Caribbean Disturbance 92L Moving Over the Yucatan; Erin Forms Off of Africa

By: Dr. Jeff Masters , 2:40 PM GMT on August 15, 2013

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The tropical wave in the Western Caribbean near the Yucatan Peninsula (92L) is growing more organized this morning, after an evening when it lost most of its heavy thunderstorm activity. Satellite loops show a modest-sized area of heavy thunderstorms that are increasing in intensity and areal coverage, but there are a no signs of a surface circulation. Winds at surface stations in the Western Caribbean also do not show a surface circulation. The highest surface wind reports this Thursday morning were at Western Caribbean buoy 42056 about 140 miles east southeast of Cozumel, which had east winds of 25 mph, gusting to 34 mph, at 10 am EDT. Wind shear is a moderate 10 - 20 knots over the the wave, which should allow slow development today until its west-northwest movement at 10 - 15 mph carries it over the Yucatan Peninsula Thursday afternoon. Four hurricane hunter flights were scheduled to fly into 92L today--an Air Force mission tasked to provide a center fix early this afternoon, two NOAA P-3 missions aimed at collecting real-time radar data to feed into the HWRF model, and a flight by the NOAA jet to collect dropsonde data around the periphery of 92L. However, all of these flights were cancelled, given that 92L did not organize as much as much as it could have.


Figure 1. MODIS satellite image of Invest 92L taken at 12:30 pm EDT Thursday August 15, 2013. Image credit: NASA.

Forecast for 92L
92L will trek across the Yucatan Peninsula Thursday evening and arrive in the Southern Gulf of Mexico on Friday, when it will have the opportunity to strengthen. The 06Z Thursday 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, but 92L may be far enough north that this influence will be negligible. Given all these factors, 92L should be able to become at least a tropical depression by Saturday, A trough of low pressure over the northern Gulf of Mexico will dip down by Saturday evening over the Central Gulf of Mexico, potentially increasing wind shear to a high 20 - 30 knots, stalling any further intensification. This trough may also be able to pull the storm northwards to a landfall between Eastern Louisiana and the Florida Panhandle, as the 00Z Thursday run of the European model is suggesting. This would bring a plenty of tropical moisture into the Southeast U.S., resulting in a large area of 4+" of rain. However, the other models show a more westerly track for 92L, with landfalls possible in Texas or Mexico south of the Texas border, and there is high uncertainty where 92L may go once it enters the Gulf of Mexico. In their 8 am EDT Wednesday Tropical Weather Outlook, NHC gave 92L a 50% of developing by Saturday, and a 60% chance of developing by Tuesday.


Figure 2. MODIS satellite image of Tropical Storm Erin taken at 10:30 am EDT Thursday August 15, 2013. At the time, Erin had maximum sustained winds of 40 mph. Image credit: NASA.

Tropical Storm Erin
The season's fifth named storm of the year, Tropical Storm Erin, has formed over the far Eastern Atlantic off the coast of Africa. Erin is over warm waters of 27°C and is under a moderate 10 - 15 knots of wind shear, which should allow continued development today and Friday. Erin is a small storm, as seen on satellite loops. The 12Z Thursday SHIPS model forecast predicts that wind shear will be low to moderate for the next five days, which favors development. However, the waters beneath Erin will steadily cool to a marginal 26°C by Friday, and the atmosphere will steadily get drier, as the storm encounters the Saharan Air Layer (SAL), discouraging development. Erin's west-northwest motion will cut the storm off on Sunday from a moist source of air to its south--the semi-permanent band of tropical thunderstorms called the ITCZ (Inter-Tropical Convergence Zone.) The storm should weaken beginning on Sunday, which would result in Erin turning more to the west as the east-to-west blowing surface trade winds begin to dominate the steering of the shallower storm. We may see a situation like occurred for Tropical Storm Dorian in late July--intensification to a 60 mph tropical storm, followed by a slow decay and dissipation. The latest run of the GFS model calls for Erin to dissipate well before reaching the Lesser Antilles Islands.

Typhoon Utor dissipates
Typhoon Utor has dissipated after hitting Southeast China about 150 miles southwest of Hong Kong on Wednesday as a Category 1 storm with 90 mph winds. The typhoon is being blamed for 1 death in China, and sank a 21-person cargo ship off the coast. In the Philippines, where Utor hit as a Category 4 storm with 140 mph winds on Monday, 8 deaths are being blamed on the storm, and damage is estimated at $20 million.

Jeff Masters

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1242. nash36
Quoting 1233. IKE:
The next 3 days......




92L can feel free to NOT take the easterly route! We have had MORE than enough rain in Charleston this summer. We do not need another 3-5 inches this weekend.
Member Since: August 24, 2012 Posts: 3 Comments: 481
Quoting 1234. GTstormChaserCaleb:
LOL this is getting entertaining. I am actually amused you think this.


Caleb, I've got a lot of respect for you, but you need to take your own advice...
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Quoting 1219. Levi32:
If you're looking for something interesting to watch with 92L, look for any increases in low-level organization over land today. Yes, I said over land. Although deepening rarely occurs over land, sometimes the circulation can become better organized, especially when the land is flat, like the Yucatan. We saw it with Barry in June. Since convection has been east of 92L's wave axis, as it moved inland this morning, solar heating has been almost normal over the Yucatan under clear skies, and the resulting afternoon convection could potentially do interesting things to 92L's low-level structure.


Opal was sort of similar, at least with the land interaction over the Yucatan.

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Quoting 1223. Joanie38:


Ha! You have got to be kidding me?!?!? I haven't read anything like that. So they think it's going to make landfall in SWLA!?! 92L won't do much other than be a huge rainmaker..no one knows where 92L is going YET.


92L isn't coming to SWLA due to my hiatus of hurricanes for five years. This is my last year of it and I plan to enjoy each and every minute.

That said, a small barely TS with nice rain would certainly help us with the drought here in west central LA.
Member Since: August 22, 2009 Posts: 0 Comments: 3113
Quoting 1162. Grothar:


I discussed this at length the other night while you were. Pay attention. I won't go through it again, but take an excerpt from the National Science Foundation article published in the American Meteorological Society


The model emphasizes the importance of a Lagrangian recirculation region within a tropical-wave critical layer (the so-called pouch), where persistent deep convection and vorticity aggregation as well as column moistening are favored for tropical cyclogenesis. Distinct scenarios of hybrid wave–vortex evolution are highlighted. It was found that easterly waves without a pouch or with a shallow pouch did not develop. Although not all waves with a deep pouch developed into a tropical storm, a deep wave pouch had formed prior to genesis for all 16 named storms originating from monochromatic easterly waves during the 2008 and 2009 seasons. On the other hand, the diagnosis of two nondeveloping waves with a deep pouch suggests that strong vertical shear or dry air intrusion at the middle–upper levels (where a wave pouch was absent) can disrupt deep convection and suppress storm development.


I love you, there's nothing to hide,
It's better than burning inside,
I love you, no use to pretend,
There! I've said it again.

Member Since: September 18, 2010 Posts: 0 Comments: 4576
Quoting 1233. IKE:
The next 3 days......




Little rain heading toward ya brother..WOW
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1236. Matt74
Quoting 1196. GeorgiaStormz:
This blog is ridiculous
No.. This blog is pure entertainment sometimes... ( with a lot of great info too though)
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Quoting 1221. stormgirI:
as sept rolls around the steering pattern just ain't gonna flip a switch just because the calendar says sept 10th. steering is much the same with weak storms heading into mehico and cv storms going ots with the fish.
LOL this is getting entertaining. I am actually amused you think this.
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1233. IKE
The next 3 days......


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1232. Levi32
Quoting 1216. TomTaylor:
And I think its worth remembering it depends where you look. Some layers are certainly drier than normal. Some layers are more important than others.

I can't look cause I'm on my phone, but TPW anomaly certainly does not give us the full picture.


True, but ~80% of a typical atmosphere's water vapor is contained below 4km, and since hurricanes are most sensitive to low to mid-level moisture levels, the PWAT value will be very sensitive to changes at any level there. I've never seen 700mb RH below normal near a TC without PWAT being below normal as well.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
1231. ncstorm
Magic ingriedents for TC formation-Dr. Steve Lyon

My list of active ingredients starts with the typical five you can find in most tropical weather textbooks (not in any specific order).

1) Warm water 80 degrees Fahrenheit or higher
2) Pre-existing disturbance
3) Unstable air for rain
4) Weak wind shear
5) Well-defined inflow in low layers and outflow at high layers

Of course, tropical storms only form away from the equator; only a few rare exceptions have formed inside of 5 degrees north or south latitude.

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Quoting 1218. MississippiWx:


There is a nice spin just to the NW of those coordinates. 925mb map might agree as well.



Keep in mind the satellite is likely a little old and needs to catch up some possibly......I have seen it too often that land friction will get rid of weaker swirls and enable a more dominate swirl to occur. This just might be happening as it could actually strengthen some over land.
Member Since: Posts: Comments:
I see we now have TS Erin, guess she didn't want to be depressed first. And 92L is still refusing to say where he wants to go and how he'll get there. It's probably safe to say it'll be Tadwald Time tonight, and probably over 700 posts in the next four hours or so. Yep, it's August in WU.
Member Since: August 22, 2009 Posts: 0 Comments: 3113
1227. Patrap
Never shake a Fresca Can o soda...




Member Since: July 3, 2005 Posts: 415 Comments: 125628
Quoting 1216. TomTaylor:
And I think its worth remembering it depends where you look. Some layers are certainly drier than normal. Some layers are more important than others.

I can't look cause I'm on my phone, but TPW anomaly certainly does not give us the full picture.

Still on vacation?
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1225. Gearsts
Quoting 1188. Levi32:


They aren't the same, but are closely linked. Stable air creates dry air because a stable air layer sinks, which compresses it and dries it. My point was that although the eastern north Atlanic is always dry in an absolute sense, it is currently not drier than normal, but it is more stable than normal due to high pressure there. If Erin had formed in this location in 2010 or 2012, I wager she would have become a hurricane. Right now she probably won't.
So this year is all about the magical 50w line with the SST's there been above normal but then TC have the TUTT north of PR. :/
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Quoting 1211. stormgirI:

you say that like its a bad thing. folks coming on here gettin blasted for making a forecast and then sticking too it. where's the logic in that huh? dry air is huge out there and i got news for ya it ain't going away anytime soon...
When that ridge weakens which it is showing signs of doing that is when the dry air goes away and Erin and the one to follow will be paving that path for the big ones in September just in time for the official peak of the season. The only reason we are seeing the dry air right now is the positioning and strength of the ridge. As these fall like troughs come and go they help kick out the ridge and displace it from its normal spot, sometimes even weakening to the point that there is no ridge. Some people need to understand the logic and science into that before posting out of the blues.
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Quoting 1212. AtHomeInTX:


Good to see you too. :) Keeping an eye on things is a good thing to do. Don't know if you saw this I posted earlier. As you say, ya never know.

GMZ001-160845-
SYNOPSIS FOR THE GULF OF MEXICO
444 PM EDT THU AUG 15 2013

.SYNOPSIS...A TROPICAL WAVE IS MOVING ACROSS THE YUCATAN
PENINSULA WITH A LOW PRESSURE ALONG THE WAVE AXIS NEAR 20N89W.
THE LOW PRESSURE WILL MOVE OFFSHORE THE NW YUCATAN PENINSULA TO
NEAR 21.4N 91.2W FRI AFTERNOON...NEAR 23.4N 92.6W SAT AFTERNOON...
REACH NEAR 25.4N 93.3W SUN AFTERNOON...AND MOVE INLAND MON NIGHT
OVER SW LOUISIANA...WITH THE POSSIBILITY OF TROPICAL CYCLONE
FORMATION WHILE MOVING THROUGH THE GULF OF MEXICO.



Ha! You have got to be kidding me?!?!? I haven't read anything like that. So they think it's going to make landfall in SWLA!?! 92L won't do much other than be a huge rainmaker..no one knows where 92L is going YET.
Member Since: Posts: Comments:
Quoting 1206. MississippiWx:


I haven't seen anything out of the ordinary today. Looks pretty normal to me. Of course, normal = ridiculous, for the most part.



What I don't understand is offending someone on the internet, someone you've never met, in a public forum for any opinion or likewise. The need to put someone down or likewise is beyond me.

What I don't understand even more is getting offended by someone on the internet, someone you've never met, who is simply another person putting text into a public forum. The need to argue, defend yourself, or get angry is beyond me.
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1220. nash36
Quoting 1213. IKE:

It is interesting to follow the models on 92L. Problem is....we can't trust them.


Amen to that.

Right now, it is just a low pressure mess with nothing for the models to firmly latch on to. It does actually make tracking more fun, because of all of the changing synoptics and unknowns.
Member Since: August 24, 2012 Posts: 3 Comments: 481
1219. Levi32
If you're looking for something interesting to watch with 92L, look for any increases in low-level organization over land today. Yes, I said over land. Although deepening rarely occurs over land, sometimes the circulation can become better organized, especially when the land is flat, like the Yucatan. We saw it with Barry in June. Since convection has been east of 92L's wave axis, as it moved inland this morning, solar heating has been almost normal over the Yucatan under clear skies, and the resulting afternoon convection could potentially do interesting things to 92L's low-level structure.

Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting 1180. TampaSpin:
I believe a LLC is forming at 20.5N 87.5W......sorry to disagree with anyone!

http://www.ssd.noaa.gov/PS/TROP/floaters/92L/flas h-swir-short.html


There is a nice spin just to the NW of those coordinates. 925mb map might agree as well.

Member Since: July 15, 2006 Posts: 17 Comments: 10156
Quoting 1101. MisterPerfect:
anybody remember this?

I do.



I stayed at a Holiday In Express last night? j/k...NHC?
Member Since: September 18, 2010 Posts: 0 Comments: 4576
Quoting 1100. TropicalAnalystwx13:
I think it's worth repeating what Levi said in his video this evening. The tropical Atlantic is not drier than average. Total precipitable water anomalies across the region are above-average and forecast to remain that way. The issue lies in the fact that the air is more stable than normal, which is a direct byproduct of us seeing stronger ridging across the open Atlantic this season.


And I think its worth remembering it depends where you look. Some layers are certainly drier than normal. Some layers are more important than others.

I can't look cause I'm on my phone, but TPW anomaly certainly does not give us the full picture.
Member Since: Posts: Comments:
The San Antonio/Austin NWS appears to be interested in the storm for possible rain chances next week.

THE PCPN FORECAST
EARLY NEXT WEEK WILL BE DEPENDENT ON WHAT OCCURS OVER THE GULF
THIS WEEKEND. A TROPICAL WAVE IS MOVING ACROSS THE YUCATAN THIS
AFTERNOON AND WILL ENTER THE BAY OF CAMPECHE ON FRIDAY. THIS WAVE
HAS THE POTENTIAL TO BECOME A TROPICAL STORM. THE LATEST SPAGHETTI
PLOTS HAVE THIS SYSTEM MOVING ONSHORE ANYWHERE FROM VERACRUZ TO
BROWNSVILLE TO HOUMA. BEARS WATCHING.
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1214. Proflaw
The "pouch paper" link:
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1213. IKE

Quoting GeorgiaStormz:


I find it funny how after all the models joined the NAM solution, it leaves the pack.

And then after being an early model to switch to the western track, the CMC is back over GA again...

And the GFS.....well....the GFS is just kinda....confused.....it splits this up, forms numerous drifting lows along the front into the SE, but seems to make the main low pressure area into Mexico to finish dying.


I still kinda want it to come to Ga since it's gonna rian anyway, regardless of this system forms into something significant or comes our direction
It is interesting to follow the models on 92L. Problem is....we can't trust them.
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Quoting 1202. Joanie38:


Well HI AtHomeInTX!! I hope you are well. We are just keeping an eye on things, I guess you never know what could happen. :) Good to see you.:)


Good to see you too. :) Keeping an eye on things is a good thing to do. Don't know if you saw this I posted earlier. As you say, ya never know.

GMZ001-160845-
SYNOPSIS FOR THE GULF OF MEXICO
444 PM EDT THU AUG 15 2013

.SYNOPSIS...A TROPICAL WAVE IS MOVING ACROSS THE YUCATAN
PENINSULA WITH A LOW PRESSURE ALONG THE WAVE AXIS NEAR 20N89W.
THE LOW PRESSURE WILL MOVE OFFSHORE THE NW YUCATAN PENINSULA TO
NEAR 21.4N 91.2W FRI AFTERNOON...NEAR 23.4N 92.6W SAT AFTERNOON...
REACH NEAR 25.4N 93.3W SUN AFTERNOON...AND MOVE INLAND MON NIGHT
OVER SW LOUISIANA...WITH THE POSSIBILITY OF TROPICAL CYCLONE
FORMATION WHILE MOVING THROUGH THE GULF OF MEXICO.

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Quoting 1193. LargoFl:
925 MB..thats pretty deep isn't it?..


I find it funny how after all the models joined the NAM solution, it leaves the pack.

And then after being an early model to switch to the western track, the CMC is back over GA again...

And the GFS.....well....the GFS is just kinda....confused.....it splits this up, forms numerous drifting lows along the front into the SE, but seems to make the main low pressure area into Mexico to finish dying.


I still kinda want it to come to Ga since it's gonna rian anyway, regardless of this system forms into something significant or comes our direction
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Patience people... patience. I'll be back in a hour or two.
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1208. Dakster
Quoting 1201. nash36:
And I see some people like to repeat themselves and chest pat. No room for that in here. Give it a rest.


How else can you achieve silver back male status?

I don't recall it being Nov. 30th... The season isn't over -in fact we haven't past the middle of September yet. Which, IIRC, is the height of the season.
Member Since: March 10, 2006 Posts: 0 Comments: 9732
1207. Grothar
Quoting 1197. sar2401:

I must have been walking the dog. :-) So they're called pouches because they actually look like a pouch? I never would have guessed. When did this begin. I swear, I never hear the term until about three years ago. Of course, I also may have been out walking the dog then.


4 years ago.
Member Since: July 17, 2009 Posts: 63 Comments: 23727
Quoting 1196. GeorgiaStormz:
This blog is ridiculous


I haven't seen anything out of the ordinary today. Looks pretty normal to me. Of course, normal = ridiculous, for the most part.
Member Since: July 15, 2006 Posts: 17 Comments: 10156
1203. FOREX
Quoting 1180. TampaSpin:
I believe a LLC is forming at 20.5N 87.5W......sorry to disagree with anyone!

http://www.ssd.noaa.gov/PS/TROP/floaters/92L/flas h-swir-short.html


I see what you see. Who knows. Cantore didn't mention it.
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Quoting 1176. AtHomeInTX:


Hi Joanie. Just hearing what you are in SE TX.


Well HI AtHomeInTX!! I hope you are well. We are just keeping an eye on things, I guess you never know what could happen. :) Good to see you.:)
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1201. nash36
And I see some people like to repeat themselves and chest pat. No room for that in here. Give it a rest.
Member Since: August 24, 2012 Posts: 3 Comments: 481
1200. LargoFl
Quoting 1192. TampaSpin:
Is it not past some peoples bed time....GEESH!
school will be starting soon..things will quiet down some
Member Since: August 6, 2011 Posts: 4 Comments: 33375
Quoting 1186. washingtonian115:
Thirdly as levi and many others have stated..The Atlantic has been more stable than normal.I always back up my forecast.Don't get that twisted.

I don't think we'll see that verify (Igor like storm) because of sst and moisture levels that are absent this year.We are not at 2010 levels in the central/eastern Atlantic.
I like the disagreement and everyone is entitled to their opinions, you have presented a valid argument as to why you think there won't be a storm like Igor this year, and who knows you might be right. What people fail to realize is that the closer to home storms are the ones to be more worried about not really the Cape-Verde ones.
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Quoting 1172. Perfectweather23:
well back in may i looked at the same dry air and shear maps and said nothing much would happen through at least late august.... of course under my other name that was . and so far dry air and shear has held storms at bay and we are almost into late august. and the maps show a same type of dry air and righ breaking down patter for at least 2 more months anyway. but i could be wrong this time


bye bye...
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1197. sar2401
Quoting Grothar:


I discussed this at length the other night while you were. Pay attention. I won't go through it again, but take an excerpt from the National Science Foundation article published in the American Meteorological Society


The model emphasizes the importance of a Lagrangian recirculation region within a tropical-wave critical layer (the so-called pouch), where persistent deep convection and vorticity aggregation as well as column moistening are favored for tropical cyclogenesis. Distinct scenarios of hybrid wave–vortex evolution are highlighted. It was found that easterly waves without a pouch or with a shallow pouch did not develop. Although not all waves with a deep pouch developed into a tropical storm, a deep wave pouch had formed prior to genesis for all 16 named storms originating from monochromatic easterly waves during the 2008 and 2009 seasons. On the other hand, the diagnosis of two nondeveloping waves with a deep pouch suggests that strong vertical shear or dry air intrusion at the middle–upper levels (where a wave pouch was absent) can disrupt deep convection and suppress storm development.

I must have been walking the dog. :-) So they're called pouches because they actually look like a pouch? I never would have guessed. When did this begin. I swear, I never hear the term until about three years ago. Of course, I also may have been out walking the dog then.
Member Since: October 2, 2004 Posts: 0 Comments: 9856
This blog is ridiculous
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Quoting 1187. IKE:

He/she never uses caps. Not the original.


No? I'm confused then...hehe...stormKAT? Stormtop5000? One of them used all caps all the time. I get them all confused now :)
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1193. LargoFl
925 MB..thats pretty deep isn't it?..
Member Since: August 6, 2011 Posts: 4 Comments: 33375
Is it not past some peoples bed time....GEESH!
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.