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 scott39:
Levi- Does Alex look like hes moving faster and also wrapping up better?
Im not levi but i bilieve its moving a little faster and its getting convection back in the center
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Levi- Does Alex look like hes moving faster and also wrapping up better?
Member Since: June 13, 2009 Posts: 0 Comments: 6774
Excellent, I sure hope we can get a better bead on what Sir Alex is gonna do from the new info gathered by the HH's.

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on the visible it looks like he may be moving NNE..
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Quoting Joanie38:
This is what our local mets said today in Lake Charles Tropical weather discussion...

The models have been trending farther northward for the last couple of advisories. This means that we will need to watch what happens closely. Although a direct hit in SWLA is not likely, the closer the storm comes to us, the more effects we will feel.

Stay tuned.

Thoughts anyone??


Possible, not entirely plausible, but they look to be covering their bases...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting will45:
Headed home i think 26000 ft.
There on there way to the storm right now
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Quoting will45:
Headed home i think 26000 ft.



nop not headed home there heading there in too the storm
Member Since: May 21, 2006 Posts: 5091 Comments: 115079
Quoting Dakster:
It is a good thing that Jimmy Buffet cancelled his concert. The high THC content of his concerts would certainly affect a hurricane.

LMAO! the music might make the cyclone turn away
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My bad heading out 145 SE of Houston
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Quoting Patrap:
.."Put on my Flip Flops..

Stepped on a Tar Ball..

Why are all dese tourists covered in Oil".. ?



LMAO Pat...
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Quoting Dakster:


This explains alot.. RD was a great comedian.

Ohh and you can't get hit by a cyclone if you wear the My Little Pony shower curtain as a cape - now where is cycloneoz?? He should have that in his next video.



Muahahahahaha! Now there's an image for you!
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting atmoaggie:
This is bull, too.
Alex doesn't have the time to reach his max potential, even if conditions were nearly perfect. And I don't know whom is correct, but the OHC in the SW gulf isn't terrific by a couple of sources, though your link shows they figure it to be rather good.

Western Gulf OHC way below that of the Caribbean:


But if the storm holds on to its outer bands, local ocean heat near the center may not be a problem. It could potentially draw heat from the Epac, Caribbean, eastern Gulf and open Atlantic simultaneously, but its size in that case would limit rapid intensification.
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HH Flight AF304 is 128mi SSW of New Orleans on the way to Alex's house ...
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Quoting Dakster:
Orca,

I noticed you are leaving out an important hurricane model and wanted to know why?

The JFV model, the one that always brings the storm to South Florida as a Cat5.

Quoting Floodman:


Let me take this one! No threat as long as you have your shower curtain up!


JFV model
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It is a good thing that Jimmy Buffet cancelled his concert. The high THC content of his concerts would certainly affect a hurricane.
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Quoting HoustonTxGal:
Do anyone have a HH status?




yes there haveing a party and for get us
Member Since: May 21, 2006 Posts: 5091 Comments: 115079
Gonna be like a Bret, defies the models and keeps going north
Member Since: July 14, 2008 Posts: 1 Comments: 9630
Quoting HoustonTxGal:
Do anyone have a HH status?


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This is what our local mets said today in Lake Charles Tropical weather discussion...

The models have been trending farther northward for the last couple of advisories. This means that we will need to watch what happens closely. Although a direct hit in SWLA is not likely, the closer the storm comes to us, the more effects we will feel.

Stay tuned.

Thoughts anyone??
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Quoting hydrus:
It truly has the dynamics of a western Pacific typhoon. far out.


So can a WPac typhoon shed its outer convective band layers and undergo rapid core intensification?
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Do anyone have a HH status?
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Quoting atmoaggie:
??? You're in a great mood today....




LOL
Member Since: May 21, 2006 Posts: 5091 Comments: 115079
so what you do not all ways need the nearly perfect or perfec for a cat 4 or 5 re called Celia in the E Pac it be came a cat 5 overe sea temper that where not made for a cat 5
Member Since: May 21, 2006 Posts: 5091 Comments: 115079
Quoting ElConando:
This thing is gonna be a cat 5 you'll see. Oh and I'm not copying Atmo
??? You're in a great mood today....
Member Since: August 16, 2007 Posts: 6 Comments: 12461
All right there Jimmy Buffet. No wasting away in oilville.
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Quoting dsenecal2009:
CIMSS MIMIC last frame @ 21z/4:00pm CDT

Link

The 48 hour loops are a whopping 13MB so I am posting a link to the image.


For non-MB+ loops, try Plymouth State: Link
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For those seeing this new center, there is none. Clearly Alex already has a well defined COC punctuated by inflow feeder bands and an Anticyclone. The IR images are deceiving, the visible shows this outer convection starting to rap around the center but none forming.


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Quoting Floodman:


"I tell ya, I don't get no respect...I could tell my parents hated me. My bath toys were a toaster and a radio."


This explains alot.. RD was a great comedian.

Ohh and you can't get hit by a cyclone if you wear the My Little Pony shower curtain as a cape - now where is cycloneoz?? He should have that in his next video.
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Quoting ElConando:
Levi is there currently a weakness in the N GOM?


Yes. If there wasn't, Alex would not be stalled. Dropsondes are confirming SSE winds in the mid-levels which supports a weakness in the ridge. It's failing to pull Alex north very fast right now, however.
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cctexas, I figure we're all going to get to watch all these theories tested out this year.
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Starting to fire around the center. This could be take off
Member Since: June 13, 2009 Posts: 0 Comments: 6774
COC of Alex is at 20.5N/91.7 W in my opinion and drifting north.
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Quoting RecordSeason:
618:

Because the NHC and other mets are low balling it for as long as possible for political or economic reasons.

real intensity forecast
This is bull, too.
Alex doesn't have the time to reach his max potential, even if conditions were nearly perfect. And I don't know whom is correct, but the OHC in the SW gulf isn't terrific by a couple of sources, though your link shows they figure it to be rather good.

Western Gulf OHC way below that of the Caribbean:
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Levi is there currently a weakness in the N GOM?
Member Since: September 6, 2009 Posts: 2 Comments: 3719
Orca you are excused this time. But I want to see it in your next update. Use small "My Little Pony" icons for the 12 hour tracking points.
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Quoting Floodman:


"I tell ya, I don't get no respect...I could tell my parents hated me. My bath toys were a toaster and a radio."
You are quoting one of my favorites Flood.:)
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Cat5.



The one that hits an outhouse, with a My Little Pony shower curtain?
roflmao!!!!
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Quoting AstroHurricane001:


So kind of like Dolly in 2008.



Quite possibly, if it shoots for Texas instead of Mexico.
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Quoting Levi32:


Nope....look at a visible loop and tell me where the center is.



too me on the Visble it looks like it is off the nhc track this a little
Member Since: May 21, 2006 Posts: 5091 Comments: 115079
.."Put on my Flip Flops..

Stepped on a Tar Ball..

Why are all dese tourists covered in Oil".. ?



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678. gator23 10:07 PM GMT on June 28, 2010
Quoting AustinTXWeather:

no worries man, I try to bring levity to this blog

LOL I'm a woman > must be the Longhorn symbol- did my undergrad and grad there. ;) Anyway, I appreciate the good humor. Thx again
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Quoting drg0dOwnCountry:
602.
Have a look here:

What will oil in the Gulf of Mexico do to a hurricane?
From the time of the ancient Greeks to the days of the wooden ships and iron men, mariners dumped barrels of oil onto raging seas to calm them during critical moments of violent storms (Wyckoff, 1886.) Oil does indeed calm wind-driven waves, thanks to the reduction in surface tension of the water that oil causes. Ripples with a wavelength shorter than 17 mm are affected by surface tension, and these ripples then cause a feedback that reduces the height of larger waves with longer wavelengths (Scott, 1986.) The reduction of surface tension also impacts the flow of air above the water, and reduces the amount of sea spray thrown into the air, both of which could affect the wind speed. Oil also damps waves by forming a thick, viscous film at the top of the water that resists water motion (Scott, 1999.) Oil also helps calm raging seas by switching off of the wind energy input needed by the wave to break. This occurs because the surface film of oil prevents the generation of ripples on the exposed crests of the waves, and this smoother surface makes the wind less able to grab onto the wave and force it to break.

So, what would happen to a hurricane that encounters a large region of oily waters? A 2005 paper by Barenblatt et al. theorize that spray droplets hurled into the air by a hurricane's violent winds form a layer intermediate between air and sea made up of a cloud of droplets that can be viewed as a "third fluid". The large droplets in the air suppress turbulence in this "third fluid", decrease the frictional drag over the ocean surface, and accelerate the winds. According to this theory of turbulence, oil dumped on the surface of the ocean would reduce the formation of wind-whipped spray droplets, potentially calming the winds. The authors propose spraying oil on the surface of the ocean to reduce the winds of a hurricane. However, the turbulence theory championed by Barenblatt et al. has been challenged by other scientists. In a 2005 interview with Newscientist magazine, turbulence expect Julian Hunt at University College London, UK, remarks, "I am very doubtful about this approach." Hunt studies turbulence both theoretically and in the laboratory, and believes that the high wind speeds in a hurricane are not caused by sea spray. In an article he wrote for the Journal of Fluid Dynamics, Hunt suggests that variations in the turbulence between different regions of the hurricane cause sharp jumps in wind speed, which are responsible for the hurricane's strongest winds. link

Huh?
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Quoting AstroHurricane001:
The northeastern portion of Alex looks almost like it's trying to separate from the main core and move northeastward. Florida and the Southeastern states are getting a soaking.



Here's Darby's vortex being absorbed into the Pacific side of Alex:

It truly has the dynamics of a western Pacific typhoon. far out.
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I think Alex is slowly but surely getting its act together, wouldn't surprise me if by 2am we have Hurricane Alex.
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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.