92L Poised to Develop in Gulf of Mexico; Erin Struggling in Far Eastern Atlantic

By: Dr. Jeff Masters , 2:09 PM GMT on August 16, 2013

Tropical wave 92L crossed over Mexico's Yucatan Peninsula overnight, and the center of the disturbance is now located in the Gulf of Mexico along the west coast of the Yucatan Peninsula. Satellite loops show that 92L has a well-developed surface circulation, but there are no heavy thunderstorms near the center. A moderate-sized region of heavy thunderstorms does lie to the northeast and east of the center, over Cancun, Cozumel, and southwards to Belize. An upper-level low pressure system over the Gulf of Mexico is pumping dry air into 92L, slowing development. Wind shear is a moderate 10 - 20 knots over the the wave, which should allow slow development today. The hurricane hunter flight scheduled for today has been cancelled.


Figure 1. MODIS satellite image of 92L taken at 1:30 pm EDT Friday August 16, 2013. Image credit: NASA.

Forecast for 92L
The 12Z Friday SHIPS model forecast predicts that 92L will remain in an area of low to moderate wind shear through Saturday, and ocean temperatures will be a favorable 29 - 30°C. The topography of the Southern Gulf of Mexico's Bay of Campeche can aid in getting a storm spinning more readily, as well. Given these favorable conditions for intensification, 92L should be able to become a tropical depression by Saturday, and a tropical storm by Sunday. A trough of low pressure over the northern Gulf of Mexico will dip down by Sunday over the Central Gulf of Mexico, increasing the wind shear to a high 20 - 30 knots just to the north of 92L. This trough may also be able to pull the storm northwestwards to a landfall in Texas on Monday or Tuesday, as the 00Z Friday runs of UKMET and NAVGEM model predict. If 92L does follow this more northwesterly path, intensification into a strong tropical storm would be difficult, due to the high wind shear. An alternate scenario is presented by our two top-performing models, the European and GFS. They predict that 92L will take a nearly due west track, resulting in a landfall south of Tampico, Mexico on Monday. The storm would have more of an opportunity to strengthen in this scenario, since wind shear would be lower. Either scenario is reasonable, and residents of the Mexican and Texas Gulf Coast should anticipate the possibility of a tropical storm hitting the coast as early as Sunday night. Regardless of 92L's track, a flow of moist tropical air along the storm's eastern flank will form an atmospheric river of moisture that will bring a wide swath of 4+ inches of rain to the Gulf Coast from Louisiana to the Florida Panhandle over the next few days. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 92L a 50% of developing by Sunday, and a 60% chance of developing by Wednesday. I put these odds higher, at 70% and 80%, respectively.


Figure 2. MODIS satellite image of Tropical Depression Erin taken at 10:30 am EDT Friday August 16, 2013. At the time, Erin had maximum sustained winds of 35 mph. Image credit: NASA.

Tropical Storm Erin
Tropical Storm Erin is over the far Eastern Atlantic off the coast of Africa, and continues west-northwest at 15 mph. Erin is small and weak and has lost nearly all of its heavy thunderstorms, as seen on satellite loops. This is probably due, in part, to the fact the storm is over waters of 25.5 - 26°C, which is a marginal temperature for tropical cyclones. Erin is also having trouble with dry air from the Saharan Air Layer (SAL), and the storm's west-northwest motion is beginning to cut Erin off from a moist source of air to its south--the semi-permanent band of tropical thunderstorms called the ITCZ (Inter-Tropical Convergence Zone.) The latest 00Z runs of the major global computer models, except for the GFS, call for Erin to dissipate by early next week. Given Erin's struggles today, I expect the storm will be dead by Sunday.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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Quoting 1223. moonlightcowboy:


I think the difference in yours/Levi's/Kori's scenario the system would become subtropical. The scenario I'm thinking of, I guess, is the system remaining a true, warm-core characteristic. Subtropicals take on a messy characteristic in appearance. The scenario I've perplexed myself with imagining is having a rotating surface low that becomes vertically aligned directly underneath the ULL, maybe meeting at the mid-levels, and remaining a true, warm-core tropical system, very neat and definitively tropical in appearance and structure.


Thanks for clarifying what you meant. Would this not occur if the ULL circulation dissipates, yet the LLC moves under the moisture and is able to fire up thunderstorms? Working its way up from the surface? In that case, I am not sure that would be considered the two merging.

However, I am only speculating - and someone with greater expertise would be better to comment.
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Quoting 1223. moonlightcowboy:


I think the difference in yours/Levi's/Kori's scenario the system would become subtropical. The scenario I'm thinking of, I guess, is the system remaining a true, warm-core characteristic. Subtropicals take on a messy characteristic in appearance. The scenario I've perplexed myself with imagining is having a rotating surface low that becomes vertically aligned directly underneath the ULL, maybe meeting at the mid-levels, and remaining a true, warm-core tropical system, very neat and definitively tropical in appearance and structure.

I guess I should have made myself a bit clearer initially. ;)



And, I just don't think this has ever happened like that. And, if it has, I sure as heck cannot remember it, and most certainly doesn't happen often.
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1239. sar2401
Quoting Grothar:


The last thing we need is an XXX.

LOL. I was thinking the same thing but I thought I'd let you take the ban this time. :-)
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Quoting 1232. L1990:
im about to jump out of my chair starring at this screen waiting for convection to fire its driving me up the wall


DMax with ex-Dorian and now 92L has normally started to kick in around midnight EDT.
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Quoting 1225. Rmadillo:


Maybe at 11?
It would be a longshot I think, but at 20/1...I'd be in! Maybe more 11AM tomorrow. The NHC is hinting with the probability shift at 8 that it's more now or never.
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Quoting 1208. Rmadillo:
If that center we are identifying does in fact become dominant and move northerly, it will pass over some of the deepest Mojo in the GOM.

Axes up!

Looks like that LLC to the west of the YucAtan is completely faded away now.


Look at 21N, 91.5W. The LLC is still there, and appears to be running from the ULL.
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1235. sar2401
Quoting Rmadillo:


The NAM is one of the better models, except when it isn't.

The NAM is only good for storms that form and develop in waters directly off the CONUS. It's a very poor model in this situation.
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1234. Grothar
Quoting 1219. CosmicEvents:
We could even get a hybrid sub-TD with this set-up. For now I'm looking for convection flaring up, and where.


The last thing we need is an STD.
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I need to upgrade my system to Google Earth 2.0 with 10% more WV.

This 92L is very interesting, as many mentioned it would be last week.
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1232. L1990
im about to jump out of my chair starring at this screen waiting for convection to fire its driving me up the wall
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Quoting 1224. WXGulfBreeze:


That's what it's looking like - hope it stays that way (the worst stays to the East). Heard on the radio today that we had 17" of rain in July (half that a year ago, even less in 2011), more this month, and the ground is saturated.

Been a lousy beach season on the panhandle.


Panama City has had three feet of rain since June 1. We are waterlogged already.
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What is that big red area on that map that Mr Patrap posted between NOLA and 92L mean?
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Quoting 1224. WXGulfBreeze:


That's what it's looking like - hope it stays that way (the worst stays to the East). Heard on the radio today that we had 17" of rain in July (half that a year ago, even less in 2011), more this month, and the ground is saturated.

Been a lousy beach season on the panhandle.
a bit afraid it may take up with the more northern spin and starting heading West which in turn will bring the rain our way.
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So it looks like 92L just took a big jog south. Might help it later on given the BOC's spin inducing qualities, and the longer it takes to move north, the longer it will take to hit unfavorable shear.
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1227. sar2401
Quoting flhurricanesurvivor:
NWS predicting 3-10 inches here in the panhandle. I am hoping for the 3" here in Fort Walton, seems like east of us - Panama City and Tallahassee might get the worst of it.

But that rain won't be from 92L. It's from impulses that are traveling along a quasi-stationary front that's draped across the area. Each of these will drag Gulf moisture along and provide rain through the weekend. It really doesn't matter what 92L does, we will still get the rain from that quasi-stationary front.
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Via FB

NOAA NWS National Hurricane Center

An area of low pressure continues over the southwestern Gulf of Mexico, but the system remains poorly organized with the associated shower and thunderstorm activity located well to the east and northeast of the low center. Environmental conditions could become somewhat more favorable for development while the low moves generally toward the west-northwest during the next couple of days. It has a medium chance of becoming a tropical cyclone during the next 48 hours and five days.

Get the latest on the tropics anytime by visiting the NHC website at www.hurricanes.gov
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Quoting 1219. CosmicEvents:
We could even get a hybrid sub-TD with this set-up. For now I'm looking for convection flaring up, and where.


Maybe at 11?
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Quoting 1211. flhurricanesurvivor:
NWS predicting 3-10 inches here in the panhandle. I am hoping for the 3" here in Fort Walton, seems like east of us - Panama City and Tallahassee might get the worst of it.


That's what it's looking like - hope it stays that way (the worst stays to the East). Heard on the radio today that we had 17" of rain in July (half that a year ago, even less in 2011), more this month, and the ground is saturated.

Been a lousy beach season on the panhandle.
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Quoting 1210. daddyjames:


Not sure what would distinguish one from the other in your statement, but apparently it does happen. Visually, the same appears to be possibly occurring with 92L. But, too soon to call it, I suppose.


I think the difference in yours/Levi's/Kori's scenario the system would become subtropical. The scenario I'm thinking of, I guess, is the system remaining a true, warm-core characteristic. Subtropicals take on a messy characteristic in appearance. The scenario I've perplexed myself with imagining is having a rotating surface low that becomes vertically aligned directly underneath the ULL, maybe meeting at the mid-levels, and remaining a true, warm-core tropical system, very neat and definitively tropical in appearance and structure.

I guess I should have made myself a bit clearer initially. ;)
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Quoting 1217. VR46L:
The NAM has an interesting take on it

Synthetic Infrared 4 km NAM Nest Forecast


The NAM is one of the better models, except when it isn't.
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Quoting 1215. SuperStorm093:
dry air isnt rocket fuel
Wow here we have a newer comer who knows a lot more then some who have been on here for longer
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1220. VR46L
Quoting 1214. Rmadillo:


ROCKET FUEL is highly flammable.


Yep !!!

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Quoting 1213. Rmadillo:


I agree. Although even a STS will deliver some interestinginess.
We could even get a hybrid sub-TD with this set-up. For now I'm looking for convection flaring up, and where.
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Anyway this should be an interesting D-MAX tonite.

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1217. VR46L
The NAM has an interesting take on it

Synthetic Infrared 4 km NAM Nest Forecast
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1216. sar2401
Quoting GTstormChaserCaleb:
It's completely wrapped around the ULL giving an eye like appearance something similar to STS Andrea in 2007.


Seems like good evidence that, once the low is able to finally form and start up some convection of its own, a move to the west will finally begin.
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Quoting 1214. Rmadillo:


ROCKET FUEL is highly flammable.
dry air isnt rocket fuel
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Quoting 1212. SuperStorm093:
Lol at the CNN guy saying it could explode.


ROCKET FUEL is highly flammable.
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Quoting 1209. moonlightcowboy:



If this ULL indeed finds the surface and remains warm-core, that will surely be very interesting.


I agree. Although even a STS will deliver some interestinginess.
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Lol at the CNN guy saying it could explode.
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NWS predicting 3-10 inches here in the panhandle. I am hoping for the 3" here in Fort Walton, seems like east of us - Panama City and Tallahassee might get the worst of it.
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Quoting 1205. moonlightcowboy:



I'd like to watch the loop. Not trying to be difficult here, but I suspect "co-located" and actually merging/stacking themselves are still two entirely different things. The Lee post report sounds like they were in very close proximity and as a result, the warmcore storm finally became subtropical.

That may be what you and Levi are calling merging, I'm not, but will agree we've seen several become subtropical like Lee, but that's not what I'm saying. I'm saying this LLC and the ULL actually becoming vertically stacked, "merged" - not the same thing, imo.

Enjoy, carry on! ;) Not gonna argue.


Not sure what would distinguish one from the other in your statement, but apparently it does happen. Visually, the same appears to be possibly occurring with 92L. But, too soon to call it, I suppose.
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Quoting 1206. Rmadillo:
Never turn your back on a ULL possibly working down to the surface.



If this ULL indeed finds the surface and remains warm-core, that will surely be very interesting.
Member Since: December 31, 1969 Posts: Comments:
If that center we are identifying does in fact become dominant and move northerly, it will pass over some of the deepest Mojo in the GOM.

Axes up!

Looks like that LLC to the west of the YucAtan is completely faded away now.
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Quoting 1202. KoritheMan:


lol, even if this thing does hit us, I'm not bothered at all. It's a typical run of the mill wind and rain event for the northern Gulf Coast. Actually, we get more wind during a blustery cold front in December. ;)
You are due for a retired name storm.
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Never turn your back on a ULL possibly working down to the surface.
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Quoting 1190. daddyjames:


mlc read the final post-analysis of Lee at the NHC, then let us know what happened.



I'd like to watch the loop. Not trying to be difficult here, but I suspect "co-located" and actually merging/stacking themselves are still two entirely different things. The Lee post report sounds like they were in very close proximity and as a result, the warmcore storm finally became subtropical, and that we've certainly seen.

That may be what you and Levi are calling merging, I'm not, but will agree we've seen several become subtropical like Lee, but that's not what I'm saying. I'm saying this LLC and the ULL actually becoming vertically stacked, "merged" - not the same thing as becoming subtropical, imo.

Enjoy, carry on! ;) Not gonna argue.
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1204. Patrap
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Quoting 1201. Patrap:
I think that naked swirl will continue to dive south and dissipate with time, allowing the ULL to take over.
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Quoting 1197. unknowncomic:
All those folks in Louisiana that went out and bought supplies for 92L, no worry. Its a long season and you may still need them. If you don't, keep the receipt and return them.


lol, even if this thing does hit us, I'm not bothered at all. It's a typical run of the mill wind and rain event for the northern Gulf Coast. Actually, we get more wind during a blustery cold front in December. ;)
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1201. Patrap
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Quoting 1194. Tropicsweatherpr:
Hi Kori. Why NHC lowered to 40%? I wouldn't have touched the numbers to wait and see what happens tonight and tomorrow.


To be honest, I have no idea. The environment seems more favorable over the western Gulf, and actually seems to be improving overall. It's not great, but relative to 24 hours ago, it's a little better.
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Quoting 1181. sar2401:

What a nimrod. No models at all for 92L show it, but that sucker could explode at any time. OTOH, Erin is a dead duck, just forget, it has no chance. The AMS must be giving out certifications from Cracker Jack boxes lately. How embarrassing.



the news networks are run by idiots and weirdo progressives who just want to b.s. you one way or another....don't trust em, at best they are lying to you and at worst they are controlling you like big brother.....

you can really see how full of crap they are when the sensational stories calm down and they have to hype a storm to get market share to sell commercial time.....they are liars and the media is never to be trusted....
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1198. Patrap
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All those folks in Louisiana that went out and bought supplies for 92L, no worry. Its a long season and you may still need them. If you don't, keep the receipt and return them.
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I wonder if the weakening upper low north of the Yucatan won't try to work its way down to the surface with time? Last light visible images suggest that there is a definite cyclonic twist to the low clouds in that region, albeit not as well-defined as the official low-level swirl west of Campeche.

If that happens, I imagine the models would shift east again, probably to around Intracoastal City, Louisiana.

Granted, there's no explicit model support for this, but the GFS and ECMWF have frequently shown the energy associated with this broad disturbance being split in two.
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Wonder what an NHC track would be like if it were a TD?

Brownsville to Panama City would be InTheCone.
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Hi Kori. Why NHC lowered to 40%? I wouldn't have touched the numbers to wait and see what happens tonight and tomorrow.
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Lee deepened baroclinically; the central pressure was dropping even while the center itself was devoid of convection.

mlc, sorry, but that's the very definition of a surface low collocating/merging with an upper low. It's also one of the defining characteristics of subtropical cyclones.
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Quoting 1182. VR46L:
Watching the big picture .. the front seems to be about to capture the east of 92L... I really see a large rain event for Northern Gulf ... but doubt a storm for Western Gulf

Another piece of shortwave energy getting ready to exit off the coast of Texas, that might be able to change the steering and pull it north from its stationary position.
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1191. Patrap
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather