Alex may head north to Texas or Louisiana

By: Dr. Jeff Masters , 6:36 PM GMT on June 27, 2010

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Tropical Depression Alex has held together fairly well during its passage over Mexico's Yucatan Peninsula, and stands poised to re-intensify back into a tropical storm once it emerges from the coast tonight. Alex brought heavy rains to northern Honduras, Mexico's Yucatan Peninsula, and Belize over the weekend. It was not a good beach day in Cozumel yesterday, as 9.25" of rain fell. Cancun received 2.05" over the weekend, and Belize City received 4.57". Satellite loops show that Alex's heavy thunderstorms are mostly gone near the center, though there are some impressive bands of precipitation well away from the center. There is an upper-level high pressure system a few hundred miles west of Alex, and the clockwise flow air around this high is bringing upper-level winds out of the northwest of about 5 knots over the storm, contributing to the 5 knots of wind shear observed in this afternoon's wind shear analysis from the University of Wisconsin's CIMSS group. Sea Surface Temperatures are very warm, 29 - 30°C, and dry air is currently not a problem for Alex.


Figure 1. Afternoon satellite image of Alex.

Forecast for Alex: which model should you trust?
While the track forecast for Alex today through Monday is fairly well-assured, the longer range forecast has become highly uncertain. An increasing number of our reliable models are now indicating Alex may take a more northerly track beginning on Tuesday, with possible landfall on the Texas coast near Galveston on Friday (according to the 8am run of the GFS model) or into western Louisiana on Wednesday (the 8am run of the Canadian model.) The key question remains how Alex will react to the trough of low pressure expected to swing down over the Eastern U.S. on Monday and Tuesday. Most of the models were predicting that the trough would not be strong enough to swing Alex to the north, and several of them continue to predict this. The 8am runs of the NOGAPS and ECMWF models, for example, take Alex into the Gulf coast of Mexico 150 miles south of Texas, on Wednesday. The GFDL and HWRF models split the difference, with the GFDL predicting a Thursday landfall in southern Texas near Brownsville, and the HWRF predicting a Thursday landfall near Corpus Christi. Morris Bender of the GFDL group has just provided me the track forecast from an improved experimental version of the GFDL that shows landfall between Corpus Christi and Galveston. So which model should you trust? Last year, the best performing models at the 3 - 4 day forecast range were the GFS and the Canadian, and these are the models that are currently calling for the more northerly track towards the upper Texas coast and Louisiana. Residents of those areas should review their hurricane preparedness plans and anticipate that Alex could make landfall as early as Wednesday in their vicinity. Residents of the Mexican coast south of Brownsville should make similar plans, as Alex could just as easily hit there.

Re-intensification of Alex is likely once the center of Alex moves offshore, though this will initially be slow due to the current disorganized state of the storm and the relatively low total ocean heat content in the 100-mile-wide stretch of water on the west side of the Yucatan Peninsula. Once Alex moves more than 100 miles from the Yucatan, total heat content of the ocean increases substantially, and Alex will have the opportunity to intensify significantly. A longer time spent over water will give Alex more of a chance to strengthen, and it is possible Alex could intensify into a major hurricane if landfall is delayed until Thursday or Friday. However, Alex's intensification may be limited the farther north it gets, as water vapor satellite images show plenty of dry air over Texas that might interfere with development. Wind shear might also be an issue for Alex if it pushes far enough north, and a slow-moving storm tends to pull up cold water from the depths, limiting intensification. In short, Alex has the potential to intensify into a major hurricane, but there are plenty of roadblocks that make this only a 10% probability in my estimation.


Figure 2. Skill of computer model forecasts for Atlantic named storms during 2009. OFCL=Official NHC forecast; GFS=Global Forecast System model; GFDL=Geophysical Fluid Dynamic Laboratory model; HWRF=Hurricane Weather Research Forecasting model; NOGAPS=Navy Operational Global Prediction System model; UKMET+United Kingdom Met Office model; ECMWF=European Center for Medium Range Weather Forecasting model; CMC=Canadian GEM model; TVCN=one of the consensus models that lends together all (or most) of the above models; BAMM=Beta and Advection Model (Medium Layer.) Image credit: National Hurricane Center 2009 verification report.

Elsewhere in the tropics
A tropical wave (Invest 94L) a few hundred miles north of the northernmost Lesser Antilles Islands has been pretty much torn apart, and is no longer a threat to develop.

Next post
Wunderground's severe weather expert Dr. Rob Carver will likely be posting an update on Alex late tonight. My next update will be Monday by 10am EDT.

Jeff Masters

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Quoting Levi32:
Also, the dry air currently over Texas won't be remaining that dry....it is associated with an upper low (200mb) that will be gone by the time Alex gets close.



Exactly. Forget "dry air" - not a factor.
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Quoting StormW:
Hi Levi;Taz!



hi
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This is what I think it will do.

At 5:00@11:00,it will reform into a tropical storm.

11:00pm today-June 30th-Steady intensification,+5 knots every advisory,may pull of a small RI.

Afterwards-I don't know?
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A larger cyclone Like Alex take s a Lot of time to gather a Lot of Moementumn and the intensity Guidance has been good so far with the storm.
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Thanks Storm... back to lurking.
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180. swfla
It appears that the oil spill is going to be impacted no matter which way Alex goes from here. Part of the feeder ban is going over SW Fla.

Link
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poor BP
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Also, the dry air currently over Texas won't be remaining that dry....it is associated with an upper low (200mb) that will be gone by the time Alex gets close.

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i'm thinking swfl is going to get some biggggg storms along the coast tonight,wouldn't be suprised to see some severe wx reports,alot of theses storms will contain gusty winds around 40-50mph!!!!
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Quoting StormW:
TROPICAL DEPRESSION ALEX SPECIAL SYNOPSIS JUNE 27, 2010 ISSUED 3:25 P.M.

Awesome!!!!! I so needed that list of abbreviations lol
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It's lost convection to the NW, but the structure of Alex is really astonishingly good for a storm that just spent a day over land. And the NW section is now over water. Have a feeling we'll see round two of RI.

I'm not even going to comment about the increasingly probable track except to make a Captain Obvious comment: A major in Louisiana at this particular time would be a catastrophe.

The products that I will be looking at the most now, other than satellites of Alex, are WV and current analysis maps of the CONUS to see just what that trough is up to. Otherwise it's just playing model roulette.
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Analyzed positioning of the trough, 300 mb:

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Quoting smmcdavid:


Anyone?


The intensity forecasts are low, and the models aren't particularly skillful with those. There is no reason why Alex shouldn't strengthen into a hurricane with that amount of time over the gulf with little wind shear if any at all. A major hurricane is entirely possible if it has more than 3 days over water. Worst-case scenario it could even challenge Audry.
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Quoting smmcdavid:


Anyone?


Like someone already mentioned (i think it was stormchaser2007) there could be dry texas air. Also, like Levi said, the models are likely under a bit in intensity.
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18z Early Cycle NHC model tracks
Alex
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)

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Alex needs life support..and he's about to get it.
Link
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Tornadic thunderstorm moving from Detroit area into Southwestern Ontario.
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Quoting smmcdavid:
I see the northern shift in the models, but am I also seeing a less intense forecast... maybe not even getting to hurricane strength? Wouldn't it have more time to strengthen if it were to go more North?

Now I'm confused.


Anyone?
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Quoting Ameister12:
Alex is about to emerge.


Yes, and GetReal surmised this approximate exit hours ago. Good job, GR!
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Floater - Rainbow Color Infrared Loop
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This looks significant. 12Z Late cycle models:

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Alex is about to emerge.
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GFS Parallel
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afternoon all,

i thought anytime a storm comes through the gulf they evacuate the platforms?
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Thanks everyone; as soon as I posted I saw the change in the track and understand the more favorable conditions unfolding... and I totally understand that 72 out is a max to even have a supportable clue....

I am keeping Alex on the fore of the thoughts....

Truly appreciate you all!!

Geo -- CDR445 -- (Houston)
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Tropical Depression Alex Video Update

Posted on June 22, 2010 at 10:30 AM

Updated today at 10:59 AM
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Quoting Grecojdw:
I would like to know how rare it is to see a trough like this digging so far South at the end of June?


It's not all that uncommon. That is part of the reason why you see W. FL landfalls and storms re-curving towards the open ocean in June and October. At the beginning and end of the season, is when those type of influences are felt furthest south.

When we get into the heart of the season, tracks are generally determined by high pressure. Although there are some exceptions.

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Quoting Stormchaser2007:


Again?

I havent been here since last night.

Deleted it...


That's the 3rd time today a map with all the GFS ensembles on it has been posted, which makes the model consensus look very distorted. I'm just trying to make sure nobody gets the wrong idea.
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I'd be kinda' sick if I was anywhere from Corpus to Nola right now...and I'm sick about the oil and what that means to those it effects directly and indirectly(all of us).
.
But, as much as I dislike the NHC forecaster Brennan, it's best to keep in mind this tidbit from his last discussion. ALL OF THE MODEL UNCERTAINTY WITH THE TRACK OF ALEX OFFERS A
REMINDER TO NOT TO FOCUS ON THE EXACT FORECAST TRACK...PARTICULARLY
IN THE EXTENDED PART OF THE FORECAST PERIOD...WHERE AVERAGE
FORECAST ERRORS CAN BE 200 TO 300 MILES.
.
.
This could very well be a cyclone that effects the cows in South Texas the most.
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Quoting GlobalWarming:


are they concerned?


Everyone is concerned and the info they relay is always above par as the Big 3 here all have fine folks.

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Quoting Levi32:


Again....heavily heavily weighted by the GFS....50% of those model tracks are all the GFS. Don't post that map as it is misleading....the model consensus is not that weighted towards Texas yet.


Again?

I havent been here since last night.

Deleted it...
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Based on where the TVCN is at, you can expect the NHC to shift the track to 24-25N for landfall unless they decide to go north of that consensus.
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Its funny how they forget that Florida is also part of the spill region too:0
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Deleted
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Quoting GlobalWarming:
hey pat, are your local mets up there in nola, talking much about alex, lately?


Since it was a Invest.

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Quoting smmcdavid:
I see the northern shift in the models, but am I also seeing a less intense forecast... maybe not even getting to hurricane strength? Wouldn't it have more time to strengthen if it were to go more North?

Now I'm confused.


Backup, you're not confused - on the money rather. ;P (ssshhh)
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Well I guess its time to go to the store...


Edit to clarify: for my Cane supplies.
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ESL GOM RTAP Imagery
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Quoting Stormchaser2007:
Wow....



Again....heavily heavily weighted by the GFS....50% of those model tracks are all the GFS. Don't post that map as it is misleading....the model consensus is not that weighted towards Texas yet.
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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.