Alex continues to slowly organize

By: Dr. Jeff Masters , 7:17 PM GMT on June 28, 2010

Share this Blog
2
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 957 - 907

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65Blog Index


Data from NOAA Buoy 42005, about 120 NMi WNW of Alex CoC.

current p tendency -2.3 mb/h
Link
Member Since: Posts: Comments:
Some of you are focusing on the higher level clouds too much. They can be deceiving. Look at the low level ones.
Member Since: Posts: Comments:
anyone have the google maps image of the hunters, are they near the center
Member Since: Posts: Comments:
Quoting Dakster:


Uhhh.. With that weakness how can it be possible to think Alex is going to make landfall in Mexico?


Because it's temporary.
Member Since: Posts: Comments:
Guys, please take a look at the visible before before assuming that the center is relocating. Trust me, I fell for it earlier today as well.
Member Since: Posts: Comments:
Quoting StormW:


Correct.

jinkies...pardon me while I get the sangria and put on some Jerry Jeff Walker to deal with this...
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Don't the models account for this/ move north then the ridge builds back in pushing Alex west
Member Since: Posts: Comments:
950. JLPR2
Quoting oddspeed:
Look at that face:


haha! XD
scary LOL
Member Since: Posts: Comments:
Quoting DestinDome:
It looked like a movement to the NE in the last frames or wobble wobble?
Wobble
Member Since: Posts: Comments:
could someone send the link so i can open the hurricane hunters in google earth
Member Since: Posts: Comments:
Quoting Dakster:


Uhhh.. With that weakness how can it be possible to think Alex is going to make landfall in Mexico?



be come it wont
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Wait for recon.


I am, I'm not saying there's a new center, and I know visibles can trick the eyes lol. I was just observing.
Member Since: Posts: Comments:
Quoting xcool:
WOW NE


So it moved NE, and is moving NNE/NE
Member Since: Posts: Comments:
Quoting Stormchaser2007:


Wait for recon.
i keep seeing it too
Member Since: Posts: Comments:
Quoting reedzone:
Guys, maybe it's just me but I see a new center at 91.6W, 20.9N ... Does anybody see this, it's the last frame of the visible. A center fix to the NE?



Um no...and it's not going to form a new center 5 miles north of the current one.
Member Since: Posts: Comments:
941. xcool
oddspeed HAHA
Member Since: Posts: Comments:
Quoting kmanislander:
Alex is about to put on a show in intensification. Deep convection blowing up everywhere now it seems. I would not be surprised to see this make hurricane status well before the forecast point for that to happen.

The weakness in the steering has now extended East over LA which would encourage a path due N from where it is now. If that ridge does not build back quickly the track forecast may have to be adjusted Northward once again particularly if Alex drops a few mbs tonight.
If Alex strengthens and moves north faster than expected, it might split the ridge altogether and go ashore on the northern Gulf coast.
Member Since: Posts: Comments:
whats new with the HH
Member Since: Posts: Comments:
Oddspeed--LOL
Member Since: Posts: Comments:
Going out for some exercise since it looks like an interesting evening LOL

Back later
Member Since: August 19, 2006 Posts: 0 Comments: 15948
Quoting StormW:


Now that's a weakness!


Uhhh.. With that weakness how can it be possible to think Alex is going to make landfall in Mexico?
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Ok that's fine.



chat with me on my blog if you want too no more on why by not the main blog
Member Since: Posts: Comments:
Thanks storm for explaining that to me so the track will change now?
Member Since: Posts: Comments:
It looked like a movement to the NE in the last frames or wobble wobble?
Member Since: Posts: Comments:
Quoting Tazmanian:




50? yet me look you mean 26



i dont no i this like new stoplight now that all on that
Ok that's fine.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:


Hanna, take a look out west, north of the four corners, that's a very small ridge...look to the east of ALEX...Strong ridge...look north of, and in between Alex....what do you see?

um, a great big area for Alex to travel further north???
Member Since: September 5, 2007 Posts: 0 Comments: 3488
Quoting reedzone:
Guys, maybe it's just me but I see a new center at 91.6W, 20.9N ... Does anybody see this, it's the last frame of the visible. A center fix to the NE?



Wait for recon.
Member Since: Posts: Comments:
Look at that face:
Member Since: Posts: Comments:
Quoting reedzone:
Guys, maybe it's just me but I see a new center at 91.6W, 20.9N ... Does anybody see this, it's the last frame of the visible. A center fix to the NE?

Theres no new center there is only one center and thats the one we are tracking .
Member Since: Posts: Comments:
Quoting StormW:


Now that's a weakness!

what does that mean exactly, as far as the path?
Member Since: Posts: Comments:
690.

We are watching a real monster coming alive. This cannot end up good in any way - wind, surge, oil - you name it.
Member Since: Posts: Comments:
Quoting kmanislander:


Nothing but a huge weakness which = due N


Still think the door is wide wide open for a Texas landfall. Alex just needs to get his rear in gear and start moving before he misses the weakness completely.
Member Since: Posts: Comments:
Hey Storm what is going on with Alex?
Member Since: Posts: Comments:
Quoting reedzone:
Guys, maybe it's just me but I see a new center at 91.6W, 20.9N ... Does anybody see this, it's the last frame of the visible. A center fix to the NE?

A system with this intensity is highly unlikely to develop a new center.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
There is no new center, it is the same center and has been all along
Member Since: Posts: Comments:
Member Since: Posts: Comments:
THERE IS ONLY ONE CENTER PEOPLE! ... the storm is doing exactly what it is supposed to, it isn't splitting centers or moving east! IT IS HEADING NW...
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
Ok. Anyways why did you take like 50 pictures of stoplights?




50? yet me look you mean 26



i dont no i this like new stoplight now that all on that
Member Since: Posts: Comments:
Quoting StormW:


I saw that...thanks...Levi and I were discussing water vapor loop imagery earlier on that situation.


Bro he is coming very far North then the NHC is showing......been saying that for some time.
Member Since: Posts: Comments:
914. xcool
WOW NE
Member Since: Posts: Comments:
Quoting kmanislander:
Alex is about to put on a show in intensification. Deep convection blowing up everywhere now it seems. I would not be surprised to see this make hurricane status well before the forecast point for that to happen.

The weakness in the steering has now extended East over LA which would encourage a path due N from where it is now. If that ridge does not build back quickly the track forecast may have to be adjusted Northward once again particularly if Alex drops a few mbs tonight.
Wow Kman great update there. Good to see you on the blog.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting StormW:


Hanna, take a look out west, north of the four corners, that's a very small ridge...look to the east of ALEX...Strong ridge...look north of, and in between Alex....what do you see?


Nothing but a huge weakness which = due N
Member Since: August 19, 2006 Posts: 0 Comments: 15948
I dont understand what does that mean?
Member Since: Posts: Comments:
909. xcool
reedzone new center
Member Since: Posts: Comments:
Quoting Patrap:
ALEX aviationweather.gov/adds/satellite

Thanks Pat! Beautiful imagery!
Member Since: Posts: Comments:
Noticed the weakness in the steering layer as well. This thing definitely has room to slide a little further north than forecast. The GFS, CMC and GFDL definitely accounted for this in previous runs. However, the abrubt shift of these models to the south earlier today left me scratching my head. Still think they were on to something.
Member Since: Posts: Comments:

Viewing: 957 - 907

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 | 46 | 47 | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | 63 | 64 | 65Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Overcast
47 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron