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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Well, I gotta run... I know a super cute 3 year old that is going to wake me up awfully early.

Check in tomorrow AM after I drop the kiddo off at school.

Good night all... even Pete.
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2455. guygee
Quoting Patrap:

.."Happiness,
..is a Warm Column

"When I hold you in my spiral bands..."
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Hey storm,check out the new steering for 700-850???looks like a NNW shot towards the TX/LA border,but i don't know the high is also noted as stregthening /building east over the plains,also noticed it looks like alex has ingested/ing darbies energy!!!
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Quoting Floodman:


3 at landfall, a CAT at her height

flood she was A CAT at her hieght or a cat 5
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Quoting P451:
84HR Loop of Alex. Water Vapor.


Thanks P451, as always. It's so evident on there that it was in "rapid strengthening mode" right before it hit land. I wouldn't be surprised if it was a major right now if the Yucatan did not exist. Thankfully it does.
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2448. MZV
If I didn't know anything of the wind speed ... I'd have called that a hurricane on the imagery.

Heck, with 65 MPH winds, all Alex needs to do is move at a pace of 10MPH and he *is* a hurricane.
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2446. bappit
Quoting AstroHurricane001:
Convection flaring up in the COC, but look at the outer spiral bands bringing all those thunderstorms over Texas, Florida and Cuba. This is just bizarre, and if those bands stay attatched, this is going to be one megagigantic hurricane.


God, please save us from the term "megagigantic". The thunderstorms over Texas and Mexico currently are definitely not part of Alex. I would also assert that the clouds over the eastern Gulf are not part of Alex either. We got a big weather pattern with a tropical storm embedded in it. I disagree with the Doctor that 2/3 of the Gulf of Mexico is covered by Alex.

If you want to argue it as a glass half-full/half-empty kind of thing, okay--but pushing the all-encompassing tropical storm circulation idea creates a problem since how do you tell where any tropical storm leaves off and the rest of the atmosphere holds sway. It all becomes one muddled mess.

I vote for a big weather pattern with a tropical storm embedded in it.
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Quoting atmoaggie:
Ding! Ding! Ding!


no, just ding...Total energy can be similar for a (for example) small cat 3 and a very large TS. Total angular momentum is what makes Alex both slow and potentially deadly. And the non-linear aspect of intensification means it doesn't have to be that slow, either...
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Quoting AlexEmmett:

um last tiem i checked the stronger it get the more north it gets and the storm is so big i will still affect the oil and its still moving north

??? Deep steering winds show, uhh, the other way, honestly.

Member Since: August 16, 2007 Posts: 6 Comments: 12463
Hurricane warning: Baffin Bay - Brownsville
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Quoting RecordSeason:
SUMMARY OF 1000 PM CDT...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...21.0N 91.6W
ABOUT 440 MI...710 KM ESE OF LA PESCA MEXICO
ABOUT 505 MI...810 KM SE OF BROWNSVILLE TEXAS
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/HR
PRESENT MOVEMENT...N OR 0 DEGREES AT 5 MPH...7 KM/HR
MINIMUM CENTRAL PRESSURE...985 MB...29.09 INCHES

As previously pointed out, that location is definitely 0.2 degrees east of the previous location, which means the storm has averaged NNE at a 5 to 2 N to E ratio.

This should drastically shift all models and all forecasts.


shift which way?
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Quoting kmanislander:


It was too good an opening to pass up LOL.

Back later.


I know...hard to pass up the easy ones sometimes
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Not enough heat potential in water to support too much intensification......
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I think TX is gonna get rocked with a Cat-3. Hope all you peeps over in S. Texas have stocked up.
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Quoting Orcasystems:


Oh great everyone is here... where is Shep??


Who's Shep?
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Quoting RecordSeason:
2325:

But it covers more area and therefore has access to more energy.

This storm is going to take like 7 to 10 days to die out even over land if I am wrong and it goes somewhere other than Florida.
The only energy it has is under it's eyewalls, period. (or circulation center, given a system lacking eyewalls). Take a look at any storm just after the eye has crossed the shore. Whatever is hanging out over water is irrelevant.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting txjac:


What number hurricane was Wilma ...2, 3, 4?


3 at landfall, a CAT at her height
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting tennisgirl08:
I mean this in no disrespect to the people of texas or mexico - but thank goodness this thing is headed away from the oil spill region and the northern gulf states. Whew!

Bullet....dodged!


???? its going 010 @ 6 kts
Unless it resumes its proper track... its going straight to the oil.
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Quoting tennisgirl08:
I mean this in no disrespect to the people of texas or mexico - but thank goodness this thing is headed away from the oil spill region and the northern gulf states. Whew!

Bullet....dodged!

um last tiem i checked the stronger it get the more north it gets and the storm is so big i will still affect the oil and its still moving north
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Quoting Grothar:

Thing is, it's on the far northern edge of the NHC's cone. So shouldnt they be adjusting the cone to include more of texas and less of mexico? And why are the 00Z models still initializing NNW or even NW if it's confirmed to be moving N??
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You mean Kevin Costner doesn't have all the oil cleaned up yet?
Member Since: September 18, 2007 Posts: 0 Comments: 1074
2428. WxLogic
A/B High starting to bridge (at least attempting to) with the developing high in the 4 Corners region... but there's still a decent weakness in the Louisiana area.



The N to NNE component might continue for a couple hours, but if the A/B keeps building west as the weakness closes up north then NHC track will hold... might not even matter how much N progress it makes... the building High N of Texas will be able put it back on track.
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Quoting Orcasystems:


Happiness is a long walk down a fairway carrying a putter :)


I disagree happiness is a long walk down a fairway with all your clubs in the caddy to the hole :).
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2426. KEEPEROFTHEGATE (Mod)
01L/H/A/C1
MARK
21.0N/91.4W
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whats the chances of it moving more towards houston?
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Quoting StormW:


I guess Alex is starting to MOOOOOve!


Do you think that Alex will only make it to the NHC forecast of 90 mph? Thanks!
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Quoting StormW:


I guess Alex is starting to MOOOOOve!

yah it MOOOing away
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2420. tkeith
Quoting StormW:


I guess Alex is starting to MOOOOOve!
Now this really reminds me of Dolly...even Storm is on it :)
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I mean this in no disrespect to the people of texas or mexico - but thank goodness this thing is headed away from the oil spill region and the northern gulf states. Whew!

Bullet....dodged!
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2417. Patrap
Quoting hideawaygulf:
great Awesome...thanks!! Hey..do you know what the "ensemble" models are and why they differ from computer models?


Google NHC Model Overview
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Quoting errantlythought:


IT'S GONNA RAIN.

are u rooker if so the TWC anit helping your carreer
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2415. Patrap
ALEX RECON HH Tail # 304 Latest Message
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Quoting Patrap:
ATCF images (Hurricane Track Models)

Current Storms:
Alex
great Awesome...thanks!! Hey..do you know what the "ensemble" models are and why they differ from computer models?
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Quoting swampliliy:


Curdles my toes..... :))


Oh great everyone is here... where is Shep??
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2411. 7544
nice to see the n ne croud now in agreement

alex has a few tricks to playout yet before he resumes his corse
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2410. Patrap




A hurricane's "hot towers" can increase its intensity by adding power to boost the storm's heat engine. For the first time, research meteorologists have run complex simulations of these phenomena using a very fine temporal resolution. They have combined this new simulation data with satellite observations to study the innerworking of the "hot towers" in never-before-seen detail.
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2409. Ossqss
Hummmm, basic physics taking place that
the models are not coded for with respect to oil sheen?
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Quoting Patrap:

.."Happiness,

..is a Warm Column




Happiness is a long walk down a fairway carrying a putter :)
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Alex is exploding convection. Not good news. I have an eerie feeling that Alex will strengthen well above what the NHC forecast of only 90 mph.
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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.