
064  
WFUS54 KLIX 271504  
TORLIX  
LAC075-087-271530-  
/O.NEW.KLIX.TO.W.0025.150927T1504Z-150927T1530Z/  
 
BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE NEW ORLEANS LA  
1004 AM CDT SUN SEP 27 2015  
 
THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A  
 
* TORNADO WARNING FOR...  
SOUTHWESTERN ST. BERNARD PARISH IN SOUTHEASTERN LOUISIANA...  
NORTHWESTERN PLAQUEMINES PARISH IN SOUTHEASTERN LOUISIANA...  
 
* UNTIL 1030 AM CDT  
 
* AT 1004 AM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM  
CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED 11  
MILES SOUTHEAST OF POYDRAS...OR 18 MILES EAST OF BELLE CHASSE...AND  
MOVING WEST AT 10 MPH.  
 
* LOCATIONS IMPACTED INCLUDE...  
POYDRAS.  
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
 
TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST  
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF YOU ARE IN A MOBILE  
HOME OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND  
PROTECT YOURSELF FROM FLYING DEBRIS.  
 
 
 
LAT...LON 2971 8991 2995 8985 2991 8974 2987 8970  
2986 8968 2986 8966 2987 8962 2986 8960  
2976 8963 2976 8964 2975 8965 2971 8964  
2968 8965  
TIME...MOT...LOC 1504Z 104DEG 10KT 2979 8971  
 
 
Before I sign off, I would reiterate for folks who travel the Florida I-10 corridor for work during the week for them to follow the rainfall rates and possibly re-route to Hwy 90 for their commutes this week. The I-10 stretch from Pensacola to Tallahassee drains poorly and you get lots of accidents during heavy rain events from hydro-planning (and the inevitable trucks that also tend to spin out). I am about to do a 40 mile I-10 drive to a neighboring city but the rain has not been that bad in the Big Bend yet.

See Yall in the am tomorrow..........................WW.
567. 7544
Quoting 560. Patrap:




hi pat can i get a link to that radar with the arrows you posted thanks
Quoting 567. 7544:



hi pat can i get a link to that radar with the arrows you posted thanks



Just quote my radar post and it will appear in the comment box, save and use when needed,
College of DuPage Meteorology
Severe Weather and Flash Flood Warnings
Note: This page will reload every 2 minutes. Warnings are listed with the most recent first.
Click on the station ID to bring up list of recent severe weather statements.
TORNADO WARNING     NEW ORLEANS LA - KLIX 1004 AM CDT SUN SEP 27 2015


Quoting 552. Stormwatch247:

Did the models drop 99L - is it still an entity on the weather map? Although there is a lot of wind shear, and an ULL located in the W Gulf, it will be interesting to see what happens in the next 24-48hrs. Will it try to develop at the last moment? At the very least, there might be flooding rains and rough seas .. somewhere along the Gulf coast.
The Magic 8 Ball has found 99L on this snappy map. The upper level low in the center of the Gulf is actually a surface low, and it has the same surface pressure as 99L. As usual with all storms this seazson, 99L will mostly affect peninsular Florida with moderate rain, while the Panhandle and south Alabama will be lucky to see an inch by Wednesday. The chances of development, either at the last moment or now, according to the 8 Ball, is "Highly Doubtful". When asked about the future of 99L, the Ball responded with "Who?".

Bad day to be in Key West, unless you like rain.
Previous discussion... /issued 400 am CDT sun Sep 27 2015/

Short term...

Water vapor and infrared satellite imagery this morning shows
that a vigorous upper level low is located over the northwestern
Gulf of Mexico. There is also a surface low that has formed in the
vicinity of the upper low over the western Gulf of Mexico this
morning. On the east side of this low pressure system...strong
difluence aloft and a 60 knot jet streak are noted this morning. Deep
tropical moisture will continue to feed into the area today...with
precipitable water values increasing to around 2 inches by the afternoon. With strong
forcing in place aloft...expect to see showers and thunderstorms
begin to develop by middle-morning and become fairly numerous over
most of the forecast area this afternoon. Some of the rainfall
could be locally heavy at times given the high precipitable water value
airmass...but have opted to not issue a Flash Flood Watch at this
time as the duration of the heavy rains should be limited.

The upper level low will slowly move to the northeast through
Monday and Tuesday...and should eventually merge with some
northern stream energy digging into the Tennessee Valley by
Tuesday night. As the upper low moves into the lower Mississippi
Valley...it looks like some drier air in the middle-levels will wrap
around the upper low and begin to advect into the region on
Tuesday. For today and tomorrow....thermodynamic support will be
decent...with MLCAPE values of around 1000 j/kg. As the middle-levels
dry out on Tuesday...clouds will begin to break up a bit...and
expect to see higher MLCAPE values closer to 2000 j/kg by Tuesday
afternoon. Precipitable water values will drop back to around 1.75 inches by
Tuesday afternoon...but these readings will still be higher than
normal for this time of year.

Overall...rainfall forecasts for today and tomorrow will range
from around a half an inch for the Baton Rouge area to around 2
inches along the Mississippi coast where the highest moisture
content is expected. Daytime temperatures will tend to be near or
slightly cooler than normal due to the cloud cover and expected
rainfall over the area. Overnight lows will be warmer than normal
due to the high dewpoints across the area.

Long term...

There are some fairly significant model differences that arise in
the long term forecast. The Euro keeps a strong upper level ridge
in place across the forecast area for the weekend and the GFS
shows a trough digging into the region. Given the run to run
consistency of the Euro...and what appears to be a slightly better
initialization this morning...have leaned more toward the Euro
solution for the latter half of the week.

On Wednesday...a trough axis should continue to linger over the
area central Gulf Coast. Overall forcing should be weaker than
seen on Monday and Tuesday...but there should be enough
instability and Omega in place across the area to support some
scattered convective development through the day on Wednesday. A
weak frontal boundary could also be passing through the
area...providing and additional focus for convective activity.

A surge of dry air should advect into the region Wednesday night
and Thursday as the upper level trough axis pulls to the east and
strong negative vorticity advection and deep layer northerly flow
develops across the Gulf south. There could be some weak cold air
advection...but the primary driver of the weather should be the
much drier and more stable airmass moving into the area. Middle
and upper level ridging should continue to build to the east on
Friday...and the upper level ridge axis should be centered over
the lower Mississippi Valley by Saturday. Increasing subsidence
aloft should limit cloud development from Thursday through
Saturday...and temperatures should warm back into the upper 80s
due to the combination of stronger solar insolation and sinking
air throughout the atmospheric column.
Quoting 567. 7544:



hi pat can i get a link to that radar with the arrows you posted thanks
It's the WU Nexrad radar. Choose the "storm tracks" and "labels" options to show the arrows. Choose a frame delay of greater than 0.05 seconds unless you like seeing those arrows flopping around at supersonic speed.
99L looks very disorganized at the current time. The LLC looks to be north of the Yucatan in the southern Gulf heading NNW. Could just be a swirl but there is no define low pressure and the system is just a blob of convection. Still conditions are marginally favorable for some development over the steamy Carribbean/Gulf water.



It's a big rainmaker regardless of development.
Quoting 563. Hurricanes101:

99L to me looks better than last night. Bands of rain are forming in the SE Gulf and heading up over the western part of Florida
You think the low looks better than last night? I'm having a lot of difficulty associating those rain bands, such as they are, with 99L, compared to the influence of the surface low currently moving inland over Louisiana. If the low is really right off the northern tip of the Yucatan and only 1008 mb, it should be too weak and too far away to be doing much in the way of rainbands in Florida. I don't think 99L is developing at all the way the models had predicted.

TROPICAL STORM NIALA DISCUSSION NUMBER 11
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI CP062015
500 AM HST SUN SEP 27 2015

A BURST OF DEEP CONVECTION THAT STARTED OUT AS A SMALL CLUSTER OF
THUNDERSTORMS IN THE NORTHERN QUADRANT OF NIALA EXPANDED AND WRAPPED
AROUND OVER THE PREVIOUSLY EXPOSED LOW LEVEL CIRCULATION CENTER
/LLCC/ OF THE STORM JUST BEFORE 1000Z THIS MORNING. AS A
RESULT...IT HAS BEEN VERY DIFFICULT TO LOCATE THE LLCC IN THE
INFRARED SATELLITE IMAGERY. THERE WAS A 0705Z ASCAT PASS OVER
NIALA...WHICH PROVIDED A GOOD IDEA OF THE POSITION OF THE SYSTEM
LAST EVENING...IN ADDITION TO SHOWING A PEAK SURFACE WIND SPEED OF
AT LEAST 40 KT. THE LATEST SUBJECTIVE DVORAK SATELLITE ESTIMATES OF
CURRENT INTENSITY RANGE FROM 3.5/55 KT AT PHFO TO 3.0/45 KT FROM SAB
AND JTWC. THE LATEST ADT ESTIMATE FROM UW-CIMSS IS 2.4/34 KT. SINCE
THERE HAS BEEN LITTLE SIGNIFICANT CHANGE IN THE OVERALL STRUCTURE OF
NIALA...THE INITIAL INTENSITY FOR THIS ADVISORY WILL BE HELD AT 45
KT.

THE CURRENT MOTION IS 250/06 KT. NIALA HAS BEEN TRANSITIONING
TO A SHALLOW SYSTEM DUE TO INCONSISTENT COVERAGE OF DEEP CONVECTION
NEAR THE INNER CORE. AS A RESULT...THE PRIMARY STEERING MECHANISM
FOR THE SYSTEM APPEARS TO BE THE CIRCULATION AROUND A STRONG
SUBTROPICAL HIGH LOCATED MORE THAN 1600 NM TO THE NORTH. THE CURRENT
FORECAST TRACK IS VERY CLOSE TO THE PREVIOUS ADVISORY THROUGH 36
HOURS...WITH SOME SLOWING AND A SLIGHT ADJUSTMENT TO THE RIGHT
DURING DAYS 2 THROUGH 5. THIS CLOSELY FOLLOWS THE LATEST TVCN AND
GFEX CONSENSUS TRACK GUIDANCE...WHICH APPEARS TO BE STRONGLY
INFLUENCED BY THE SUBTROPICAL HIGH TO THE NORTH.

THE LATEST UW-CIMSS AND SHIPS GUIDANCE FOR ENVIRONMENTAL VERTICAL
WIND SHEAR IN THE VICINITY OF NIALA AT 1200Z IS 30 TO 40 KT FROM THE
WEST-SOUTHWEST. THIS IS LIKELY THE MAIN CULPRIT FOR THE HOSTILE
CONDITIONS THAT THE TROPICAL STORM HAS BEEN EXPERIENCING SINCE
EARLY SATURDAY. THE INTENSITY GUIDANCE ALMOST UNANIMOUSLY WEAKENS
NIALA THROUGH THE FORECAST PERIOD...WITH ICON AND SHIPS
DISSIPATING THIS SYSTEM COMPLETELY AFTER 48 HOURS. THE ECMWF ALSO
DISSIPATES THE SYSTEM AFTER DAY 4...WHILE THE GFS CONTINUES TO
MAINTAIN NIALA AS A TROPICAL LOW FROM DAYS 3 THROUGH 5. OUR
FORECAST OF CONTINUED GRADUAL WEAKENING IS A BLEND OF THESE
TRENDS...REDUCING NIALA TO A POST TROPICAL/REMNANT LOW ON DAY 3...
BUT NOT DISSIPATING IT COMPLETELY DURING DAYS 4 AND 5. NOTE THAT THE
WIND RADII FOR NIALA WERE ADJUSTED BASED ON THE 0704Z ASCAT PASS.

THE TROPICAL STORM WATCH HAS BEEN DISCONTINUED FOR THE BIG ISLAND.
NOTE THAT WITH NIALA PASSING SOUTH OF THE MAIN HAWAIIAN ISLANDS
DURING THE NEXT FEW DAYS...THE TIGHT PRESSURE GRADIENT BETWEEN NIALA
AND THE SUBTROPICAL HIGH TO THE NORTH WILL MAINTAIN STRONG TRADE
WINDS...WITH LOCAL AREAS OF GALE FORCE WINDS IN SOME CHANNELS AND
COASTAL WATERS...ACROSS THE MAIN HAWAIIAN ISLANDS AT LEAST THROUGH
TONIGHT. ALSO...ABUNDANT TROPICAL MOISTURE STREAMING UP TOWARD THE
BIG ISLAND WILL CONTINUE TO PRODUCE THE THREAT OF FLASH FLOODING ON
PARTS OF THAT ISLAND THROUGH MONDAY.


FORECAST POSITIONS AND MAX WINDS

INIT 27/1500Z 16.3N 154.0W 45 KT 50 MPH
12H 28/0000Z 16.1N 154.9W 40 KT 45 MPH
24H 28/1200Z 15.8N 156.2W 35 KT 40 MPH
36H 29/0000Z 15.6N 157.2W 30 KT 35 MPH
48H 29/1200Z 15.5N 158.2W 30 KT 35 MPH
Quoting 577. sar2401:

You think the low looks better than last night? I'm having a lot of difficulty associating those rain bands, such as they are, with 99L, compared to the influence of the surface low currently moving inland over Louisiana. If the low is really right off the northern tip of the Yucatan and only 1008 mb, it should be too weak and too far away to be doing much in the way of rainbands in Florida. I don't think 99L is developing at all the way the models had predicted.




I guess I do not think it is better organized, thanks for setting me straight
Quoting 577. sar2401:

You think the low looks better than last night? I'm having a lot of difficulty associating those rain bands, such as they are, with 99L, compared to the influence of the surface low currently moving inland over Louisiana. If the low is really right off the northern tip of the Yucatan and only 1008 mb, it should be too weak and too far away to be doing much in the way of rainbands in Florida. I don't think 99L is developing at all the way the models had predicted.




99L is just adding additional moisture to the flow coming up out of the Caribbean. The ULL (now associated surface low) in the western GOM seems to be the driving force pulling all the moisture north into the eastern GOM.
581. 7544
Quoting 574. sar2401:

It's the WU Nexrad radar. Choose the "storm tracks" and "labels" options to show the arrows. Choose a frame delay of greater than 0.05 seconds unless you like seeing those arrows flopping around at supersonic speed.


thanks for this got it now thanks again :)
Quoting 563. Hurricanes101:

99L to me looks better than last night. Bands of rain are forming in the SE Gulf and heading up over the western part of Florida

Quoting 562. Patrap:


Quoting 563. Hurricanes101:

99L to me looks better than last night. Bands of rain are forming in the SE Gulf and heading up over the western part of Florida


Seems to me the former 99L has become part of the circulation of the WGOM Low
583. beell

12Z CIMSS Shear
Shear-caster'
A pretty nice shot looking out into the GOM from Marco Island (S.W. Florida). Some pretty nasty weather offshore.
Quoting 561. Patrap:


This low pressure system is expected to be by my neck of the woods in 72 hours, and stays put for a few days.


.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM SUNDAY... THE SHORT TERM PERIOD APPEARS TO BE A
CONTINUATION OF ONE OF THE LONGER CLOUDY STRETCHES WE`VE SEEN IN A
WHILE. MONDAY KEEPS THE DEEP EASTERLY FLOW OF MOISTURE LOCKED INTO
THE AREA WITH SOUTHERLY MID LEVEL FLOW AROUND A GOMEX IMPULSE TO
BRING SOME WEAK PVA. THE SURFACE FLOW WILL BE BOLSTERED FROM RECENT
DAYS BY AN AREA OF LOW PRESSURE THAT NHC IS GIVING A 40 PERCENT
CHANCE OF ACQUIRING TROPICAL CHARACTERISTICS OVER THE NEXT 5 DAYS
(THOUGH WORTH NOTING THAT IT WILL NOT APPROACH LAND). THE PREVALENCE
OF CLOUD AND PERHAPS LIGHT RAIN MAKING THE COOLER GFS-BASED MOS MORE
APPEALING THAN THE WRF-BASED. THE ONSHORE FLOW WEAKENS AND TURNS TO
SOUTHERLY ON TUESDAY. ALSO SOME MOISTURE AND VORTICITY CENTERS
STREAM OUT OF THE GULF OF MEXICO INTO MAINLY THE WESTERN AND CENTRAL
CAROLINAS. LOOKS LIKE ANOTHER CLOUDY DAY WITH HIGHS STRUGGLING TO
HIT 80 AND SOME LIGHT RAIN IN MANY PLACES...WITH PERHAPS SOME HIGHER
QPF WELL INLAND.


But...
COOL AND DRY ADVECTION
FRIDAY INTO SATURDAY SHOULD YIELD HIGHS IN THE 70S AND LOWS NEAR
60/UPPER 50S BUT ALSO THE FIRST SUNSHINE THE AREA HAS EXPERIENCED IN
QUITE A WHILE.
Hoorah

Quoting 457. Jedkins01:



Hah no problem it's impressive you remembered to reply to my comment :)

BTW, yeah Katrina and Andrew had some impressive eyewall lightning. lightning in tropical systems is kind of an interesting and complicated topic, of which I've blabbed about many times, though it's getting a bit late to get into it with too great of detail tonight, lol.


Yea, from what I understand warm core systems don't have the kind of updraft that mesocyclones have.
588. beell
Quoting 584. Patrap:

Shear-caster'


Hopefully, no one is surprised!
(by the shear)
Quoting 579. Hurricanes101:



I guess I do not think it is better organized, thanks for setting me straight
I wish it did look better organized since 99L was supposed to be a big rainmaker, and I need it. It really hasn't been looking impressive right from the start. I'm just hoping some moisture will stay around long enough to give me something other than drizzle. The last time Alabama was affected by a TS was with Claudette in 2009. At least that gave me almost four inches of rain, even as the storm dissipated. From this piece of junk so far, I haven't even got enough to measure.
038  
WFUS54 KLIX 271616  
TORLIX  
LAC075-087-271645-  
/O.NEW.KLIX.TO.W.0026.150927T1616Z-150927T1645Z/  
 
BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE NEW ORLEANS LA  
1116 AM CDT SUN SEP 27 2015  
 
THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A  
 
* TORNADO WARNING FOR...  
WEST CENTRAL ST. BERNARD PARISH IN SOUTHEASTERN LOUISIANA...  
NORTHWESTERN PLAQUEMINES PARISH IN SOUTHEASTERN LOUISIANA...  
 
* UNTIL 1145 AM CDT  
 
* AT 1116 AM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM  
CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED  
NEAR POYDRAS...OR 10 MILES EAST OF BELLE CHASSE...AND MOVING WEST  
AT 10 MPH.  
 
* LOCATIONS IMPACTED INCLUDE...  
BELLE CHASSE...CHALMETTE...VIOLET...POYDRAS AND MERAUX.  
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
 
TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST  
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF YOU ARE IN A MOBILE  
HOME OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND  
PROTECT YOURSELF FROM FLYING DEBRIS.  
 
 
 
LAT...LON 2973 9006 2991 8999 2989 8994 2987 8992  
2987 8991 2997 8996 2987 8972 2970 8978  
TIME...MOT...LOC 1616Z 107DEG 8KT 2981 8984  
 
 
 
11  
 
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Quoting 572. Patrap:

Some of the rainfall could be locally heavy at times given the high precipitable water value
airmass...but have opted to not issue a Flash Flood Watch at this
time as the duration of the heavy rains should be limited.


Well, I'm issuing a Flash Flood Warning from my front porch.
Basin is extremely busy for nothing to be getting organized
Nice look at the "swirl" associated with 99L as it moves out into the GOM. You can also see the "swirl" in the western GOM.
Quoting 589. sar2401:

I wish it did look better organized since 99L was supposed to be a big rainmaker, and I need it. It really hasn't been looking impressive right from the start. I'm just hoping some moisture will stay around long enough to give me something other than drizzle. The last time Alabama was affected by a TS was with Claudette in 2009. At least that gave me almost four inches of rain, even as the storm dissipated. From this piece of junk so far, I haven't even got enough to measure.


It could still easily be a big rainmaker
Quoting 589. sar2401:

I wish it did look better organized since 99L was supposed to be a big rainmaker, and I need it. It really hasn't been looking impressive right from the start. I'm just hoping some moisture will stay around long enough to give me something other than drizzle. The last time Alabama was affected by a TS was with Claudette in 2009. At least that gave me almost four inches of rain, even as the storm dissipated. From this piece of junk so far, I haven't even got enough to measure.


You like to measure rain, don't you? :)
Quoting 593. Sfloridacat5:

Nice look at the "swirl" associated with 99L as it moves out into the GOM. You can also see the "swirl" in the western GOM.



not sure if it will develop

Quoting 588. beell:



Hopefully, no one is surprised!
(by the shear)




Indeed, if it were not there, the 99L thang could have been a real player moving N.
Quoting 580. Sfloridacat5:



99L is just adding additional moisture to the flow coming up out of the Caribbean. The ULL (now associated surface low) in the western GOM seems to be the driving force pulling all the moisture north into the eastern GOM.
I agree, and so does the Magic 8 Ball. The Ball model last night was ruminating about the (then) mid-Gulf but un-invested low was the same central pressure as 99L. That's generally not a good sign for the low moving north to intensify, especially with the shear remaining high rather than decreasing. Mr. 8 Ball has been suckered enough this season with other "major" models clinging to unreality while the satellite and surface maps show different. It looks like you have a much better chance of rain than me, but that chance isn't any greater than some of the sea breeze thunderstorm days you've had with no "tropical development".
600. beell


MESOSCALE DISCUSSION 1827
NWS STORM PREDICTION CENTER NORMAN OK
1023 AM CDT SUN SEP 27 2015

AREAS AFFECTED...SERN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 271523Z - 271730Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A BRIEF TORNADO WILL REMAIN POSSIBLE INTO EARLY AFTERNOON WITH GENERALLY WEAK/TRANSIENT MESOCYCLONES POTENTIALLY EVOLVING W/NW NEAR A WEAK WARM FRONT.

DISCUSSION...A TRANSIENT LOW-LEVEL CIRCULATION QUICKLY INTENSIFIED AND RAPIDLY DIMINISHED OVER ST BERNARD PARISH IN A SPAN OF LESS THAN A HALF HOUR. 15Z SURFACE ANALYSIS PLACED A 1009 MB CYCLONE AROUND 150 SSW KHUM WITH A WEAK WARM FRONT EXTENDING NE ACROSS PARTS OF PLAQUEMINES AND ST BERNARD PARISHES. LOW-LEVEL SHEAR IS MODEST PER KLIX VWP DATA AND IS LIKELY TO REMAIN SO PER MORNING GUIDANCE AS STRONGER ELYS ARE ASSOCIATED WITH THE PARENT MID-LEVEL VORTICITY MAX S OF THE MOUTH OF THE SABINE VALLEY /PER LCH VWP DATA/. STILL...ENHANCEMENT TO SRH INVOF THE BOUNDARY COULD FOSTER OCCASIONAL LOW-LEVEL CIRCULATIONS AND POSSIBLY A BRIEF TORNADO WITHIN EMBEDDED CLUSTER CONVECTION ACROSS SERN LA.

..GRAMS/CORFIDI.. 09/27/2015
Yeah, shear is just ripping across the central GOM. We'd be looking a couple tropical systems forming if it weren't for all that shear.
That mojo you were talking about moving in to you Patrap. 99L has created a very nice upper level environment. Shear has plummeted from yesterday over 99L. How much stronger will the convection in the channel get today? You and New Orleans stay safe now.
Showers really starting to pump in from the southeast, with the breeze it sounds sorta peaceful. But I want to see the sun again.
Quoting 595. FunnelVortex:



You like to measure rain, don't you? :)
No, but my weather station and computer does. I like to see rain, and hear rain, and feel rain. That has been in short supply this season. Claudette really felt like a tropical storm after it made landfall in the Panhandle and moved into south Alabama, even though it had diminished to a TD by then. Not being a native here, I assumed that a TD always felt like that, with 45 mph gusts and big thunderstorms. I also assumed that they occured reasonably often. I didn't think it would be six years and counting before we had another one.
Quoting 603. win1gamegiantsplease:

Showers really starting to pump in from the southeast, with the breeze it sounds sorta peaceful. But I want to see the sun again.



On radar you can see them training off the ocean right over Wilmington. Got really rainy and breezy here a little while ago
I have a current Rainfall Rate outside of 3.4 inches per Hour in this cell.
Quoting 601. Sfloridacat5:

Yeah, shear is just ripping across the central GOM. We'd be looking a couple tropical systems forming if it weren't for all that shear.
yep i agree. But I'm not keeping my eye off it yet. But hey I'm forecasting, not wishcasting.
little fearful about 99 not for wind but the rain. could be a long duration downpours. keep a life vest handy.
Quoting 602. DeepSeaRising:

That mojo you were talking about moving in to you Patrap. 99L has created a very nice upper level environment. Shear has plummeted from yesterday over 99L. How much stronger will the convection in the channel get today? You and New Orleans stay safe now.
Read post #583. Shear hasn't diminished at all. What's affecting LA today is from a surface low moving onshore that was in the mid-Gulf yesterday. It has nothing whatever to do with 99L. Frankly, I don't think there's a problem with anywhere staying safe from 99L, and Tampa is likely to get more rain from it than New Orleans.
Quoting 605. K8eCane:




On radar you can see them training off the ocean right over Wilmington. Got really rainy and breezy here a little while ago
Why, it's like deja vu all over again for you guys! :-) Another stationary front off the SC coast with a low pumping in moisture and showers from the Atlantic. Another case of rain that has nothing to do with our putative invest 99L. I'm not sure any rain anywhere is associated with 99L. The Magic 8 Ball is not happy with the major models today.

186  
WFUS54 KLIX 271645  
TORLIX  
LAC075-087-271715-  
/O.NEW.KLIX.TO.W.0027.150927T1645Z-150927T1715Z/  
 
BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE NEW ORLEANS LA  
1145 AM CDT SUN SEP 27 2015  
 
THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A  
 
* TORNADO WARNING FOR...  
WEST CENTRAL ST. BERNARD PARISH IN SOUTHEASTERN LOUISIANA...  
NORTHWESTERN PLAQUEMINES PARISH IN SOUTHEASTERN LOUISIANA...  
 
* UNTIL 1215 PM CDT  
 
* AT 1144 AM CDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM  
CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED  
OVER POYDRAS...OR 7 MILES EAST OF BELLE CHASSE...AND MOVING WEST AT  
10 MPH.  
 
* LOCATIONS IMPACTED INCLUDE...  
BELLE CHASSE...POYDRAS AND VIOLET.  
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...  
 
TAKE COVER NOW. MOVE TO A BASEMENT OR AN INTERIOR ROOM ON THE LOWEST  
FLOOR OF A STURDY BUILDING. AVOID WINDOWS. IF YOU ARE IN A MOBILE  
HOME OR OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND  
PROTECT YOURSELF FROM FLYING DEBRIS.  
 
 
 
LAT...LON 2973 9006 2985 9004 2985 9003 2989 9001  
2989 8994 2987 8992 2987 8991 2989 8992  
2990 8978 2972 8981  
TIME...MOT...LOC 1644Z 097DEG 7KT 2982 8988  
 
 
 
11  
 
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Quoting 600. beell:



MESOSCALE DISCUSSION 1827
NWS STORM PREDICTION CENTER NORMAN OK
1023 AM CDT SUN SEP 27 2015

AREAS AFFECTED...SERN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 271523Z - 271730Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A BRIEF TORNADO WILL REMAIN POSSIBLE INTO EARLY AFTERNOON WITH GENERALLY WEAK/TRANSIENT MESOCYCLONES POTENTIALLY EVOLVING W/NW NEAR A WEAK WARM FRONT.

DISCUSSION...>> A TRANSIENT LOW-LEVEL CIRCULATION QUICKLY INTENSIFIED AND RAPIDLY DIMINISHED OVER ST BERNARD PARISH IN A SPAN OF LESS THAN A HALF HOUR. <<15Z SURFACE ANALYSIS PLACED A 1009 MB CYCLONE AROUND 150 SSW KHUM WITH A WEAK WARM FRONT EXTENDING NE ACROSS PARTS OF PLAQUEMINES AND ST BERNARD PARISHES. LOW-LEVEL SHEAR IS MODEST PER KLIX VWP DATA AND IS LIKELY TO REMAIN SO PER MORNING GUIDANCE AS STRONGER ELYS ARE ASSOCIATED WITH THE PARENT MID-LEVEL VORTICITY MAX S OF THE MOUTH OF THE SABINE VALLEY /PER LCH VWP DATA/. STILL...ENHANCEMENT TO SRH INVOF THE BOUNDARY COULD FOSTER OCCASIONAL LOW-LEVEL CIRCULATIONS AND POSSIBLY A BRIEF TORNADO WITHIN EMBEDDED CLUSTER CONVECTION ACROSS SERN LA.

..GRAMS/CORFIDI.. 09/27/2015
A summary of the 2015 season in one sentence...
615. JLPR2
Looks to me like Ida either is about to or already degenerated into a broad area of low pressure.


Quoting 611. sar2401:

Why, it's like deja vu all over again for you guys! :-) Another stationary front off the SC coast with a low pumping in moisture and showers from the Atlantic. Another case of rain that has nothing to do with our putative invest 99L. I'm not sure any rain anywhere is associated with 99L. The Magic 8 Ball is not happy with the major models today.




LOL 99L definitely Puny. Shear rules it seems
Quoting 594. Hurricanes101:



It could still easily be a big rainmaker
For peninsular Florida, it could be a 1-2 inch rainmaker. The Panhandle and south Alabama will be lucky to see an inch. New Orleans Lakefront Airport has seen 0.58" so far, with a maximum wind gust of 17 mph earlier this morning. This is coming from a low at least as strong as 99L, and a lot better organized. Things could change over the next 48 hours, of course, but 99L doesn't look like much of a threat (or hope) for any more tahn moderate rain right now.
Quoting 615. JLPR2:

Looks to me like Ida either is about to or already degenerated into a broad area of low pressure.



Considering that Ida has been shot, stabbed, run over with a Mack truck, and beaten with a baseball bat, but still lives, I think I'll wait for a while before I believe it's really degenerated this time. :-)
620. FOREX
Quoting 597. FunnelVortex:



not sure if it will develop
Yep, looks like the center is clearly moving NNW and all the convection moving NNE. Not looking good for development.
Quoting 607. hurricanes2018:


Getting better organized.
Quoting 616. K8eCane:



LOL 99L definitely Puny. Shear rules it seems
Shear plus that approaching slug of dry air at the surface does not presage an easy life for 99L. As we saw with Bill and the mid-Gulf low now moving inland over LA, anything that skedaddle and get out of the Gulf has a chance to make it ashore. 99L is spending way too much time dwaddling around off the Yucatan.

Tight swirl with 99L, but very little convection over the center. It does look like it's trying to wrap a couple bands around it's western side.
It needs to turn and head N.E. with the shear to have any chance.
Quoting 610. sar2401:

Read post #583. Shear hasn't diminished at all. What's affecting LA today is from a surface low moving onshore that was in the mid-Gulf yesterday. It has nothing whatever to do with 99L. Frankly, I don't think there's a problem with anywhere staying safe from 99L, and Tampa is likely to get more rain from it than New Orleans.
Would you like some tissue.?
Quoting 610. sar2401:

Read post #583. Shear hasn't diminished at all. What's affecting LA today is from a surface low moving onshore that was in the mid-Gulf yesterday. It has nothing whatever to do with 99L. Frankly, I don't think there's a problem with anywhere staying safe from 99L, and Tampa is likely to get more rain from it than New Orleans.


Don't think there's a problem with everywhere staying safe? Little early for such proclamations. Shear tendency is down over 99L, why convection is growing in the channel to the east of center. I never said what's affecting LA had anything to do with 99L. Was talking about shear over 99L not associating that with what's happening in LA. I see how you could have read it that way.

Quoting 601. Sfloridacat5:

Yeah, shear is just ripping across the central GOM. We'd be looking a couple tropical systems forming if it weren't for all that shear.
Shear plus lack of vertical instability, dry air, and too many continental fronts making it out into the Gulf too early. For those enamored with the Gulf SST's equals "Rocket Fuel!", the SST chart shows the northern Gulf starting to fall toward the magic 27.6 line, below which TC formation becomes a lot harder.

Quoting 625. hydrus:

Would you like some tissue.?


I think we need to see what Grothar's Magic Balls say.
Can anyone post a magic 8 ball forecast? I really look forward to those and haven't seen one in 45 minutes. TIA.

Static non hot-linked loop of 99L.

Quoting 566. weathermanwannabe:

Before I sign off, I would reiterate for folks who travel the Florida I-10 corridor for work during the week for them to follow the rainfall rates and possibly re-route to Hwy 90 for their commutes this week. The I-10 stretch from Pensacola to Tallahassee drains poorly and you get lots of accidents during heavy rain events from hydro-planning (and the inevitable trucks that also tend to spin out). I am about to do a 40 mile I-10 drive to a neighboring city but the rain has not been that bad in the Big Bend yet.

See Yall in the am tomorrow..........................WW.


It does drain poorly? Strange because the road is highly elevated. I know it may sound weird, but I've never really been on I-10 in the Tallahassee area during heavy rain. Mainly because I usually take US-19/Appalachee Parkway from Tampa to Tallahassee instead of the interstate because it's about 100 miles shorter and thus saves fuel.

I don't drive on I-10 west of Tallahassee too often either, have only done it every once in a great while. Last time I was driving on I-10 and encountered really heavy rain was is Louisiana about 8 years ago.
Another naked cyclone: Niala southeast of Big Island with exposed COC:

Seems to me the direction of the wind shear has changed a little bit from yesterday over invest 99. Yesterday it seemed more of a WSW direction and now today it looks more like SW to SSW. Wonder if that would help wrap some convection on the north side of the circulation???
Quoting 632. Gearsts:




It kind of reminds me of hurricane Isabel.
Quoting 580. Sfloridacat5:



99L is just adding additional moisture to the flow coming up out of the Caribbean. The ULL (now associated surface low) in the western GOM seems to be the driving force pulling all the moisture north into the eastern GOM.
I just tried to plus your comment and flagged instead..forgive...The evolution of this system will be a learning experience for me...They all are really...
Quoting 619. sar2401:

Considering that Ida has been shot, stabbed, run over with a Mack truck, and beaten with a baseball bat, but still lives, I think I'll wait for a while before I believe it's really degenerated this time. :-)


I think it might open up into a remnant low... Before regenerating again.

Ida is a tough cookie,
Quoting 632. Gearsts:



My former neighbor, a protestant minister, moved with her Taiwanese husband to Taiwan last year. I wonder how she likes the weather over there in comparison with our German boredom ;-) Hope she and everyone else stays safe the next days.
And a nice evening for everyone in here!
Quoting 628. sar2401:

Shear plus lack of vertical instability, dry air, and too many continental fronts making it out into the Gulf too early. For those enamored with the Gulf SST's equals "Rocket Fuel!", the SST chart shows the northern Gulf starting to fall toward the magic 27.6 line, below which TC formation becomes a lot harder.




Yep Fall is coming and SST's are falling in the northern gulf, not so rocket fuely anymore as a couple weeks ago. We've already had 3 frontal passages with cooler air already this September which has helped contribute to the cooling SST's in addition to the sun angle quickly falling now.
Quoting 632. Gearsts:




It's like a giant buzzsaw.
Quoting 626. DeepSeaRising:



Don't think there's a problem with everywhere staying safe? Little early for such proclamations. Shear tendency is down over 99L, why convection is growing in the channel to the east of center. I never said what's affecting LA had anything to do with 99L. Was talking about shear over 99L not associating that with what's happening in LA. I see how you could have read it that way.


Yes, I thought you were talking about the rain affecting New Orleans now, not what 99L may or may not do. The shear over 99L's rather indistinct location is at least 20 knots. Given that a northern path heads 99L into 30 and 40 knots of shear, it's hard to see that happening. The best hope for survival is hang a right and head for (where else) Florida, where shear still remains at 20 knots, but less than 40 knots. The convection that appears to be growing is just convection tracking to the NE to escape the shear north. 99L doesn't really have the big load of moisture with it we've seen with other TC, and it's not likely to develop one. That's why I said I don't think there's a big problem with anywhere staying safe from 99L. This does not include deaths from self-inflicted causes, like driving into water and drowning. That's going to happen anywhere there's even strong thunderstorms. Leaky roofs are also not covered. :-)

643. MahFL
Quoting 507. tiggerhurricanes2001:

I know one thing for sure, recon flight doesn't need to be cancelled today. Convection is on the increase near the LLC


No it's not, the center is exposed :

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT SUN SEP 27 2015

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Tropical
Depression Ida, located a little more than 1000 miles east-northeast
of the northern Leeward Islands.

An area of low pressure is located over the southern Gulf of
Mexico just north of the Yucatan Peninsula. This system and
a broad trough of low pressure over the western Gulf of
Mexico are producing a large area of disorganized showers and
thunderstorms extending from the northwestern Caribbean Sea
northward over the eastern Gulf of Mexico. Upper-level winds are
expected to be only marginally conducive for development while this
system moves northward toward the northern Gulf Coast during the
next couple of days. Regardless of tropical cyclone formation, this
disturbance is likely to produce locally heavy rainfall over
portions of the northern Gulf Coast and southeastern United States
during the next few days. The Air Force Reserve reconnaissance
aircraft that was scheduled for today was canceled, but another
mission is scheduled for tomorrow, if necessary. For additional
information on this system, see High Seas Forecasts issued by the
National Weather Service and products from your local National
Weather Service office.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...low...30 percent

Showers and thunderstorms have become better organized since
yesterday in association with an elongated area of low pressure
located about midway between the central Bahamas and Bermuda.
Additional slow development of this system is likely during the next
day or two while it moves toward the northwest at 5 to 10 mph. After
that time, development is not expected due to unfavorable
upper-level winds. For more information on this system, see High
Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...60 percent
* Formation chance through 5 days...medium...60 percent
if i were 99 i'd stall right where it is. hang loose and wait for better ul.s

Grey n drizzly here in SW Florida. 81.9 feels like 91
Pressure 29.96 in
Visibility 9.0 miles
Clouds Scattered Clouds 1200 ft
Mostly Cloudy 2500 ft
Overcast 5000 ft
Heat Index 91 F
Dew Point 78.6 F
Humidity 90%
JeffMasters has created a new entry.
Quoting 629. GeoffreyWPB:



I think we need to see what Grothar's Magic Balls say.


Well, Geoff. We've known each other for years. I'm not like the little boy in school who runs behind everybody and corrects them and tells them their work is wrong and how stupid they are and only he knows the answers.

I will occasionally correct a wrong blob observation, but that is important. :) Unfortunately, I only have one crystal ball. The only thing it ever tells me is this, "A peacock today; a feather duster tomorrow"

A code by which I have always tried to live my life. I think that is why I respect you so much over the years.


The only chance of seeing a Hurricane form at this stage of the season is if something develops in the western or central Caribbean. And with the amount of high wind around I would'nt hold my breath. So now we watch and wait to wee happens over the next 4 or 5 weeks.
COME ON 99

Quoting 640. Jedkins01:



Yep Fall is coming and SST's are falling in the northern gulf, not so rocket fuely anymore as a couple weeks ago. We've already had 3 frontal passages with cooler air already this September which has helped contribute to the cooling SST's in addition to the sun angle quickly falling now.
It has indeed. I think people forget how shallow the northern Gulf is on average. That helps heat it up fast when the heat of summer arrives, but it falls just as fast when the fronts and cooler temperatures hit. The last time I had a high above 85 was September 20, and the last four days have seen highs in the mid-70's and lows in the low 60's. That's not the kind of air mass that will maintain 86 degree SST's in the northern Gulf.

The interesting thing to me is how all these negative factors seem to be recognized now that we have 99L as yet another underperformer. When 99L was still a collection of electrons in the model maps, it seemed like people were just ignoring these negative factors while hoping that magic would turn 99L into "The Storm". Who knows, with this crazy season, but we certainly have not seen a history of underperformers suddenly blowing up into monsters.
Quoting 460. Mediarologist:



I'm not going to say what that looks like to me.. it's quite amusing though.

lol
Three models show 98L eventually ending up somewhere in my neck of the woods.Hopefully bringing just rain and nothing more...
Been looking better and better, imo, since yesterday....