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 StormW:


The G4?


Not sure. Think so. It just updated anyway so I can't post it.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
The HH plane is turning NW away from Alex.

Member Since: June 9, 2007 Posts: 4 Comments: 15947
1304. JLPR2
Quoting hunkerdown:
Because they were reading this blog, and well, the rest is history...


yeah, they read the beer part and had to turn around to get some XD
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1303. Patrap
NOAA 42 is the G-4

The GOM TEAL Flight is the HH C-130


000
NOUS42 KNHC 271500 COR
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1100 AM EDT SUN 27 JUNE 2010
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 28/1100Z TO 29/1100Z JUNE 2010
TCPOD NUMBER.....10-027 CORRECTION

I. ATLANTIC REQUIREMENTS
1. TROPICAL STORM ALEX
FLIGHT ONE - NOAA 49
A. 29/0000Z
B. NOAA9 0601A ALEX
C. 28/1730Z..........CORRECTED
D. NA
E. NA
F. 41,000 TO 45,000 FT

FLIGHT TWO - TEAL 70
A. 29/0000, 0600Z
B. AFXXX 0701A ALEX
C. 28/2030Z
D. 21.1N 93.4W
E. 28/2300Z TO 29/0600Z
F. SFC TO 10,000 FT

FLIGHT THREE - TEAL 71
A. 29/1200, 1800Z
B. AFXXX 0801A ALEX
C. 29/0845Z
D. 21.8N 94.2W
E. 29/1100Z TO 29/1800Z
F. SFC TO 10,000 FT

2. SUCCEEDING DAY OUTLOOK: CONTINUE 6-HRLY FIXES.
POSSIBLE G-IV FLIGHT FOR 30/0000Z.

3. REMARKS: NOAA 42 WILL BE DOING RESEARCH FLIGHTS INTO
ALEX WITH TAKEOFFS EVERY 12 HRS FOR THE NEXT TWO DAYS.
(28/0800Z, 28/2000Z ETC.) OPERATING ALTITUDE 12,000 FT.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
JWP

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Quoting DestinJeff:
bad news for south TX



Well, that's only one model.



18Z GFDL shows just south of Brownsville TX landfall. I believe that this is north of what it predicted in 12Z, though. The NAM and the GFS also show S. Texas. The model you're showing is the HWRF.
Member Since: April 1, 2010 Posts: 9 Comments: 2699
Quoting StormW:
Barometer Bob is doing a special show tonight, and he's asked me to ask the gang here to tune in. He's having me on at around 8:30 p.m. Show starts at 8:00


Storm, thanks! Uhhh this may be a stupid question, but exactly where do we "tune in"?
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1298. IMA
Quoting katadman:

Hi, Ima. Didn't you tell me last year that you are out in Pipe Creek?
Most of the people I've been talking to here in S.A. are aware of the storm and it's impending approach.

Hi, katadman. I was in Pipe Creek, and most of my personal belongings are still there. When my ex and I separated last year I move back to San Antonio, between Leon Valley & Helotes but closer to Helotes.

Were most of the people you were talking to insurance folks? lol
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Quoting StormW:


The G4?


No recon, but recon has just started to descend
now, that reading was at like 4,000 feet
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Quoting HurricaneSwirl:


That's cool.. it's like a mix between visible and IR. Visible but with a kinda 3D effect that lets you judge how tall/cold the cloud tops are..


GOES Project Science
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Quoting Patrap:


Its the G-4 Hi Flyer up at 45K dropping sondes around the GOM.





Its not the C-130 HH.


I don't think I'm on the G-4, I turned that layer off????
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Look at how much Alex dominates the airflows in the entire region. It's pretty disturbing, IMHO, picturing what it'll look like by late tomorrow.
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Quoting MrstormX:


That's cool.. it's like a mix between visible and IR. Visible but with a kinda 3D effect that lets you judge how tall/cold the cloud tops are..
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Mrstormx---that's a great pic!!
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Quoting GlobalWarming:


It's future direction, perhaps.
It can't be future direction if it is heading from the south central Caribbean and showing NW.
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Quoting Thundercloud01221991:
can someone explain to me why the HH are turning and heading NW?
Because they were reading this blog, and well, the rest is history...
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Quoting texascoastres:
STSIMONISLANDGA ike is the reason they changed the hurricane categories to not include the storm surge anymore. Yes, Ike was a cat2 but with the storm surge of a cat 4. By the way, just type in "Hurricane Ike damage at crystal beach or Gilcrest or highisland) and see just exactly what happened due to Ike. Doesnt sound like you got the concept of what it was like here. Not trying to start an arguement but I dont think you know in this case


Crystal Beach, Gilcrest and High Island were destroyed. Many of the area had nothing left, not even the slabs of where the houses USE to be.
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1285. Torgen
Quoting StormW:
Barometer Bob is doing a special show tonight, and he's asked me to ask the gang here to tune in. He's having me on at around 8:30 p.m. Show starts at 8:00


Link? I'll try out these new headphones I bought for the computer, see if they counteract my hearing loss. :)
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I think he was trying to say that Ike was only a cat 2, but very destructive... that we can't base damage just on hurricane intensity. I really think you read his post wrong.
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They did get 996.2 before they turned lol.

My guess is they're still testing out steering flow and shear before they actually investigate the storm.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
1279. Patrap
Quoting washingaway:
Why did the plane turn?


Its the G-4 Hi Flyer up at 45K dropping sondes around the GOM.





Its not the C-130 HH.
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Quoting Levi32:


Pointing from the half-cutoff advisory box at the bottom of the image....the arrow points from the box to Alex...it's just unusually far away from it on the map.
Thanks. I know it usually signifies the direction of movement but it looked extra long so I wasn't sure.
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Texas can I have some of the rain from Alex?Send a little bit to South Florida please....
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Quoting homelesswanderer:


Lol. I'm in Vidor. At least MRES after Ike will keep longer than the paper box with peanut butter, crackers and apple juice after Rita. I don't think those were official MRES. lol


and how do you like vidor? Sorry, but I usually drive thru there as fast as I can!!
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Something may be wrong...

Member Since: June 9, 2007 Posts: 4 Comments: 15947
STSIMONISLANDGA ike is the reason they changed the hurricane categories to not include the storm surge anymore. Yes, Ike was a cat2 but with the storm surge of a cat 4. By the way, just type in "Hurricane Ike damage at crystal beach or Gilcrest or highisland) and see just exactly what happened due to Ike. Doesnt sound like you got the concept of what it was like here. Not trying to start an arguement but I dont think you know in this case
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So what do the 18Z models look like? How about the GFDL?
Member Since: April 1, 2010 Posts: 9 Comments: 2699
1271. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting stillwaiting:
Hey reedzone,where exactly is "north of southern TX"????,LOL....like what is the line of demarcaction between north tx and south tx??


Umm south of Corpus Christi I guess lol
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Why did the plane turn?
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Still a gap in convection due to dry air.. needs to filter that out too before more intensification begins but the cloud tops are cooling around the COC.



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Homeless - you got mail...
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Woodman/homeless...beaumont here...My brother is wx man @ kfdm 6 in Bmt.
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1265. Cranica
Wait, why is the recon plane flying away from the storm? The most recent obs have them heading west away from the core, I wonder if they saw something on radar.
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I am hoping that Alex goes in well south of Brownsville. I live about 50 miles south of Corpus (fairly close to Baffin Bay), and the farmers in this area have THE best crops that my 80 year old father has EVER seen! The harvest will be starting in about 2 weeks, and storm would destroy 100's of millions of dollars worth of crops, never mind all of the "normal" destruction of a 'cane.
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can someone explain to me why the HH are turning and heading NW?
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Quoting stillwaiting:
Alex blog,w/forecast path,all "north tx/la"casters are welcome to join in the debate!!!(I think my cone might raise a few eyebrows!!!)


My eyebrows just raised. Hope ur wrong but u could be on to something
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Quoting KarenRei:


Heck, I remember people on this blog, even while Ike was landfalling, talking about how lame and how much of a letdown it was.

Dawn told a different story.


If they were talking about it being a let down they obviously were not in my house, during the storm lol
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Hey reedzone,where exactly is "north of southern TX"????,LOL....like what is the line of demarcaction between north tx and south tx??
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1257. JLPR2
1181. Snowlover123 7:26 PM AST on June 28, 2010

Did you cry with Toy Story? 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.

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