Alex may head north to Texas or Louisiana
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
Reader Comments
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wow......now that's close....i'm in Denham Springs!
I vote for LaFondas or Petes
But seriously, check your supplies and such. I have tooooo many friends who wait until the last possible minute
OMG!!! YOU are SO like me!! Welcome to the Weatherunderground!!!
SIGNIFICANT MOISTURE ASSOCIATED WITH TROPICAL DEPRESSION ALEX IS
BEING DRAWN ACROSS MUCH OF THE GULF OF MEXICO SUPPORTING
SCATTERED SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE BASIN E OF
94W. ALEX IS APPROACHING THE BAY OF CAMPECHE AND SHOULD MOVE
OVER WATER WITHIN THE NEXT 12 HRS. ONCE THIS OCCURS...ALEX IS
FORECAST TO RESTRENGTHEN TO TROPICAL STORM FORCE.
ELSEWHERE...WEAK SURFACE RIDGING IS ACROSS THE NE GULF EXTENDING
FROM A 1015 MB HIGH OVER CENTRAL ALABAMA. ALOFT...AN UPPER LEVEL
TROUGH COVERS THE NW GULF CENTERED OVER LOUISIANA...WITH
MID-UPPER RIDGING COVERING THE ERN HALF OF THE BASIN. EXPECT
CONTINUED SHOWER ACTIVITY ACROSS MUCH OF THE BASIN AS MOISTURE
WITH ALEX REMAINS ACROSS THE AREA. FOR MORE INFORMATION AND
UPDATES REGARDING THIS SCENARIO...VISIT OUR WEBPAGE AT
WWW.NHC.NOAA.GOV.
I been to Pete's its pretty cool! Our Nitetown haha!
G' evening hh
Lots of typhoons develop within the monsoon trough, and Alex was very similar as he developed within a monsoonal-type pattern of convergence in the Caribbean, and this kind of a system can take many days to develop but when it finally does it is usually very large and has lots of energy with it. Typhoons also have non-stacked low and mid-level centers during their formative stages, which was the case with Alex as well.
It's too early for such a prediction, but I would say the more up north it hits Texas, the more it would impact us given the size of Alex.
Definitely take a stat/probability course if you can. You will be cured of this befuddling aversion to probabilty. I'd be hard pressed to come up with field of work that relies more heavily on the mathematics of uncertainty than weather forcasting. It's definitely near the top of the list regardless.
June 27, 2010 at 4:00 p.m.
LOCAL WEATHER FORECAST
SIGNIFICANT FEATURE…Trough over the western Caribbean and Jamaica.
Comment
Tropical Storm Alex induces a Trough over the western Caribbean.
TODAY'S FORECAST
Tonight… Showers linger over much of the island.
Tomorrow… Morning showers over much of the island, decreasing cloud in the afternoon, scattered showers and thunderstorms over central and western parishes.
3-DAYS FORECAST (starting tomorrow)
Tue... Fair morning, Scattered afternoon showers and isolated thunderstorms over central and western parishes.
Wed/Thu.. Mainly sunny morning, isolated afternoon showers and thunderstorms over central and western parishes.
Regionally… A Tropical Wave moves south of Jamaica tomorrow.
rar
Actually its the opposite...18z GFS shifted more towards the Central Texas Coast aligned with the 18z HWRF and GFDL I dont even think the CMC shows Southeast Texas or Louisiana anymore...all the models are zeroing in on the Central Texas Coast...Corpus Christi is a good bet
In the last 24 hrs Darby has removed more WV from the air in that general area & dumped it as rain than Alex..
Dang it! Where do you get this data as well XD
Already learning lots, thanks Levi!
I will be the first one to admit steering currents and modeling is a crazy science, but when most say north, and NHC says south, it makes you wonder? Heck, very few of the experts here expect a landfall south of Texas (most models don't).
Probabilities are needed for a lot of things in weather forecasting but there is no need to try to be so specific with development potential, for instance. I go with "low" "moderate" or "high" chances of development. And making a probability forecast for landfall is kind of pointless....even the NHC just goes with a cone of uncertainty. That's all I do....section of coastline that it might make landfall on.
Because they have that limited 75x75 domain, they don't see what occurs outside of that, which could affect track, which short term is not an issue but out past 72 hours affects track.
what is that big swirl in the atlantic...top right of the picture?
Wow, I didn't realize anyone else from Prairieville was on here.
Masters is a beast
That's just a ULL (Upper Level Low)
Upper Level Low north of PR..
Do you really think the NHC would post erroneous report for political reasons? That's not going to happen. To many people in involved to keep in under wraps. And I don't think they would do it anyway.
ive been thinking the same
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