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 RCThunder:
Does anyone have a long-term animated graphic showing the satellite of Alex from his inception as an Invest many days ago?
I'll wager that P451 has posted that a couple of times...that's one of his best contributions here. Keep an eye out...
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Quoting scott39:
Man oh Man --- Its hard to believe our CHIEF MET cant get the direction right of Alex!!
Way to start the season. Alex is what I would call a "face-palm system". I think StormW would agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I just had the best pear I have EVER had, that and my leftover chicken bones indicate that we may need to wait until the am to see what model the tea leaves will favor...
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2653. WxLogic
Quoting StormW:
00Z Steering Layers forecast maps from PSU e-WALL, Valid 12Z 29 JUN 2010,

Indicate landfall north of NHC forecast track...near Brownsville. I'll be looking at things closely in the a.m.

I think one problem is, the mid layer steering set is not taking into account, that Upper to Mid level low off the Bahamas...It's not showing up on mid layer, and weak on deep layer. It's the A/B high that is supposed to nose in, and help turn Alex more NW-WNW, aiding the other small ridge.



That suspicion might come true if Alex keeps having an easterly component to its motion as then that ULL is actually being successful at eroding the western flank of the A/B High.
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Quoting StormJunkie:


love that everyone is starting to go to Flash player...So much faster and less resource intensive than Java loops.


Yup. I don't particularly enjoy using those java loops. That's why I had to make my own flash loop of the GHCC site (but it allows me to make those animations automagically ;) ).
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2651. angiest
Quoting PcolaDan:


I bet you still lay on the lawn and see bunnies in the clouds, don't you? :)


A long time ago the late great Harold Taft of KXAS in Ft Worth advised parents to have their children come look at the weather forecast. He had a satellite image with clouds that looked like a rabbit.
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2650. Drakoen
Recon heading in for another pass
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2649. jpsb
Quoting Levi32:
Good evening all. Alex appears to be undergoing stead intensification, and while still over the shallow shelf waters of the Yucatan too...it hasn't even hit the higher TCHP yet.
Hi Levi, looking forward to your take on things, how is the calculus going?
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2647. Patrap
ALEX RECON HH Tail #304 Latest Message
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting MiamiHurricanes09:
Recon going back to check out the COC. If pressure drops 2mb again I will certainly be surprised.

i wouldnt
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2644. amd
Quoting redux:
I find it amazing the low probabilities being tossed around for this thing to become cat 3 +.

just looking at it makes me think it has the capability to be a very powerful storm.


the shear forecast isn't cut out of stone, and Alex has to get rid of the large separation between the developing COC and the large feeder band to the NW first. Basically, there's a chance that shear and some dry air COULD hold the intensity of Alex down a bit.

However it is always important to note that the NHC themselves always say that intensity is the hardest thing for them to forecast, and is susceptible to errors.
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2643. guygee
Quoting atmoaggie:
Join?
Already done Atmo, and I hate to do it to anyone, first was this past week in fact.
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Recon going back to check out the COC. If pressure drops 2mb again I will certainly be surprised.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Patrap:
Swooosh..ahhhhhhhhh..

"Impressive" \
"That's no moon...it's a space station."
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Quoting Patrap:


The TSA folks never even knew what a Slide rule was..



"Hey Chief,..dis guy here has a sliding Ruler thingee he says is for work"...
I hope it wasn't a nice one with steel edges...
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2639. scott39
Man oh Man --- Its hard to believe our CHIEF MET cant get the direction right of Alex!!
Member Since: June 13, 2009 Posts: 0 Comments: 6890
WOW, that IR image is impressive! Alex is going crazy.
Member Since: September 18, 2007 Posts: 0 Comments: 1074
2637. Patrap
Quoting atmoaggie:
Well, you can forget it. I am not going through security again!


The TSA folks never even knew what a Slide rule was..



"Hey Chief,..dis guy here has a sliding Ruler thingee he says is for work"...
Member Since: July 3, 2005 Posts: 426 Comments: 129093
Quoting TexasHurricane:


Definitely getting his act together...

he's not even in the hots stuff yet right levi
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Quoting StormW:


I can't rule it out...how far north, I don't know yet...gotta see how things have evolved in the a.m.
Hey Storm have a Good Rest and will check with you in the AM.... Oh yea Thanks for all you do and Great Show earlier....

Taco :o)
Member Since: July 7, 2005 Posts: 6 Comments: 3261
Quoting Chicklit:
Alex is starting to look like a gorilla.


I bet you still lay on the lawn and see bunnies in the clouds, don't you? :)
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2633. MZV
Quoting RCThunder:
Does anyone have a long-term animated graphic showing the satellite of Alex from his inception as an Invest many days ago?


Please don't post that as a multi-megabyte CIMSS MIMIC animation! ArrGghGHH
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Quoting atmoaggie:
Yeah, that's right. Well, better than no data, right?

Hey, now, I hadn't seen this one before. Neat product that shows some serious details: http://rammb.cira.colostate.edu/ramsdis/online/loop_timestamp_640.asp?data_folder=rmtc/rmtcsasec5ir 404

Thermal IR with a good color scale for TCs.


love that everyone is starting to go to Flash player...So much faster and less resource intensive than Java loops.
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Quoting AlexEmmett:

umm look at it guys dont make the man angry
It needs to fill in that gap between the COC and the band to the north.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Inbound... confirmation of track??



AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting AlexEmmett:

umm look at it guys dont make the man angry


Definitely getting his act together...
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Quoting atmoaggie:
Yeah, that's right. Well, better than no data, right?


Yup, I agree to that. That's why I'm using those alternatives now until the GHCC server starts behaving again.
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Quoting Levi32:
It is possible that although waters are still shallow where Alex currently is, he has finally started moving a bit today, and he may have moved off of the cool patch he upwelled for himself further south from where he is now, and he is likely over fresh warm water up at 28-29C, shallow though it is.


Hey Levi, question for you. I've been putting a lot of thought into this and can't figure it out, maybe you have some insight. I understand TCHP is measured by how deep the top layer of warm water is (and the temperature of that water). Shallow continental shelf areas can't have high TCHP due to the fact the water column is just too shallow. Is it safe to assume that the top, warmer layer of water goes all the way down to the sea floor in these areas? And if this is true, how can a storm upwell cold water in these hot/shallow areas when there is no cold water at the seafloor? I understand that the storm will use up a lot of that energy in these areas, but I don't understand how it can upwell anything. I remember Dr.Masters mentioned cold water upwelling in very shallow warm areas last season and it perplexed me then.
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Quoting xcool:
AlexEmmett no clue y

um becuase people dont want to know that things that our gov spends tons of money on are wrong
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Quoting rareaire:
evening all. I see Alex is gaining weight!


Rare, how you doing? Ready to ride?
Member Since: August 2, 2006 Posts: 10 Comments: 9922
First comes the CDO, then comes the updraft, followed by pressure dropping and eureka an eye is born.
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remember how they had a plane going through today that was not a recon? it was for collecting data for the models. did they plug that data into the models yet? if not, when will the models show that data in their forecasts?
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2621. Patrap
Swooosh..ahhhhhhhhh..

"Impressive"

..young Skyewalker..


Member Since: July 3, 2005 Posts: 426 Comments: 129093
Is there a possibility that the storm will just continue north?
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Does anyone have a long-term animated graphic showing the satellite of Alex from his inception as an Invest many days ago?
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Quoting Patrap:


B concourse I presume.

Figures,Im at the Bar over on A.
Well, you can forget it. I am not going through security again!
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2617. tkeith
Quoting Tazmanian:
i think thenhc sould do a hurrican watch for LA this too be safe
Stormptop has not mentioned NOLA yet Taz...we'll have to wait
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Quoting redux:
I find it amazing the low probabilities being tossed around for this thing to become cat 3 +.

just looking at it makes me think it has the capability to be a very powerful storm.

umm look at it guys dont make the man angry
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Quoting Tazmanian:
i think thenhc sould do a hurrican watch for LA this too be safe


For some reason, my mind is sorta agreeing to that.
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2614. xcool
AlexEmmett no clue y
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting jlp09550:


Only reason I use GHCC's site is because it's updated more frequently.. about every 5-15 minutes. The one you provided is updated at the 15th and 45th minute of the hour.
Yeah, that's right. Well, better than no data, right?

Hey, now, I hadn't seen this one before. Neat product that shows some serious details: http://rammb.cira.colostate.edu/ramsdis/online/loop_timestamp_640.asp?data_folder=rmtc/rmtcsasec5ir 404

Thermal IR with a good color scale for TCs.
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2612. Levi32
Quoting truecajun:


that's what i'm thinking. this one is for Texas. there i said it. this is the first time i have ever "called" a storm on here. i'm a little nervous :0


Lol, trust me this is one of the harder ones to call....you usually don't have to call a storm of this type in June with a June-type longwave pattern.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
More symmetrical.


Gorilla tossing Buffalo.
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Quoting KaNaPaPiJoSa:


Toby Keith


oh yeah.
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i think thenhc sould do a hurrican watch for LA this too be safe
Member Since: May 21, 2006 Posts: 5091 Comments: 115362
2608. redux
I find it amazing the low probabilities being tossed around for this thing to become cat 3 +.

just looking at it makes me think it has the capability to be a very powerful storm.
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NHC track and models have it turning NW right now and its not doing that, I dont know what to believe.
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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.