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 658. bappit:
The line of convergence to the east is stealing energy from the circulation. The last invest through the NW Caribbean had a similar line of convergence trailing the circulation.


Seem as if the "pouchers" would agree

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664. Skyepony (Mod)
MSWX~ That recon map you keep posting blanks out the direction of everything under 10kts. It's making something that is swirling weak at the center look really broad with nothing going on in the middle.
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NOLA in the cross hairs, grass getting green in TX, winter time fast approaching, arctic blasts' on the way, hurricane season bout dead anyway.

And that's a fact Jack.
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Certainly not the fastest forming tropical cyclone, but it is coming together...
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Quoting 648. Neapolitan:
It may increase in a while, but at the moment, the ATCF says it's still but a disturbance, and not yet anywhere close to 50-60 knot tropical storm:

AL, 97, 2013100218, , BEST, 0, 191N, 858W, 30, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
its gonna take a little bit it only started a good cyclonic turn right around lunch time
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Quoting 648. Neapolitan:
It may increase in a while, but at the moment, the ATCF says it's still but a disturbance, and not yet anywhere close to 50-60 knot tropical storm:

AL, 97, 2013100218, , BEST, 0, 191N, 858W, 30, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, S,


If you look at my post I said 45mph Karen. However it would appear stronger based on sat.
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BP evacuating some workers from oil, natural gas platforms in the Gulf of Mexico due to low-pressure system that could strengthen - @Reuters
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The line of convergence to the east is stealing energy from the circulation. The last invest through the NW Caribbean had a similar line of convergence trailing the circulation.
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Tropical Depression :)
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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 18:48Z
Date: October 2, 2013
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: 22

18:48:30Z 18.050N 85.333W 977.1 mb
(~ 28.85 inHg) 282 meters
(~ 925 feet) 1009.0 mb
(~ 29.80 inHg) - From 165° at 11 knots
(From the SSE at ~ 12.6 mph) 24.3°C
(~ 75.7°F) 21.3°C
(~ 70.3°F) 11 knots
(~ 12.6 mph) 12 knots
(~ 13.8 mph) 0 mm/hr
(~ 0 in/hr) 12.0 knots (~ 13.8 mph)
109.1%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 18:39:00Z (first observation), the observation was 170 miles (274 km) to the E (97°) from Chetumal, Quintana Roo, México.

At 18:48:30Z (last observation), the observation was 192 miles (309 km) between the ENE and E (79°) from Belize City, Belize.
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653. Skyepony (Mod)
That lowest pressure was actually just into those west winds. It's just forming. That slightly ill stacked from the surface to ~975' shows in the HDOBs.
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Quoting 648. Neapolitan:
AL, 97, 2013100218, , BEST, 0, 191N, 858W, 30, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
Yay 30kts.
Member Since: June 11, 2013 Posts: 20 Comments: 2781
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650. FOREX
Quoting 649. cajunkid:
I bet we have Karen by this evening. Just saying.


nah.
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I bet we have Karen by this evening. Just saying.
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97L may very well increase in a while, but at the moment, the ATCF says it's still but a disturbance, and not yet a depression--much less the high-end tropical storm some are claiming. As TA13 says, looks can be deceiving:

AL, 97, 2013100218, , BEST, 0, 191N, 858W, 30, 1007, DB, 34, NEQ, 0, 0, 0, 0, 1010, 150, 90, 0, 0, L, 0, , 0, 0, INVEST, S,
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647. whitewabit (Mod)
Member Since: August 17, 2005 Posts: 362 Comments: 31358
646. Skyepony (Mod)
Quoting 634. Tropicsweatherpr:


No West Winds found yet?


There was a decent bit of light west winds found 0-9 kts.
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Invest 97L has probably become organized enough to be a tropical depression according to recon. Probably no Karen until tomorrow.
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Quoting 640. kmanislander:


Comes back to our conversation this morning about this system still struggling to get it together


Yep.
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Quoting 641. HighTideNPcola:


Glad to have the chaperones on the blog. What would we do without their "I know it all" opinions. (rolling eyes)


What are you even talking about? I correct someone who is badly misinforming the blog and now I'm a know-it-all? K.
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1008.8 w/ 33 knot gust at bouy 42056
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Quoting 581. MississippiWx:


They are and have been going through the "center". Nothing but a whole page of 1008mb pressures. This is very broad.


Glad to have the chaperones on the blog. What would we do without their "I know it all" opinions. (rolling eyes)
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Quoting 639. MississippiWx:
Because of proximity to land and future impact on the US, they might declare it a TD. Satellite presentation is another reason. Otherwise, the guts of the system are very very suspect for classification. Need to see the eastern side.



Comes back to our conversation this morning about this system still struggling to get it together
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Because of proximity to land and future impact on the US, they might declare it a TD. Satellite presentation is another reason. Otherwise, the guts of the system are very very suspect for classification. Need to see the eastern side.

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Quoting 630. opal92nwf:

And the more it strengthens and fortifies itself now, the better it will fare in the GOMEX.
exactly cause once in the gulf a weak system will likely not fair too well but a stronger system may be able to hold its own
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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 18:38Z
Date: October 2, 2013
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: 21

18:38:30Z 18.233N 85.717W 979.3 mb
(~ 28.92 inHg) 258 meters
(~ 846 feet) 1008.4 mb
(~ 29.78 inHg) - From 169° at 6 knots
(From between the SSE and S at ~ 6.9 mph) 24.4°C
(~ 75.9°F) 23.6°C
(~ 74.5°F) 7 knots
(~ 8.0 mph) 4 knots*
(~ 4.6 mph*) 1 mm/hr*
(~ 0.04 in/hr*) 3.4 knots* (~ 3.9 mph*)
57.1%*
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 18:29:00Z (first observation), the observation was 171 miles (274 km) to the E (85°) from Chetumal, Quintana Roo, México.

At 18:38:30Z (last observation), the observation was 170 miles (274 km) to the E (96°) from Chetumal, Quintana Roo, México.
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Large feeder bands are developing.
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This is still a trough of low pressure in the NW Carribean around 19.4N and 86W this will not be classified at 5pm... 20% chance
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Quoting 629. Skyepony:
Recon found 1008.4mb


No West Winds found yet?
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Quoting 622. SuperStorm093:
I find it so funny, when people wishcast with NO BACKING based off the HH and everything, no one ever says anything to them. But the moment I say something about a storm not forming or preventing, I get hated and called a troll lol. Just shows what you guys are here for. The CAT 5 devastating storms.


It is not what you say but how you say it. You seem like you are probably young and have not learned how to speak tactfully yet. You have made good points, but it is how you have delivered the info that is taken the wrong way.
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97L is probably on the verge of becoming a tropical cyclone pending further organization of the surface center. Overall the satellite presentation is great.
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631. IKE
1008.3 mb
(~ 29.78 inHg)
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Quoting 606. TropicalAnalystwx13:

I often tell people that say a storm won't be bad based on how it looks at the time that a system's current appearance has nothing to do with how it will eventually turn out. The opposite applies now. It has a decent structure but that doesn't mean it's destined to be a monster, especially since wind shear and dry air will be a problem in the Gulf.

And the more it strengthens and fortifies itself now, the better it will fare in the GOMEX.
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629. Skyepony (Mod)
Recon found 1008.4mb
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Quoting 610. opal92nwf:

Although one thing we're pretty certain about is:

97L ain't gonna be no 95L! lol


There's a lotta warm water out there and a large even a week circulation could spin up a lot of energy. And I'm not wishcastin' I always wish for fair winds and good times!!!
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627. Skyepony (Mod)
Broad yes. Looking at the google mapped one I wouldn't be shocked by a vortex message. 97L is looking good for this time of day..
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Broad or not, there are winds and pressure to support a td.



Still has a long ways to go though, no doubt. We'll see how it looks this evening. There's beginning to be some dry gaps between convection and clouds have warmed quite a bit recently aside from band on east side of center. Looks like it's still trying to consolidate.
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Quoting 597. LargoFl:
Pressure at a low 990 MB at landfall..thats Strong...


Geez. the GFS keeps nudging landfall further south down the coast huh. Should we in central and southern Fla. be concerned Largo?
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Quoting 615. beell:


It was a very, very, snide comment dj. Run back through it.

;-)


LOL - I'm slow on the uptake today . . . forgive me ;)
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I find it so funny, when people wishcast with NO BACKING based off the HH and everything, no one ever says anything to them. But the moment I say something about a storm not forming or preventing, I get hated and called a troll lol. Just shows what you guys are here for. The CAT 5 devastating storms.
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Product: Air Force High Density (HDOB) Message (URNT15 KNHC)
Transmitted: 2nd day of the month at 18:28Z
Date: October 2, 2013
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: 20

18:28:30Z 18.733N 85.700W 977.2 mb
(~ 28.86 inHg) 278 meters
(~ 912 feet) 1008.5 mb
(~ 29.78 inHg) - From 250° at 4 knots
(From the WSW at ~ 4.6 mph) 24.5°C
(~ 76.1°F) 22.9°C
(~ 73.2°F) 5 knots
(~ 5.8 mph) 6 knots
(~ 6.9 mph) 0 mm/hr
(~ 0 in/hr) 4.8 knots (~ 5.5 mph)
120.0%
Time Coordinates Aircraft
Static Air Pressure Aircraft
Geopotential Height Extrapolated
Surface Pressure D-value Flight Level Wind (30 sec. Avg.) Air Temp. Dew Point Peak (10 sec. Avg.)
Flight Level Wind SFMR
Peak (10s Avg.) Sfc. Wind SFMR
Rain Rate Estimated Surface Wind (30 sec. Avg.)
Using Estimated Reduction Factor Peak Wind at Flight Level to
Est. Surface Reduction Factor

HDOB Observations

Independent Calculations from Tropical Atlantic

At 18:19:00Z (first observation), the observation was 151 miles (242 km) to the SSE (153°) from Cancún, Quintana Roo, México.

At 18:28:30Z (last observation), the observation was 171 miles (275 km) to the E (85°) from Chetumal, Quintana Roo, México.
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This is not what you want to see if you want a system to strengthen quickly. As has been the case the ENTIRE time, it is a slow organization. It has gradually improved each day. It might make tropical depression status tonight. Winds are very light and circulation broad for now.

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It is a very large question mark - complete with the little dot at the bottom.
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97L is a lot of things, but definitely not a tropical cyclone.
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Gonna take a break from the action but just noting that lots of non-regulars come on the Blog for information, and specifically Dr. Masters excellent discussions, when a storm actually threatens any part of Conus.

Be mindful of that fact and try to keep it cool and civil....In terms of those that may be threatened by this system, your Official source is NHC (National Hurricane Center) and their advisories. Given the time-tables for this system once it gets into the Gulf, your best bet is to keep an eye on, and take precautions, based upon the Official 3-Day track from NHC.

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616. FOREX
Quoting 612. BrandiQ:
Is this really a panhandle storm or should anyone on the gulf be watching... this I believe is where Wilma formed and about this time in 05


It's up in the air right now.
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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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