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 Drakoen:
Slowly becomming better organized


Yup that is more recent and confirms that what is in the last frame on this link: Link is not an eye because convection fills over it. Knew it couldn't be an eye.
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Got a message that the LSU ESL server has been overloaded with Hits today at times.


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New recon just left Louisiana enroute to Alex with arrival about an hour and a half.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Convection in and around the center beginning to fire.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
thanks stormW!
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Because of stalling and organizing that is taking place.....where would a much stronger storm go if you don't know....JUST SAYIN

This is the Steering layer at 200-700mb....currently which would be for a Major Cane....this could be the steering for a Larger Cane but, not a Major as steering layers will change as the Trough keeps Coming thur...



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Quoting MiamiHurricanes09:
The NHC does.


Hmm thats a first, wasn't sure if Navy or NHC is better.
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it will be interesting to see if Alex's pressure has dropped any with this new burst of convection over the center ... maybe a good CDO forming???
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Quoting JDSmith:


Thanks, Taz.



welcome
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What is it that you guys are seeing at the pro site?
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TROPICAL STORM ALEX LOCAL STATEMENT
NATIONAL WEATHER SERVICE BROWNSVILLE TX
1112 AM CDT MON JUN 28 2010

...ALEX INTENSIFYING AND HEADED TOWARD SOUTH TEXAS...

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND
RECOMMENDED ACTIONS FOR PEOPLE AND MARINE INTERESTS IN THE LOWER
RIO GRANDE VALLEY...KING RANCH...AND THE LOWER TEXAS COASTAL
WATERS.

.WATCHES/WARNINGS...
A HURRICANE WATCH IS IN EFFECT FOR THE FOLLOWING LOCATIONS...
KENEDY...COASTAL WILLACY AND COASTAL CAMERON...AND THE ADJACENT
COASTAL WATERS INCLUDING THE LAGUNA MADRE.

A HURRICANE WIND WATCH IS IN EFFECT FOR THE FOLLOWING LOCATIONS...
INLAND WILLACY AND INLAND CAMERON COUNTIES.

A TROPICAL STORM WIND WATCH IS IN EFFECT FOR THE FOLLOWING
LOCATION...HIDALGO COUNTY.

.STORM INFORMATION...
AT 10 AM CDT...THE CENTER OF TROPICAL STORM ALEX WAS LOCATED NEAR
LATITUDE 20.3N...LONGITUDE 91.7W. THIS WAS ABOUT 530 MILES
SOUTHEAST OF BROWNSVILLE AND SOUTH PADRE ISLAND TX. THE STORM WAS
MOVING NORTH NORTHWEST AT 7 MPH.

.SITUATION OVERVIEW...
TROPICAL STORM ALEX IS EXPECTED TO STEADILY INTENSIFY AS IT MOVES
AWAY FROM THE YUCATAN PENINSULA AND INTO THE SOUTHWEST GULF OF
MEXICO THIS AFTERNOON AND TONIGHT. BY LATE TUESDAY...ALEX SHOULD
REACH HURRICANE STRENGTH AND MAY REACH CATEGORY TWO STRENGTH AS IT
EDGES TOWARD THE COAST OF NORTHEAST MEXICO OR DEEP SOUTH TEXAS.

ALEX IS EXPECTED TO BECOME RELATIVELY LARGE IN SIZE...QUITE A BIT
MORE THAN DOLLY IN 2008. THUS...IMPACTS FROM WIND...RAIN...AND
STORM SURGE MAY IMPACT A FAIRLY LARGE AREA EVEN IF THE CENTER OF
THE STORM MAKES LANDFALL DOZENS OF MILES NORTH OR SOUTH OF THE
MOUTH OF THE RIO GRANDE
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Quoting MrstormX:
Whos got a fix on the best coordinates...
The NHC does.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
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Quoting StormW:


Go the the pro site, click the Satellite imagery section...go to color water vapor, and do the long animation...that will give you a good idea since you can't see the weathertap view.
Ok, definitely buying that now.
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Quoting Tazmanian:




94L is X 94L


Thanks, Taz.
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Whos got a fix on the best coordinates...
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Slowly becomming better organized
Member Since: October 28, 2006 Posts: 57 Comments: 29887
Anyways, congrats and a pad on the back to all of the regulars

super or regular pad, bud sir?
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Quoting StormW:


Thanks, but no pat on the back necessary...just doin' the best I can with what I'm looking at, and what I've learned from years of studying.
Na you deserve a pat on the back. You worked during the weekend which not many mets do, well unless they work at like a news station or something like that.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Sail1 (append 420) ULL off Bahamas. w/o Alex, this would get more bits... inconclusive ASCAT miss gives it a wind shift at the surface, but NHC has it down to mid-level only, not to the surface. Getting into 30knts shear soon, but it is a nice swirl...
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Here's a link to a 17hr loop of satellite/radar combination which shows the last three changes in forecast track by NHC. It shows just the center line of the cone so you can see the changes in track forecast. We're not supposed to concentrate on the center line I know, but this shows the changes more easily.

SFWMD Satellite/Radar Loop

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Quoting Baybuddy:
Thanks pat and miami. Hey TAZ!



hi . Baybuddy


if you guys want to joine me on facebook its David Thomas
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does anyone have a link to alex sat immagery for the past hours? thanks in advance
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The feed is the best to have open on a TAb in the cue.

aviationweather.gov
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Quoting duajones78413:
So if it stalls in the deeper water, will it still churn up cooler water?
A cyclone of this strength is likely to upwell very little water if not none.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting JDSmith:
94L/ULL:




850 MB Vorticity:




What do y'all think about that? It lacks convective activity, but if it keeps up, it may be able to build some out of the environment it's in.

The circulation is massive.

For kicks, look at the 200MB vort. It's crazy.






Upper Div


Lower Con


How often do these things transition into the 850mb range?




94L is X 94L
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Quoting Jeff9641:


I agree Jeff this whole track could shift if Alex continues to sit and build to the NNE. Alex is wanting to build under the convection to it's NE. If that occurs it will be in a location to get scooped up by the next trough and move NNE toward the C gulf coast. I stalled storms are hard to predict ie TS FAY in 2008.


Like I said earlier, the longer Alex stalls the better chance it has to go WEST. The trough is only going to be there for so long. This is why the models have begun to trend back to the left. If there is going to be more of a northerly component to the movement than west, its going to be in the next 24 hours as the trough swings across the central and eastern US, then as the 1024 high builds in Alex will be forced back WNW or even west. Alex will not even get close to 90 W.
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I've probably walked more of a distance here in my house than the distance Alex has moved in the past 6 hours.. and considering I've been right here on the computer chair...
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Thanks pat and miami. Hey TAZ!
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Quoting StormW:
Levi, you still here?


I are.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
A quick review of buoy data across the GOM shows that pressures maybe 1 or 2 mb higher today than yesterday. The only thing I can read into that is that the ridge is still holding its' ground. I have found the the NOAA-ADDS website seems to have the sharpest satellite pictures at the moment. Looks like Alex is regressing after some vertical development earlier in the afternoon.

Link
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94L/ULL:




850 MB Vorticity:




What do y'all think about that? It lacks convective activity, but if it keeps up, it may be able to build some out of the environment it's in.

The circulation is massive.

For kicks, look at the 200MB vort. It's crazy.






Upper Div


Lower Con


How often do these things transition into the 850mb range?
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Quoting Baybuddy:
How long has alex been stalled?
He emerged yesterday evening and has moved very little.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
So if it stalls in the deeper water, will it still churn up cooler water?
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Quoting HoustonTxGal:


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.


Idk this thin doesn't even have a CDO just yet, but I can definitely see how it looks like an eye!
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NHC them self's have stated any intensity forecast is very uncertain. If Alex goes more North, Category 2-3 is likely, if Alex goes the same path, Category 1 or a low end Category 2 is likely.
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Quoting Patrap:
Afternoon TAzaroo.

Alex still driving the Class nutzo.



hi pat
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Quoting Levi32:


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.
Plus stalling will lead to intensification, well not in the area it is now but if it does stall further north yes.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Afternoon Tazaroo.

Alex still driving the Class nutzo.
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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.