Alex continues to slowly organize

By: Dr. Jeff Masters , 7:17 PM GMT on June 28, 2010

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Tropical Storm Alex continues to slowly grow more organized as it steams away from Mexico's Yucatan Peninsula. Satellite loops show that Alex's heavy thunderstorms continue to increase in areal extent, and low level spirals bands are slowly building to the south and north. The clockwise flow around an upper-level high pressure system a few hundred miles west of Alex is bringing about 15 knots of wind shear to the storm, which is slowing intensification. Heavy thunderstorm activity is limited on the storm's northwest side, thanks to the shear and some dry continental air flowing off the coast of North America. Sea Surface Temperatures are very warm, 29°C. The latest Hurricane Hunter center fix, at 12:07 pm CDT, showed a central pressures of 990 mb, a 1 mb rise in six hours. Top winds were holding steady near 60 mph. Alex has stalled out the last few hours, as it began to "feel" the trough of low pressure to its north breaking down the high pressure ridge that has been pushing the storm to the west-northwest. This stall has allowed the storm to churn up cold water from the depths, which is probably interfering with development. Satellite loops show that Alex has a very large circulation covering about 2/3 of the Gulf of Mexico. We can expect that should Alex become a Category 2 or stronger hurricane, its storm surge will affect a much wider stretch of coast than Hurricane Dolly of 2008 did.


Figure 1. Afternoon satellite image of Alex.

Track forecast for Alex
The latest 12 UTC (7am CDT) runs of our most reliable computer models have come into much better agreement. A consensus forecast arrived at by averaging together most or all of the tracks of our top models--the GFS, ECMWF, GFDL, NOGAPS, HWRF, UKMET, and GFDN--is pretty much what NHC always uses as the basis of their forecast. This consensus forecast has narrowed in on the region just south of the Texas/Mexico border as being the most likely landfall location, with the usual cone of uncertainty surrounding it. The computer model that had been making the northernmost landfall predictions, the Canadian model, is now projecting a landfall 100 miles south of the Texas/Mexico border. There has been a general southward shift of the models in their latest runs, and the most northerly landfall location, near Port Mansfield, is now being predicted by the HWRF model. The earliest landfall time is Wednesday morning, and the latest is Thursday morning. Which model should you trust? Last year, the best performing models at the 3 day forecast period were the GFS, Canadian, ECMWF, and GFDL.

With steering currents relatively weak, the uncertainty in landfall location is high. The average error in an NHC 72-hour track forecast last year was 230 miles, which is about the distance from Brownsville to Port O'Connor. Consider also that the NHC cone of uncertainty is the region where 2/3 of the time (using the last 5 years of statistics) the center of a storm will go. Forecast errors tend to be equally large along track (speed errors) and cross-track (deviations from side-to-side), so that means that about 20% of the time a storm will not be in the cone of uncertainty. Given the slow motion of Alex and the recent uncertainty of the computer models, people living just beyond the edge of the cone of uncertainty should not be confident yet that Alex will miss them.

To get the probability of receiving tropical storm force winds or hurricane force winds for your location, I recommend the NHC wind probability forecasts. The 10am CDT (15 UTC) wind probability product predicted that Brownsville, Texas had the highest odds of getting a direct hit from Alex:

Brownsville, TX: 67% chance of tropical storm conditions (winds 39+ mph), 16% chance of hurricane force winds (74+ mph). This is the cumulative probability through Saturday morning. The wind probability forecasts also include separate probabilities for each 12-hour period between now and three days from now, and each 24 hours for the period 4 - 5 days from now.

La Pesco, MX: 49% tropical storm, 6% hurricane.

Tampico, MX: 31% tropical storm, 4% hurricane.

Corpus Christi, TX: 45% tropical storm, 6% hurricane.

Freeport, TX: 23% tropical storm, 2% hurricane.

Galveston, TX: 21% tropical storm, 1% hurricane.


Figure 2. Skill of computer model forecasts of 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.

Uncertainty in the NHC Cone of Uncertainty
A research project funded by NOAA known as the Joint Hurricane Testbed has produced a remarkable number of tools now in operational use at the National Hurricane Center to improve hurricane forecasts and warnings. One of these projects, called "Prediction of Consensus TC Track Forecast Error and Correctors to Improve Consensus TC Track Forecasts", was an effort by Dr. Jim Goerss at the Navy Research Lab to improve the accuracy of the NHC "cone of uncertainty" (AKA the "Cone of Death") showing where a storm is expected to track 2/3 of the time. The radius of the circles that make up the cone are based on error statistics of the official NHC forecast over the past five years. We can expect in certain situations, such as when the models are in substantial disagreement, a consensus forecast made using these models will have much greater than average errors. Since the NHC typically bases their forecast on a consensus forecast made using a combination of reliable hurricane forecasting models, it is instructive to view the "GPCE" (Goerss Prediction Consensus Error) circles to see if the uncertainty cone should be smaller or larger than usual. The consensus forecast I'll look at is called "TVCN", and is constructed by averaging the track forecasts made by most of (or all) of these models: GFS, ECMWF, NOGAPS, GFDL, HWRF, GFDN, and UKMET. In the case of this morning's 12 UTC (7am CDT) June 28 run of these models, here is what the radius of the "cone of uncertainty" should be, in nautical miles:

12 hours: 42 nm
24 hours: 73 nm
36 hours: 96 nm
48 hours: 112 nm
72 hours: 173 nm
96 hours: 327 nm
120 hours: 376 nm

And here is the radius of NHC's "cone of uncertainty" for their official forecast, based on the average errors for the past five years:

12 hours: 36 nm
24 hours: 62 nm
36 hours: 85 nm
48 hours: 108 nm
72 hours: 161 nm
96 hours: 220 nm
120 hours: 285 nm

So, the GPCE error estimates are showing that the latest forecasts for Alex out to 72 hours are 4% - 17% higher in uncertainty than average. The 4 - 5 day forecasts are 32% - 49% more uncertain than average--but of course, we expect Alex to be inland at those times.

Intensity forecast for Alex
Alex is currently over a region of ocean with relatively low total ocean heat content (about 10 - 30 kJ/cm^2). By Tuesday and Wednesday, the heat content will increase to 40 - 70 kJ/cm^2, which is high enough to allow Alex to rapidly intensify. Wind shear is currently a moderate 15 knots, and is projected by the SHIPS model to decrease to the low range, below 10 knots, on Tuesday and Wednesday. The combination of low wind shear and high ocean heat content should allow Alex to intensify into a hurricane. NHC is giving Alex a 78% chance of being a hurricane on Wednesday morning, and a 16% chance it will be a major hurricane at that time. Water vapor satellite images, though, show plenty of dry air over Texas and the adjoining waters, and this dry air may turn out to be a significant detriment to Alex. Another factor limiting Alex's intensification may be that the atmosphere is more stable than usual right now--temperatures at 200 mb are a rather warm -50°C, and are expected to warm an additional 1 - 2 degrees by Wednesday. Another factor limiting Alex's intensification may be its slow forward speed. Alex has already stalled out once, and may stall out later in its path, as well. A stalled-out 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 enough roadblocks that I give a 20% chance of this happening.

Elsewhere in the tropics
None of the reliable computers models is calling for tropical storm formation over the the next seven days in the Atlantic.

Wind and ocean current forecast for the BP oil disaster
It currently appears that Alex will not directly affect the oil slick location, other than to bring 2 - 4 foot swells to the region on Wednesday. However, because Alex is such a deep low pressure region, strong southeast winds of 15 - 25 knots will blow over the oil slick region today through Wednesday, according to the latest marine forecast from NOAA. The resulting currents should act to push oil to the west and northwest onto portions of the Louisiana, Mississippi, and Alabama coasts, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Oil will also move westward along the central Louisiana coast towards the Texas border.

Resources for the BP oil disaster
Map of oil spill location from the NOAA Satellite Services Division
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA's interactive mapping tool to overlay wind and ocean current forecasts, oil locations, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

Portlight continues its Haiti response
Hurricane season is here, and Haiti is not ready. Over 1.5 million Haitians are living outside in tents or under tarps, and are highly vulnerable to a hurricane. Portlight is working on constructing steel shelters out of shipping containers for homeless Haitians, as detailed in the Haitian Relief Recap blog post. Please visit the Portlight.org web site or the Portlight blog to learn more and to donate to Portlight's efforts in Haiti.


Figure 3. Still frame from the remarkable video taken inside the Haitian Presidential Palace during the 2010 earthquake.

To remind people of just how devastating the earthquake was, the Haitian government released a video earlier this month showing the inside of the Haitian Presidential Palace during the mighty Haitian earthquake.

Next post
Dr. Rob Carver is planning on making a post late tonight, and I'll have an update by 9:30am CDT on Tuesday.

Jeff Masters

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Quoting kmanislander:
Alex starting a new phase



Getting better organized.
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No, No, No , we don't want it here in Corpus Christi !
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Sorry if this has been discussed or answered.
How long do ridges typically stick around? I know that this storm is projected as a Tex-Mex border storm. I just wanted to know how long will the ridge be in place to guard against something more northerly. Thanks.
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Quoting jeffs713:

It looks like maybe the north end of Padre. The GFS has a tendency to act like a windshield wiper, especially along the gulf coast (remember, the GFS did the same thing with Ike).

yep, I remember we thought Ike was coming our way; got our offices cleaned out and then he decided to go a little north.
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Cameron County Judge (TX) claims that if Alex heads near Brownsville the Levees there might not be able to sustain the storm. Watch the video pretty scary stuff.
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2052. Patrap
Alex has to separate that whole inner envelope where all his Mojo is currently from the Yucatan Proper and stack that Column and like a recent post mentioned. A cat One by Dawn is a reasonable route dujour atm.

Fondue anyone..?

Member Since: July 3, 2005 Posts: 421 Comments: 127647
Quoting hamla:
why is jim cantorie in venice la.????????

idk but its a bad omen
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Quoting F4PHANTOM:
Weakness will close before Alex can take advantage .


Agreed. The models are spot on. TX/MX border
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Alex starting a new phase

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2048. tkeith
Quoting hamla:
why is jim cantorie in venice la.????????
not for the shrimp...
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2046. xcool
67 knots found at flight level
omgggggg
Member Since: September 26, 2009 Posts: 2 Comments: 15626
Quoting RecordSeason:
#1. Alex is not developing an eye first because it needs a well-established CDO before any of that happens.

#2. Alex is not rapidly intensifying because this is the NHC term of rapidly intensifying:

A decrease in the minimum sea-level pressure of a tropical cyclone of 1.75 mb/hr or 42 mb for 24 hours.

===

Nature cares little about text book distinctions. This storm has a better structure than most category 2 hurricanes. So get over it.

You will see very much intensification before it's all said and done, so just watch.


well said Record! The Satellight images speak for themselves.
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Quoting extreme236:


Yeah, calling 13 year old kids idiots is very mature.
Yes and then slamming me and telling me that rapid intensification is occurring, pretty funny if you ask me.

Now. Enough of the drama and back to the tropics.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting Patrap:


Shucks Blood,..baby gon rip dat line and mabe due the single out Holmes

roflmao!

Alex definitely didn't have the fish!
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2042. hamla
why is jim cantorie in venice la.????????
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Quoting extreme236:


Yeah, calling 13 year old kids idiots is very mature.

yah miami is a good blogger leave him alone
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Quoting Hardcoreweather2010:
Not good


UH OH, shift northward again...
Member Since: April 1, 2010 Posts: 9 Comments: 2699
Quoting TropicalNonsense:


i would say something but your posts speak for themselves.

you have a lack of knowledge and a maturity problem Hurricaneswirl-
but quite obviously this is not a conversation for the Good Dr's Blog.




Yeah, calling 13 year old kids idiots is very mature.
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Just did a blog on Alex.
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Quoting RecordSeason:
#1. Alex is not developing an eye first because it needs a well-established CDO before any of that happens.

#2. Alex is not rapidly intensifying because this is the NHC term of rapidly intensifying:

A decrease in the minimum sea-level pressure of a tropical cyclone of 1.75 mb/hr or 42 mb for 24 hours.

===

Nature cares little about text book distinctions. This storm has a better structure than most category 2 hurricanes. So get over it.

You will see very much intensification before it's all said and done, so just watch.
If it had the structure of a category 2 hurricane the T-numbers will be much higher. Poof!
Member Since: September 2, 2009 Posts: 130 Comments: 21091
2034. Patrap
Quoting Delsol:


lay'er down an' smack 'em yack 'em.


Shucks Blood,..baby gon rip dat line and mabe due the single out Holmes

Member Since: July 3, 2005 Posts: 421 Comments: 127647
Not good
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Quoting MrstormX:
Huge!

WOW.....it looks like Alex is sucking in everything!
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Quoting RecordSeason:
#1. Alex is not developing an eye first because it needs a well-established CDO before any of that happens.

#2. Alex is not rapidly intensifying because this is the NHC term of rapidly intensifying:

A decrease in the minimum sea-level pressure of a tropical cyclone of 1.75 mb/hr or 42 mb for 24 hours.

===

Nature cares little about text book distinctions. This storm has a better structure than most category 2 hurricanes. So get over it.

You will see very much intensification before it's all said and done, so just watch.


Wow, um...no? Category 2 hurricanes have an inner core feature with some type of eye or eyewall features. Alex has none of these, as recon is showing us.
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TCHP:

We just rptd TCU DSNT SW-N CU ALQDS here at BPT. Tropical moisture, trough, whichever. We got some much-needed rain from all this here toady.
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2028. bassis
Thank you for your input Mr. W on hurricane Hollow
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Quoting MechEngMet:
Progster and Atmo: both very good examples of 2D models of why the quarterback has to lead the receiver of the pass. The earth is a sphere, therefor 3D.

Lacking steering influence can anyone tell me why Alex won't go north?
Inertia.
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Quoting MrstormX:
Huge!



And quite nice to look at as well.
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news reporting... Mayor of South Padre Island telling people there to board up and leave.
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Quoting StormW:


Good evening!


Howdy Storm love! Gracias for all your amazing knowledge and accurate forecasting. How's it going?
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2020. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15626
I definitely don't see this undergoing RI, at least not right now. It's still reorganizing after it's trip over the Yucatan. Probably will be a hurricane in the morning, and then we can see where it goes from there.
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2017. Delsol
Quoting muddertracker:
excuse me..stewardess...I speak jive!

"Blood can't hang say north east goes seven up."


lay'er down an' smack 'em yack 'em.
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Re #1910 abt Matagorda Bay:



Isn't Matagorda in the TS watches on there? If so, it means landfall in that area of the coast is at least possible, if not probable.
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Quoting Patrap:


Latest RECON HH TAIL # 304 Message
Please make sure your tray tables are in their upright and locked positions.
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Quoting RecordSeason:
1969:

Watch and learn Miami

NHC blew this one.

It's going for Florida. Heck, it may even cross the Yucatan again first.


Man if you're right, you're gonna get one heck of a prop from people. I just don't see it getting past TX. We'll see.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting HurricaneSwirl:


He's probably a lot smarter than he is now..


As what I was thinking, only I wasn't trying to stoop to his level. However, I happen to think miamihurricane could school a lot of the bloggers on here. If I had a son as smart of him I would be wicked proud.

Good for you Miami for not letting him get to you.
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Huge!

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2009. 7544
record are u stating a wilma track when u say fla ,
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Quoting RecordSeason:
1969:

Watch and learn Miami

NHC blew this one.

It's going for Florida. Heck, it may even cross the Yucatan again first.
The NHC's forecast will have no affect on where Alex goes. I wish you would've listened to StormW when he was on with Barometer Bob, you would've learned a lot.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
2007. Patrap
.."Happiness,

Is a Warm Column"..
Member Since: July 3, 2005 Posts: 421 Comments: 127647

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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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