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 stillwaiting:
alex looks like he's turning into a monster!!!!!(large)...


Think Dolly but Double Sized, ick
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2256. Patrap
.."da wheel in da gulf goes round and round"..
Member Since: July 3, 2005 Posts: 427 Comments: 129435
Remember folks, Alex is more scared of us than we are of him. Because he knows once he comes ashore he dies.
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Quoting Orcasystems:


I did not say that... but that is a correct assumption :)


Orca, should I immediately begin to prepare here in Tampa?
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2253. scott39
Quoting kmanislander:


Well, we know he won't be a fish storm !
That would be a big fish in the E Atlantic. Its a Whale in the GOM.
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2251. hercj
Quoting MiamiHurricanes09:
No, but I like using the NHC recon site better because it updates faster.

If you are interested, here is the link:

NHC Aircraft Reconnaissance

Thanks Miami. Can't seem to get the recon to come online through google earth.
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Is it me or does Alex look like it's moving now? (in a nnw direction?)
Member Since: September 1, 2008 Posts: 0 Comments: 672
Alex may go well right of the 12-hr. NHC forecasted center position.

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Ahem, back to Alex LOL
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alex looks like he's turning into a monster!!!!!(large)...
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Why do I have a feeling Alex is about to drink our milk shake?
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2244. Patrap



Member Since: July 3, 2005 Posts: 427 Comments: 129435
Quoting kmanislander:


My sides are hurting LOL
LOL! Alex the cow.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting brla61:

i agree that's why i mostly lurk.everyone needs to relax. the experts and proper authorities will let us know when to push the "action" button. i stress action and not panic


If I were to listen to some on here tonight, I would be putting up my hurricane shutters...and I'm in Tampa! LOL
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http://pro.accuweather.com/adcbin/professional/uggfx/page.htm?gfxcode=uf24
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Quoting MrstormX:
Alex now beats Fay by 1mb.

no more fayisms
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Quoting atmoaggie:
Aw, dang. Boo. Though it is doing some churning...


My sides are hurting LOL
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Quoting kmanislander:


I guess we'll milk this one for all it's worth !

Cowcaster? We'll milk this one? Ugh, so much cheese...

get it :P
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Quoting ElConando:


360 is north so for 010 degrees it is for now going just east of due north?


I did not say that... but that is a correct assumption :)
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2236. Patrap
Quoting ElConando:


360 is north so for 010 degrees it is for now going just east of due north?


Dat should rattle the masses.
Member Since: July 3, 2005 Posts: 427 Comments: 129435
Quoting atmoaggie:
Moo.


Moocaster!
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Quoting hercj:

Miami is the tropical atlantic site down?
No, but I like using the NHC recon site better because it updates faster.

If you are interested, here is the link:

NHC Aircraft Reconnaissance
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2233. Patrap
ALEX RECON HH Tail # 304 Latest Message
Member Since: July 3, 2005 Posts: 427 Comments: 129435
2232. brla61
Quoting PanhandleChuck:
Wow, this is the roughest crowd I've seen all season. Only been on here for three years, but I know when to lay low.

i agree that's why i mostly lurk.everyone needs to relax. the experts and proper authorities will let us know when to push the "action" button. i stress action and not panic
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Quoting Orcasystems:
I have it going 010@8kts
Let the fun begin.



AOI


360 is north so for 010 degrees it is for now going just east of due north?
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2230. Max1023
Alex has been going NNE for awhile now, based on aircraft fixes it seems that this motion is not just a jog. This essentially forces the landfall location north as Alex will have to cover more distance to reach the coast, gaining more latitude as he travels. Hopefully he misses the old loop current eddy while he's at it.
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2229. bassis
Dr. carver should be updating any minute now
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Quoting kmanislander:


I guess we'll milk this one for all it's worth !
Aw, dang. Boo. Though it is doing some churning...
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Quoting drg0dOwnCountry:




See the image from the movie the day after tomorrow. Starting to look that HUGE. Welcome to climate change.


That is one huge system and it's scaring me.
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Quoting PanhandleChuck:


I hear ya, I gave everybody another chance and cleared my ignore list. I kinda enjoy all of the brawling and I couldn't see the whole picture with some of the blocked people. LOL


Yeah, that in itself is a good enough reason to keep the ignore list empty!
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Alex now beats Fay by 1mb.
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Quoting MiamiHurricanes09:
No idea.

ill google it for u guys
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Quoting tkeith:
Alex is a cow storm.

cowcaster...


I guess we'll milk this one for all it's worth !
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2222. LSU79
Ok here goes. Someone correct me if my thought process is out of whack. Believe me all I know is, the sun is shining or it's raining. I know I saw on here the stonger the storm the more north it goes. Well, given the events of the last few hours i.e. the weak ridge to the west, the trough to the north and the ridge to the west, and with Alexs' pressure dropping to, I believe I saw 980mb, he would be likened to the proverbial schoolyard bully. His strength is actually in his low pressure, and size not his winds. So with that being said it would seem to me that he could have his way on the schoolyard (GOM). So with the weakness to his north and should he gain a bit of speed he would actually be creating his playground on his terms and noone can do anything to stop him. So if he wants to go north he will, if he chooses west so be it. Let's just say Alex has become the schoolyard bully of storms.
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Quoting tkeith:
Alex is a cow storm.

cowcaster...
Moo.
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2220. KEEPEROFTHEGATE (Mod)
01L/H/A/C1
MARK
20.6N/91.5W
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2219. xcool


Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
i see eyes hmmm ?

cool soon if the 2mb/per hr drop doest stop
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Quoting StormW:


I'll take a look...probably an oversight on my part...been jumping back and forth on sites Oh...I will send you an email next time...He does have the show recorded on podcast


Excellent, no rush. I was just curious about the "typhoon" like way Alex is behaving and the sheer size is all. Get to it when you can, had some random questions about it lol. I think it had to do with actual behavior of these type of systems compared to regular Atlantic systems.lol. But please my dear take your time. :)
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Quoting CaneWarning:


I've found myself lurking quite a bit since Alex formed. People are on edge more when we have an active storm. I tend to get myself in trouble in times like these. :)


I hear ya, I gave everybody another chance and cleared my ignore list. I kinda enjoy all of the brawling and I couldn't see the whole picture with some of the blocked people. LOL
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Quoting AlexEmmett:

that is a heck of a ts though one for the record books for ts's though
No idea.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2214. tkeith
Alex is a cow storm.

cowcaster...
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Quoting atmoaggie:

Nice!


Well, we know he won't be a fish storm !
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2212. help4u
Alex ,more like a heffer!!!!!
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Quoting BahaHurican:
I rarely go out of my way to insult pple in here, but something about the way you are posting is making want to really blow u out of the water. Be that as it may.....

I'm curious which cat two storms you have seen which looked worse than Alex does now. We'd LOVE to see some imagery if you can find it..... on your other points, you made two non sequiturs in response to the post u quoted. First, you said something about nature not paying attention to textbook definitions, when the poster was actually speaking about OTHER BLOGGERS paying attention to the correct usage of terminology (what's Mother Nature got to do with what he said?). Second, you said something to the effect of "RI soon to come" when the blogger was actually saying no RI happening right now.

I'm getting rather weary of your constantly bombastically bombarding statements about Alex moving NE and hitting Florida based on a brief bobble and your "gut feeling". Give me some meteorological proof, and stop trying to ram your gut feeling down MY throat.

YMMV.
Very, very well said Baha.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
2210. KEEPEROFTHEGATE (Mod)
01L/H/A/C1
MARK
20.6N/91.5W
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2209. hercj
Quoting MiamiHurricanes09:
Winds still not catching up. Advisory will likely have winds of 65mph and a pressure of 985mb.

Miami is the tropical atlantic site down?
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I have it going 010@8kts
Let the fun begin.



AOI
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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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