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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2887. Patrap
ALEX NASA MSFC viewer
Member Since: July 3, 2005 Posts: 423 Comments: 127814
Quoting Seastep:
Ike at 135mph:




that is so funny! Glad someone remembers the lesson. lol
Member Since: Posts: Comments:
2885. emguy
What we do know...Alex has likely reached the western most extent of the ridge now (hence the slow down-stalling action). I continue to support some erosion of the ridge like another poster showed on the NAM because out afternoon t-storms moved south to north today in SW Florida. Usual good sign that we are on the western edge of the ridge.

My only speculative word of caution regarding Alex is the elongation of the lower and mid banding in a NNE direction/pattern (not as concerned with this at being seen at upper levels also right now).Think of the spiral bands as isobars and that would lend me to believe the parth of least resistance is northerly or maybe even NNErly with time. Especially when considering the pattern evolution coming down the pike. Just some of my thoughts.
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2883. hydrus
Quoting TampaWeatherBuff:


Let me guess. Patrap's ex? ;)
Dat wuz a ggoodun:)
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Quoting GlobalWarming:


Poor, GW, really, how come? for being oblivious to the inevitable reality, good one, scott. the nhc is rarely wrong, bro. admit it, this will be a mexico storm, and that's that.


it will only be a MEXICAN Storm if they tamper with it.
look at how strong the trough is myfriend.

i just dont see it. possibly South Texas but not Mexico.
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Quoting washingaway:


Extrap is not a model.


Let me guess. Patrap's ex? ;)
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2880. xcool
GlobalWarming bye jfv.back to tropical weather
Member Since: September 26, 2009 Posts: 2 Comments: 15648
2879. Seastep
Ike at 135mph:


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Quoting ATL:


Which "party lines" do you think the NHC follows?


They dont follow any partylines whatsoever

conservative? they are responsible for putting out crucial information that could affect millions. Until you are in their shoes, not fair for anyone to judge what they do
Member Since: March 10, 2010 Posts: 1 Comments: 7530
Quoting LongGlassTube:
I expect the GFS and the EXTRAP model to be in agreement for quite some time.



Extrap is not a model.
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2873. scott39
Quoting hydrus:
Might be feeling the trough.
which makes me think if it starts turning more N now because of the trough,landfall aint gonna be in Mexico.
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Alex will be atleast a cat2 if this strengthening continues. what do you guys think?

i think the intensity models stink myself. [laughs]

I think TAMPA SPIN had it right earlier.
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10 p.m. Discussion says center is at 19.4N, 91.3W and the Navy site says 19.2N and 91.1W, obviously Navy time is behind NHC time.

Alex is getting comfy in its new environment.


Glad you all are keeping close eye on things and sharing this information with the rest of us.

Goodnight and see you and Alex in the a.m.
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Quoting ATL:

They explained. It's the outlier in this case. The Euro has been steadfast the whole time and its consistency will cause the NHC to weight it more heavily in their forecasts.


Its funny, because the HPC has been saying for days that the EMCWF is a outlier itself.

...TROPICAL STORM ALEX...

HPC RECOMMENDS FOLLOWING THE OFFICIAL NHC FORECAST AND ALL OTHER
INFORMATION CONCERNING TROPICAL STORM ALEX DURING THE SHORT RANGE
FCST PERIOD. THE 12Z GFS IS A SLOWER/FARTHER NORTH OUTLIER... THE
00Z ECMWF AND 12Z UKMET ARE MORE SRN OUTLIERS AND THE 12Z NAM/09Z
SREF MEAN ARE IN BETWEEN THESE TWO BUT MORE PROGRESSIVE AND DEEPER
WITH ALEX.

CONCERNING THE NRN EXTENT OF ALEX... A VORT LOBE/INVERTED TROUGH
AXIS WILL SWEEP TO THE NORTH AND WEST APPROACHING THE CENTRAL/WEST
GULF COAST STATES. THE 12Z GFS IS CONTAINING SIGNIFICANT
CONVECTIVE FEEDBACK ISSUES WHICH AFFECTS THE DAY 2 AND 3 QPF...
WHILE THE 00Z ECMWF APPEARS TO CONTAIN NO FEEDBACK AND MIGHT BE
BETTER TO USE. FOR MORE ON THE QPF ASPECT FROM THIS END... PLEASE
REFER TO THE QPFPFD LATER THIS AFTN.


...MODEL TREND GRAPHICS AT
WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...
...500 MB FORECASTS AT
WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

MUSHER

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2868. fsumet
Quoting TropicalNonsense:
WOW ..i am shocked the NHC is throwing out the GFS MODEL.

WHAT GIVES? THE GFS SPECIALIZES IN TROUGHS AND FRONTS.


What they meant was they are throwing out the old GFS for the parallel GFS run which is further south and more in line with the GFDL and HWRF.
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2867. ATL
Quoting NOLALawyer:


I am here for a reason. I don't trust or believe the party line that the NHC pushes. I find much more usful information here from guys like StormW in terms of perdicting where these storms will go. I went to sleep the Friday night of Katrina thinking Florida was a lock, woke up and took my fiance' to the airport at 6 am, drove 2 hours to pick up my kids and came back to Mandville in pure pandemonium. I evacuated at 4pm Saturday, got into Lake Charles around 1 am. That was the end of my confidence in the NHC. I find them too conservative when it comes to "possibles," which is likely motivated by political considerations.


Which "party lines" do you think the NHC follows?
2866. Levi32
Quoting GTcooliebai:
Lets see how good you pros are: anyone remembers this storm?



Allen.
Member Since: November 24, 2005 Posts: 635 Comments: 26601
2865. Patrap
Hurricane Allen 1980
Member Since: July 3, 2005 Posts: 423 Comments: 127814
Quoting gordydunnot:
2804 I've got to get some rest that storm looks like it's headed se I hope it doesn't do a loop into fl.


I'm sorry, how does it going south east portend a Florida landfall!? If anything I think that would rip it apart.
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Quoting Bordonaro:
Quoting LSU791:
I can still remember Katrina. All the models and all the exprts were all over a Florida landfall. They continually dicounted an outliers that dared to defy the majority. Then suddenly we in LA had 48 hours to prepare. Never discount the "NERD" for he knows more that you think. In reading the NHC statement one phrase popped out to me " An UNUSUALLY DEEP longwave trough." Kind of make you say hmmmm...

That "unusually strong upper level trough over the NE US is going to make for a VERY interesting next 3 or 4 days. IF that trough weakens the upper level ridge over the northern GOM, there is going to be a shift further northward!!


I am here for a reason. I don't trust or believe the party line that the NHC pushes. I find much more usful information here from guys like StormW in terms of perdicting where these storms will go. I went to sleep the Friday night of Katrina thinking Florida was a lock, woke up and took my fiance' to the airport at 6 am, drove 2 hours to pick up my kids and came back to Mandville in pure pandemonium. I evacuated at 4pm Saturday, got into Lake Charles around 1 am. That was the end of my confidence in the NHC. I find them too conservative when it comes to "possibles," which is likely motivated by political considerations.
Member Since: Posts: Comments:
2861. Patrap
0215 UTC

Member Since: July 3, 2005 Posts: 423 Comments: 127814
Lets see how good you pros are: anyone remembers this storm?

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2859. hydrus
Quoting scott39:
Why has Alex slowed down?
Might be feeling the trough.
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2858. xcool
you i think care about Ph.D's. jfv
Member Since: September 26, 2009 Posts: 2 Comments: 15648


AOI
Member Since: Posts: Comments:
I expect the GFS and the EXTRAP model to be in agreement for quite some time.

Quoting Hardcoreweather2010:
GFS you are charged with the impersonation of the XTRAP model

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2854. hydrus
Quoting floridaT:
since wilma was mentioned if i remember right when it was parked off cancoon the models were all over the place but as soon as wilma moved the models were dead on. i got to witness wilma make landfall on the beach in marco from the fifth floor. it was amazing just when ya thought wind cant blow any harder it did.
You were on the fifth floor during Wilma? I would bet you wont forget that for a while.
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2853. ATL
Quoting TropicalNonsense:
WOW ..i am shocked the NHC is throwing out the GFS MODEL.

WHAT GIVES? THE GFS SPECIALIZES IN TROUGHS AND FRONTS.

They explained. It's the outlier in this case. The Euro has been steadfast the whole time and its consistency will cause the NHC to weight it more heavily in their forecasts.
2852. xcool
GlobalWarming lol .poor jfv
Member Since: September 26, 2009 Posts: 2 Comments: 15648
Quoting ATL:

Has it continued to shift/wobble SW?
Now moving NW slowly.
Member Since: September 2, 2009 Posts: 130 Comments: 21122
2848. scott39
Why has Alex slowed down?
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2847. ssmate
Quoting Baltimorebirds:
You know yesterday when the models were all indicating a mexico landfall not many was on here.Now that it's threatning the u.s then here they come.
That tells me there are fewer people in Mexico on this Blog than the US. What does it mean to you?
Member Since: Posts: Comments:
Time: 02:54:30Z
Coordinates: 19.2333N 91.2167W
Acft. Static Air Press: 924.8 mb (~ 27.31 inHg)
Acft. Geopotential Hgt: 608 meters (~ 1,995 feet)
Extrap. Sfc. Press: 991.0 mb (~ 29.26 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 50° at 0 knots (From the NE at ~ 0.0 mph)
Air Temp: 22.6°C (~ 72.7°F)
Dew Pt: 18.9°C (~ 66.0°F)
Peak (10s) Flt. Lvl. Wind: 4 knots (~ 4.6 mph)
SFMR Peak (10s) Sfc. Wind: 22 knots (~ 25.3 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
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WOW ..i am shocked the NHC is throwing out the GFS MODEL.

WHAT GIVES? THE GFS SPECIALIZES IN TROUGHS AND FRONTS.
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2843. Seastep
Quoting IKE:


Would you say that if the 5 day track was right over you?


I would be loving it. Ike is a perfect example. ;)
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2842. Levi32
New center fix has Alex moving northwest at 310 degrees at 4mph, still very slow, since the last vortex message.
Member Since: November 24, 2005 Posts: 635 Comments: 26601
CoC has move slightly NW
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2840. ATL
Quoting Levi32:
991.0mb.


Atlantic USAF High-Density Observations


000
URNT15 KNHC 280303
AF304 0401A ALEX HDOB 39 20100628
025400 1914N 09115W 9249 00607 9911 +228 +186 360006 007 020 001 00
025430 1914N 09113W 9248 00608 9910 +226 +189 050000 004 022 000 00
025500 1914N 09111W 9252 00602 9910 +224 +192 184008 010 024 003 00
025530 1913N 09110W 9249 00608 9914 +221 +193 191009 010 999 999 03
025600 1913N 09110W 9249 00608 9915 +221 +194 224008 009 999 999 03
025630 1911N 09111W 9247 00611 9914 +221 +195 220009 009 999 999 03
025700 1913N 09112W 9253 00603 9910 +226 +195 204004 007 022 002 00
025730 1914N 09113W 9249 00605 9910 +225 +196 043004 007 024 001 00
025800 1915N 09114W 9249 00608 9911 +228 +197 047008 009 021 000 00
025830 1916N 09116W 9248 00610 9912 +225 +197 051011 013 020 000 00
025900 1917N 09117W 9250 00610 9915 +228 +198 040020 022 025 000 00
025930 1918N 09118W 9248 00614 9918 +223 +198 043026 027 030 003 00
030000 1919N 09119W 9246 00619 9925 +215 +198 056028 030 034 001 00
030030 1920N 09120W 9246 00623 9931 +210 +197 067034 035 034 000 00
030100 1922N 09122W 9251 00624 9937 +208 +194 071036 037 034 001 00
030130 1923N 09123W 9251 00628 9943 +204 +191 069037 039 035 001 00
030200 1924N 09124W 9248 00636 9948 +205 +186 067036 037 035 000 00
030230 1925N 09125W 9248 00638 9950 +210 +182 068034 034 031 002 00
030300 1926N 09127W 9252 00638 9954 +206 +179 068033 034 031 000 00
030330 1928N 09128W 9250 00641 9956 +208 +177 070030 031 031 000 00
$$

Has it continued to shift/wobble SW?

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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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