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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1291. hydrus
Quoting 1281. ncstorm:


what were the words today to describe Erin..choking, at its end, dead, horrible, naked, terrible..

when will this blog learn?
Do not lump us all in with the inexperienced N.C.....Some of us got the smarts reel gould..:)
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It'll be interesting if current trends continue for the next 4 hours. We do appear to have a LLC with convection close east and west currently...it really should be a sub-TD right now based on sat, especially considering the proximity to Nola.
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1289. WxLogic
Good Evening... 92L merged with the ULL and taking advantage of the instability is creating...

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Pewa up to 45 knots.

CP, 01, 2013081700, , BEST, 0, 99N, 1749W, 45, 1004, TS, 34, NEQ, 40, 30, 10, 40, 1009, 180, 40, 0, 0, C, 0, , 0, 0, PEWA, D,
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LSU loop of GOM,
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Based on the CIMSS vorticity maps, I think I would get behind the idea that the ULL is trying to work down and might be causing yet another circulation duel as a result. In the last 3 hours the LLC we've been watching has lost some of its strength and vorticity is increasing to the NNE. If the LLC continues to move south though, it may be out of the picture in only a few hours, allowing this ULL to possibly work down unchallenged.

But we'll have to wait and see. This storm is getting more and more unpredictable by the minute...

Edit: Also, another thing I noticed in the maps is how weak the 200mb vorticity is now. At the same time, the 500mb and 700mb vorticity is getting stronger. Might be a big hint towards where that rotation is going, and it rhymes with crown.
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I think 22.3N/90.2W has now become the dominant center for 92L , but that's just my take.
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1284. hydrus
Quoting 1274. tkdaime:
the storm to the se of td erin looks impressive i think that will become gabriele and the one on african coast will be humberto the storm in gulf will be ferdanan
It is definitely worth watching..
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Funktopless...
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Some of us have been watching that ULL for awhile now. Patrap and Gro I know are.
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1281. ncstorm
Quoting 1272. Tropicsweatherpr:
Erin back to TS.

AL, 05, 2013081700, , BEST, 0, 182N, 340W, 35, 1006, TS


what were the words today to describe Erin..choking, at its end, dead, horrible, naked, terrible..

when will this blog learn?
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The JTWC have issued a Tropical Formation Alert for both 98W and 99W. The JMA have already classified both as TDs.

98W



99W

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Quoting 1271. sar2401:

92L has hardly even had a track, and there still seems to be some doubt as to where the low is actually located. How could these track errors possibly be calculated based on such limited information?


Previous cycle GFDL, adjusted using a variable intensity offset correction that is a function of forecast time. Note that for track, GHMI and GFDI are identical
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Quoting 1267. moonlightcowboy:



There's going to be data, something somewhere, that supports situations like this where a ULL usually has dominance of a weaker warm-core surface low. It may ultimately be just that, that the surface structure is weak compared the even small ULL's. I wrote a piece about ULL's some years back and their substantial effects, but I cannot remember a situation as I described evolving into a well-structured, warm-core system. When the ULL's come into proximity we usually get a messy looking system, void of real hurricane structure.

And, if we can make that supposition now, and unless these two do distance themselves again, what will ultimately happen is we'll either see a subtropical system form, or we may see either dissipate. And, the idea of my imagination has about as much chance of happening as me winning the lottery. ;P


LOL - but there is a chance! Slim that it may be. I think the same would happen as happened with Lee, initially development is attributed as tropical, but post analysis determines otherwise. Afterall, why quibble over the facts at that particular moment when - at least with Lee - there are more important things to consider.

Looking back at the visible loops, I retract what I said about the two possibly marrying as the LLC seems to be doing all that it can to avoid the ULL. Seems like the llc is leaving the ULL at the alter. :D

Edit: Or at the very least is delaying the commitment.
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1277. Levi32
Quoting 1254. Skyepony:
How about we compare some model track error for 92L.. error in nm 0hr, 24hr, 48hr..

NAM 54.9 104.4 77.9
NVGM 48.2 118.5 205.3

go ships!
SHIP 0 50.4 69.6

someone find this model!
GHMI 0 48.7 18.9

HWRF 15.4 72.2 108.4
LBAR 0 55.4 144.8

GFDI 0 48.7 18.9
GFDL 18.2 77.2 90.5

DSHP 0 50.4 69.6
FIM9 32.4 154.1 -

crow for the CMC haters..
CMC 47.7 78.3 37.5

AVNO 39.6 99.5 108.8
BAMD - 82.9 76.2
BAMM - 63.2 56.6
BAMS - 61.5 43.8

& the gfs ensemble mean..
AEMN 46.3 99.9 39.8


That's the interpolated GFDL ensemble mean forecast from the previous 6-hour cycle.
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This is one instance where I don't agree well with the National Hurricane Center.

The decrease to 40%, even with the current official center fix being west of Campeche, does not make sense with the upper low gradually weakening. That will be even more true if a more northern low is becoming dominant, as I think.
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1275. hydrus
Quoting 1261. Grothar:
It does appear, at least on this image, that the more northern low is getting stronger and might be the dominant one as most people are observing.



Evening Gro. I thought the north one ( 92L I hope ) was going to win out over the ULL. The ULL was a neat surprise, considering none of the models really picked up on it. If you look closely, one can see large gravity waves on the west side of 92L..
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1274. tkdaime
the storm to the se of td erin looks impressive i think that will become gabriele and the one on african coast will be humberto the storm in gulf will be ferdanan
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1273. ncstorm
Quoting 1265. Grothar:


Well how long can you stare at a practically stationary system? I just come on every few hours to see who's fighting. We should know of any interesting changes in a few hours. It looks like things might be a'changing.



Gro, you crack me up..LOL..guilty as charged over here as well..
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Erin back to TS.

AL, 05, 2013081700, , BEST, 0, 182N, 340W, 35, 1006, TS
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1271. sar2401
Quoting Skyepony:
How about we compare some model track error for 92L.. error in nm 0hr, 24hr, 48hr..

NAM 54.9 104.4 77.9
NVGM 48.2 118.5 205.3

go ships!
SHIP 0 50.4 69.6

someone find this model!
GHMI 0 48.7 18.9

HWRF 15.4 72.2 108.4
LBAR 0 55.4 144.8

GFDI 0 48.7 18.9
GFDL 18.2 77.2 90.5

DSHP 0 50.4 69.6
FIM9 32.4 154.1 -

crow for the CMC haters..
CMC 47.7 78.3 37.5

AVNO 39.6 99.5 108.8
BAMD - 82.9 76.2
BAMM - 63.2 56.6
BAMS - 61.5 43.8

& the gfs ensemble mean..
AEMN 46.3 99.9 39.8

92L has hardly even had a track, and there still seems to be some doubt as to where the low is actually located. How could these track errors possibly be calculated based on such limited information?
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Quoting 1263. sar2401:

Is this from your own rain gauge? Tyndall AFB is reporting 21.23 inches since June 1.


I'm going by what TWC said earlier. Also, Tyndall is not Panama City. Some areas here got almost 20" on 3/4th of July. Our drainage ditches are full right now. The sewer grate at the store earlier had water through the grates.
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1269. Skyepony (Mod)
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Quoting 1265. Grothar:


Well how long can you stare at a practically stationary system? I just come on every few hours to see who's fighting. We should know of any interesting changes in a few hours. It looks like things might be a'changing.


I know! I've been staring at it's nakedness all day! Finally glad it's putting some clothes on!
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Quoting 1241. daddyjames:


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.



There's going to be data, something somewhere, that supports situations like this where a ULL usually has dominance of the weaker warm-core surface lows. It may ultimately be just that, that the surface structure is weak compared to even the small ULL's.

I wrote a piece about ULL's some years back and their substantial effects, but I cannot remember a situation as I described evolving into a well-structured, warm-core system. When the ULL's come into proximity we usually get a messy looking system, void of real hurricane characteristics and structure.

And, if we can make that supposition now, and unless these two do distance themselves again, what will ultimately happen is we'll either see a subtropical system form, or we may see either dissipate. And, the idea of my imagination has about as much chance of happening as me winning the lottery. For a brief moment, however, it was an interesting thought! ;P
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Quoting 1260. SuperStorm093:
Nothing really going on though, wait till we get an actual storm to track.


Yeah... I'm disappointed with 92L... I've come to really hate ULLs. I'm not a wishcaster I just hate that the models give us something and then they are always wrong. Damn weather is complex!
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1265. Grothar
Quoting 1256. Dragod66:
slow blog tonight surprisingly.


Well how long can you stare at a practically stationary system? I just come on every few hours to see who's fighting. We should know of any interesting changes in a few hours. It looks like things might be a'changing.
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1264. hydrus
Quoting 1248. Newswatcher:
Central SC didn't get out of the mid-60s. Makes it feel like autumn.
It didnt get out of the 60,s here on the plateau either...Loved it.
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1263. sar2401
Quoting Kristina40:


Panama City has had three feet of rain since June 1. We are waterlogged already.

Is this from your own rain gauge? Tyndall AFB is reporting 21.23 inches since June 1.
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Quoting 1207. unknowncomic:
You are due for a retired name storm.


Yes, but it certainly won't be this garbage.
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1261. Grothar
It does appear, at least on this image, that the more northern low is getting stronger and might be the dominant one as most people are observing.



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Quoting 1256. Dragod66:
slow blog tonight surprisingly.
Nothing really going on though, wait till we get an actual storm to track.
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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. ;)


Ok that makes more sense because surface lows stack with upper level lows all the time. In fact its the end of the life cycle for mid latitude systems. The surface low gets trapped under the upper level low and cut off from the temperature gradients and slowly weakens.

This is also seen in subtropical storms as well. They either come from mid latitude cyclones over the north atlantic that move southward into warmer waters. The surface cyclone begins to feed off the latent energy released while the system aloft is still cold core....or at least neutral core.

An alternative to that is a tropical low/tropical wave getting tugged under a upper level low. The surface cyclone is already tropical in nature and its just the very upper levels that is cold core. These tend to become tropical faster than the others.

Speaking of a fully tropical storm being associated with an upper level low, I've seen several do it but at the moment only one is really standing out in my brain ( I've got a cold so not up to par) and that was hurricane hanna from 2008. She became trapped within the upper level low while near the Bahamas though I remember the National Hurricane Center saying she may have briefly became subtropical.
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1258. hydrus
Quoting 1249. L1990:
so bored here... wishing to be evacuated
Really.??!! Where do you live.?
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Quoting 1250. stormpetrol:
I have a feeling the door is not yet closed on 92L might give us a surprise still! Erin is probably once again a Tropical storm. 10n-13n to 40w to 50w worth watching.The African wave that's just about to hit the water at a lower latitude could be player in a few days, just my take.
i agree, that could be caribbean tracker, will see
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slow blog tonight surprisingly.
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AL, 92, 2013081700, , BEST, 0, 210N, 917W, 25, 1009, LO
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1254. Skyepony (Mod)
How about we compare some model track error for 92L.. error in nm 0hr, 24hr, 48hr..

NAM 54.9 104.4 77.9
NVGM 48.2 118.5 205.3

go ships!
SHIP 0 50.4 69.6

someone find this model!
GHMI 0 48.7 18.9

HWRF 15.4 72.2 108.4
LBAR 0 55.4 144.8

GFDI 0 48.7 18.9
GFDL 18.2 77.2 90.5

DSHP 0 50.4 69.6
FIM9 32.4 154.1 -

crow for the CMC haters..
CMC 47.7 78.3 37.5

AVNO 39.6 99.5 108.8
BAMD - 82.9 76.2
BAMM - 63.2 56.6
BAMS - 61.5 43.8

& the gfs ensemble mean..
AEMN 46.3 99.9 39.8
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1253. hydrus
Quoting 1204. Patrap:
Looks like it is nearly stationary. Good thing shear is in the forecast. Do not like thinking about what could happen if there was none.
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Quoting 1249. L1990:
so bored here... wishing to be evacuated
WHAT? if you are thinking that this will be a big storm your horribly wrong and to want to be evacuated ????
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1251. PRweathercenter
12:34 AM GMT on August 17, 2013
Quoting 1204. Patrap:
it lokks like the mid level circulatin is winning over the low level, that could bring 92 l closer to your area
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1250. stormpetrol
12:33 AM GMT on August 17, 2013
I have a feeling the door is not yet closed on 92L might give us a surprise still! Erin is probably once again a Tropical storm. 10n-13n to 40w to 50w worth watching.The African wave that's just about to hit the water at a lower latitude could be player in a few days, just my take.
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1249. L1990
12:31 AM GMT on August 17, 2013
so bored here... wishing to be evacuated
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1248. Newswatcher
12:31 AM GMT on August 17, 2013
Central SC didn't get out of the mid-60s. Makes it feel like autumn.
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1247. Grothar
12:30 AM GMT on August 17, 2013
Quoting 1239. sar2401:

LOL. I was thinking the same thing but I thought I'd let you take the ban this time. :-)


?

It is just that they are harder to track and you don't know where they will go. At least with a well-defined system, it might be easier. Although, I must admit, 92L has done exactly what I thought I would do since the beginning.
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1246. VR46L
12:30 AM GMT on August 17, 2013
Quoting 1235. sar2401:

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.


I saw Skye posted the errors so far this morning on 92L and the NAM was one of the better ones on it .
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1245. L1990
12:29 AM GMT on August 17, 2013
Quoting 1238. TimSoCal:


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


good to know ... im central time so im waiting for 11 i guess
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1244. SuperStorm093
12:29 AM GMT on August 17, 2013
This will become either a weak sub tropical cyclone or TD. No way it reaches TS / Hurricane Status, not enough time.
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1243. originalLT
12:29 AM GMT on August 17, 2013
I think another center is forming at 22.2N and 90.5W--if this is the ULL I think it will bore down to the surface.
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1242. wunderweatherman123
12:29 AM GMT on August 17, 2013
i hear we have a wave train coming ^_^
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1241. daddyjames
12:28 AM GMT on August 17, 2013
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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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather