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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Area forecast discussion
National Weather Service New Orleans la
341 PM CDT Wednesday Oct 2 2013


Long term...
the main focus late week through the weekend relates to the tropics.
A tropical wave is currently tracking northwest across the western
Carribean just east of the Yucatan. A hurricane hunter aircraft is
currently flying through the system to investigate. The latest from
the National Hurricane Center currently is calling for a 70 percent
chance of this wave developing into a tropical cyclone in the next 5
days. Medium range models send mixed messages on the development of
the wave. The European model (ecmwf) keeps it open while the GFS suggests a closed
circulation develops. These models were not designed to forecast
cyclogenesis of tropical cyclones. However... can give a good idea
of timing.
Unfortunately...large differences between the two at this
time. The GFS brings the tropical system across the coastal waters
Friday night/Saturday morning. European model (ecmwf) about 24 hours slower with a
similar but slightly further west track. The main determining
factor is approaching upper trough and associated cold front.
The
initial closed upper low will drop out of the Pacific northeast
towards the Rocky Mountains. From there the low will curl northeast
towards the upper Mississippi River valley while the base of the
trough still surges south and east on Saturday. The GFS has been
more accurate with faster solutions with the most recent couple
frontal passages which leads to leaning towards it vs the European model (ecmwf). If
thats the case and the County Warning Area remains on the western side of the
tropical system...most of the rain will remain east of the area with
only coastal waters and adjacent parishes/counties being impacted
with very rough seas and coastal flooding. If upper trough is
slower...the tropical system will make it further north before
curving northeast. At this time...the general consensus of model solutions
bring the trough in faster so the tropical system curves northeast
earlier but the range does go from the western side of the County Warning Area to
the Florida Panhandle so it remains to be seen which Route it/ll
take.
No big changes made to probability of precipitation this weekend but may need too drop
probability of precipitation if on the dry side of things.
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1115. GatorWX
Doing pretty well for time of day and general lack of core.

Member Since: January 1, 2008 Posts: 0 Comments: 3783
Based on what I'm seeing I have to agree with the center relocating to the ne with the mlc. That might have a better chance now. Will see.
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wow look at the coc visible loop
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Quoting 1070. IKE:
1007.0 mb
(~ 29.74 inHg)
Weather related..."The Rain Song" George Harrison was the inspiration
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The low level center appears to be near 20n and 85w, where the MLC is co located. Convection is on the increase in this location even during DMIN and this will likely create a dominating surface low, further northeast of the dying low hurricane hunters were sampling, they need to head northeast.
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1110. Torito
Quoting 1103. PalmBeachWeather:
You can call me SIS


sarcasm, SIS.
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Looking so good now!:)
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I must say-I've lurked here for a loooong time and I must say-in recent months, theres been waay too much quarreling. It's convinced Gro to leave :( and as much as I love the info, the sites etc you guys post, I have to leave now because the quarreling. I might come back later but its really annoying to listen to. This is the weakness of this blog. Its a great forum filled with smart people. I have greatly expanded my knowledge of the weather here. I would love to continue to do that but there's too much fighting. I would ignore people but it seems everyone's joining in. I hope this can get cleared up.
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Quoting 1093. hydrus:
O.K. I am goin out on a tree. I say this sucker gets a moniker by 5pm tomorrow..:)


May get it shortly if the HH can verify a new center. The old location they were looking at would not have made the grade.
Member Since: August 19, 2006 Posts: 0 Comments: 15865
1105. will40
should see W winds on next pass
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Wow if I went by this I'd say it was a TS but like some have been say under the hood it needs work.. The mechanic will fix the problem shortly...LOL
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Quoting 1102. Torito:


sarcasm, bro.
You can call me SIS
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1102. Torito
Quoting 1092. PalmBeachWeather:
NO


sarcasm, bro.
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Largest inhibitor at this time is broad structure. However, it is trying to consolidate it seems. Yes, dry air is a forward factor, but the moisture field is expanding around the system as well. CIMSS shear map shows moderate shear with a nice anticyclone overheard. Current environment would lend credence to further consolidation and an improving structure. These systems are strange, as we've seen very poignantly this season, and some systems can fight off single inhibitors like the dry air or shear. It's definitely capably of nurturing itself, growing its own moisture field, especially with a slow forward speed and the anticyclone overhead. We'll see before too long. Consolidation is the key right now, getting vertical, producing moisture.





Member Since: July 9, 2006 Posts: 184 Comments: 29610
Quoting 1081. clwstmchasr:


I thought you liked to discuss weather? This is not discussing, you are just throwing out darts.

I've been lurking for a good part of the day, and I have to agree with this. He's been just throwing darts without the real facts on what's going on.
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Quoting 1091. TropicalAnalystwx13:


That would be the spot for a new center depending on what they find after making a few passes
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1098. GatorWX


What happened??

Member Since: January 1, 2008 Posts: 0 Comments: 3783
A whole page of 1007.1mb pressures. Very broad is still right, but looks classifiable. Winds still very weak.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
Quoting 1091. TropicalAnalystwx13:
Guys, is that a pinhole eye I see? ;)

JK
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According to the data by HH so far this can still be classified, I suspect before the mission is over we'll have TS Karen.
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1094. Torito
Pressure still dropping.

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1093. hydrus
Quoting 1069. kmanislander:


Many weak and disorganised systems look really potent on loop imagery but lack the machinery down in the engine room. Remember Debby some years ago in the Caribbean ?. If loop imagery was the deciding factor it would have been classisifed a 50 MPH TS however the true position was it was nothing more than a potent wave looking like a TS.

97L is a bit like that. Barring some revelation from data not yet found by the HH this still has work to do
notwithstanding how it looks from aloft.
O.K. I am goin out on a tree. I say this sucker gets a moniker by 5pm tomorrow..:)
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Quoting 1090. Torito:


Wow, Bamm looks very reliable there....... -.-
NO
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Member Since: July 6, 2010 Posts: 113 Comments: 32527
1090. Torito
Quoting 1053. LargoFl:


Wow, Bamm looks very reliable there....... -.-
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Quoting 1077. Drakoen:


The joke went over your head :(
Wooooosh
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Quoting 1077. Drakoen:


The joke went over your head :(


Im on my phone, lots going on, so I really wasn't paying attention.
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Quoting 1081. clwstmchasr:


I thought you liked to discuss weather? This is not discussing, you are just throwing out darts.
The topic of what I just said is about the weather. salty
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Quoting 1079. GatorWX:


looks like it could be showing a sign a organization finally! look at the blowup around the COC
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1085. Drakoen
If that is where the system is then it is pretty much vertically stacked and farther northeast than originally thought.
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Center reforming to the NE near 20N/85W
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Quoting 1065. hurricanehanna:


side note...my daughter rides horses and in the Halloween Show she will be dressed up as Si and her horse will be Phil.... do you know how hard it is right now to find a grey beard? lol There will be a lot of Duck Dynasty trick or treaters this year.
That's cool ... I bet there will be lot's of the Dynasty gang for Halloween
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Just checked latest models. Looks to me if they are increasing in intensity. Looks like the GFS, HWRF and GFDL have a strong TS or Hurricane impacting NWFL.
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Quoting 1074. CybrTeddy:
1007mb, 30mph looks right based on the latest recon pass.


ATCF file says 35kts.
Member Since: July 15, 2006 Posts: 17 Comments: 10284
1079. GatorWX

Member Since: January 1, 2008 Posts: 0 Comments: 3783
Seems to me the circulation is farther north than what they suspected.
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1077. Drakoen
Quoting 1072. Hurricanes101:


Not sure, but the maps I am seeing shows the western gulf, not the NW Caribbean.


The joke went over your head :(
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Quoting 1065. hurricanehanna:


side note...my daughter rides horses and in the Halloween Show she will be dressed up as Si and her horse will be Phil.... do you know how hard it is right now to find a grey beard? lol There will be a lot of Duck Dynasty trick or treaters this year.
My grandaughter wants to be FLO the Progressive girl for Halloween...The white outfit and the "RED" lipstick....
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1075. LargoFl
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1007mb, 30mph looks right based on the latest recon pass.
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This system has the appereance of a strong ts which at current I believe its just a minimal ts.This things can be very decieving just remember Ernesto of last year.
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Quoting 1068. Drakoen:


They have a glitch or the maps? Ambiguous given the days events


Not sure, but the maps I am seeing shows the western gulf, not the NW Caribbean.
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1071. Drakoen
***...1007mb pressure minimum 19.950N 85.233W with supporting winds...***
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1070. IKE
1007.0 mb
(~ 29.74 inHg)
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Quoting 1045. hydrus:
Overall, this system looks rather impressive. I believe there are a couple of small upper level features that have kept 97L from organizing quickly other than dry air.


Many weak and disorganised systems look really potent on loop imagery but lack the machinery down in the engine room. Remember Debby some years ago in the Caribbean ?. If loop imagery was the deciding factor it would have been classisifed a 50 MPH TS however the true position was it was nothing more than a potent wave looking like a TS.

97L is a bit like that. Barring some revelation from data not yet found by the HH this still has work to do
notwithstanding how it looks from aloft.
Member Since: August 19, 2006 Posts: 0 Comments: 15865
1068. Drakoen
Quoting 1063. Hurricanes101:
Some of you showing recon maps have a glitch. Looks like you are showing recon in the western gulf.


They have a glitch or the maps? Ambiguous given the days events
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What cooler waters? Huh? Waters are plenty warm.





Member Since: July 9, 2006 Posts: 184 Comments: 29610
Not impressed at all, no winds really. And DMIN is about to rip whatever it accomplished apart.
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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.