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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1588. xcool
bohonkweatherman yep
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Quoting MiamiHurricanes09:
We found the center. Pressure at 991.0mb.

234500 1913N 09105W 9236 00615 9910 +218 +143 258002 004 016 001 00



OMG 991mb
Member Since: May 21, 2006 Posts: 5091 Comments: 115131
I guess we can now put Alex in the same group as Fay in terms of examples of storms strengthening over land?
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1585. hydrus
Quoting Levi32:
Alex developing an eye northwest of Belize at 07:45UTC last night:

And that really is an eye right?
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If Alex surpasses winds of 55 mph, I'll be pretty doubtful that this thing was a tropical depression other land.
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Alex is only 50 miles off the coast, right? Isn't the REALLY hot water 100 or so miles out? Alex is impressive.
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I think a Stronger storm has a better chance to move more north than a weaker storm?
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.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1580. Levi32
Found the center with 991.0mb but looks like it was unable to go right through the center to the south side due to it being so close to the coast. SFMR easily finding uncontaminated TS-force surface winds.

000
URNT15 KNHC 272353
AF304 0401A ALEX HDOB 20 20100627
234400 1915N 09108W 9249 00604 9913 +219 +138 033013 017 019 003 03
234430 1914N 09107W 9236 00615 9910 +220 +141 004006 007 017 002 03
234500 1913N 09105W 9236 00615 9910 +218 +143 258002 004 016 001 00
234530 1912N 09104W 9255 00599 9911 +215 +147 201008 010 019 001 00
234600 1911N 09102W 9248 00609 9915 +216 +150 186015 018 019 002 03
234630 1912N 09101W 9241 00616 9915 +218 +154 181022 024 999 999 03
234700 1914N 09101W 9242 00612 9916 +212 +157 160023 027 037 004 03
234730 1915N 09103W 9250 00604 9913 +217 +158 133021 022 032 004 00
234800 1916N 09104W 9252 00601 9912 +218 +158 117023 026 034 006 00
234830 1918N 09106W 9254 00601 9917 +207 +158 105034 038 039 007 00
234900 1919N 09107W 9258 00604 9926 +199 +157 091033 033 037 009 00
234930 1920N 09108W 9244 00621 9928 +203 +154 090034 034 035 008 00
235000 1921N 09110W 9248 00622 9933 +201 +150 086034 035 034 007 00
235030 1923N 09111W 9244 00628 9938 +198 +147 081039 041 036 007 00
235100 1924N 09112W 9247 00628 9940 +202 +145 076041 043 035 005 00
235130 1925N 09114W 9246 00633 9947 +191 +144 070041 043 035 004 00
235200 1926N 09115W 9244 00637 9950 +191 +142 068040 041 035 005 00
235230 1927N 09116W 9250 00636 9952 +205 +140 067037 038 033 001 00
235300 1929N 09118W 9246 00642 9954 +205 +139 066036 037 032 000 00
235330 1930N 09119W 9248 00642 9956 +205 +140 065036 036 031 000 00
$$
Member Since: November 24, 2005 Posts: 635 Comments: 26647
Quoting stillwaiting:
w/a pressure reading that low and alex re-emerging expect RI this evening he'll catch up to the pressure drop (stregthen) as its inner core appears to be trying to form a eye,hurricane by tomorrow morning IMO..


If not, it will definitely be a strong TS.
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1578. Patrap
991mb Respectable and down a lot after a Land crossing.

A testament to Alex's voracity and size.

Member Since: July 3, 2005 Posts: 424 Comments: 128348
We found the center. Pressure at 991.0mb.

234500 1913N 09105W 9236 00615 9910 +218 +143 258002 004 016 001 00
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1576. CCkid00
Quoting Weather456:
Winds usually lag behind pressure readings, which means it should not take long for the winds to catch up to the 991 pressure reading. Alex could respond by becoming a strong TS before 2mr's 11am advisory.

does this change anything with your track forecast? i'm new on here and i'm learning....been watching for 6 years. thanks!
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Cant wait for the new model runs. We might see more of a shift to the east.
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Quoting Joanie38:
Hi StormW..I have a favor..could you read my post 1512 and tell me what your opinions are on that??? Thanks so much!!! :)


Evening Joanie.
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1572. JLPR2
Quoting Weather456:
Winds usually lag behind pressure readings, which means it should not take long for the winds to catch up to the 991 pressure reading. Alex could respond by becoming a strong TS before 2mr's 11am advisory.


what worries me is that the pressure could keep dropping :\
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Quoting Tazmanian:
i hate too be a wishcaster but with the HH find vary low mb reading am starting to think that a strong cat 4 or 5 hurricane is becomeing more and more likey now



but well see


IMO strong 3 or weak 4 MAX with strong 2 being the most likely.

Most storms don't come near their maximum potential.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting Levi32:
Alex developing an eye northwest of Belize at 07:45UTC last night:

I saved that image. Wow.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Question. A few people have said that Alex is acting more like a typhoon. How so? or How are they different from a hurricane? Anyone? Thanks.
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w/a pressure reading that low and alex re-emerging expect RI this evening he'll catch up to the pressure drop (stregthen) as its inner core appears to be trying to form a eye,hurricane by tomorrow morning IMO..
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Quoting CybrTeddy:
What worries me though, if this does quickly gain strength with already pressures at 991 mb, that could make Alex feel the trough's weakness more easily, and influence it more northward.


Not good not good at all. This may wind up in the middle of the GOM depending on when and where the trough picks it up.
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Hi StormW..I have a favor..could you read my post 1512 and tell me what your opinions are on that??? Thanks so much!!! :)
Member Since: June 16, 2008 Posts: 0 Comments: 507
You cannot beat StormW or Weather456 IMO. Great jobs
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Quoting Levi32:
Alex developing an eye northwest of Belize at 07:45UTC last night:


Working up a sweat!
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I think Alex is fixing to put on a show..
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Quoting Weather456:
Winds usually lag behind pressure readings, which means it should not take long for the winds to catch up to the 991 pressure reading. Alex could respond by becoming a strong TS before 2mr's 11am advisory.


Rapid Intensification?
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Remember SFMR readings are a 10 sec average reported every 30 seconds, so you need to see consecutive readings.
Member Since: September 23, 2005 Posts: 14 Comments: 11179
1560. ATL
Quoting KarenRei:


Tropical storm... heck, 991 is normal for a Cat 1

Remember Alex's massive size. It needs a lower pressure to maintain all those feeder bands. Still should be a TS instead of a TD at this point though.
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Little doubt that Alex is going between Galveston and Shreveport,expect the models to shift eastward due to rapid intensification! Devastating effects for oil relief.God bless the northern gulf!
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Quoting Weather456:
Winds usually lag behind pressure readings, which means it should not take long for the winds to catch up to the 991 pressure reading. Alex could respond by becoming a strong TS before 2mr's 11am advisory.
Exactly.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
1557. angiest
If memory serves, Hurricane Agnes actually formed over the Yucatan...
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1556. help4u
Is their a reason gfdl model run had higher winds after landfall in texas than when on the coast.had 84 knot winds pretty far inland.
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1555. Levi32
Alex developing an eye northwest of Belize at 07:45UTC last night:

Member Since: November 24, 2005 Posts: 635 Comments: 26647
Winds usually lag behind pressure readings, which means it should not take long for the winds to catch up to the 991 pressure reading. Alex could respond by becoming a strong TS before 2mr's 11am advisory.
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1552. JLPR2
Alex is one heck of a depression XD
The reading at the center should be interesting
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wheres the North turn,
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Quoting CybrTeddy:
What worries me though, if this does quickly gain strength with already pressures at 991 mb, that could make Alex feel the trough's weakness more easily, and influence it more northward.


I was just about to say that. If this gets stronger than expected, look for a more northward movement.
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i hate too be a wishcaster but with the HH find vary low mb reading am starting to think that a strong cat 4 or 5 hurricane is becomeing more and more likey now



but well see
Member Since: May 21, 2006 Posts: 5091 Comments: 115131
1548. xcool
Alex hmmm bad feel.
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Quoting HurricaneSwirl:
No contamination, there are too many readings close to it, it's been a steady downward trend, no suspect data there.
Yup.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Quoting Baltimorebirds:
That's a tropical storm right there.


Tropical storm... heck, 991 is normal for a Cat 1
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Quoting StormW:
Good evening Stef; Alaina!


Evening Storm! Just being amazed at Alex.
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No contamination, there are too many readings close to it, it's been a steady downward trend, no suspect data there.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
What worries me though, if this does quickly gain strength with already pressures at 991 mb, that could make Alex feel the trough's weakness more easily, and influence it more northward.
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This reading also means that the GFDL 18Z intensity forecast should be dismissed with prejudice.
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1540. jpsb
Quoting Baltimorebirds:
Yaaay.I can blog again.I was on a 24 hour ban.I got in trouble by a troll.
Welcome back, don't feed the trolls, lol.
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but where is the center of this thing, I would have thought with those coordinates they have passed they would have hit it by now
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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.