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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Wonder what happen Recon hasn't left yet?
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Have to go now. Back later
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It appears that there is a low level COC stabilizing at 17.0N 85W. Constant convection evident on Belize radar.

Can anyone post the steering currents? Slow internet down here.
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This is the time of day yesterday when that little troll got out of his cage. I wonder if we will see him again...
Member Since: October 20, 2012 Posts: 7 Comments: 2873
Quoting 253. MississippiWx:


Kman,

The answer to our question is probably an elongated center from north to south or NNE to SSW.


The vort at 10,000 feet shows the elongation. Very N to S oriented.

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Member Since: July 15, 2006 Posts: 171 Comments: 53841
990



The GFS is consistently the eastern outlier.
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That's a much better link.
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Florida Waterspout Chasers
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Not too bad at all, better than yesterday!
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Quoting 184. StormTrackerScott:


A relocation in like that would cause a big track shift. A shift like that would cause 97L to miss the Yucatan and go thru the Channel as the GFS showed yesterday.



Steering currents are your dependent variable(s) in a path equation here, not vort center, it won't make that much of a difference.


What could make a big difference is model initialization of initial conditions. Initial conditions are extremely crucial, but given the relatively tight model cluster with relative consistency in this early of a stage, a drastic change isn't likely.

I mentioned recently that the only thing that could really cause a significant shift right would be if 97L had strong deepening into a hurricane, which seems quite unlikely.
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Quoting 245. KEEPEROFTHEGATE:
hang on we gonna take it up a notch in a few
im hanging cant wait to see
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Quoting 234. MississippiWx:

If current trends continue we could see 97L wrap up quite nicely over the next 24-36 hours. Though it will likely only be able to attain 60-70 Mph winds while over the gulf.
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Quoting 247. kmanislander:
Vorticity picking up fast. Perhaps 97L has broken the cycle of boom and bust



Kman,

The answer to our question is probably an elongated center from north to south or NNE to SSW.
Member Since: July 15, 2006 Posts: 17 Comments: 10249
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97L looks like Joe Dirt, tail and all.
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Quoting 244. MississippiWx:


It has been tilted for basically its entire life. The mid-level center has constantly been to the northeast of the surface or near surface center. What I'm looking at is low cloud motions. Obviously, low cloud motions don't always tell the exact story. Pressures do. We will have to see what recon says if they fly.


Agree on that.
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992
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Lol.



That says 992mb, btw.
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Vorticity picking up fast. Perhaps 97L has broken the cycle of boom and bust

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Area forecast discussion
National Weather Service New Orleans la
811 am CDT Wednesday Oct 2 2013

Update...


&&

Previous discussion... /issued 413 am CDT Wednesday Oct 2 2013/


Long term...
the biggest challenge in the forecast comes in the long range
period as several factors play an important role in the forecast
for this weekend.A trough is expected to dip southeast across the
Pacific northwest towards the Rocky Mountains later this week.
Saturday into Sunday this feature will be amplifying as it tracks
across the middle section of the country. A cold front will be
marching south ahead of the trough towards the County Warning Area this weekend.
At the same time models depict a tropical low moving into the
northern Gulf of Mexico. Models are having a hard time resolving
this feature and probably will continue to have trouble with it
until it gets more developed. The hurricane center highlights this
area and has this disturbance at a 50 percent chance of becoming a
tropical cyclone over the next 3 to 5 days.

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
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Quoting 236. bigwes6844:
hmmm getting interesting i see GM bloggers!
hang on we gonna take it up a notch in a few
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Quoting 237. kmanislander:


I get the impression that the system is tilted overhead with the MLC displaced to the NNE of the surface low. I see the area you are referring to but the surface pressure there seems much too high to be the low center which leads me to wonder if the system is not vertically stacked at this time.

There is a long feeder band on the western side that loops all the way down to near 18 and 85 which is where the lowest pressure is presently located based upon available data.

Look at the inflow from the West over Roatan that appears to be feeding into the area near 18 and 85

See loop here


It has been tilted for basically its entire life. The mid-level center has constantly been to the northeast of the surface or near surface center. What I'm looking at is low cloud motions. Obviously, low cloud motions don't always tell the exact story. Pressures do. We will have to see what recon says if they fly.
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Quoting 214. Patrap:

Yeah, that's all quoted from here if anyone wants to know. "The A.B. Wood Low Head High Volume Screw Pump"
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242. eddye
kman a hater ignore him
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Quoting 203. LargoFl:
IF it makes that right hand turn it may miss that sheer up by the northern gulf coast..we need to stay alert...it may not weaken as much as currently thought if it Does make the turn.


The only chance this makes a right turn into the west coast of Florida is if it becomes much stronger than anticipated. Steering for a shallow cyclone strongly supports a track much further to our west. If this were a hurricane in the current position with initial conditions being the same, we would be talking anywhere from the Eastern Panhandle to southwest coast FL.

But(and a fairly confident but at that), I do not think it will each anywhere near he intensity to involve such a track.

You can never rule it out though, especially because tropical cyclone forecasting intensity is still of pretty bad skill.

I think there is good reason to expect 97L to remain weak in this case though.
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Member Since: July 15, 2006 Posts: 17 Comments: 10249
It is holding on to it's convection and has some nice outflow.

Member Since: October 20, 2012 Posts: 7 Comments: 2873
Quoting 221. MississippiWx:


Hard to tell at this point. Hopefully recon will be able to confirm. Regardless, the system is still not very organized. The pressures could be higher overall than originally thought.


I get the impression that the system is tilted overhead with the MLC displaced to the NNE of the surface low. I see the area you are referring to but the surface pressure there seems much too high to be the low center which leads me to wonder if the system is not vertically stacked at this time.

There is a long feeder band on the western side that loops all the way down to near 18 and 85 which is where the lowest pressure is presently located based upon available data.

Look at the inflow from the West over Roatan that appears to be feeding into the area near 18 and 85

See loop here
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hmmm getting interesting i see GM bloggers!
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Quoting 234. MississippiWx:


Well... 1000 mb heading for coast. Reasonable run so far. However, GFS haven't been doing great for Houston, TX as I noticed for WxChallenge so we'll see.
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Member Since: July 15, 2006 Posts: 17 Comments: 10249
Quoting 227. Patrap:


That thing looks like it can turn into a monster.
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I think the center is around 18.5-19N 85.5W. Take with a huge grain of salt of course.
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Thanks Dr. Masters, repost from last blog.
Quoting 1364. MississippiWx:


Lol. Ok, Scott. There are other people here who have kept up with this. I'm not going to argue about who is right or wrong with you. It's too childish. The evidence is back in the previous blog and this one and it speaks for itself.

Hey Everyone, I see Drew is holding the fort down, for now.
Just checking in.
We should see a moderate Tropical Storm for the central gulf coast, similar to what we saw with Andrea back in June, though the system may look a tad better depending on how shear and dry air impact the storm when it enters the Gulf. Besides 97L I wouldn't expect much more from the Atlantic for the next two weeks, but getting one to three more systems is a plausible outcome before the end of hurricane season.
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With the current movement I see it missing the Yuc and skirting just NE of it. It's already too far N IMO and moving NE. Just don't see it happening.
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Quoting 216. stormpetrol:

That still looks like a complete disconnect between the llc and mlc, just like yesterday. imho
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POSS T.C.F.A.
97L/XX/XX/
MARK
19.85N/85.25W
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FIM 7 294HR

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Still has work to do.

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Looking a lot more organized than 4 hours ago. I think MissWx's center guess is reasonable. With all the dry air living next door, I don't see much happening rapidly whether it breathes or not. They are flying into this, right? Need a recording of Gene Wilder about now: "It's alive, it's alive, it's alive!"
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Quoting 217. kmanislander:


The buoy at 20 N and 85 W has a pressure of 1011 mbs which makes a center at the suggested coordinates unlikely IMO.


Hard to tell at this point. Hopefully recon will be able to confirm. Regardless, the system is still not very organized. The pressures could be higher overall than originally thought.
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Look at 27HR it is back over the GOM
Quoting 212. LargoFl:
12z gfs is pushing it Into the yucatan now........
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she slips across just ne of the yuc with her feet just in shallow water
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Quoting 211. WaterWitch11:
had to google palatable

I was talking to my dad about the saints. he says that mr. brees does a lot for others and the he is not a hot dog shaking his bottom all over the field :)hope they have a great season.

Near Van Ness, San Francisco
Elevation
49 ft
Mostly Cloudy
Temperature
57.2 F
Feels Like 57.2 F


With 3 young Sons and a Beautiful Uptown Home, The Brees Family is alongside Archie and Miss Olivia Manning with Cooper, Eli, and Peyton.

; )

Drew delivered us unto the Promised Land.

He's a Demi God here.
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Quoting 204. MississippiWx:
19N 84.5W best estimate from me:



The buoy at 20 N and 85 W has a pressure of 1011 mbs which makes a center at the suggested coordinates unlikely IMO. Winds also out of the SSE at 17 knots which would be well below the winds the system is carrying.
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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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