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 Patrap:
The Se flow into Uptown NOLA is bringing the Worst Crude smell yet over us.

That's so awful! I hope it doesn't affect your health.
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Quoting Levi32:


NHC considers 80 to be the threshold, but I've seen rapid intensification in less.....it's just an estimate of when the ocean has enough heat to really ramp a storm up if conditions are right.


Alright, well it looks like it has plenty of 60-80 to deal with.. I guess it's wait and see again to see what it does with it.
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Quoting StormW:


Exactly! We musta posted at the same time.


We did.
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Galveston Latest Discussion:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
233 PM CDT SUN JUN 27 2010

.DISCUSSION...
A FRONTAL BOUNDARY MAY PUSH INTO SE TX FROM THE NORTH ON MONDAY
BUT STALL ACROSS THE NORTHERN PARTS OF THE AREA. THIS WILL KEEP
SOME 20 POPS IN THE FORECAST FOR THE OVERNIGHT PERIOD AS WELL AS
HIGHER POPS ALONG THE COAST AS MORE TROPICAL MOISTURE BEGINS TO
MOVE INTO SE TX.

TUE/WED FORECAST HINGES ON THE TRACK OF TD ALEX. ALEX IS
BEGINNING TO EMERGE INTO THE BAY OF CAMPECHE AND WILL LIKELY
STRENGTHEN AS IT MOVES BACK INTO OPEN WATERS. RIGHT NOW THE
FORECAST FOR SE TX WILL FOLLOW THE PREVIOUS FORECAST PACKAGE. THE
NAM/ECMWF SOLUTIONS KEEP ALEX SOUTH ACROSS THE GULF INTO NORTHERN
MEXICO. NHC OFFICIAL FOREACST AGREES WITH THIS SCENARIO. ONE
CANNOT COMPLETELY DISCOUNT THE 12Z CANADIAN/GFS SOLUTIONS BUT
THEY SEEM TO BE THE OUTLIERS FOR NOW. KEEPING TRACK OF THE MODEL
TRENDS THE NEXT DAY OR TWO WILL BE IMPORTANT FOR FUTURE FORECASTS
AND ANY CHANGES SHOULD ALEX MAKE A MORE NORTHWARD TRACK. AS
SUCH...WILL KEEP SOME HIGHER POPS IN THE COASTAL WATERS BUT
MAINLY 30/40 POPS INLAND FOR MID WEEK. POPS FOR NOW SLACK OFF FOR
THE END OF THE WEEK AS ALEX SHOULD BE WELL INLAND BY THIS TIME
BUT GIVEN ENOUGH MOISTURE LINGERING AROUND SE TX...WOULD NOT BE
SURPRISED IF TYPICAL AFTERNOON THUNDERSTORM ACTIVITY CONTINUES.

39

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Quoting kmanislander:
Motion over land will not necessarily be continued once a system exits over water. Friction rates are different and so is the effect from topography. We need to let it get offshore for about 4 to 6 hours to see how the track settles down.


Exactly. The slower forward movement is not caused by land though and suggests a northward curve in trajectory either way. We'll have to see what direction it sets its sights in after fully clearing the Yucatan.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
looking forword too where they put the cone of DOOM
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The center is currently ~19.16N 90.42W about 5miles E of the BOC and moving WNW slowly.

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Hey Storm how you been ?
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Land friction,,center repositioning..lotsa stuff in Play right now as she clears the coast and Like Chief says''

Itsa gonna take a tad while to shake out some motion.
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting StormW:
Hey gang...let's put away the micrometers on the current motion...he's gonna wobble until he clears land.


LOL. See my post 376
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Motion over land will not necessarily be continued once a system exits over water. Friction rates are different and so is the effect from topography. We need to let it get offshore for about 4 to 6 hours to see how the track settles down.
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What an interesting start to the 2010 Atlantic Hurricane Season...
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ALEX NASA MSFC Viewer
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting Levi32:


2 things.....longwave IR imagery is one of the worst ways to determine the center, especially when you have visible imagery during the daytime. Secondly, posting 2 images is impossible to determine a motion.

View this loop then tell me what you see.


Well I didn't want to load the blog down with a loop so I posted the 2 images.
In that loop you posted I still see a west track like I said maybe I am wrong..
Thanks for the input !!
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GGEM Ensemble Circles

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im sorry, i see nothing more than an almost constant wnw track...just north of due west...there might have been a few wobbles...but no nw or nnw turn is evident at this time...
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Not dead north but more N than before.
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Looking at the latest visible loop, it has shifted more north.
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Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting atmoaggie:

But is also exactly what the GFDL calls for. Which then forecasts a left turn than into S TX.

Yup which is why I am afriad central to northern texas is not out of the clear either. Depends how long it stalls. Seems everytime I track a storm it always jogs to the east a bit farter than many think and forecast. Hope that trend isnt happening here (when I say east in this case it would appear north but the whole track actally shifts east if it hits central or northern texas versus southern tx or mex.
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Floater - Dvorak Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting MrstormX:


Link to the FIM please



Link
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Quoting atmoaggie:

But is also exactly what the GFDL calls for. Which then forecasts a left turn than into S TX.


A lot will depend on how long is sits in one place and how quickly it rebuilds while stationary or nearly so.
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Just came in from doing yard work ...any news or directions on Alex? Any info appreciated.
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Quoting HurricaneSwirl:


Yeah I think temps are high enough for it to restrengthen at a decent pace, but RI imo is out of the question for now. How many Kilojoules per cm^2 are usually needed for rapid intensification?


NHC considers 80 to be the threshold, but I've seen rapid intensification in less.....it's just an estimate of when the ocean has enough heat to really ramp a storm up if conditions are right.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
Quoting Grothar:


Thanks 101, I never expected a compliment from you so impressively written. It was nice of you. I didn't think it would post.


lol I was talking more about the structure of the wave, but it was a very nice pic of it that you posted
Member Since: March 10, 2010 Posts: 1 Comments: 7831
Quoting lopaka001:
These images show a western track can somebody confirm?
Alex COC is the dark blue spot east of Ciudad de Carmen in the 1815 utc frame and in the 1940 utc frame the COC is right on the cove of Carmen.




Once again, don't use infrared imagery for movement of weak systems. Convection usually distorts where the actual system is located. Use visible loops to discern motion.
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Quoting Levi32:
Ocean heat content is minimal off the west coast of the Yucatan. Restrengthening/organizing should be gradual until Alex gets farther away from land and more out into the gulf.



Yeah I think temps are high enough for it to restrengthen at a decent pace, but RI imo is out of the question for now. How many Kilojoules per cm^2 are usually needed for rapid intensification?
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Quoting watchingnva:


your eyes are fine....hes barely going just north of due west with maybe a little slow down and wobble thrown in...lol


Now its going more NW than it was 3 hrs earlier.
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Quoting kmanislander:


Good afternoon.

A slowing or stall almost always precedes a change in direction and this just as Alex is about to head back over water. A motion to the NW or N from this point would maximise the amount of time available for strengthening away from land and create a stronger system more inclined to push Northerly.

But is also exactly what the GFDL calls for. Which then forecasts a left turn than into S TX.
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Quoting Hurricanes101:


It posted very impressive


Thanks 101, I never expected a compliment from you so impressively written. It was nice of you. I didn't think it would post.
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Why do the models differ so much from the 5-day forcast track?
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just had a hefty thunderstorm here in Denham Springs, La.....about 45 min. northwest of New Orleans. if i'm looking at it correctly, it is actually an outer band of Alex, which is amazing to me, being how far south it is.
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Quoting lopaka001:
These images show a western track can somebody confirm?
Alex COC is the dark blue spot east of Ciudad de Carmen in the 1815 utc frame and in the 1940 utc frame the COC is right on the cove of Carmen.




2 things.....longwave IR imagery is one of the worst ways to determine the center, especially when you have visible imagery during the daytime. Secondly, posting 2 images is impossible to determine a motion.

View this loop then tell me what you see.
Member Since: November 24, 2005 Posts: 635 Comments: 26661
30 mins till the new track... what lat now do you think nhc will put landfall?
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Quoting WaterWitch11:


i don't know what to tell you. my brother worked for schlumberger a few years back and he told me they evacuate when a tropical storm enters the gulf.

for all i know i could be remembering it wrong. that's why i said:
"I THOUGHT"

My husband works in the GOM and that was always what they've done. If something enters the gulf, they begin their evac plans which takes a day or two then they send'em home until they get the all clear.
Member Since: August 10, 2009 Posts: 0 Comments: 64
Quoting watchingnva:


your eyes are fine....hes barely going just north of due west with maybe a little slow down and wobble thrown in...lol


sorry your wrong
Member Since: March 10, 2010 Posts: 1 Comments: 7831
Quoting StormW:


It will most likely run into central America.
Like I said, I will take your word for it ATM but looks more northerly to me. I am just trying to learn and "see" what everyone else sees.
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GOM WV False Color,LARGE
Member Since: July 3, 2005 Posts: 426 Comments: 128875
Quoting Grothar:


Thanks Taz



welcome
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Quoting Levi32:
Ocean heat content is minimal off the west coast of the Yucatan. Restrengthening/organizing should be gradual until Alex gets farther away from land and more out into the gulf.



one thing going for Alex, it will have time to strengthen
Member Since: March 10, 2010 Posts: 1 Comments: 7831
Quoting hurricanejunky:


Go to this satellite loop

Click on trop pts and tell me the COC is not moving west of the forecast points. Maybe my eyes are broken but I doubt it...


your eyes are fine....hes barely going just north of due west with maybe a little slow down and wobble thrown in...lol
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Man I am not feeling right about the track of this storm. The models dont jump like that without a reason. I personally would be real concerned in Texas and LA. Even if landfall is in central Texas the rain that is going to cme with this is going to be a ton.
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Quoting Tazmanian:




it work


Thanks Taz
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Quoting neonlazer:
Well, my grandparents do live in Port Authur..not far from the coast at all. But i am a computer and tropical geek, anything this big gets me very excited. I am the kind that letz all my friends know if its coming this way..lol One is sad he might be up north when if it comes towards us..(hurricane party organizer guy..lol) Not saying i want it to come here..but yea..the excitement part of me wants it to come here..yea..i think yall get it.
Be on guard! Depending where you live when a hurricane hits, your "hurricane party" could turn into a "farewell party"!
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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