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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I was kinda mad today. OPIS - an oil industry reporting service - had an article saying Alex likely to landfall in Mexico or Texas. (As a way to alert those of us working in the energy industry.)

Took a lot of stuff in this blog (the early AM one) but I thought Rob Carter had written it - they didn't attribute to him. He had written the late night one.

I sent a terse note.

Ooopps. I've been reading too many blogs - they all runnin' together in my head.
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Quoting nash28:


Agreed on "some hurricanes can bust the high." However...

This particular storm is NOT going to be deep enough to bust the high. Not even close. Dean could have been a good candidate to bust the high, but even Dean could not do that. It didn't help that the high was a ridiculous MB! But I digress.... This system is not going to pull a Wilma type turn.


The high is not too strong
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Quoting kmanislander:


Go here. It's also on Google earth but I don't have that on this computer. You have to get familiar with reading the lat and long as well as the pressure and wind readings. Shouldn't take you too long to get the hang of it.
Quoting kmanislander:


Go here. It's also on Google earth but I don't have that on this computer. You have to get familiar with reading the lat and long as well as the pressure and wind readings. Shouldn't take you too long to get the hang of it.
LinkI usually just go here.
Member Since: October 9, 2008 Posts: 0 Comments: 8347
Quoting RecordSeason:
Hehe.

Alex is huge.

My barometer at home is recording 1007mb, which is near TD central pressure, lol.

Man he is huge indeed. I live in Springfield, LA, about 10 degrees north and a degree and a half east of the center.

He's got Ike beat so easy it's a joke. Was wondering why my ears were feeling funny. It's probably the pressure drop that's been going on for 2 days now.


Buffalo NY is recording a pressure of 29.64 right now, or 1003.7 mb. Alex must extend up there too, right? /sarcasm
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting whs2012:


If this were to happen, how strong would the system have to be, and where would you suspect landfall?




any where form TX too LA and it could be come a strong cat 4 or low end cat 5
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Member Since: Posts: Comments:
JUST FYI:
I was on the NWS conference call @ 4pm and they stated that Tropical Storm Alex will make landfall S. of or very near Brownsville, TX.

I understand things change. Just stating what was dicussed.

Hope everyone continues to stay vigilant and prepared.

-Jeff
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1550. Detrina
Quoting atmoaggie:

Use your head-filter. Alex isn't going to Florida....


I just wanted to hear someone else say it, thanks!
I read something earlier about some forecaster in Britain building a case for a possible *florida impact* due to some funky formula about solar activity or something, sounded a bit out there but I am no expert, I just wait for the neighbor to tell me to get the boat out of the water and throw the furniture in the pool:)
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1549. nash28
Quoting RitaEvac:
Remember if this thing explodes and gets bigger and stronger, it can and is known for hurricanes to bump the ridge, and they can weaken a ridge and push more poleward than what models can predict.


Agreed on "some hurricanes can bust the high." However...

This particular storm is NOT going to be deep enough to bust the high. Not even close. Dean could have been a good candidate to bust the high, but even Dean could not do that. It didn't help that the high was a ridiculous MB! But I digress.... This system is not going to pull a Wilma type turn.
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Quoting Roark:
Thank you sir! Lat/lon no problem for an old aviator like me. You're a gentleman & a scholar! (And your secret is safe with me!)




are you JFV?
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Quoting SomeRandomTexan:
Doesn't look like it is going NNE/NE to me... give me some data showing this RECORDSEASON


it drifted ENE over the last 3 hours

its not really a movement though, hence why the NHC says stationary
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of all we no it could be comeing for LA
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Quoting nash28:
Taz- It IS in fact heading for the TX/MX border. Brownsville area most likely.


ok
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1543. Roark
Thank you sir! Lat/lon no problem for an old aviator like me. You're a gentleman & a scholar! (And your secret is safe with me!)
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And he's the size of being able to bump a ridge and doing what it wants
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Quoting RecordSeason:
My barometer at home is recording 1007mb, which is near TD central pressure, lol...


Are you sure your barometer is correct? I'm in Vermilion parish near the coast and recording 1012.9 mb, rising slowly..
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Doesn't look like it is going NNE/NE to me... give me some data showing this RECORDSEASON
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Quoting nash28:
Taz- It IS in fact heading for the TX/MX border. Brownsville area most likely.
Don't be so sure, some interesting twists are beginning to come into play.
Member Since: September 2, 2009 Posts: 130 Comments: 21193
Out for dinner. Back later
Member Since: August 19, 2006 Posts: 0 Comments: 15813
I heard your question CyberTeddy
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There are still questions as to where it is going

lets not pretend we all know where it is going without a doubt, because seriously we dont have a clue
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1535. IKE
Quoting RecordSeason:
Hehe.

Alex is huge.

My barometer at home is recording 1007mb, which is near TD central pressure, lol.

Man he is huge indeed. I live in Springfield, LA, about 10 degrees north and a degree and a half east of the center.

He's got Ike beat so easy it's a joke. Was wondering why my ears were feeling funny. It's probably the pressure drop that's been going on for 2 days now.


You okay?
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Quoting MrstormX:
Recon to scared to go near the center lol


LOL maybe Alex got so strong that they're afraid it'll suck them right in to another dimension LOL
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting Roark:


Got a link to this data for a complete Noob like me? :) Thanks!


Go here. It's also on Google earth but I don't have that on this computer. You have to get familiar with reading the lat and long as well as the pressure and wind readings. Shouldn't take you too long to get the hang of it.
Member Since: August 19, 2006 Posts: 0 Comments: 15813
1532. Daveg
Quoting nash28:
There will be no NNE movement of this system. None.

It is coming into agreement and the synoptics are showing this as well.


I would agree with that, but couldn't there more more of a north movement than the sharp west turn?

Seems a few of the models are wanting to bring it in a bit farther north again.

Just curious.
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Quoting nash28:
Better start buying the southern solutions folks. TX/MX event. Why?

Alex's stall will not allow much more poleward movement before the Great Plains ridge builds back in behind the trof. You can see this on WV imagery.



My thoughts exactly but obviously much can still happen and likely will! Alex full of surprises!
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Quoting Detrina:


Hush! I do not want to hear the F word.

Use your head-filter. Alex isn't going to Florida....
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Remember if this thing explodes and gets bigger and stronger, it can and is known for hurricanes to bump the ridge, and they can weaken a ridge and push more poleward than what models can predict.
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Quoting jlp09550:




this storm is big
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1525. nash28
Taz- It IS in fact heading for the TX/MX border. Brownsville area most likely.
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no no its not heading for Mexico hit heading for JFV
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1523. nash28
There will be no NNE movement of this system. None.

It is coming into agreement and the synoptics are showing this as well.
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1521. Roark
Quoting kmanislander:
AF 304 still looks to be Southbound and descending


Got a link to this data for a complete Noob like me? :) Thanks!
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Quoting whs2012:



What's the non-tasked mission?


Research, 3D Doppler Radar
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Quoting Tazmanian:
not heading for Mexico


that settles it then...
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1517. nash28
Better start buying the southern solutions folks. TX/MX event. Why?

Alex's stall will not allow much more poleward movement before the Great Plains ridge builds back in behind the trof. You can see this on WV imagery.

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Quoting RitaEvac:
For some reason I think models are gonna change to Corpus after the G4 runs, dont know why.


Agree. Unfortunately we are due.
Member Since: August 14, 2007 Posts: 0 Comments: 438
Quoting Kristina40:
PChuck, I used to live in the Midwest and it feels like it does before a Tornado here in Panama City. No breeze at all and 78% humidity. Pressure 29.87 and falling.


I hear you, Ohio native here and I know exactly what you are talking about
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Here it is folks.....


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Quoting RecordSeason:
1466:

Use their data Miami.

The storm didn't "magically" jump 2 tenths back to the east. It had to ACCELERATE in that direction to get there.


it's not ACCELERATING anywhere. It's stationary!
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1512. Detrina
It was raining cats and dogs here in Palm Harbor, Fl with winds and lightning, can that really be from Alex? Neighbor said he heard on TV that it was.
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Why are some people wishing this on Florida? It's not coming here.
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Recon to scared to go near the center lol
Member Since: May 27, 2009 Posts: 0 Comments: 4438
AF 304 still looks to be Southbound and descending
Member Since: August 19, 2006 Posts: 0 Comments: 15813
1508. Daveg

Interesting, I see a few of the model runs are starting to come in, and are shifting a bit back to the north a smidge again.

What would cause the models to start to do that? (again noob here). Is there something they are seeing that would cause the storm to ease more that way?
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PChuck, I used to live in the Midwest and it feels like it does before a Tornado here in Panama City. No breeze at all and 78% humidity. Pressure 29.87 and falling.
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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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