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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No, no, no! You guys have it all wrong! Alex is going to hit Brownsville and follow the Inter-coastal canal all the way to New Orleans, INTENSIFYING ALL THE WAY!!!
(This is the place that you are supposed to start running in circles waving your arms over your heads, by the way)...THEN, after if hits Corpus, then Houston, it will turn SE into the gulf, circling the oil spill two or three times (sucking the oil into the atmosphere). THEN it will turn NW-ish and go up the Mississippi River, STILL INTENSIFYING, and coat every city all the way to Chicago with oily floodwaters and Hydrocarbon Tornados!
Other than that I really don't expect Alex to cause much trouble at all....
***I wander off whistling to myself and rolling my eyes***
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Quoting weatherman12345:
do you think the track will shift more towards the north??




YES and YES
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Quoting xcool:
MiamiHurric THAT OK .IMO OK THANKS.
LOL, probably sounded mean the way I said it, but just wanted to get the point across.
Member Since: September 2, 2009 Posts: 130 Comments: 21122
Quoting StSimonsIslandGAGuy:
I don't see much to support a major.


Sea surface temperatures hotter than August in most years?


Sufficient TCHP support ahead of it?


Dropping shear ahead of it?


Pressures that area already borderline Cat 1 strength? Rapidly building convection? A well-defined circulation? Sure, it's not the most likely possibility, but it absolutely is a possibility.
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Quoting LSU79:
This is the way that I see it. I am looking at it terms I can understand. The landfall of Alex is like when I go shopping with my dear wife. We stop at the first store at 10:00 in the morning. We visit 32 different stores and end up at the first store we stopped at to buy the first blouse we saw. So, when all this started it was a LA storm. Now after 32 different landfall locations in is ending up where it started, LA.


lol, you sound just like my husband!
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Quoting DestinJeff:
Situation even more troubling at next higher steering layer:



Understand that things change, but that high in the rockies needs to grow some and move south and west.


Another interesting, albeit pointless fact to me is that after being completely eaten earlier today it looks like by the steering currents Darby will forever be a part of Alex's circulation.. LOL @ a 65 mph TS obliterating a major hurricane.
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Quoting StSimonsIslandGAGuy:
Well it's just that Alex is so....big. Big storms don't typically explode in strength.

However Ike was a Cat 2, and we could see something along those lines. But Ike did not make landfall as a major hurricane in Texas. And there is a mindset among some here that a hurricane has to be major to be a real threat. It doesn't. Ike showed that very well.
can you say W-I-L-M-A
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1097. CCkid00
Quoting StormW:


NHC

LOL
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1096. USSINS
Quoting Patrap:


Pat, you and a few others, imo, are are going to wind up being right on the coc thing from earlier.
Quoting TampaSpin:
We are gonna have a MAJOR HURRICANE coming IMO gang.....its coming! BE PREPARED!


Tampa - Where do you think this will go and possibly how strong??
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The latest satellite pics of Alex scare the crap out of me, frankly. I've felt he was going to be a monster for awhile now. Today it felt like the air got sucked out of this area. Dead still, humid and hot. Animals acting crazy which leads me to believe our pressure is dropping all the way up here in Florida. I picture Mother Nature saying in her best South Park voice "You will respect my authoritayyyyyy"
Member Since: June 27, 2010 Posts: 0 Comments: 760
1092. Patrap
Member Since: July 3, 2005 Posts: 423 Comments: 127810
1091. xcool
MiamiHurric THAT OK .IMO OK THANKS.
Member Since: September 26, 2009 Posts: 2 Comments: 15648
1090. Levi32
Quoting CCkid00:

Levi, i hear you are one of the top four most knowledgeable on here......what do u think of the weakness? do u think there will be a forecasted landfall change? thanks! i've watched on here for 6 years. i'm just hear learning (and laughing at some of the craziness).


Well I don't know about that lol but thank you.

I think the potential for a bit farther north than the NHC has it is definitely there. We'll see how it moves compared to the forecast track during the course of the night. The NHC is near the southern-most portion of my greatest concern area for landfall. I think Alex could get as far north as Corpus Christi or Rockport if he gets moving...but if he maintains a speed this slow and doesn't move as fast as the model forecasts, he could get forced back west sooner and still end up south of Texas. He has to take advantage of the weakness currently to his north for it to be of any worth.
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Afternoon, all. Been lurking most of the afternoon. It appears with the stall, the ensuant northward movement and the trough being much deeper than expected, we will see major shifts from the models andshould also see a substantial shift in the official track forecast. The northern movement we have been seeing will be amplified at 48 hrs along the track.
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Quoting HurricaneSwirl:


looks like it wants to fill in the western side


Starting to look like a fast wrapper and he can't sing a freaking tune.
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Ive been looking at water vapor and steering currents, I'm just not seeing the Mexico solution right now. That trough is still digging, probably not much further. Even so, it has weakened the ridge over the Gulf quite a bit.
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Quoting Patrap:
Alex out the Yucatan Bunker after that sand stall..

He looks ready and now hes reaching for the,..looks Like a 9 iron..


Hmmm, this is going to be interesting..




cinderella boy....tears in his eyes I guess
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Quoting xcool:
NHC not god & i know they got p.H.D SO WHAT.
So what? The NHC are experts, real big experts. I don't think anyone on this blog has a Ph.D in the field of meteorology, so it's more than a "so what". No disrespect towards the truly intelligent people on the blog, just my thinking.
Member Since: September 2, 2009 Posts: 130 Comments: 21122
definantley wouldn't want to be that person. They may have tomake a call soon.
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1081. Patrap
Member Since: July 3, 2005 Posts: 423 Comments: 127810
1080. LSU79
This is the way that I see it. I am looking at it terms I can understand. The landfall of Alex is like when I go shopping with my dear wife. We stop at the first store at 10:00 in the morning. We visit 32 different stores and end up at the first store we stopped at to buy the first blouse we saw. So, when all this started it was a LA storm. Now after 32 different landfall locations in is ending up where it started, LA.
Member Since: August 17, 2007 Posts: 0 Comments: 17
1078. CCkid00
Quoting StormW:


I believe so...however I don't think it was forecast to be that large. I've been watching out west, and the ridge appeared as if it would build in farther south and stronger...when you're watching water vapor, it's hard to determine sometimes, until hours pass and ya get to see how things are evolving. If that's all the ridge there is going to be, then there's gonna be a problem.

thanks Storm! been watching for 6 years on here and there is a handfull i especially pay attention to. your one of them! i read all your blogs. thanks!
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Storm,
Do you think that the nhc might changer their path? if so, where to?
Member Since: September 1, 2008 Posts: 0 Comments: 672
Quoting CybrTeddy:
GOES East satellite loop of Alex. Defiantly organizing now.

Link


looks like it wants to fill in the western side
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Quoting StSimonsIslandGAGuy:
I don't see much to support a major. Models are not showing it. Neither does the NHC forecast. I think a cat 2 is quite likely, and it wouldn't shock me to see Alex be a 3. But a major is certainly not inevitable.


we know how unreliable intensity guidance are though

a major is not much more than a CAT 2, so I would say its easily a possibility
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Quoting StormW:


NHC
Nohorth Carolina ??? :)
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Quoting Patrap:
Alex out the Yucatan Bunker after that sand stall..

He looks ready and now hes reaching for the,..looks Like a 9 iron..


Hmmm, this is going to be interesting..



A few (~4-5) more hours of this and convection will be wrapped around the center.
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1072. jdj32
HH Information for Google Earth

http://tropicalatlantic.com/recon/ge/Recon_Data_for_the_Atlantic_Basin.kmz
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Quoting MiamiHurricanes09:
Alex improving on overall structure and firing some decent convection to say the least.





may be a eye wall of some kind?
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Quoting StormW:


NHC

I'm not telling them...are you gonna tell them???
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This is not even funny anymore. Can't believe that weakness! If I was BP, I would start moving people out now.
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1067. CCkid00
Quoting Levi32:
Guys.....what....1 hour of perhaps 6mph northerly movement is not a significant deviation from the NHC track. Give it time....if the long-term motion is well north of the NHC track then it will be significant. Rapid-scan imagery is addicting with images every 10 minutes but storms in weak steering currents wobble all over the place. Have patience before saying "Houston we have a problem".

Levi, i hear you are one of the top four most knowledgeable on here......what do u think of the weakness? do u think there will be a forecasted landfall change? thanks! i've watched on here for 6 years. i'm just hear learning (and laughing at some of the craziness).
Member Since: Posts: Comments:
mrsalagranny, never take your eyes of one of these. I've only lived on the Gulf Coast for a little over five years but Mom and Dad lived down here for about 15 prior to that and I've learned they will do what they wish. I can remember going to bed last season on a Saturday evening here in Panama City with nothing of interest going on in the tropics and waking up with a TS 40 miles off our coast. That was a wake up call.
Member Since: June 27, 2010 Posts: 0 Comments: 760
1065. xcool
NHC not god & i know they got p.H.D SO WHAT.SORRY IMO..
Member Since: September 26, 2009 Posts: 2 Comments: 15648
GOES East satellite loop of Alex. Defiantly organizing now.

Link
Member Since: July 8, 2005 Posts: 259 Comments: 23892
A lot of "ifs" being thrown around atm, im just gonna sit back and see how this plays out, and listen to the experts here!
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Alex improving on overall structure and firing some decent convection to say the least.

Member Since: September 2, 2009 Posts: 130 Comments: 21122
1061. IMA
Latest discussion for San Antonio for the rest of the week:

The forecast for the middle of the week is highly dependent upon
tropical cyclone Alex and is a blend of GFS/guidance from NHC. The
current track keeps Alex's landfall well to our south which means
south central Texas will be on the wetter side of the system as it
makes landfall. The outer fringes of Alex will cause rain chances
to increase across our area on Wednesday and stay in the forecast
through the rest of the workweek. Regardless of the eventual track
of Alex...given the antecedent rain event through the next 24
hours...saturated or near saturated soils are expected in advance
of the rainfall from troublesome Alex. Therefore...a renewed
chance for flash flooding and river flooding is expected through
the end of the workweek and possibly into the weekend as Alex
slows down and shears apart.
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1060. xcool
TampaSpin lol
Member Since: September 26, 2009 Posts: 2 Comments: 15648
1059. xcool
homelesswanderer .good working alot.
Member Since: September 26, 2009 Posts: 2 Comments: 15648
Quoting stormpetrol:
I actually think the center of Alex is drifting slightly a little east of due north.
Thank you! Back from laundry. I said that earilier but I'm just an amateur observer.
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Quoting StormW:


NHC

them boys are pacing around right now
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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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