97L in Western Caribbean Still a Threat to Develop

By: Dr. Jeff Masters , 1:58 PM GMT on October 02, 2013

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A tropical disturbance (Invest 97L) over the Western Caribbean is moving to the northwest at 10 mph and is generating heavy rains over the Cayman Islands and Western Cuba. Grand Cayman Island had picked up 2.32" (59 mm) of rain as of 9:30 am EDT on Wednesday. Satellite loops show that 97L has a modest area of heavy thunderstorms that have increased substantially in areal coverage and in intensity since Tuesday, but there is little rotation apparent. Cayman Islands radar also does not show any rotation to the echoes, but there are several prominent low-level bands of heavy rain. The storm has low wind shear of 5 - 10 knots to work with, as well as an upper-air anticyclone aloft that is providing good ventilation above it. Dry air is over the Yucatan Peninsula and Gulf of Mexico, as seen on water vapor satellite loops, and this dry air is slowing development. Ocean temperatures are a very warm 29°C (84°F). An Air Force hurricane hunter flight is scheduled for Wednesday afternoon.


Figure 1. Wind forecast for 2 pm EDT Saturday October 5, 2013, from runs of the GFS model done six hours apart. The more recent run, initialized at 06Z (2 am EDT) on Wednesday, October 2 (left panel) predicts that 97L will have top winds below 35 knots (40 mph, light orange colors). This run showed the center of 97L making landfall in the Florida Panhandle about 120 miles east of Alabama late Saturday afternoon.The run initialized six hours earlier, at 00Z (right panel), showed a stronger storm, with top winds of 40 - 45 knots (46 - 52 mph.) This run showed the center of 97L making landfall near the Alabama/Florida border Saturday night. The images were generated using our wundermap with the model layer turned on.

Forecast for 97L: development into at least a tropical depression likely
Wind shear is expected to remain low on Wednesday, then steadily increase to the moderate range on Thursday, then to the high range on Friday, according to the latest SHIPS model forecast. On Wednesday night, 97L will cross the northeastern tip of Mexico's Yucatan Peninsula, bringing 3 - 6" of rain to the peninsula and to Western Cuba. Passage over the Yucatan will act to disrupt the storm. The atmosphere will grow drier as 97L moves northwards over the Gulf of Mexico on Thursday and Friday, and the drier air combined with increasing wind shear will retard development, making rapid intensification unlikely. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will be able to turn 97L more to the northeast as it approaches the coast on Friday. The GFS model develops 97L into a tropical storm, and predicts landfall will occur along the Florida Panhandle. The European model, which does not develop 97L into a tropical storm, is farther west, taking the storm over Eastern Louisiana. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 97L 2-day odds of development of 40%, and 5-day odds of 50%. I give a 30% chance 97L will be Tropical Storm Karen with top winds of 40 - 60 mph at landfall between Louisiana and the Florida Panhandle on Saturday, a 5% chance it will be stronger, and a 65% chance it will be a tropical depression or mere tropical disturbance. Heavy rains of 3 - 6" can be expected falling the coast from Louisiana to the Florida Panhandle on Saturday, even if 97L does not develop into a tropical depression.


Figure 2. MODIS satellite image of 97L, taken at 12:30 pm EDT on October 2, 2013. Image credit: NASA.

Tropical Storm Jerry in the Central Atlantic no threat
Tropical Storm Jerry continues to slowly wander over the Central Atlantic, far from land. Jerry is not a threat to any land areas.

Jeff Masters

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Quoting 414. LargoFl:
48-60 hours models have a pretty strong Tropical Storm..
50mph is not a strong ts, thats a weak one.
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48-60 hours models have a pretty strong Tropical Storm..
Member Since: August 6, 2011 Posts: 4 Comments: 38410
CLOUD TOPS are beginning to warm, and will do so for the next 4-5 hours or so until dmin. This thing wont make it to TS force today for sure.
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HDOB is turned on... 1st obs, just posted
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Quoting 406. aprinz1979:


Nope Al Gore did along with AGW


Oh god...

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Quoting 405. NOLAGOLF:
Shrimps on the menu
Oo,I want some.
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Quoting 404. MississippiWx:
Recon on their way. Give it another hour or so.

oh boy here we go! blog gonna go crazy if theyfind a TD or TS karen
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Finally HDOB starting to coming
Member Since: August 14, 2008 Posts: 4 Comments: 4972
Quoting 360. Xyrus2000:


Going out into the open ocean in an open top boat in the middle of thunderstorms capable of producing waterspouts? And then then driving practically through a waterspout?

This isn't ballsy. It's stupid. Very stupid. They were lucky they weren't Darwin award winners.
I guess that's what makes the "world go round" If we were all the same it sure would be boring...The variation of people makes it interesting. Some people even make "Duck Calls"
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Quoting 397. ChillinInTheKeys:


Wow!!! Member since 1970... So YOU invented the Internet!!!


Nope Al Gore did along with AGW
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Shrimps on the menu
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Recon on their way. Give it another hour or so.

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Comes down to the timing of the front I guess...does the GFS or the Euro have it right? These look like they're taking guidance from the GFS.





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Quoting 377. DavidHOUTX:


I wouldn't be surprised at all to see a westward model shift. I don't think it will shift enough west to get in our area unless the storm really picks up speed (it seems as if it has started moving faster). The front appears to have slowed a little bit also.

If it were to come in our direction, I don't see anything that would lead me to believe it will even reach the TX coast line before heading off to the NE.



Let the parochial prognosticating begin!
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Back from lunch. Nice to see the Blog back in full tropical action mode after the last 3 week lull and bickering over climate change issues.

97 is really expanding her moisture envelope; not sure what is happening in the surface yet but it looks to be a nice sized system if it can close off.

Please remember that the very large overall circulation that we are seeing takes a lot of time to consolidate; a lot of air to move. That in an of it'self would dictate a slow move towards TD status (with a well defined low pressure coc) in spite of whatever wind speeds might be out there in the periphery. 30mph plus winds in the proto-bands does not a tropical cyclone make unless the Hunters can close off a low level circulation at those speeds.
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Quoting 397. ChillinInTheKeys:


Wow!!! Member since 1970... So YOU invented the Internet!!!


He's Al Gore!
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Quoting 392. csmda:


Yeah, I much rather liked the idea of taking a "direct" hit or having it come in a bit to the east. Not happy that it might come in so that we get the worst side. But not going to worry too much as everything in this area so far was supposed to hit us and never really did, at least not with anything substantial.


Wow!!! Member since 1970... So YOU invented the Internet!!!
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The guys on TWC just said they might name the system in the west "Atlas" if it is widespread enough and dumps enough snow...
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Quoting 370. MississippiWx:


I've seen a couple of statements like this. 97L is moving a good 10mph. Not stationary at all.



What I am looking at is what appears to be a near stationary circulation located at 17N 85W

To me the cloud tops are moving to the NW essentially blowing over the LLC.

Link

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Not very impressive ATT...
Member Since: July 4, 2005 Posts: 204 Comments: 8871
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392. csmda
Quoting 384. MississippiWx:


Even if the system goes into Louisiana, the system is likely to be heavily weighted to the east which would put the FL Panhandle very much on the bad weather side. The GFS also still shows landfall in the Panhandle which is obviously a very respectable idea.


Yeah, I much rather liked the idea of taking a "direct" hit or having it come in a bit to the east. Not happy that it might come in so that we get the worst side. But not going to worry too much as everything in this area so far was supposed to hit us and never really did, at least not with anything substantial.
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The GFS has consistently called for a very compact cyclone to form out of this wave, and that appears to be happening now. This probably makes the intensity forecasts less reliable than normal...?
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Florida should have a good deal of moisture coming into the region beginning this evening.
Member Since: January 1, 2008 Posts: 0 Comments: 2950
I expect 70/100 at the next TWO.
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Quoting 386. FunnelVortex:


Lots of high cloud tops.
but they are beginning to warm and will do so till dmin
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I think we have to take into account that there is not a well defined center for these models to latch on to. Once the HH gets out there and finds one it will give the models a better starting point.

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Quoting 382. Patrap:




Lots of high cloud tops.
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< Return to Decoder | Recon Archive | Refresh Page
Tropical Atlantic Live Reconnaissance Decoder
Decoded data from last 30 minutes: AF Trop. RECCO (URNT11) (23) (Minutes since ob are noted)

Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 2nd day of the month at 16:42Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 301)
Mission Purpose: Investigate sixth suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 02

Mandatory Data...

Observation Time: Wednesday, 16:38Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 26.0N 87.8W
Location: 307 miles (495 km) to the SSE (153°) from New Orleans, LA, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,320 meters
Flight Level Wind: From 190° at 13 knots (From the S at ~ 14.9 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -15°C
Flight Level Dew Point: -40°C
Weather (within 30 nautical miles): Scattered clouds (trace to 4/8 cloud coverage)
400 mb Surface Altitude: 7,600 geopotential meters

Remarks Section...

Surface Wind Speed (likely by SFMR): 17 knots (~ 19.6mph)
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Quoting 379. FOREX:


Yes it seems Florida panhandle is out of the woods perhaps.


Even if the system goes into Louisiana, the system is likely to be heavily weighted to the east which would put the FL Panhandle very much on the bad weather side. The GFS also still shows landfall in the Panhandle which is obviously a very respectable idea.
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383. bwi
Buoy just updated:

Conditions at 42056 as of
(11:50 am CDT)
1650 GMT on 10/02/2013:
Unit of Measure: Time Zone:
Click on the graph icon in the table below to see a time series plot of the last five days of that observation.

5-day plot - Wind Direction Wind Direction (WDIR): SE ( 130 deg true )
5-day plot - Wind Speed Wind Speed (WSPD): 23.3 kts
5-day plot - Wind Gust Wind Gust (GST): 29.1 kts
5-day plot - Wave Height Wave Height (WVHT): 6.9 ft
5-day plot - Dominant Wave Period Dominant Wave Period (DPD): 8 sec
5-day plot - Average Period Average Period (APD): 5.4 sec
5-day plot - Mean Wave Direction Mean Wave Direction (MWD): ESE ( 116 deg true )
5-day plot - Atmospheric Pressure Atmospheric Pressure (PRES): 29.83 in
5-day plot - Pressure Tendency Pressure Tendency (PTDY): -0.02 in ( Falling )
5-day plot - Air Temperature Air Temperature (ATMP): 77.9 °F
5-day plot - Water Temperature Water Temperature (WTMP): 84.2 °F
5-day plot - Dew Point Dew Point (DEWP): 77.5 °F
5-day plot - Heat Index Heat Index (HEAT): 80.2 °F
5-day plot - Wind Speed at 10 Meters Wind Speed at 10 meters (WSPD10M): 25.3 kts
5-day plot - Wind Speed at 10 Meters Wind Speed at 20 meters (WSPD20M): 27.2 kts
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For some reason I feel that just like the many other storms, it will look good then once DMIN hits it will strip it of convection then the process starts all over again and again.
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There was this little storm from the same neighborhood that spun up pretty quick back when I was about to start the 3rd grade... Nah!



She put that on hold for a few weeks.
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379. FOREX
Quoting 375. MississippiWx:
The GEM is finally developing 97L into a tropical cyclone, I see. Hard to believe it hasn't been on the development bandwagon. GEM as well as UKMET take the system into Louisiana.




Yes it seems Florida panhandle is out of the woods perhaps.
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Quoting 370. MississippiWx:


I've seen a couple of statements like this. 97L is moving a good 10mph. Not stationary at all.





Agreed, and it should keep moving at a steady forward speed NW.
Member Since: July 4, 2005 Posts: 204 Comments: 8871
Quoting 365. redwagon:


What with the steering, if models start nudging W, 97L in theory could run up on us, stall out against the front, and spin off rain for days?


I wouldn't be surprised at all to see a westward model shift. I don't think it will shift enough west to get in our area unless the storm really picks up speed (it seems as if it has started moving faster). The front appears to have slowed a little bit also.

If it were to come in our direction, I don't see anything that would lead me to believe it will even reach the TX coast line before heading off to the NE.
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NWS NOLA/Slidell 08:11 Disco

Taking a peep at the models again today it looks like the European model (ecmwf)
continues to be slower with the progression of the front and would
allow the tropical feature to get further west and much closer to
the forecast area. The GFS on the other hand is more progressive
with the front by about 12 hours and keeps the tropical feature to
the east of the forecast area keeping the bulk of the
precipitation to the east of the area. Have generally kept the
same forecast from previous forecasts but have bumped up probability of precipitation some
this weekend. After the front fall will make an appearance and you
will definitely feel the difference in the overnight lows as thy
will dip into the 50s early next week and daytime highs will be in
the low 80s. High pressure builds in behind the front yielding for
some clear days. 13/mh

Read more at http://www.wunderground.com/DisplayDisc.asp?Discus sionCode=LIX&StateCode=LA&SafeCityName=New_Orleans #XfjFuSGxzxxbkTU2.99
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The GEM is finally developing 97L into a tropical cyclone, I see. Hard to believe it hasn't been on the development bandwagon. GEM as well as UKMET take the system into Louisiana.


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Quoting 366. sporteguy03:

Back in the Rockies moving slowly eastward.Link
ughhhh!! that makes me mad these fronts take forever!! i want cooler air tired of the humidity need sum relief.
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Member Since: July 4, 2005 Posts: 204 Comments: 8871
Quoting 364. Skyepony:
Wish recon would turn on the High Density (HDOB) Messages.. That's some of my fav data from them. Usually that is on.


Twas wundering the same skyepony.

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Quoting 367. ecomarine:


I have it at 17N 85W.

Seems to be almost stationary at this mark.


I've seen a couple of statements like this. 97L is moving a good 10mph. Not stationary at all.
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368. FOREX
Quoting 365. redwagon:


What with the steering, if models start nudging W, 97L in theory could run up on us, stall out against the front, and spin off rain for days?


looking less and less likely of a panhandle landfall.
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Quoting 351. GetReal:


My best guess is 19.5N 85.0W


I have it at 17N 85W.

Seems to be almost stationary at this mark.
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Quoting 362. bigwes6844:
where is the front located anyone? this storm seems to be picking up speed for sum reason

Back in the Rockies moving slowly eastward.Link
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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