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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I am getting tired of watching Alex. He needs to make up his mind and go somewhere.
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Quoting Patrap:


Da Lawyers got involved and well..ya know what happens then..


Overruled at the side bar LOL
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1854. nash28
Guys and gals...

If you look at the WV, you can see the trough in LA that is ever so slowly beginning to move out to the E. This "break" in the ridge between the ULH west of Alex, the trough in S LA and the ULL is creating the slow poleward motion. Once this trough moves off, the ridge will begin to build back in, thus forcing Alex back to the WNW.
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Quoting Orcasystems:


Stop that... give Shep back his stir stick


My bad I'm not trying to stir anything xtrap is showing a northward movement. Just surprised. I know it means nothing though. It is stationary.
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Impressive convective burst right over the COC.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Spaghetti models

Link
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1850. jpritch
Quoting midgulfmom:
Phahaha...don't forgot about blogomania!


It's the blogorrhea you have to watch out for. ;)
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Quoting MrstormX:
Alot of buzz in the media that Alex is going to be upgraded tonight, I doubt it probably just a ratings thing... but its scary none the less.


Winds lagging pressure is the story for now. Give Alex 6 hours for 70 mph
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1848. scott39
When is Alex suppossed to get the lead out and start moving?
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Quoting ElConando:
So... its going Due north now?
Yes.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1846. tkeith
Quoting kmanislander:


Pass the xanax please BWAHAHAHA


there is medicine for blogitis....
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Alot of buzz in the media that Alex is going to be upgraded tonight, I doubt it probably just a ratings thing... but its scary none the less.
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Quoting ElConando:
So... its going Due north now?


Stop that... give Shep back his stir stick
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1843. Patrap
Quoting Progster:



what happened to filming 2 guys pitching baseballs at each other on a rotating ferris wheel devoid of horses?


Da Lawyers got involved and well..ya know what happens then..
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting Ossqss:
Uh, where did the ensemble modeling go from WU?



They're there.
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Quoting midgulfmom:
Phahaha...don't forgot about blogomania!


Pass the xanax please BWAHAHAHA
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So... its going Due north now?
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Quoting DestinJeff:


oh no you just didn't


Its a wobble, not to mention a poor looking fix. I wouldn't put much faith in it.
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Quoting connie1976:
Miami,
I didn't think it could go to Miami....but I was worried about the oil.... :(
It isn't coming to Miami and that is almost certain. What we have to watch is the high by Colorado as it advects towards the east.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting atmoaggie:
Get a Tye-dye shirt creation platform (a.k.a. a record player on speed) and gently drop a marble on it with a little lateral momentum, while it is in motion while recording with a high frame rate camera. Playback in slow-mo and you'll see just what is going on with coriolis.



what happened to filming 2 guys pitching baseballs at each other on a rotating ferris wheel devoid of horses?
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1834. Patrap
00z Early Cycle NHC model tracks
Alex
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)




Dynamic Models (More sophisticated models)




Early Model Wind Forecasts


Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting kmanislander:


Yeah, well blogging all day without a break can give you mapitis LMAO.

Also loopitis and other afflictions.
Phahaha...don't forgot about blogomania!
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wonder if Alex has this up his sleeve by going north for a good while...

Member Since: July 14, 2008 Posts: 1 Comments: 9630
1830. scott39
Quoting WPBHurricane05:


Looks almost......northeast.....

Probably just a wobble.
What is this a webble or a TC?
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1829. 7544
Quoting Patrap:
ALEX slowly gaining some Attitude in Motion and with the organization as well.


Floater - Rainbow Color Infrared Loop


yeap if he gets any further north he will cove the whole gom
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1828. Ossqss
Uh, where did the ensemble modeling go from WU?

Edit, that just appeared, LoL

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Quoting Orcasystems:
I am not going to say the Vort report is north of track...

You don't have to..you proved it!
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I didn't see your reasoning many posts ago...Could you explain it to me please. I live in swla.
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1825. Patrap
Quoting pipelines:


around and around the dry air goes....when will it get circulated out no one knows.....once it does though Alex will get its first real shot at some strengthening.


Its mixing it all out and I think your gonna be correcto..
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Wow. Been lurking and reading for a few days but the quality of info on this board has been sinking fast over the last few hours.

Thanks to Levi, Storm, Nash and a few others who know what the heck they are talking about. Much of the rest is, well, not so useful.
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Miami,
I didn't think it could go to Miami....but I was worried about the oil.... :(
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north south north south, east west, come on Alex make up your damn mind
Member Since: July 14, 2008 Posts: 1 Comments: 9630
1821. scott39
Quoting Daveg:
And yet another bounce back to the north for all the models. Very interesting to say the least.

OH-- What a shock!
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1820. gator23
Quoting reedzone:


lol sorry gator23, I'm not sure where this is going, I come up with tracks, but nothing is written in stone. To say this is not going to hit Texas is unprofessional. Everyone from Northern Mexico to Texas should watch Alex for right now, people should be preparing in the watch areas. With the stalling, the forecast remains uncertain.

one thing I can guarantee you is if TWC says its heading your way, your in the clear.
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Quoting MiamiHurricanes09:
There you go. Alex is moving northward. Period.


Looks almost......northeast.....

Probably just a wobble.
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Quoting kmanislander:


Kings College, London.


Awesome what a neat city to go to school.
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1817. Patrap
ALEX slowly gaining some Latitude in Motion and with the organization as well.


Floater - Rainbow Color Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 128630
Quoting tropicallsu:
This is what this blog is for, anyone can give their own personal opinions & predictions, I know, no one knows where Alex will make landfall,Besides GOD, If we can't give our own predictions & opinions, I guess we all are guilty of that, This is what makes these blogs so much interesting,So, I am not trying to offend anyone with a Doom & Gloom situation, I am just giving my own opinions. So please keep to your own business.You know who you are...Thanks


Saying stuff like "will impact", "will make landfall" can affect those who actually believe it. I gotta go, sorry if I upset you, everyone is subject to their opinion, but I don't like it when people push their forecasts.
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1815. Hhunter
south padre island under request for voluntary evacuation..
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Quoting Patrap:


around and around the dry air goes....when will it get circulated out no one knows.....once it does though Alex will get its first real shot at some strengthening.
Member Since: July 10, 2008 Posts: 0 Comments: 227
Quoting Orcasystems:
I am not going to say the Vort report is north of track....



AOI

There you go. Alex is moving northward. Period.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MrstormX:


Already stronger then cat 1 Cindy
I'm surprised to see that wind speeds are still lagging behind the quickly decreasing pressure. But when they do catch up Alex will likely take off.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MrstormX:


Impressive! Where at?


Kings College, London.
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1809. Daveg
And yet another bounce back to the north for all the models. Very interesting to say the least.

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1808. Hhunter
Bastardi 8pm update. says alex at risk for rapid intensication..also says the slower it moves the more the risk for the more northern move....so corpus beyond keep your head in the game ...cat 3-4 not impossible...
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Quoting gator23:

Reed, this is downright logical and sensible of you. There is no room for that on this blog.


lol sorry gator23, I'm not sure where this is going, I come up with tracks, but nothing is written in stone. To say this is not going to hit Texas is unprofessional. Everyone from Northern Mexico to Texas should watch Alex for right now, people should be preparing in the watch areas. With the stalling, the forecast remains uncertain.
Member Since: July 1, 2008 Posts: 13 Comments: 7396

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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.