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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alex looks like it stall
Member Since: Posts: Comments:
Quoting oddspeed:

yep... i think we have an eye forming,


Alex looks to be getting all geared up now that he is getting into the warm waters. It does look like an eye wall is forming in the last few frames.
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Quoting msgambler:
Pat, I have noticed all day that unless you are saying Mexico or S. Texas then you risk decapitation.


Off wit dere Heads..

Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting oddspeed:

yep... i think we have an eye forming,


Now I dunno about an eye haha, but it's definitely getting back in business.
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Quoting Baybuddy:
How long has alex been stalled?


In situ nearly 24 now
Member Since: July 3, 2005 Posts: 423 Comments: 127804
How long has alex been stalled?
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Quoting StSimonsIslandGAGuy:


I agree. Getting to Cat 2 in the 54-60 hour period when landfall is estimated to occur would not be a big stretch. But Cat 3 would be a big stretch, in my opinion.
I think some RI might occur once Alex moves further north in latitude as upwelling is causing the TCHP to be very low there. Category 2 seems likely, category 3, not so much.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting StSimonsIslandGAGuy:
Actually I think the fact Alex is nearly stalled now decreases the possibility of a landfall north of Mexico. Gaining latitude now would increase the threat to the north Gulf coast and Texas---since it is not gaining much latitude, when the NW or WNW motion starts, I think it is more probably than not that Alex will not get far enough north to make landfall in the USA.


I agree that a stalling for now ultimately leads to a landfall farther south...but if he waits even longer (he's already far far slower than every forecast) he might make a 2nd northward move before even reaching the west gulf coast. We'll have to see if he finally gets his rear in gear tonight and starts moving.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
Quoting Jeff9641:


I know I had a hard day at work but I'm not that tired yet.


Haha, not doubtin ya, my eyes aren't the best. Could very well be a wobble.


Man, someone else needs to block out all the frames on the visible loop except for the first and last one. So I can make sure I'm not crazy with how much better organized it got. Really surprised me.
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Pat, I have noticed all day that unless you are saying Mexico or S. Texas then you risk decapitation.
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Dang i gotta figure out now who to ignore and who not to again.......LOL
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Details,..minor details..


Member Since: July 3, 2005 Posts: 423 Comments: 127804
Quoting HurricaneSwirl:
Alex starting to look impressive again on visible loop:

Link

The last frame is really wowing me compared to the first, wow. Notice how the convection is stationary while you can see the COC slide right underneath it into the middle so it starts looking symmetric again.

yep... i think we have an eye forming,
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RGB in the daylight hours, much easier (at least for me) to see.
Link
Member Since: Posts: Comments:
Quoting angiest:


That could be due to the lack of geanularity in the NHC's forecast points. Hitting cat 3 just before landfall could easily be missed when you only get 6 or 12 hour points.
But the NHC never states that it will become a category 2 hurricane, so the WU cone is incorrect regardless of the time frame between intensity points.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting StSimonsIslandGAGuy:
Actually I think the fact Alex is nearly stalled now decreases the possibility of a landfall north of Mexico. Gaining latitude would increase the threat to the north Gulf coast and Texas---since it is not gaining much latitude, when the NW or WNW motion starts, I think it is more probably than not that Alex will not get far enough north to make landfall in the USA.
Maybe but not going W may mean a 2nd trough picks it up.
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Quoting StSimonsIslandGAGuy:
Actually I think the fact Alex is nearly stalled now decreases the possibility of a landfall north of Mexico. Gaining latitude would increase the threat to the north Gulf coast and Texas---since it is not gaining much latitude, when the NW or WNW motion starts, I think it is more probably than not that Alex will not get far enough north to make landfall in the USA.


I agree with you it's stalling so long it's gonna miss that weakness/opportunity to go north.
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Quoting Fl30258713:


That's nice to know. I've been using Chrome and doing the hard way. :-) lol
Lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
Quoting MiamiHurricanes09:
That's not the point. He/she was telling me that the WU cone showed it reaching category 2 strength, which means that that data is untrue. I showed in my post that the NHC never takes it past category 1 strength.


That could be due to the lack of granularity in the NHC's forecast points. Hitting cat 3 just before landfall could easily be missed when you only get 6 or 12 hour points.
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Radio Malibu..



BOOM
BOOM!!!!!
Member Since: July 3, 2005 Posts: 423 Comments: 127804
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
It is likely that that person is not using a browser that supports the 3 tabs above the comment box. It is best for he/she to download Firefox.


That's nice to know. I've been using Chrome and doing the hard way. :-) lol
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Quoting RecordSeason:
435:

Miami, do you comprehend the NHC forecast is different from other met's forecast?

The NHC certainly has never shown themselves to be reliable in intensity forecasts, and are often off by a category or two in eventual peak intensity. Sometimes more!
That's not the point. He/she was telling me that the WU cone showed it reaching category 2 strength, which means that that data is untrue. I showed in my post that the NHC never takes it past category 1 strength.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
478. JLPR2
Quoting CaribbeanIslandStorm:


Hey, could send me the link wear you got that pass?


here you go
Link
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Quoting Patrap:


I may need a Budweiser corpsman,..


Comin' your way Sir!
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
It is likely that that person is not using a browser that supports the 3 tabs above the comment box. It is best for he/she to download Firefox.


Chrome probably should support it, but I wouldn't be surprised if the code in the blog is checking for specific browsers and rejecting all others.
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Quoting SamTeam:


I noticed that; can we get you a new flack jacket & helmet? You've been getting it most of the day!


I may need a Budweiser corpsman,..
Member Since: July 3, 2005 Posts: 423 Comments: 127804
sorry guys had to go out a lot today so when will we likely see 95L and maybe 96L
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This is what Alex is doing right now but farther east. How long he moves north?? NHC had Bret going into Mexico on Bret because I remember this, and look how far north he went. Alex hasn't turned yet, then models start playing catch up down the road.
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Quoting Fl30258713:


http://wiki.wunderground.com/index.php/WunderBlogs_-_Adding_links_(URLs)

It is likely that that person is not using a browser that supports the 3 tabs above the comment box. It is best for he/she to download Firefox.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
457....Start your own blog then...or go tie flys.
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Quoting JLPR2:
11hr old ASCAT showing the African wave emerging with a nice, large and closed low but with light winds


now I want to see the new pass, I wonder if it'll catch the area -.-


Hey, could send me the link wear you got that pass?
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Quoting Patrap:


That was a rumor earlier.

But I almost got decapitated for it.

LOL


I noticed that; can we get you a new flack jacket & helmet? You've been getting it most of the day!
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Quoting Patrap:


That was a rumor earlier.

But I almost got decapitated for it.

LOL
you are right though:)
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Alex starting to look impressive again on visible loop:

Link

The last frame is really wowing me compared to the first, wow. Notice how the convection is stationary while you can see the COC slide right underneath it into the middle so it starts looking symmetric again.
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Quoting Patrap:


That was a rumor earlier.

But I almost got decapitated for it.

LOL

i've always wanted to see a full blown storm split in two. lol
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Quoting Houstonia:
My apologies if this has already been posted...

... I thought this was interesting. I don't know much about it, but from what I've heard, his record is pretty good.

Link

British weather forecaster says Alex will move much further north and east...

Piers Corbyn reveals revolutionary forecast concepts. WeatherAction long-range forecasts are produced using Piers Corbyn's Solar Weather Technique which is the most advanced and reliable long-range forecasting system in the world.

The technique uses predictable aspects of solar activity - particle and magnetic effects from the Sun - as the basis for forecasting weather many months and even years in advance. The essence of the technique is explained in scientific presentations (see News Archive).
If Alex moves east of Louisiana I will personally give Portlight some money. The forecast that man is giving really doesn't intrigue me to believe it.
Member Since: September 2, 2009 Posts: 130 Comments: 21109
460. JLPR2
11hr old ASCAT showing the African wave emerging with a nice, large and closed low but with light winds


now I want to see the new pass, I wonder if it'll catch the area -.-
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Quoting StSimonsIslandGAGuy:
The NHC track puts Alex ashore between 54 and 60 hours, and intensification to 85 kts would be possible. I think a Cat 2 is quite possible, but reaching major intensity is unlikely.


Cat 3 is probably only possible if Alex hits Texas. Mexico would likely see a 2.
Member Since: November 24, 2005 Posts: 635 Comments: 26594
Well let me say this before I head home. Alex is meandering DUH! lol! Also I am not sold on this Ridge developing at all. If it doesn't develop I think there will be hell to pay. JMO. Till tomorrow. Blog your heads off people!
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Quoting sarahjola:

i agree. to the one who wants stats with comments- this is an opinion blog. even the experts are just guessing and so far have been kinda wrong. not one met. or expert has said that this would stall out for so long. usually when a storm stalls its cuz its changing direction or relocating coc. Alex is not all the powerful yet. its just big. its still a tropical storm, not a hurricane. coc's have relocated before in tropical storms and hurricanes. nothing is impossible.


I'm speaking to the issue of assertions without reasoning behind them like "it's going to ……." or "Some one said." I'm not looking for footnote quality referencing but a little more verifiability than a lot of posts. Yes it is an opinion based forum but a degree of responsibility for verifiable referencing and a reasoned response advances the learning of folks like me. All opinions are not of equal value. There are reasoned informed opinions and then their's the guy on the square ranting about the black copters coming.
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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.