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 think Alex is slowly but surely getting its act together, wouldn't surprise me if by 2am we have Hurricane Alex.
Member Since: Posts: Comments:
Quoting Levi32:
What really bugs and concerns me is the possibility for this to crawl very slowly inland if it heads for Texas. A Mexico landfall should be fairly quick....a Texas landfall, on the other hand, has more iffy steering currents that could result in this thing just crawling ashore and being a very nasty situation with wind and rains pounding the coast for over a day.

18z GFS has the darn thing taking 24 hours to move inland after starting to lash the coast with the core of the storm.

66 hours:



90 hours:



So kind of like Dolly in 2008.

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From a few hours ago:

Tropical Tidbit for Monday, June 28th, with Video
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting gator23:

please see post 657 it didnt get the play it deserved.


"I tell ya, I don't get no respect...I could tell my parents hated me. My bath toys were a toaster and a radio."
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this storm is going too be a cat 5 you see watch you nevere no
Member Since: May 21, 2006 Posts: 5089 Comments: 114071
Quoting OracleDeAtlantis:
I know I'm not the only one seeing this ...

Also ... uh ... can say the red spot of Jupiter yet?







Alex's center is not reforming. It is much too strong for that at this time. I've never seen 990mb centers relocate. Only weak ones. Plus deep convection is rebuilding over the center.
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Quoting OracleDeAtlantis:
I know I'm not the only one seeing this ...

Also ... uh ... can say the red spot of Jupiter yet?







Nope....look at a visible loop and tell me where the center is.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting AstroHurricane001:


Why not mix in a little litotes interspersed with a double negative?


You could.. But then the double entendre just gets lost and the true meaning of the sentance becomes a juxtaposition of the relative intent of the writer.
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667. Dakster 3:05 PM PDT on June 28, 2010
Orca,

I noticed you are leaving out an important hurricane model and wanted to know why?

The JFV model, the one that always brings the storm to South Florida as a Cat5.




The one that hits an outhouse, with a My Little Pony shower curtain?
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Quoting iluvjess:


Postponed until July 11.
Yes, I did word that the wrong way. Thanks for the correction.
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Quoting reedzone:


GFS is showing like a Frances (2004) situation then? I lost power for 2 weeks over that storm and we only got the TS winds for 48 hours.


Maybe....it's something to watch for. It would be a very bad situation if it happens like that. A Texas landfall is very likely to be a slow, painful process.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting GlobalWarming:
levi, what's that system in the CATL on the gfs? a threater?


Let me take this one! No threat as long as you have your shower curtain up!
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The northeastern portion of Alex looks almost like it's trying to separate from the main core and move northeastward. Florida and the Southeastern states are getting a soaking.



Here's Darby's vortex being absorbed into the Pacific side of Alex:

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CIMSS MIMIC last frame @ 21z/4:00pm CDT

Link

The 48 hour loops are a whopping 13MB so I am posting a link to the image.
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691. LSU79
Quoting scott39:
Its obvious on the last few visible frames that not only is Alex starting to speed up but hes going due N. Also, anybody from the Fl. Panhandle all the way to Mexico needs to stay aware of this developing situation. It could hook left into Mexico,or head for the N Gulf Coast. Models are great but thier not GOD. Nobody on the USA or Mexican gulf coast needs to take thier eye off this potiential monster. Here i already sharpened the blade up for you cut away!

Well as I have said I am not a weathercaster but I agree. I have been through these things for 47 years and every now and then one comes along and does just the opposite of what everyone thinks it will. So I agree with you.
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I know I'm not the only one seeing this ...

Also ... uh ... can we say the Red Spot of Jupiter, yet?





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Quoting Tazmanian:




too me the storms looks too be moveing a little E


It looks like Alex is wobbling.
Member Since: February 21, 2008 Posts: 1 Comments: 340
Quoting msgambler:
Jimmy Buffet concert cancelled due to weather. Possible high tides causing stage problems.


Postponed until July 11.
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Quoting Dakster:
Orca,

I noticed you are leaving out an important hurricane model and wanted to know why?

The JFV model, the one that always brings the storm to South Florida as a Cat5.


Ohhhh... I will plead the 5th just like Flood just did :)
Member Since: October 1, 2007 Posts: 81 Comments: 26493
Quoting GlobalWarming:
levi, what's that system in the CATL on the gfs? a threater?


Maybe. One storm at a time though....I'll be focusing more on future development possibilities after Alex has made landfall.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting scott39:
Why is Alex only forecasted to be a Cat1 possibly low Cat2 at landfall, with such a good enviroment to develope in?


... dry air.
Interesting will be to watch how Alex modifies its environment so that dry air won't interfere with rapid intensification.
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Quoting Levi32:
What really bugs and concerns me is the possibility for this to crawl very slowly inland if it heads for Texas. A Mexico landfall should be fairly quick....a Texas landfall, on the other hand, has more iffy steering currents that could result in this thing just crawling ashore and being a very nasty situation with wind and rains pounding the coast for over a day.

18z GFS has the darn thing taking 24 hours to move inland after starting to lash the coast with the core of the storm.

66 hours:



90 hours:



GFS is showing like a Frances (2004) situation then? I lost power for 2 weeks over that storm and we only got the TS winds for 48 hours.
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Orca do I detect a jvf model in your Google run.
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Quoting jlp09550:


The convection is starting up again.... uh oh
Member Since: May 27, 2009 Posts: 0 Comments: 4355
aviationweather.gov/adds/satellite
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Quoting atmoaggie:

Did ya have to remind us about him and his former self?
*frown*
Awwww..come on..it's not so bad...I mean look, UT has the LBJ library..and it has a section that talks about what a wonderful humanitarian he was...complete with all his civil rights accomplishments...you guys are off the hook!
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Quoting AustinTXWeather:


LOL I was just totally feeling tense when I looked at the radar & saw the northern movement... then I read this and had a good laugh - thanks for that.

no worries man, I try to bring levity to this blog
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Quoting jlp09550:




too me the storms looks too be moveing a little E
Member Since: May 21, 2006 Posts: 5089 Comments: 114071
Quoting gator23:

please see post 657 it didnt get the play it deserved.


You guys are horrible :P
Member Since: May 27, 2009 Posts: 0 Comments: 4355
Quoting RecordSeason:
The storm is going to go north, then re-curve and hit Florida.

Yeah, you're local, and young, thus some patience has been doled out...
...
...but the time has come.

Grow up!
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Wow! Explosion near the center is impressive on the last few frames.

Wait till that northern band wraps in and we'll have a hurricane by 11.
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Quoting gator23:

he was talking about his administration, BOOM!


LOL I was just totally feeling tense when I looked at the radar & saw the northern movement... then I read this and had a good laugh - thanks for that.
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Quoting MrstormX:
Gov. Rick Perry has issued a disaster proclamation


OMG, if I were a funny man, the things I could with THAT statement...
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What really bugs and concerns me is the possibility for this to crawl very slowly inland if it heads for Texas. A Mexico landfall should be fairly quick....a Texas landfall, on the other hand, has more iffy steering currents that could result in this thing just crawling ashore and being a very nasty situation with wind and rains pounding the coast for over a day.

18z GFS has the darn thing taking 24 hours to move inland after starting to lash the coast with the core of the storm.

66 hours:



90 hours:

Member Since: November 24, 2005 Posts: 628 Comments: 26455
Member Since: February 21, 2008 Posts: 1 Comments: 340
Quoting muddertracker:
Our former Aggie yell leader likes to proclaim a lot..lol

Did ya have to remind us about him and his former self?
*frown*
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Perry issues disaster declaration orders National Guard activated
Member Since: May 27, 2009 Posts: 0 Comments: 4355
Quoting NRAamy:
628. sdcbassman 2:58 PM PDT on June 28, 2010
Quoting GlobalWarming:


You rightfully deserve it, Storm! You're resourceful inside of this place, is absolutely invaliable. Evening, by the way.


Can someone translate this??????



JFV-ese....



Thanks Amy!! It makes sense now.
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Quoting Dakster:


Actually, no.... it is a DOUBLE Oxymoron so it cancels itself out. Accu, Professional, and Weather should not be in the same sentance. It violates a few English grammar rules.


Why not mix in a little litotes interspersed with a double negative?
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602: I don't see your message, but, I wanted to make you aware that a history of alarmism concerning any subject follows the one responding in 640.
Sometimes it is good to know the mental state of those you get info from. Just trying to be helpful...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting MrstormX:
Gov. Rick Perry has issued a disaster proclamation
Our former Aggie yell leader likes to proclaim a lot..lol
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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.