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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2007. Patrap
.."Happiness,

Is a Warm Column"..
Member Since: July 3, 2005 Posts: 414 Comments: 125584


AOI


I think the un-tasked HH is bent and going home.
Member Since: Posts: Comments:
2005. palmpt
Quoting MiamiHurricanes09:
The funny thing is that he is just making a complete fool of himself. Even though he is 28 years old he doesn't know what the term "rapid intensification" is.


It's cool. What he said was unnecessary.
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ITS MOVING NNE! WOW! this thing just fired a really nice blob of conection too.
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2003. Patrap
Quoting kmanislander:


We don't want this ramping up too quickly. The big ones create their own environment.






Member Since: July 3, 2005 Posts: 414 Comments: 125584
Quoting kmanislander:


We don't want this ramping up too quickly. The big ones create their own environment.


Hmmm.... that would explain the pressure drops...
Member Since: May 27, 2009 Posts: 0 Comments: 4355
2000. Patrap


Latest RECON HH TAIL # 304 Message
Member Since: July 3, 2005 Posts: 414 Comments: 125584
Member Since: Posts: Comments:
Quoting Orcasystems:


It was easier to assume his nick was right... and add him to the list, then to try and explain that to him :)
Agreed.
Member Since: October 9, 2008 Posts: 0 Comments: 8242
Quoting MrstormX:


Hey Recon could find those winds in the next run, its not impossible.


We don't want this ramping up too quickly. The big ones create their own environment.
Member Since: Posts: Comments:
If your out there storm great job on the BB show! And I appreciate the answers to my questions.
Member Since: July 8, 2005 Posts: 259 Comments: 23012
1992. scott39
Quoting MiamiHurricanes09:
Very important graph for sure.

Thanks, That helps alot. You might have already made a comment on the forecasted ridge building and i missed it. Your thoughts please?
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WOW Big Bursts
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1990. Patrap
Is intermission after the 10pm Scene 2..?
Member Since: July 3, 2005 Posts: 414 Comments: 125584
Looking like a strong TS should. Interested to see when the eye will start developing.
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Quoting jaevortex:


-frowns- That was unnecessary language. He's 13 and probably a lot smarter then you were at 13. poof!


ok ... if so im sorry- Miami. but it really does look to be RIC.
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BTW, I noted earlier some pple dismissing CLIPER and CLIP5 as "not models". However, there is a reason why these two simple statistical models are included; they are, basically, the mean of known climatological movements. While no two storms are the same, I think it's pretty telling that the climatological average movement of storms from the initial position on the last run is due north, or NE to the LA area. It doesn't mean Alex is going that way, but he sure wouldn't be "breaking new ground" by doing so....
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Quoting RecordSeason:
Anyone who is remotely honest with themselves has to admit this storm is moving E to NE now...

Link
I think we need a N/NE support group.
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I'm more worried about all the water this thing is going to be pushing. Not so much the winds. Ugh!
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Quoting F4PHANTOM:
Ridge in east building west.


Minimally.

And the blocker that was forecast to come down and support is moving NORTH and weakening.

Look at the whole map, not just what supports your theory.
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Quoting jaevortex:


-frowns- That was unnecessary language. He's 13 and probably a lot smarter then you were at 13. poof!


He's probably a lot smarter than he is now..
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Quoting stormwatcherCI:
Why do you have to call him an idiot. If you were forecasting storms for so long why don't you put your extensive knowledge to work at helping him learn and if he is wrong on something explain to him why. Insults don't help.


It was easier to assume his nick was right... and add him to the list, then to try and explain that to him :)
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Quoting kmanislander:
I said 6 hours for 70 mph. I may have to change that to 6 hours for 75 mph.


Hey Recon could find those winds in the next run, its not impossible.
Member Since: May 27, 2009 Posts: 0 Comments: 4355
Quoting MiamiHurricanes09:
The funny thing is that he is just making a complete fool of himself. Even though he is 28 years old he doesn't know what the term "rapid intensification" is.


Sad..
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I live 50 miles WNW of Brownsville, getting prepared for Alex. What sort of information, local conditions, perhaps video posted to youtube (as long and electric is still on) would this forum enjoy if Alex lands near Brownsville? I can already feel and see the wind shift from Alex. Usually SE winds, today ENE. Had some popup showers today, probably from the strong sea-breeze we are feeling. It is amazing how you can feel the effects of a system so far away.
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Tropical nonsense! POOF you go! no need to be rude to nice and informative bloggers like Miami.
Member Since: July 17, 2008 Posts: 0 Comments: 1242
Quoting cctxshirl:

hard for me to tell, but does GFS predict cctx?

It looks like maybe the north end of Padre. The GFS has a tendency to act like a windshield wiper, especially along the gulf coast (remember, the GFS did the same thing with Ike).
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1973. eye
I am not all that impressed with sat images, I see a huge dry slot and the ULL and the dry air off Texas will probably prevent RI, just slow and steady, might be like IKE, everyone thought it woud strengthen, nothing preventing it, but never reached major...stayed 105mph. Alex convection looked better before it hit Belize. Now it is sorta just spread out with a bit at the center.
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I said 6 hours for 70 mph. I may have to change that to 6 hours for 75 mph.
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Quoting TropicalNonsense:


Idiot. This is Rapid Intensification!!! I was forecasting Storms before You were born 28 Years AGO.

Go Play Football! LOL


-frowns- That was unnecessary language. He's 13 and probably a lot smarter then you were at 13. poof!
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Quoting jeffs713:
1945. Your name is SO accurate. And if I didn't know better, I would say hello to our bestest buddy, the top of storm.
+1
Member Since: October 9, 2008 Posts: 0 Comments: 8242
Quoting stormwatcherCI:
Why do you have to call him an idiot. If you were forecasting storms for so long why don't you put your extensive knowledge to work at helping him learn and if he is wrong on something explain to him why. Insults don't help.
The funny thing is that he is just making a complete fool of himself. Even though he is 28 years old he doesn't know what the term "rapid intensification" is.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1968. tkeith
Alex is obviously not coming to NOLA...haven't seen STORMTOP yet...I feel better knowing that :)
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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.

hard for me to tell, but does GFS predict cctx?
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1965. xcool
tennisgirl08 back off ,
Member Since: September 26, 2009 Posts: 2 Comments: 15603
1945. Your name is SO accurate. And if I didn't know better, I would say hello to our bestest buddy, the top of storm.
Member Since: Posts: Comments:
Quoting TropicalNonsense:


Idiot. This is Rapid Intensification!!! I was forecasting Storms before You were born 28 Years AGO.

Go Play Football! LOL
Why do you have to call him an idiot. If you were forecasting storms for so long why don't you put your extensive knowledge to work at helping him learn and if he is wrong on something explain to him why. Insults don't help.
Member Since: October 9, 2008 Posts: 0 Comments: 8242
Quoting kuppenskup:
Looks like Alex is starting to wind up now


And Cantore's getting LARGER!
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I vaguely recall that there is SUPPOSED to be a northerly component to Alex's movement for the first 24 - 48 off the Yucatan. I must admit though, that the westerly which was supposed to take it off the continental shelf seems rather.... lacking.... I'm still sticking to my notion of a Laguna Madre landfall.... but I'm now thinking a bit closer to the Corpus end than the La Pesca end..... will be interesting to see how far north this gets before a more westerly movement sets in.
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.