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 974. tkeith:
I'm afraid 92L is gonna screw up my round at TPC Sunday...maybe it will drag it's feet a bit :)


Good luck. I don't have a game this Sunday, my pals are all off the island this weekend :-(
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1040. Grothar
Quoting 933. Tropicsweatherpr:
A low has been added at 46W.




Didn't someone mention that earlier?
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It looks like the ULL is taking over and working down to the surface. If so she may be able to wrap. IMO
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Quoting 1035. nola70119:


Unless it develops landfall means little.....all the action will be to the North
and East.


Yes, but I'm thinking this may not be as east-weighted as originally thought if the upper flow pattern on the GFS comes to pass. A broadly anticyclonic environment is much better than a confluent one.
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Quoting 1031. Camille33:

nothing here in itcz the big vort is too north and will not form


You can't tell if something is a tropical wave on the basis of those maps. They can be supplementary, but they are not the sole determinant.
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Quoting 1019. KoritheMan:


Much to my chagrin (believe me, much to my chagrin), I'm favoring a Texas landfall right now. Louisiana is still a threat area though, especially western Louisiana.


Unless it develops landfall means little.....all the action will be to the North
and East.
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18z GFS shows steady development with our next wave
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Quoting 1021. RGVtropicalWx13:

Its cause we ignore the 6z and 18z runs.less data compared to the 0z and 12z runs.Besides it's only 42 hrs out Lol


Based on the way the models have handled this system from the start, I surely wouldn't get hung up on what the 18z GFS says about this going forward in terms of it's path or strength. It certainly looks much better defined now than it ever has and that's a fact.
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1032. KEEPEROFTHEGATE (Mod)
Quoting 1008. SuperStorm093:
that african wave looks horrible. and 92L isnt impressive, call me a downcaster all you want but hey its the the heart of the season and nothing really going on.
I got to correct you here so please forgive me the heart of the season is sept 10

26 days from now

and lots can happen in the next 26 days or nothing could happen iam more in the middle
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Quoting 1028. KoritheMan:


If we're talking about actual waves, there is always going to be vorticity associated with them, because that's how they're defined. What, do you think they label them tropical waves for ***** and giggles?

nothing here in itcz the big vort is too north and will not form
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1030. hydrus
Convection is trying to wrap all around a center. By tomorrow, wii will have Fernand.....thats like being hit with Hurricane Grover or sumpthin..
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Quoting 1027. GTstormChaserCaleb:
:D



I love you.
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Quoting 1026. Camille33:

i am sorry to hurt some feelings but those waves are just mcs there is no vorticity with them so nothing is forming but enjoy those bright colors!


If we're talking about actual waves, there is always going to be vorticity associated with them, because that's how they're defined. What, do you think they label them tropical waves for ***** and giggles?
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Quoting 1024. hydrus:
Went from a shrimp to a sea horse..:)
:D

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Quoting 1023. KoritheMan:


Even assuming that's true, for you to hinge your bets on absolutely no tropical activity for the next 240 hours on the basis of one computer model is ridiculous.

I think people have forgotten to use their eyes, and instead rely too much on computation.

i am sorry to hurt some feelings but those waves are just mcs there is no vorticity with them so nothing is forming but enjoy those bright colors! they will fall apart as they hit the water
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18Z GFS







Nasty weather coming to Mississippi Gulf Coast ugh...
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1024. hydrus
Quoting 1003. Patrap:
Went from a shrimp to a sea horse..:)
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Quoting 1017. Camille33:

all of them except the b storm.Chantal was present it was just a wave/weak low which it was.


Even assuming that's true, for you to hinge your bets on absolutely no tropical activity for the next 240 hours on the basis of one computer model is ridiculous.

I think people have forgotten to use their eyes, and instead rely too much on computation.
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1022. centex
Quoting 973. Levi32:


No it's not baroclinic. 92L is just dancing with an upper low like many tropical disturbances in the western Atlantic. The main surface center and the mid-upper feature aren't even stacked right now.
I agree the upper is not stacked but tropical lows don't have an upper and upper has weakened. The mid has moved more in line. In general more organized over all, lower and mid stacked and ULL being what I would call absorbed and overall system becoming more true tropical. Hard to find the old ULL anymore.

Lower



Mid



Upper

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Quoting 1001. Sfloridacat5:
18Z GFS doesn't develop 92L.
42 hours has it stretched out all across the Western GOM. (sorry Texas).

Its cause we ignore the 6z and 18z runs.less data compared to the 0z and 12z runs.Besides it's only 42 hrs out Lol
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you guys think gfs is better is joke that model forms every storm and it formed this 92l when ecmwf didnt!!
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Quoting 1013. GTstormChaserCaleb:
Where do you have this heading towards Kori, Texas or Louisiana?


Much to my chagrin (believe me, much to my chagrin), I'm favoring a Texas landfall right now. Louisiana is still a threat area though, especially western Louisiana.
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Quoting 1004. GTstormChaserCaleb:
Watch it fail and we get Fernand, I will LOL.



Anythings possible (Especially with a Low pressure sitting over 86 degree water).
But right now you could be in a small boat having a beautiful day fishing right under the center of 92L.
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Quoting 1014. KoritheMan:


Okay, so which storms has it depicted the development of in 2013? If you have the high res, by all means let us know.

all of them except the b storm.Chantal was present it was just a wave/weak low which it was.
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Quoting 1006. tkeith:
Work on Saturday, maybe that night, or a Sunday afternoon in the quarter sounds good. I'll in box you.

Wunderground has me at at 30% chance of rain for Sunday...I think that's gonna go up soon :)


Cool. Hope to see you there.
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1015. hydrus
Quoting 988. KEEPEROFTHEGATE:
yep the sun is getting low in the sky not long now

I do believe we will get a good convective cycle going once darkness falls
I think it will be interesting to watch. A strange tropical system is a feast for the eyes of tropical weather enthusiasts everywhere.:)
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Quoting 1005. Camille33:

ecmwf has been perfect this season you guys dont have the high res maps i do.


Okay, so which storms has it depicted the development of in 2013? If you have the high res, by all means let us know.
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Quoting 1010. KoritheMan:


I think it will acquire tropical characteristics and develop, but the system will probably still be east-weighted, even if not for the shear; a lot of dry air still around.

But if the upper flow relaxes as forecast, it bears monitoring, as it might try to pull a fast one and get stronger than forecast.
Where do you have this heading towards Kori, Texas or Louisiana?
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1011. Doss2k
That wave coming off Africa sure did look better yesterday. It has appeared to drift further south, which could help it avoid a repeat of Erin, but almost all of the convection died off as soon as it neared the coast. Will see how it looks in 24 hours I suppose.
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Quoting 994. scott39:
Do you look for a TD, weighted heavy on the East side before landfall, or are you leaning towards subtropical? Or are we looking at a dead turd AGAIN! Lol


I think it will acquire tropical characteristics and develop, but the system will probably still be east-weighted, even if not for the shear; a lot of dry air still around.

But if the upper flow relaxes as forecast, it bears monitoring, as it might try to pull a fast one and get stronger than forecast.
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Quoting 995. Camille33:

you need to keep insisting that too yourself you are not gona convince me!
That's because you are denial, but that is ok we understand your bromance to that model. :P
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that african wave looks horrible. and 92L isnt impressive, call me a downcaster all you want but hey its the the heart of the season and nothing really going on.
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I am in SWLA, I hope we get some rain...we need it, but not as bad as Texas..:( Besides, it is hard to believe ANY model until the system has formed into a TD...
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1006. tkeith
Quoting KoritheMan:


Keith, do you have any plans for next weekend?

I'll be in the quarter and was wondering if you'd like to hang out or something.
Work on Saturday, maybe that night, or a Sunday afternoon in the quarter sounds good. I'll in box you.

Wunderground has me at at 30% chance of rain for Sunday...I think that's gonna go up soon :)
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Quoting 1002. allancalderini:
There can be three invest at code red and the Euro will show nothing.For genesis this model is epic fail for tracking is another story.

ecmwf has been perfect this season you guys dont have the high res maps i do.
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Quoting 1001. Sfloridacat5:
18Z GFS doesn't develop 92L.
42 hours has it stretched out all across the Western GOM. (sorry Texas).
Watch it fail and we get Fernand, I will LOL.

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1003. Patrap
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Quoting 989. Camille33:
tropics are quiet next 240 hrs per ecmwf, nothing.
There can be three invest at code red and the Euro will show nothing.For genesis this model is epic fail for tracking is another story.
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18Z GFS doesn't develop 92L.
42 hours has it stretched out all across the Western GOM. (sorry Texas).
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Quoting 998. Camille33:
ecmwf is 100% the best model for everything


lol, no it's not.
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Quoting opal92nwf:

Wow, I forgot about that.

Although what I really think would be interesting is to have the strongest a subtropical storm could become and then see what kind of impacts it has. And something a little more well formed than Lee which was lopsided compared to Andrea in 2007.


Yes as Kori mentioned STS Lee, also Allison was a subtropical storm (although I disagree with NHC on timing when it was one, lol), and we've had several over the years... Most occur early or late in season than August... Somewhat similar to STS' are the (rare-for-the-Atlantic-Basin) monsoon depressions with huge wind fields - TS Frances in '98 remains best example. And for the subtropical whopper of all time? Many of us are absolutely convinced Sandy became a hybrid subtropical hurricane for 2-3 days, well before it's extratropical transition / landfall... largely accounting for it's extreme size. I posted an in depth analysis supporting this conclusion back then...

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ecmwf is 100% the best model for everything
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I live in Corpus Christi. Will we get any rain from 92L?
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Quoting 993. KoritheMan:


ECMWF sucks for genesis.

you need to keep insisting that too yourself you are not gona convince me!
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Quoting 986. KoritheMan:


The upper low has been slowly weakening, and the GFS kills it off within the next 24 hours. This may be a little fast, but it should still weaken and provide an environment of lower shear.

Dry air is still going to be problematic, though.
Do you look for a TD, weighted heavy on the East side before landfall, or are you leaning towards subtropical? Or are we looking at a dead turd AGAIN! Lol
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Quoting 989. Camille33:
tropics are quiet next 240 hrs per ecmwf, nothing.


ECMWF sucks for genesis.
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Hello all-

Well, where will the next system form?
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Quoting 974. tkeith:
I'm afraid 92L is gonna screw up my round at TPC Sunday...maybe it will drag it's feet a bit :)


Keith, do you have any plans for next weekend?

I'll be in the quarter and was wondering if you'd like to hang out or something.
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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