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 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: Posts: Comments:
I am not going to say the Vort report is north of track....



AOI

Member Since: October 1, 2007 Posts: 81 Comments: 26511
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
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TCHP:
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1803. scott39
This is better than the movie i just watched.
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Quoting kmanislander:


Excellent !. I have one son doing law in England now.


Impressive! Where at?
Member Since: May 27, 2009 Posts: 0 Comments: 4438
1748: LOL! That is certainly an original answer. If you'd invite the Prof out to some of those frat parties you might get the bonus points anyway.

IMHO!!! This is out of the hands of meteorology at this point. The steering influence is almost nill. She's been sitting there nearly idle since she crossed the Yuk Pen. Void of any external forces the laws of physics will take over now.

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1800. help4u
Everything shifting way north.Everyone run for the hills!
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Quoting katadman:


A little opinionated there, brudda? Eye at Baffin Bay maybe.


Ok, thats enough from the peanut gallery... poof
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting USSINS:


I hope so, just graduated one. Takes the bar next month! ;)


Excellent !. I have one son doing law in England now.
Member Since: August 19, 2006 Posts: 0 Comments: 15861
damn, new runs on those point to Corpus and the damn G4 data hasnt even been put in. Thats what they were supposed to do after the G4 data, what now, gonna point to freakin Galveston? lol models I tell ya...
Member Since: July 14, 2008 Posts: 1 Comments: 9648
That's a cool map thingy Patrap.....
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Quoting xcool:
alex cat 1 come soon.


Already stronger then cat 1 Cindy
Member Since: May 27, 2009 Posts: 0 Comments: 4438
1793. 7544
record has a good clue on where alex could slip thru the backdoor and head let the nne croud have some fun its very interesting now the suspense is killing us could alex just might do the un pridictable and fool everyone
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JMO. Pictures (Maps) help to tell and support the unfolding story. I appreciate them. JMO
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Quoting Floodman:


No.Period.

The furthest east this will go is Galveston and that is a very long shot indeed, unless things have changed drastically in the last couple of hours...



A little opinionated there, brudda? Eye at Baffin Bay maybe.
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1790. Ossqss
Could it relocate? Has this very large system had a history of multiple vorts? Are we in uncharted territory? Just curious
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1789. USSINS
Quoting kmanislander:


There is hope for lawyers then ??


I hope so, just graduated one. Takes the bar next month! ;)
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1788. angiest
I go away for a few hours and you guys let the models drift north again?
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1787. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 129093
1786. Chigz
Where can I get the Rapid Scan loops of Alex??

Thanks!
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Quoting connie1976:
Miami,

Why is everyone saying that this thing is going east? Is it true?
Lots of people are making up things that are just not there, so a Florida landfall is extremely unlikely. Just look at steering currents, it's nearly impossible.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1784. xcool
alex cat 1 come soon.
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Thanks atmoaggie!!
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1782. Patrap
Will Alex drop da Chalupa ?
Member Since: July 3, 2005 Posts: 426 Comments: 129093
i know one thing written in stone is my head hitting the pillow....early day..keep up the good work...
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1780. gator23
Quoting reedzone:
Guys, please.. WE DON'T KNOW where Alex is going. We don't know if it will go south of Texas, we don't know what it will do, please stop making clear bold predictions, you could either be right or wrong.

Reed, this is downright logical and sensible of you. There is no room for that on this blog.
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1779. leo305
wow.. the CDO is looking like it may make a big comeback soon based on the satellite
Member Since: April 17, 2010 Posts: 0 Comments: 1753
1778. Patrap
RGB to Night IR

Member Since: July 3, 2005 Posts: 426 Comments: 129093
Just model runs, its not the lo and behold the mystery has been solved
Member Since: July 14, 2008 Posts: 1 Comments: 9648
1776. scott39
TX/MX TX/MX MX/TX MX/TX XT/XM TM/XX Oh my head hurts.
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Quoting connie1976:
Miami,

Why is everyone saying that this thing is going east? Is it true?
It has no steering currents, atm. Will get the push sometime tonight and resume N, NW, and then WNW.

No, we don't need to start evacuating NOLA through Tampa...
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1774. WAHA
Quoting reedzone:
Guys, please.. WE DON'T KNOW where Alex is going. We don't know if it will go south of Texas, we don't know what it will do, please stop making clear bold predictions, you could either be right or wrong.


No, you're wrong. Alex's crosshairs are about 50 miles south from the America/Mexico border.
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Quoting MechEngMet:
Bless you 1741 Ka-Man: Brevity is the soul of wit.

... additionally correct that it doesn't take a sci degree to figure out where this
bee-yotch is heading.



There is hope for lawyers then ??
Member Since: August 19, 2006 Posts: 0 Comments: 15861
1772. 7544
alex begining to tighten up we may a see the real alex in about 6 hours this one aint playin
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Quoting reedzone:
Guys, please.. WE DON'T KNOW where Alex is going. We don't know if it will go south of Texas, we don't know what it will do, please stop making clear bold predictions, you could either be right or wrong.


Expect large scale evacuations of Dallas by morning...
Member Since: September 11, 2008 Posts: 0 Comments: 59
1769. Chigz
The 00Z BAM Suite models just made a hard right and are close to Corpus! 18Z BAMs were pointing Mexico!
Yes, I know BAMs aren't the ones NHC rely on but they are of some relevance!

Nothing is written in stone yet...
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1768. 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: 129093
1767. RJT185
...does that read 987mb?
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Bless you 1741 Ka-Man: Brevity is the soul of wit.

... additionally correct that it doesn't take a sci degree to figure out where this
bee-yotch is heading.

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Miami,

Why is everyone saying that this thing is going east? Is it true?
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Quoting Tazmanian:
LOL the back line is point at LA and BP


Why is that funny?
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1763. WxLogic
Quoting kmanislander:
An open invitation but no gas to get there at this time.



Was just looking at the same steering flow. There's currently an appealing weakness in Louisianan that ALEX is feeling but it will be hard with such weak steering.
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1762. Story
MiamiHurricanes09, they have a newer update for your Google HH tracker... now that I see how to look at one...

Time: 01:04:30Z
Coordinates: 20.45N 90.7W
Acft. Static Air Press: 925.0 mb (~ 27.32 inHg)
Acft. Geopotential Hgt: 662 meters (~ 2,172 feet)
Extrap. Sfc. Press: 998.6 mb (~ 29.49 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 178° at 62 knots (From the S at ~ 71.3 mph)
Air Temp: 18.0°C (~ 64.4°F)
Dew Pt: 17.0°C (~ 62.6°F)
Peak (10s) Flt. Lvl. Wind: 62 knots (~ 71.3 mph)
SFMR Peak (10s) Sfc. Wind: 53 knots* (~ 60.9 mph*)
SFMR Rain Rate: 34 mm/hr* (~ 1.34 in/hr*)
(*) Denotes suspect data


I cant seem to run the weather overlay on it at the same time so I havent the foggiest where they are in the beast
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Quoting DestinJeff:
I think 00Z xtrp will be at the TX/LA border, thus increasing the delta between it and the model consensus.

those CIMMS maps that Taz is sick of show significant features that will influence steering, and for now they look less than set-up as forecasted.
What exactly does that mean?? You think it will hit at the tx/la border?? just asking, I'm from Louisiana and I don't want our all-star games to be messed up this weekend.
Quoting msgambler:
Evening Kman, I was gonna say that but didn't wanna be a smart elic. Good answer, IMO


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

Also loopitis and other afflictions.
Member Since: August 19, 2006 Posts: 0 Comments: 15861
1759. jpsb
Quoting AustinTXWeather:
StormW now on Barometer Bob - includes a chatroom: http://irc.hurricanehollow.org/
Thanks!
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Guys, please.. WE DON'T KNOW where Alex is going. We don't know if it will go south of Texas, we don't know what it will do, please stop making clear bold predictions, you could either be right or wrong.
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Member Since: June 9, 2007 Posts: 4 Comments: 15946

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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.