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 Levi32:


That one I have and doesn't update for another 30 minutes at least.


sorry i think the links mesed up. this is sometimes earlier Link
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Corrrection on my last post: SE winds
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3155. Levi32
Initial burst collapsed but some new cells are going up.

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3154. Levi32
I guess they use plymouth state website but all the stuff I see people post from that site are things that are not linked to on the main page....probably hidden in a directory somewhere that I don't have the link to.
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Quoting jlp09550:


Doubt there is a eye right now. It's too weak to produce an eye.


It is important to remember that a strong TS can produce an eye-like COC. It doesn't have to achieve hurricane intensity to do so. Based on the 1515 UTC visible satellite imagery that I posted (in my previous post), you can clearly see the formation of a much better defined COC from which to track this system.
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3152. xcool
i;m go back to website brb
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I'm not sure everyone understands that the further north Alex goes, regardless if turns more west down the road, New Orleans will be getting SE winds from alex and from the high the east. This will push that oil deep into the marsh.
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3150. Levi32
Quoting homelesswanderer:


LinkLink


That one I have and doesn't update for another 30 minutes at least.
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3149. xcool
Levi32 .lol
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alex is shown to be at 96.8 and 25.. this means 5 w and 3.4 N. That means to mantain the track it has to go WNW.. yet it continues jogging N and generally mover NNW.. I am fairly certain if it picks up forward speed it will be a Corpus storm.
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3147. Levi32
Quoting scottsvb:


odd I cant pull up 0Z ECMWF.. do you have link?


They pull this on me every night 40 minutes ahead of when I can get it.
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Quoting KoritheMan:
ROFL

Has anyone noticed this hilarious wording
link?
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Quoting Levi32:
What site do you all pay for that allows you to see the Euro this early every night.


LinkLink These sometimes earlier
o they're free
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Quoting CoopNTexas:
0z EURO lands south of Brownsville.


odd I cant pull up 0Z ECMWF.. do you have link?
Member Since: January 22, 2006 Posts: 0 Comments: 1723
3142. Or4590
it dry air affecting alex! no eye!
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3141. xcool
SALAMETGRAD i just about posting it
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UK MET

TROPICAL STORM ALEX ANALYSED POSITION : 20.9N 91.7W

ATCF IDENTIFIER : AL012010

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
00UTC 29.06.2010 20.9N 91.7W MODERATE
12UTC 29.06.2010 22.4N 92.6W MODERATE LITTLE CHANGE
00UTC 30.06.2010 23.8N 94.5W MODERATE LITTLE CHANGE
12UTC 30.06.2010 24.4N 96.2W MODERATE LITTLE CHANGE
00UTC 01.07.2010 25.2N 97.9W MODERATE INTENSIFYING SLIGHTLY
12UTC 01.07.2010 25.8N 100.4W WEAK WEAKENING RAPIDLY
00UTC 02.07.2010 BELOW TROPICAL STORM STRENGTH
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Link

This neat. Link from Pat. Shows surface wind and wave forecast. On the menu to the right click on wind and waves mike 21. Don't kow how accurate but interesting. :)
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Quoting Levi32:


Yes, even strong tropical storms can have eyes.

But....Alex doesn't have one yet.

OK THANKS DUDE
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Quoting btwntx08:
post ecmwf plz thx


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3136. xcool
alexhurricane1991 tell EURO that
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3134. Levi32
What site do you all pay for that allows you to see the Euro this early every night.
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3133. Levi32
Quoting AlexEmmett:

levi can weak cat one have eyes


Yes, even strong tropical storms can have eyes.

But....Alex doesn't have one yet.
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Quoting xcool:
south of Brownsville EURO=
Doesnt that put brownsville in the worst part of the storm.
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3131. Or4590
look like mexico storm to me!
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3130. JLPR2
Well I had a good laugh after searching in the blogs for my old handle, lots of random comments there XD

Alex seems to be taking its time

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3129. Levi32
Quoting homelesswanderer:


So the trough that was over four corners yesterday is not going to have an affect on steering?


No it is and is already helping break down the ridge over the Gulf of Mexico to its east. It's pretty much the tail-end of the main trough over the Great Lakes, but it kind of split off while it was over Arizona. It will be linking back up again with the main trough as it comes across the southern states.
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3127. xcool
south of Brownsville EURO=
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Quoting Daveg:
Yet more models clustering north of the border, with only a couple now south. Only time and many more model runs will tell I suppose.

Of course, the trend north has been more consistent over the last several runs, versus the back and forth bouncing around they did earlier today. If that means anything.



Actually the only models you really need to watch is the GFDL,GFS and ECMWF...rest of models are usually hit or miss...but when they hit.. its when they are the same as the 3 mentioned above. Right now they are all south of 25N @ landfall .. between 23N and 25N. Will it go there? Not 100% but I'll say 80% chance it will. My best bet is 23.2-23.8N give or take 50 miles.
Member Since: January 22, 2006 Posts: 0 Comments: 1723
Did the GFDL drop WAY south all of a sudden?
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3124. Or4590
Euro south of Browsville
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It's been over 24 hrs since Alex emerged back over water and still little change in strength, little forward motion, just sitting out there not doing much of anything exciting. Stalled-out tropical cyclones are so frustrating to watch!! :-/
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0z EURO lands south of Brownsville.
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Quoting Goldenblack:
Re: 3098

Yes, Alex has given us a few of those "false eyes" today. Correct me if I am wrong, but I don't believe we have enough of a CDO yet to verify the formation of an eye. I know that the HH are not going through every second, but I didn't see any vortex message about eye formation either on Google Earth.

Joanie: keep asking those questions. I am a learner here too.

E


I want too..I like to learn all I can about tropical systems, you just never know what they are gonna do until the LAST minute..I have seen and track some that really have made some SURPRISE moves, but with Alex, who knows for sure....:)
Member Since: June 16, 2008 Posts: 0 Comments: 507
Hi everyone,

I just took a moment to analyze the latest "visible" satellite imagery and one can clearly see that the COC of Alex is definitely moving in a NNW motion as of 1:15 am EDT (5:15 UTC).

One can also clearly see that the COC is right in line, if not just slightly W of the next forecast point. The key point to make is that the due N jog/wobble (i.e. temporary motion) has ceased and I suspect that the models will begin to cluster near the TX/MX border area in time.

At this time, it is still too early to make a definitive call as to whether it will make a landfall N or S of the TX/MX. border. That being said, I believe the probabilities are higher that it will come ashore just S of the border area. On the other hand, it is very important to remember that TC forecasting is an inexact science and this is simply the most probable scenario based on my own best educated guess.

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Quoting Levi32:


LOL

levi can weak cat one have eyes
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3118. Levi32
Quoting KoritheMan:
ROFL

Has anyone noticed this hilarious wording from the NHC in their 11:00 PM PDT Tropical Weather Outlook?

000
ABPZ20 KNHC 290534
TWOEP
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1100 PM PDT MON JUN 28 2010

FOR THE EASTERN NORTH PACIFIC...EAST OF 140 DEGREES WEST LONGITUDE..

THE NATIONAL HURRICANE CENTER HAS ISSUED THE LAST ADVISORY ON
BLANCA....WHICH HAS BECOME A REMNANT LOW ABOUT 1045
MILES WEST-SOUTHWEST OF THE SOUTHERN TIP OF BAJA CALIFORNIA.

A LARGE AREA OF SHOWERS AND THUNDERSTORMS LOCATED OVER PORTIONS OF
SOUTHEASTERN MEXICO...GUATEMALA...AND EL SALVADOR...IS ASSOCIATED
WITH THE SOUTHERN CIRCULATION OF ATLANTIC TROPICAL STORM ALEX.
LOCALLY HEAVY RAINS ARE POSSIBLE DURING THE NEXT SEVERAL DAYS AS
ALEX MOVES OVER THE SOUTHWESTERN GULF OF MEXICO. THESE RAINS COULD
CAUSE LIFE-THREATENING FLASH FLOOD AND MUD SLIDES...ESPECIALLY OVER
HIGHER TERRAIN. THERE IS A LOW CHANCE...NEAR 0 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER ROBERTS/STEWART


They obviously meant "Celia", not "Blanca". :P


LOL
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May not be an eye but does look like one
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3116. xcool
make 3 time , Alex have eyes
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Quoting Levi32:
Alex is moving at about the same speed since the last vortex fix (2 hours ago), and his heading is now NNW at 340 degrees since the last fix. New vortex message will be out soon.



So the trough that was over four corners yesterday is not going to have an affect on steering?
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Quoting tristanh72:
Quoting tristanh72:

Yes thats very true :)
Member Since: June 16, 2008 Posts: 0 Comments: 507
Quoting jlp09550:


Doubt there is a eye right now. It's too weak to produce an eye.

a weak cat 1 can have an eye
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Re: 3098

Yes, Alex has given us a few of those "false eyes" today. Correct me if I am wrong, but I don't believe we have enough of a CDO yet to verify the formation of an eye. I know that the HH are not going through every second, but I didn't see any vortex message about eye formation either on Google Earth.

Joanie: keep asking those questions. I am a learner here too.

E
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Quoting Daveg:
Yet more models clustering north of the border, with only a couple now south. Only time and many more model runs will tell I suppose.



WOW! See, we just never know..:)
Member Since: June 16, 2008 Posts: 0 Comments: 507
3110. 7544
alex has a eye whats the blob to the north of alex
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Quoting Joanie38:


Yeah well homeless, when I want to ask something I sometimes I don't...besides..i've never been a wishcaster, northcaster, or any OTHER kind of "caster"....just here learning....I love this kind of stuff..:):)


I've lurked here for a long time, but probably have less than 10 posts, but I feel I can say, don't ever be afraid to post questions on here. The folks who know things always seem to be nice enough to answer serious questions. The folks that don't know things, well, they weren't going to give you a solid answer anyways ;)
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3108. xcool
Joanie38 .hey
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Quoting pilatus:
anyone seen the developing eye on visible?


Doubt there is a eye right now. It's too weak to produce an eye.
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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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