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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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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Quoting Orcasystems:


Nope.. he just skimmed it off the blog and creamed it.


Curdles my toes..... :))
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2405. tkeith
Quoting smmcdavid:


Oh come on! ;-)
there you are :)
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Quoting Floodman:


I would have expected better from you, kman...fooo! LOL


It was too good an opening to pass up LOL.

Back later.
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One of ya'll had to say his name...
Member Since: September 6, 2009 Posts: 2 Comments: 3720
2401. leo305
lmao TWC forecast a CAT 1 hurricane at peak.. 90mph

Member Since: April 17, 2010 Posts: 0 Comments: 1753
2400. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15670
Quoting AlexEmmett:

AL ROOKER SUCKS lol


IT'S GONNA RAIN.
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Quoting AllStar17:
I find it very hard to believe that Alex will only make it to 90 mph.

i fully agree its a ts with a pressure of 985
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Quoting scott39:
Nobody needs to be happy if Alex is going N. It needs to go to the COWS!
Yet, you well know that a special section of sick individuals are cheering on the inside. And the especially sick ones cheer by keyboard after seeing everything through fear-colored glasses.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting tkeith:
Because it IS N. It is hardly moving at all for (insert name here) sakes!

umm...Pete?


Oh come on! ;-)
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great job on the show tonight storm,well he ain't stalled anymore;)
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Will the track shift a bit to the North now that Alex is still continuing north and the models are back in Texas?
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Quoting kmanislander:


I guess we'll milk this one for all it's worth !


I would have expected better from you, kman...fooo! LOL
Member Since: August 2, 2006 Posts: 10 Comments: 9922
2392. tkeith
Because it IS N. It is hardly moving at all for (insert name here) sakes!

umm...Pete?
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2391. Patrap
.."Happiness,

..is a Warm Column"..


Member Since: July 3, 2005 Posts: 424 Comments: 128282
DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1000 PM CDT...0 A GRADUAL TURN TOWARD THE NORTHWEST WITH SOME INCREASE IN FORWARD SPEED IS EXPECTED ON TUESDAY...FOLLOWED BY A GRADUAL TURN TOWARD THE WEST-NORTHWEST ON WEDNESDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 65 MPH...100 KM/HR...WITH HIGHER GUSTS. ADDITIONAL STRENGTHENING IS ORECAST...AND ALEX IS LIKELY TO BECOME A HURRICANE ON TUESDAY.

Hi there.
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Quoting RitaEvac:
wtf



Looks like the models are "splitting" again....
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Movement would need to be at around 025 degrees for NNE it is at 010 thus it is in a NORTHERNLY heading or for simplicity sake, NORTH.
Member Since: September 6, 2009 Posts: 2 Comments: 3720
2387. Chigz
According to the 10pm CST NHC, their next forecast point is almost due WNW - CANNOT see Alex following that...especially it's moving N or NNE!!
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10pm update

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Has anyone else tried to log onto Crownweather today? Is the site down? Thx.
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I find it very hard to believe that Alex will only make it to 90 mph.
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2382. tkeith
Quoting scott39:
Nobody needs to be happy if Alex is going N. It needs to go to the COWS!
yep...
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2381. Grothar
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Quoting RecordSeason:
"short cut" spiral phenomenon again

Continues to Suggest serious intensification is taking place as spiral bands are altering their course noticeably to make a tighter circulation, literally within 2 or 3 frames.
I do see what you are referring to.
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2379. scott39
Nobody needs to be happy if Alex is going N. It needs to go to the COWS!
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Hottowers
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2377. leo305
if this thing blows up tonight into a very strong Hurricane.. it may continue a more easterly track..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting CaneWarning:


That isn't a very nice thing to say about IKE. He's one of my favorite bloggers here.


LOL
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Quoting Orcasystems:


Nope.. he just skimmed it off the blog and creamed it.

you guys are making my stomach curdle lol

And so is Alex
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Break time for me. May check in once more breifly before turning in. What a start to the season.
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2373. Patrap
ATCF images (Hurricane Track Models)

Current Storms:
Alex
Member Since: July 3, 2005 Posts: 424 Comments: 128282
2372. LSU79
Quoting Patrap:


Dat should rattle the masses.

It has been moving NE/NNE for a little while. So here is a ?. I know there are 69 miles between latitude degrees. At Alex's current location what are the miles between longitude degrees? Would it be approx. 60 miles. This could be very important news for the Gulf Coast. If this continues that, in my estimation, would make a huge track shift. But what do I know.
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Quoting CaneWarning:


I'm "udderly" amazed by it all right now.
groan...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
2370. tkeith
LOCATION...21.0N 91.6W

north...91.5 8 hrs ago
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Quoting Orcasystems:


Nope.. he just skimmed it off the blog and creamed it.


I'm "udderly" amazed by it all right now.
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Hey Patrap...can you please post a link for the graphics? I used them to track Ike but can't remember where I pulled them from (thankfully didn't need to use last year!)
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Quoting RecordSeason:
"short cut" spiral phenomenon again

Continues to Suggest serious intensification is taking place as spiral bands are altering their course noticeably to make a tighter circulation, literally within 2 or 3 frames.


You could be fooled by nighttime visible.
Member Since: September 6, 2009 Posts: 2 Comments: 3720
Waiting for the new Official track
Member Since: May 27, 2009 Posts: 0 Comments: 4438
At 2227feet, winds at 77mph, hh inf. courtecy of the weather channel.Right now the W. Channel is going to release new inf. by NHC.
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Quoting Orcasystems:


OMG, you guys are making an old sailor cringe... your massacring the terminology :(

Its 010.. 10 degrees off of north...Northerly is close enough.


lol
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2363. Patrap
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
Member Since: July 3, 2005 Posts: 424 Comments: 128282
Quoting HoustonTxGal:
Wow, the weather ch. is all over it...they just now reported that Alex "may be" getting stronger.

LOL!

AL ROOKER SUCKS lol
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000
WTNT31 KNHC 290242
TCPAT1
BULLETIN
TROPICAL STORM ALEX ADVISORY NUMBER 14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL012010
1000 PM CDT MON JUN 28 2010

...ALEX GRADUALLY STRENGTHENING...


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

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2359. nash28
Quoting Chigz:
NHC reports

03 GMT 06/29/10 21.0N 91.6W
65 mph, 985 mb Tropical Storm

They are not calling a NNE movement - sticking to NORTH!


Because it IS N. It is hardly moving at all for (insert name here) sakes!
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I'll bet they upgrade at 2am...
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Quoting tkeith:
he didn't need much encouragement did he...


Nope.. he just skimmed it off the blog and creamed it.
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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.