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 Terradad:
Hello. Could a stronger system disrupt the shear in the N Gulf? Or will the strength of the system have no impact on the shear? Thanks for any replies.


The monster trough in the Central Plains will shear the system and inject low PWATS as well, which will probably keep it to a moderate tropical storm at best.
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Quoting kabloie:
GFS had it cruising the channel. It was early with that.


The GFS had it shooting the gap then the front picking it up and bringing it NE towards the Florida panhandle
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1964. KEEPEROFTHEGATE (Mod)
T.C.F.A.
97L/XX/XX/XX
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1963. GatorWX
Upper shear:

Member Since: January 1, 2008 Posts: 0 Comments: 2964
1962. Patrap
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1961. palmpt
Quoting 1955. Terradad:
Hello. Could a stronger system disrupt the shear in the N Gulf? Or will the strength of the system have no impact on the shear? Thanks for any replies.


A stronger system has a chance to avoid some shear, but the shear in the northern Gulf will impact the storm. The weaker the storm the more impact from shear.
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Quoting 1959. beell:
Possibly a little southerly shear just now impinging on the west side of 97L.

If the obs can be trusted, Surface METARS at Cancun and Cozumel really don't show much sign of deepening since recon left. I am assuming any surface center would not be far off the Yucatan coast. (60-70 nm?)



Stop it with your reasonable posts. This is a quickly deepening storm.

;-)
Member Since: July 15, 2006 Posts: 17 Comments: 10247
1959. beell
Possibly a little southerly shear just now impinging on the west side of 97L.

If the obs can be trusted, Surface METARS at Cancun and Cozumel really don't show much sign of deepening since recon left. I am assuming any surface center would not be far off the Yucatan coast. (60-70 nm?)

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1958. palmpt
Quoting 1936. GatorWX:
Kind of looks as if mid shear may be driving some drier air into the center.



Anyone else think it may be way up there in the nw semi?



It does look a bit dry on the n side presently.


It has plenty of moisture. It's mostly stacked. I think it's closed off and already a TS. Frankly, it may be ramping up. I predict a nail biter... May get to cane... Then it hits shear and tappers off. It's going to be an interesting 24 hours. But the atmosphere is right for intensification. A K storm that gets much attention.
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Maybe something like this at landfall?
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1956. Patrap
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Hello. Could a stronger system disrupt the shear in the N Gulf? Or will the strength of the system have no impact on the shear? Thanks for any replies.
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According to the CIMSS vorticity analysis the system isn't quite stacked yet. The 850mb vorticity is offset to the west of the mid and upper levels. Actually that nice blow up may actually be due to a spin-up in the mid levels.

I am thinking that due to the large anticyclone over it and the present trend, the system may form an LLC to the east of where the models have initialized. It is going to be interesting to watch.
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Storm looking better every frame tonight. Developing nicely I believe. it will be further right also, guess Cedar Key Cat1 or 2. No weatherman here, but at this time of year they always seem right of the forecast. The fuel below this storm is going to trump the dry air.
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1952. GatorWX


Member Since: January 1, 2008 Posts: 0 Comments: 2964
Quoting 1909. hamla:
wonder where cantori is headed?


He loves Pensacola Beach. Seems to be his go to spot.
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1949. kabloie
GFS had it cruising the channel. It was early with that.
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1948. GatorWX
East central Gulf wave heights... :)

Member Since: January 1, 2008 Posts: 0 Comments: 2964
Quoting 1941. StormTrackerScott:


A cane tomorrow IMO
you also said it would be a TD yesterday, so dont listen to this forecast folks. listen to the professionals on this trickly forecast
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Quoting 1933. GeoffreyWPB:


Are you seeing an east movement to it Scott?


FL Big Bend
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1945. emcf30
Animated model tracks for AL97

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Quoting 1905. TropicalAnalystwx13:
One can see how dry air to the west is inhibiting upper-level outflow from expanding in that direction like it is in the other three quadrants. This probably won't get into the core until wind shear increases prior to landfall over the weekend though.

I could see a strong tropical storm at peak, which is once again up from my previous forecast of a moderate tropical storm. *sigh*

97L really has been an over-achiever though.



You can easily see the disturbance in the southeast pulling 97L northwards into the GOM. I agree, classification at 5 a.m. at the earliest. Most likely 11 a.m. tomorrow.

That disturbance should continue to lift 97L north, then the front coming in should swoop it eastward. Sticking to a Big Bend landfall... Too far east in most people views, but I'm going by what I'm seeing on the loops.
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1943. GatorWX
Member Since: January 1, 2008 Posts: 0 Comments: 2964
Not sure on the movement. It appears as though the LLC relocated to the NNW from where it was earlier this afternoon to be co-located with the mid-level center. Not certain if this NNW jog is a new sustained track. The system is getting better organized and should strengthen over the short term. It seems to be underneath an overall favorable upper level environment and could be a tropical storm by 5:00AM eastern time tomorrow morning. Looks as though it should make a landfall between the mouth of the MS River and Appalachicola, FL probably as a mid grade tropical storm. Should be a fast mover once it gains a little more latitude and gets caught up in the strong SW flow dominating the northern GOMEX currently. Rain amounts should not be very substantial and at most in the highest rain areas 3-5 inches. Will examine again in the morning.
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Quoting 1935. EyEtoEyE:
. Hey Scott , is Karen going to be a cane ?


A cane tomorrow IMO
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1940. SirCane
Did the NHC lose its funding due to the Gov Shutdown? Are we on our own? LOL
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Quoting 1935. EyEtoEyE:
. Hey Scott , is Karen going to be a cane ?


Tampa is safe.
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1938. GatorWX
Just got home, so bare with me if I'm way off.
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1937. beell
Past 6 hrs METARS Obs

Cancun
Cozumel
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1936. GatorWX
Kind of looks as if mid shear may be driving some drier air into the center.



Anyone else think it may be way up there in the nw semi?



It does look a bit dry on the n side presently.
Member Since: January 1, 2008 Posts: 0 Comments: 2964
Quoting 1911. StormTrackerScott:
The deeper the system the more east it moves. Probably 1003 pressure right now and falling fast.

. Hey Scott , is Karen going to be a cane ?
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Quoting 1916. Tribucanes:
I'd be very surprised if this isn't reclassified by 11PM. While this is not officially Karen yet, this is clearly a TS at this point. This gets stacked overnight and we're likely to see takeoff to near hurricane strength by tomorrow.


I agreed with not classifying it at 5 pm, and I'd rather wiat for the next recon plane before coming to a conclusion, but I would be inclined to believe this is a minimal TS now. A steadily deepening one at that.
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Quoting 1911. StormTrackerScott:
The deeper the system the more east it moves. Probably 1003 pressure right now and falling fast.



Are you seeing an east movement to it Scott?
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Got to admit that's as good of a consensus you'll ever get with a developing system and all and will likely reflect the cone of uncertainty.

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Quoting 1911. StormTrackerScott:
The deeper the system the more east it moves. Probably 1003 pressure right now and falling fast.

Seems to close to ignore...
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Looks like surf for the weekend here on the panhandle. Praying this thing does'nt to anything crazy...
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I see the overall as North, I think this will be a FL Storm.
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palmpt didn't I tell you and Pat about Karma :).Looks like it will come in the form of Karen.LOL.I'll be enjoying the much need rain Karen will bring so no worries here.
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1927. Pallis
Quoting 1923. seer2012:

Are you allowed to cut and splice the models to direct the storms to your preferred destination? jk
Yes.
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Quoting 1922. ncstorm:


Interesting that some ensembles have tracks in the MDR.
Member Since: April 29, 2009 Posts: 75 Comments: 14253
1925. Pallis
Quoting 1871. weathermanwannabe:
Once NHC re-designates the system, whether to TD or TS, they start issuing their track forecasts and the 3-Day track has a pretty good track record.

Can't wait for it to finally happen so that folks can settle down and concentrate on the most important thing; to take appropriate precautions if needed, in accordance with the Official Source, regardless of what anyone on here has to say (including myself).
If you live on the Gulf coast to 50 miles inland you are supposed to already be prepared during Hurricane season. It is like chopping wood for winter. You know it is coming lazy grasshopper. History tells us that, not some official source.
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1924. Patrap
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Quoting 1837. sar2401:

You are correct, although none of the models are very trustworthy at this stage of the game. I'm sure if you lived in, say, Orlando, and wanted to wishcast a storm your way, there's a madel buried in that mass of spaghetti, I'm sure there's one in there that shifted ever so slightly east.

Are you allowed to cut and splice the models to direct the storms to your preferred destination? jk
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1922. ncstorm
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1921. Patrap


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1920. EllasD
Us ppl of Biloxi DO NOT want a K named storm
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Quoting 1913. TropicalAnalystwx13:

Recon isn't departing until 11pm EDT. It will take an hour or two to reach the center, and then a while to investigate the actual storm. If it's to be designated tonight, I'd go with 5am EDT.
Oh I just read that on Isaac's blog. :D
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1918. palmpt
Quoting 1911. StormTrackerScott:
The deeper the system the more east it moves. Probably 1003 pressure right now and falling fast.



The stronger the more poleward. The determining factor is the speed of the front, which is slower than anticipated.
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Quoting 1908. GTstormChaserCaleb:
If this is not designated a tropical storm at 11PM, I'm seriously going to eat my keyboard. :P


If this is not a tropical storm, then I never seen one!
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I'd be very surprised if this isn't reclassified by 11PM. While this is not officially Karen yet, this is clearly a TS at this point. This gets stacked overnight and we're likely to see takeoff to near hurricane strength by tomorrow.
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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.