Hurricane Hunters find tropical storm winds in TD 9

By: Dr. Jeff Masters , 7:51 PM GMT on August 21, 2012

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The Air Force Hurricane Hunters are in Tropical Depression Nine, and have discovered a region of 40 - 45 mph winds at the surface, using their SFMR instrument. Flight level winds at their 1000 foot altitude spiked as high as 49 mph. The surface pressure was 1005 mb, a typical one for a weak tropical storm. Based on these measurements, it is highly likely that NHC will name this Tropical Storm Isaac at 5 pm EDT. A large area of dry air lies just to the north of the storm, as seen on water vapor satellite loops, and this dry air is interfering with development, allowing only a few clumps of heavy thunderstorms to fire up near TD 9's center, as seen on visible satellite loops. These loops also show some arc-shaped low clouds expanding away from the heavy thunderstorm area on the south side of the center, showing that TD 9 is ingesting dry air that is creating strong thunderstorm downdrafts, robbing the storm of moisture and energy. An analysis of upper level winds from the University of Wisconsin CIMSS shows that an upper level outflow channel has opened to the southwest, and another channel is attempting to open up to the north. A large clump of heavy thunderstorms several hundred miles to the southeast of TD 9 continues to compete for moisture, and is interfering with the low level inflow and upper level outflow of the storm. The center of TD 9 will pass about 50 miles to the north of buoy 41101 near midnight tonight. The next hurricane hunter mission into TD 9 is scheduled for 2 am Wednesday, and there will be a new mission launched every six hours. The NOAA jet is first scheduled to fly into the storm on Thursday afternoon, to do a large-scale dropsonde mission to aid model forecasts.


Figure 1. Satellite image of TD 9 and 96L taken at 10:45 am EDT August 21, 2012. The two storms are connected by a thin line of low clouds. Image credit: NOAA Environmental Visualization Lab.

Intensity forecast for TD 9
The latest 2 pm EDT run of the SHIPS model predicts that wind shear will be low to moderate, 5 - 15 knots, for the next five days. Ocean temperatures will warm from 28°C today to 29°C by Wednesday afternoon, and the total heat content of the ocean will increase sharply during that period. The low wind shear and warm waters will favor strengthening. The main impediment to development through Wednesday will be dry air to the north, though the storm will also have trouble separating from the clump of thunderstorms to its southeast. I expect that TD 9 will continue to struggle with dry air through Wednesday. The official NHC forecast is of a 60 mph tropical storm moving through the Lesser Antilles on Wednesday evening; I put the most likely range of strengths for TD 9 Wednesday evening at 50 - 60 mph. Once TD 9 enters the Eastern Caribbean, wind shear will be low, oceanic heat content high, and the storm should have had enough time to moisten the atmosphere to allow steady strengthening to a hurricane. Intensity forecasts 4 - 5 days out are low in skill, though, and it would not be a surprise at all to see TD 9 struggle like so many other storms have over the past two years, and remain a tropical storm over the next five days. Conversely, rapid intensification into a Category 2 hurricane five days from now, as the official NHC is suggesting may happen, would also not be a surprise.


Figure 2. Daily Oceanic Heat Content or Tropical Cyclone Heat Potential (TCHP) for TD 9. The forecast points are from the 11 am EDT NHC advisory, and the 24 hour forecast point shown here is for 8 pm EDT Wednesday. For tropical cyclones in favorable environmental conditions for intensification (i.e., vertical wind shear less than 15 kt, mid-level relative humidity >50 %, and warm SSTs [i.e., >28.5C]) and with intensities less than 80kt, values of ocean heat content greater than 50 kJ/cm^2 (yellow and warmer colors) have been shown to promote greater rates of intensity change. TD 9 will be crossing into such a region early Wednesday morning, and will enter a region of very high TCHP south of Hispaniola on Friday morning (the 72 hour forecast point.) Image credit: NOAA/RAMMB.

Latest model runs for TD 9
The latest set of 12Z (8 am EDT) model runs for TD 9 are fairly unified for the coming three days, showing a west to west-northwest track to a point just south of Hispaniola. Most of the models then predict a more west-northwest track across Southwest Haiti and into eastern Cuba, as TD 9 responds to a small trough of low pressure over the Southeast U.S. A notable exception is our best-performing model, the ECMWF, which keeps TD 9 south of Hispaniola, and takes the storm more to the west over Jamaica by Saturday, and then into the Yucatan Channel between Mexico and Cuba by next Tuesday. We'll have to wait another day to see where the center of TD 9 consolidates before judging which model solution is likely to be correct; reformations of the center closer to bursts of heavy thunderstorm often cause the center point to shift around in the early stages of development, leading to large changes in the forecast track many days later. TD 9 is a threat to affect Tampa during the Republican National Convention, August 27 - 30. I blogged about the climatological chances of a hurricane causing an evacuation of Tampa during the convention in a post last week, putting the odds at 0.2%. The odds in the current situation are higher, probably near 2%. It would take a "perfect storm" sort of conditions to all fall in place to bring TD 9 to the doorstep of Tampa as a hurricane during the convention, but that is one of the possibilities the models have been suggesting could happen.

Disturbance 96L off the coast of Africa
A large tropical wave in the eastern Atlantic about 550 miles southwest of the Cape Verde Islands (Invest 96L) is headed west at 15 mph. This disturbance has an impressive amount of spin, as seen on visible satellite loops, and a respectable amount of heavy thunderstorm activity that is increasing. The storm is under a light 5 - 10 knots of wind shear. Given that TD 9 has moistened up the atmosphere ahead of 96L, this disturbance should have less of a problem with dry air. In their 2 pm EDT Tropical Weather Outlook, NHC gave 96L a 60% chance of developing into a tropical cyclone by Thursday afternoon. This disturbance will track nearly due west the next three days, then is expected to turn more to the west-northwest late this week, bringing it close to the northern Lesser Antilles Islands by Sunday.

Disturbance 95L in the Gulf of Mexico near the Texas/Mexico border
A region of disturbed weather (Invest 95L) is in the Gulf of Mexico, just northeast of Tampico, Mexico. In their 2 pm EDT Tropical Weather Outlook, NHC downgraded the chances of 95L developing to 20%. The Air Force hurricane hunter aircraft scheduled to investigate 95L this afternoon was cancelled. Radar out of Altamira, Mexico does not show any organization to the precipitation echoes and visible satellite loops show that 95L is small and disorganized. The computer models show that 95L should drift westwards, and may move over Mexico on Wednesday.

I'll have a new post in the morning.

Jeff Masters

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Quoting kmanhurricaneman:
anybody have a link to steering currents page.
thanks


Link

You can find it here
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3532. KEEPEROFTHEGATE (Mod)
Member Since: July 15, 2006 Posts: 192 Comments: 59571
Quoting stormchaser19:
Bryan Norcross
Okay Florida... it's time to wake up. Isaac is getting organized and the odds are increasing that it's going to be a problem... a big enough problem that preparation is likely to be required. The exact angle of approach is still uncertain, and a slight difference changes who gets the worst of it, but most plausible future tracks show an impact on the state. (There's a chance it could miss to the east, but that appears the least likely scenario.) If the storm turns near eastern Cuba, as the American GFS computer forecast shows, the storm will impact the Middle/Upper Keys and the Miami/Ft. Lauderdale area... and possibly the Tampa/Orlando area as well. (Setting up a possible nightmare scenario for Florida insurance.) This scenario would seem to limit how strong the storm could get because it would have to track over some of the Caribbean mountains, but there's still plenty of warm water between Cuba and Florida. A track farther west, however, in the direction of the European ECMWF computer forecast, the storm has impact on the west coast of the state in a big way, and perhaps the Panhandle. A hurricane on this track would seem to have an opportunity to get stronger. The bottom line, starting in the Keys immediately, it's time to begin paying attention to hurricane plans. The NHC will be deploying their full resources over the next couple of days to gather the best data, which can refine and improve the forecast... so we'll be getting the best that modern technology can provide by Friday. Stay tuned... and wake your friends up as well.
if bryan norcross said this get ready because however you put it we are going to probably deal with either tropical storm force winds or a direct hit from a hurricane lets wait and see
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3530. ncstorm
Quoting Brock31:


It was strange how spotty the power issues were for that storm.

Either way, I'm ready to dry out. I think mold is growing on me.

I would be really concerned if we took a hit from a slow moving, strong cat 2 or more. My house is in a flood zone. :(


its going to depend where Issac starts moving north..I remember floyd and the NHC said first Florida, then GA, then SC and finally NC..We aint out of the woods yet..
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Quoting SouthDadeFish:
Not sure if this has been said, but Isaac is not as well organized as conventional satellite imagery would lead one to believe. Microwave imagery reveals the center is still to the northeast of the deepest convection, but is covered by the cirrus canopy.



His circulation is also tilted.

700mb


500mb


200mb
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Quoting tkdaime:
The weather channel has done test on the new roofs in Florida and they say the new building codes make stronger roofs in Florida anybody know about this.
Yes, supposedly everything was built under new codes. If I remember correctly it was the type of nail that was used to secure the trusses of the roof that was changed, along with other things. However the structures that were built to this new code have really never been tested in a major storm. After 20+ years, confidence in these codes on a structure built right after Hurricane Andrew, assuming no modification since, is questionable.
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Quoting JasonRE:
I was excited to check the site today to see if we would get any of TS Isaac in Louisiana. Again, I'm not into damage and loss of life but the thrill of a storm is like nothing else. I come in here often during hurricane season to get the play by play from Dr. M and all of you. Is there any chance of this thing moving into the Gulf more Westerly after moving along FL? Or is it shooting straight up into the coast? Again, please don't misunderstand me, I'm not wishing hurt upon other people, I just like the thrill of the storm.

Too early to tell. Get your hurricane plan in order just in case, though.
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3526. LargoFl
This..could be very very bad next week
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Quoting SFLWeatherman:
8AM
Ugh..... this makes my stomach churn!!
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3524. VR46L
Quoting StormTracker2K:


Issac wants his ticket stamped.



Highly original use of Isaac Newton ,I like it :)


anyways looks to me ,Like 2 storms in the Atlantic, wishcasting fishes here

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This does not look pretty. Nam You!

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3522. JasonRE
I was excited to check the site today to see if we would get any of TS Isaac in Louisiana. Again, I'm not into damage and loss of life but the thrill of a storm is like nothing else. I come in here often during hurricane season to get the play by play from Dr. M and all of you. Is there any chance of this thing moving into the Gulf more Westerly after moving along FL? Or is it shooting straight up into the coast? Again, please don't misunderstand me, I'm not wishing hurt upon other people, I just like the thrill of the storm.
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Quoting LargoFl:
now both major models put Issac in the gulf



I just saw that...I sure hope the Euro does not hold to be true...
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Quoting LargoFl:
..Take Note..the GFS track has changed


This is not good for the northern gulf coast. Damn.
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Quoting LargoFl:
now both major models put Issac in the gulf

And yesterday, both models had him going up the East coast of FL, or up the East coast of the CONUS. The tracks are going back and forth like windshield wipers. Look at the center between the two extremes - not at the extremes.

Now is the time to get ready - this goes to everyone on the Gulf Coast or the Atlantic Coast. Get ready now, before the lines start.

For those in the islands - finish up your plans ASAP, and get safe.
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Quoting TropicsGirl:
I remember that day like it was yesterday - sitting on the bathroom floor with my back to the sink cabinet and my feet holding the door shut as the house was being blown apart. Definitely not something I want to experience again!!


I was doing the same thing in south Kendall, FL. I wish I had been older to understand the nature of a Category 5 hurricane making landfall...then again I wouldn't want the memories to be more vivid than they already are.
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Quoting VINNY04:
please bring a picture ujp on that. my computer wont open the link.

Well here you go and for anyone else that would like to see it.:
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Quoting wxchaser97:

Link to the steering currents
See post#3497 for link to steering currents. Doesn't look like a sudden turn NW to me. Must go more WEST before turning around base of the Azores / Bermuda high. GOM more probable..
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Quoting islander101010:
96.only.matters.to.the.fish....for.now




96L is not a fish
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Quoting SouthDadeFish:
Not sure if this has been said, but Isaac is not as well organized as conventional satellite imagery would lead one to believe. Microwave imagery reveals the center is still to the northeast of the deepest convection, but is covered by the cirrus canopy.

Its amazing how much the microwave data helps clear the debris clouds obscuring the IR image, isn't it?

What we have been seeing the last few days that many have been calling a CDO is blowoff from the southside convection falling in on itself as it rotates around the LL center. If the convective base doesnt show up on Microwave, its NOT surface based deep convection on the IR, just debris clouds/blowoff!
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3512. LargoFl
Quoting LargoFl:
now both major models put Issac in the gulf
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96.only.matters.to.the.fish....for.now
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3510. SLU
22/1200 UTC 12.2N 35.7W T2.0/2.0 96L -- Atlantic
22/1145 UTC 15.9N 58.0W T2.5/2.5 ISAAC -- Atlantic
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Quoting AussieStorm:




What does that mean for Isaac?
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i want everyone to realize that a shift 100 miles north or south could mean a great deal. until isaac gets further west we wont exactly know where it goes. euro insists gulf and 6z GFS switched to the gulf too.
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we now have tropical depression 10 advisory will be out at 11 am
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Quoting SouthDadeFish:
Windsat is starting to show a little more organization, but nothing too impressive yet besides a lot of ice to the SW of the center:


He is trying to wrap up, but some dry air is still holding him back. I'm hoping he continues to cough on the dry air.
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3505. LargoFl
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3504. Brock31
Quoting ncstorm:


I lost power for two days from Irene so you had it good..


It was strange how spotty the power issues were for that storm.

Either way, I'm ready to dry out. I think mold is growing on me.

I would be really concerned if we took a hit from a slow moving, strong cat 2 or more. My house is in a flood zone. :(
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Quoting LargoFl:
..Take Note..the GFS track has changed
BOOOOOO!
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Quoting SFLWeatherman:
2Day from now
I remember that day like it was yesterday - sitting on the bathroom floor with my back to the sink cabinet and my feet holding the door shut as the house was being blown apart. Definitely not something I want to experience again!!
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Quoting VINNY04:
please bring a picture ujp on that. my computer wont open the link.



Click for link...
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Windsat is starting to show a little more organization, but nothing too impressive yet besides a lot of ice to the SW of the center:

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Quoting coffeecrusader:
06Z Runs of GFS have shifted back to the west. Showing a massive strike on Tampa Bay area. Dr. Masters post last week regarding the Republican National Convention is looking more ominous by the day.


...ominous???

I'm thinking: "Maybe there really IS a God...!~"
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Those of you who are interested may want to read RandyB's blog here on WU... as a HHer himself, he always has a pretty pragmatic view of storms and what they may do. His current blog on pre-Isaac is interesting.

Another way to get to his blog is by using the BLOGS tab at the top of this page.
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Quoting tropicalmommie:


Hi, I live in Key West too and work retail and already things are getting crazy. I hope Isaac just stays away!
Hi I'm at rent key west vacations rental co in
Duval Square. Yes, we will, most likely, have to start kicking our guests out...by Friday? maybe Sat.
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Other thing is that why all the updates where coming out on the invest page why we got the re number for 96L at the time with the updates coming in 96L did not get the update 1st or some in
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582
NOUS42 KKEY 220950
PNSKEY

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE KEY WEST FL
550 AM EDT WED AUG 22 2012

...FLORIDA KEYS RESIDENTS AND VISITORS SHOULD MONITOR ISAAC...

AT 500 AM EDT WEDNESDAY...THE CENTER OF TROPICAL STORM ISAAC WAS
LOCATED ABOUT 1640 MILES EAST-SOUTHEAST OF THE FLORIDA KEYS. TROPICAL
STORM ISAAC IS MOVING WESTWARD NEAR 18 MPH. THIS GENERAL MOTION IS
ANTICIPATED FOR AT LEAST THE NEXT COUPLE OF DAYS. MAXIMUM SUSTAINED
WINDS ARE NEAR 45 MPH. ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR
INTENSIFICATION WEDNESDAY THROUGH FRIDAY NIGHT. THE TRACK ERROR
FORECAST CONE NOW COVERS MOST OF THE FLORIDA KEYS AND ADJACENT
COASTAL WATERS. TROPICAL STORM ISAAC POSES A THREAT TO THE FLORIDA
KEYS. THE LATEST FORECAST TRACK HAS TRIGGERED PROBABILISTIC WORDING
FOR TROPICAL STORM FORCE WINDS FOR SUNDAY AND SUNDAY NIGHT. THIS
MEANS THERE IS A GOOD POSSIBILITY THE THE KEYS WILL EXPERIENCE AT
LEAST TROPICAL STORM FORCE WINDS BY LATE SUNDAY.

NOW IS THE TIME TO CHECK YOUR DISASTER SUPPLY KIT. A DISASTER SUPPLY
KIT CONTAINS ITEMS YOU NEED TO HAVE REGARDLESS OF WHERE YOU RIDE OUT
A STORM. THIS KIT IS A USEFUL TOOL WHEN YOU EVACUATE...AS WELL AS
MAKING YOU AS SAFE AS POSSIBLE IN YOUR HOME. A LIST OF ITEMS FOR
YOUR DISASTER SUPPLY KIT AND ASSISTANCE IN DEVELOPING A FAMILY OR
PERSONAL PLAN CAN BE FOUND ON THE FEDERAL EMERGENCY MANAGEMENT
AGENCY INTERNET SITE AT: WWW.READY.GOV.

IF TROPICAL STORM OR HURRICANE WATCHES ARE ISSUED FOR THE FLORIDA
KEYS...YOUR NATIONAL WEATHER SERVICE OFFICE IN KEY WEST WILL RELEASE
INFORMATION AND IMPORTANT SAFETY PRECAUTIONS IN A TROPICAL STORM OR
HURRICANE LOCAL STATEMENT. THIS STATEMENT IS REFRESHED AT 2 OR 3
HOUR INTERVALS DURING THE ENTIRE PERIOD OF A TROPICAL CYCLONE THREAT.
THIS PRODUCT CAN BE VIEWED ON THE INTERNET AT:
WWW.WEATHER.GOV/KEYWEST.

TO RECEIVE THE LATEST INFORMATION REGARDING TROPICAL STORM ISAAC...
LIKE US ON FACEBOOK AT:
HTTP://WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE .KEYWEST.GOV

OR FOLLOW US ON TWITTER AT:
HTTPS://TWITTER.COM/NWSKEYWEST

YOU CAN ALSO MONITOR THE SITUATION BY VISITING THE NATIONAL
HURRICANE CENTER ON THE WEB AT: WWW.NHC.NOAA.GOV.

$$

BWC


ill be back at lunchtime
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Computer models and the ensembles shifted west again at 8....
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Guess I probably ought to start some preparations even though it's almost a week out from SC [if it even comes this way]. Being at the EOC means having to be ready sooner.
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15.9N 58.5W mmm
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3490. KEEPEROFTHEGATE (Mod)
T.C.F.W.
10L/TD/XX/CX
MARK
11.90N/35.06W
Member Since: July 15, 2006 Posts: 192 Comments: 59571
PR Governor Flojuño already closed public schools for today. Most of the goverment agencies are closed as well. Private sector considering shutting down operations today at noon.
Member Since: April 29, 2010 Posts: 0 Comments: 136
3488. LargoFl
Quoting LargoFl:
..Take Note..the GFS track has changed
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3487. VINNY04
Quoting wxchaser97:

Link to the steering currents
please bring a picture ujp on that. my computer wont open the link.
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3486. ncstorm
Quoting Brock31:


We are way above average already rain wise here for sure.

Although, I'm not overly concerned based on the intensity models forecasting at best a cat 1 if it hits here. If its an "Irene" type situation again, the most I can hope for is some limbs down, minor flooding in low areas and amaybe a day off work.

We didn't even lose power at my house during Irene.

Now if the forecast puts Isaac more north and over more water and we get a Bertha or Fran (1996) type situation, out come the sandbags.


I lost power for two days from Irene so you had it good..
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3485. LargoFl
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It appears on the loop that TS Isaac is moving due west at 15N:

href="http://www.ssd.noaa.gov/goes/east/carb/flas h-wv.html" target="_blank">Link
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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