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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1907. nash28
That's Clarence Oever, over...
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1906. tkeith
Quoting Patrap:
We should get a Motion Vector,,Victor

Soon.
what's the catalyst that will put Alex in motion...whatever heading he's on
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Some people on the blog picked a bad time to quit smoking.
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If Alex continues to grow to a Cat 1 or 2 and moves up the TX Coast, how wide will the wind field be? Im more interested in TS Force Winds.
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Quoting CybrTeddy:
AL, 01, 2010062900, , BEST, 0, 207N, 916W, 55, 987, TS


Interesting. NHC being fairly generous, but by the time the 11PM advisory comes around the winds will be up to that anyway.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting angiest:
Latest model is showing GFS and HWRF right on top of each other. What I have noticed is that HWRF is usually close to the GFDL. Can't say I've really ever seen this before.


Those were the 18z runs.
Member Since: June 9, 2007 Posts: 4 Comments: 15950
Alex is going thru a Rapid Intensification Cycle at this very moment.

When the convection finishes building around the eye...look out!
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I agree this is a place for opinions---but keep it real guys. Do you really think your opinions "help" the esperts?
That is such---oh never mind.
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1899. nash28
Hey Kman my friend!!

How are things down in the beauty of where you live?

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Thats deep...
Member Since: June 9, 2007 Posts: 4 Comments: 15950
1896. Patrap
We should get a Motion Vector,,Victor

Soon.
Member Since: July 3, 2005 Posts: 428 Comments: 129903
1895. angiest
Latest model is showing GFS and HWRF right on top of each other. What I have noticed is that HWRF is usually close to the GFDL. Can't say I've really ever seen this before.
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Quoting Progster:



what happened to filming 2 guys pitching baseballs at each other on a rotating ferris wheel devoid of horses?
It got floodman-icized. ;-)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
1893. nash28
How is what I wrote condescending Jeff?
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Quoting kmanislander:


Hi Nash, I know that is the conventional wisdom but the ridge that is coming in from the 4 corners is ever so weak and the ULL pushing East will delay anything trying build back from that direction. I don't think WNW is coming any time soon.


So,what are your thoughts on track KMAN?
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MrstormX
I posted side by side pics of Alex and Ike



Post 1660 page 5
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Recons going in for a NE quad pass. They should catch that new convective burst over the center.

If this pass shows the circulation has moved farther N, im buying it.
Member Since: June 9, 2007 Posts: 4 Comments: 15950
Here is link to another good IKE image

Link
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1888. scott39
Quoting kmanislander:


Hi Nash, I know that is the conventional wisdom but the ridge that is coming in from the 4 corners is ever so weak and the ULL pushing East will delay anything trying build back from that direction. I don't think WNW is coming any time soon.
Hey Kman, Can you give a summary on how TCs are steered?
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1887. Patrap
Alex now a Strong Tropical Storm with a strengthening trend continuing this evening.




Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting xcool:
no wnw no time soon


Hi xcool - what is your thoughts on Alex this evening?
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1884. MZV
Please stop with the moving east hooey. You are staring at the images too long and seeing things. Next you'll be telling us Elvis or the Virgin Mary is in there!
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1883. Patrap
Floater - RGB Color Infrared Loop
Member Since: July 3, 2005 Posts: 428 Comments: 129903
1882. xcool
;;;
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that is 65 mph unless recon finds higher winds between now and 11 PM
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Is there any chance Alex could make a landfall closer to Matagorda Bay?
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Quoting CybrTeddy:
AL, 01, 2010062900, , BEST, 0, 207N, 916W, 55, 987, TS


Up to 65 mph.

Member Since: June 9, 2007 Posts: 4 Comments: 15950
Dang, how much rain has the Yucatan gotten from Alex.
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Oh my my, Oh hell yea, you got to put on that party dress. Alex is fixing to intensify. Deep South Texas get ready!!



































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Quoting HoustonTxGal:
Hurricane Ike

Link


Alex is roughly the same size.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
AL, 01, 2010062900, , BEST, 0, 207N, 916W, 55, 987, TS
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Quoting Patrap:


Im always game for a side bar or the Quarter.

I thought it was "Side Bar in the Quarter"
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1873. xcool
no wnw no time soon
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1872. nash28
Quoting clwstmchasr:


Agree. However, it could be a bit more NW.


Yes it could. Not ruling out a little more NW or even NNW motion. But, I am not buying and of the NE or ENE garbage being thrown around here.

I have been banned many times over the last five years. Not this year. Keeping it real, honest and informative.
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Hurricane Ike

Link
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Quoting 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.


Hi Nash, I know that is the conventional wisdom but the ridge that is coming in from the 4 corners is ever so weak and the ULL pushing East will delay anything trying build back from that direction. I don't think WNW is coming any time soon.
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Alex looks like he is getting squashed on the Western side.
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1868. scott39
Quoting 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.
Theres a 99% chance the ridge is going to build back ln?
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1867. 7544
last few frames looks nne from here for now anyway next
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REEDZONE, I am sorry you don't like peoples opinions or predictions, I am sure people out there is not going to start boarding up their houses & stocking up on food just because someone on the blog said it may make landfall at a certain location lol. We leave that up to the experts, but we all can provide additional opinions & information that may help the experts out. Having hundreds of minds is sometimes better than a handfull. I know most of us on here are not experts, but It's still fun & interesting trying to track these storms.. Sorry for the conflict..Bob
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1864. Patrap
Quoting kmanislander:


Overruled at the side bar LOL


Im always game for a side bar or the Quarter.

Member Since: July 3, 2005 Posts: 428 Comments: 129903
Quoting kuppenskup:


See that's where your wrong, even god called the NHC earlier today to get a forecast update on where Alex maybe headed.


-snickers- jejejeje

WOW Alex keeps impressing with his size. He's so huge.
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Quoting Orcasystems:


Ok, thats enough from the peanut gallery... poof


Obviously, Orca has no idea what close friends we are, Flood. Oh, well....
Member Since: September 7, 2006 Posts: 0 Comments: 1081
Quoting TexasHurricane:


Its massive, anybody have an Ike comparison.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Just to change the topic a little for a nanosecond....

Here's an absolutely gorgeous ULL headed our way viewed in the WV imagery. We're likely to get some moisture from it by Wednesday, if it lasts that long.... IIRC, this is what ingested the former 94L.....

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1859. Patrap
Member Since: July 3, 2005 Posts: 428 Comments: 129903
just going to TX alone will raise the ratings on the news
Member Since: July 14, 2008 Posts: 2 Comments: 9686
I am getting tired of watching Alex. He needs to make up his mind and go somewhere.
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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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