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: 2957 - 2907

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

2957. xcool
from TX TO SW LA I KNOW KEEP SAY I KNOW KEEP SAY IF WRONG KABOOM ME.
Member Since: Posts: Comments:
Quoting Floodman:



...sleep that knits the ravel'd sleeve of care...

Or maybe:

...to sleep, perchance to dream...but what dreams may come in that sleep of death...

Wait, that last one is a bit morbid


"Thus conscience does make cowards of us all"
Member Since: Posts: Comments:
2955. Levi32
Quoting homelesswanderer:


Yeah we also have a Texas test you had to pass. They had the writing on that one. Was not popular. Lol. I guess we had it easier. Some advantages to being old.


Hm ya I guess so lol....I also hear that Met/Atmospheric Science classes back then had a lot more hands-on application of concepts, and less math proofs and technical data without as much application, like it is now.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting jsit:
letcha know about corpus in a few days.... Im thinking brownsville. so Im staying put. (but I have my car fulla gas- my water stocked up- my flashlights and etc ready to go.)


the way I figure it, you and your fam should be far and gone from Corpus in a few days - IMO. I thought originally that dry air might be a problem for Alex but it doesn't appear to be the case. There's a big burst of convection near the COC - which is what happened when Alex first started to get organized earlier near Belize. Anyhoo, this time 'round there isn't a landmass to inhibit formation but instead a HUGE incentive for the thing to get big, bad, and UGLY!
Member Since: Posts: Comments:
Quoting btwntx08:

just barely wow


BT Al's been gunning for you from the beginning. Lol.
Member Since: Posts: Comments:
2951. xcool
TexasHurricane models have no clue ,
Member Since: Posts: Comments:
xcool, you still thinking LA? That map looks to be very contradicting with the models because when i look at that i think the storm would want to shoot the gap between the two high pressures...i guess we will wait and see what plays out
Member Since: Posts: Comments:
Quoting Levi32:


Oh, I would have liked it without writing lol.


Yeah we also have a Texas test you had to pass. They had the writing on that one. Was not popular. Lol. I guess we had it easier. Some advantages to being old.
Member Since: Posts: Comments:
Where can I find the new models?
Member Since: Posts: Comments:
Quoting xcool:
all i can say is wow on models.


what??
Member Since: July 2, 2009 Posts: 0 Comments: 2811
2946. xcool
TexasHurricane confusing....y
Member Since: Posts: Comments:
2945. xcool
all i can say is wow on models.
Member Since: Posts: Comments:
Quoting xcool:



update


By this it looks like it could go north,but the models are showing west...so confusing....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
2942. bassis
this is one great view:
http://rsd.gsfc.nasa.gov/goes/

check out the east USA
Member Since: Posts: Comments:
2941. jsit
letcha know about corpus in a few days.... Im thinking brownsville. so Im staying put. (but I have my car fulla gas- my water stocked up- my flashlights and etc ready to go.)
Member Since: Posts: Comments:
2940. Levi32
Quoting tristanh72:


Used to be 1600 max, before they added writing.


Oh, I would have liked it without writing lol.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting Levi32:


Isn't it still? Each section of my SAT was 800 total possible points with 2400 total for the entire test.


Oh ok. They must have added a section. We had verbal and math. 800 each. I knew something was diferent tho.
Member Since: Posts: Comments:
Quoting Levi32:


Isn't it still? Each section of my SAT was 800 total possible points with 2400 total for the entire test.


Used to be 1600 max, before they added writing.
Member Since: Posts: Comments:
Quoting xcool:



update


So, it's going to go west as predicted by the NHC? Or follow through the weakness? The only feature that stands out to me is what's over Colorado.
Member Since: Posts: Comments:
2936. Levi32
0z CMC is still south of the border.

Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting Patrap:


winds are surface winds


Ok. Thanks Pat. :)
Member Since: Posts: Comments:
2934. scott39
Quoting xcool:



update
That looks like 2 high pressures. One coming from the E and One coming from the W to possibly Squeeze Alex due N! The high from the N looks way to far N to inluence alex back W? IMO
Member Since: Posts: Comments:
Quoting Daveg:
Models sure are grouping up more north of the borders. **Sorry if this is a double post**



Looks like a BAD time to be in Corpus Cristi. This thing is 2/3rds the size of the Gulf and is going over waters warmer than this time in 2005, PLUS the loop current eddy from last year, which is PLENTY warm, smaller but warm AND DEEP. There's NO shear and so far the dry air doesn't seem like an impediment to Alex's growth.
Member Since: Posts: Comments:
2932. Levi32
Quoting scott39:
Levi, Whats your thoughts on the high getting far enough S to turn Alex more W?


Oh it will, eventually, that's why it's going into Mexico or Texas. The question is how far north Alex will be able to get before the turn, and how sharp that turn is. Right now it could still be either Mexico or south Texas.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
2931. Levi32
Quoting homelesswanderer:


I'm sure you'll do well in it. Math was never my strong suit. Didn't take the SAT until I was 34 and I passed the math part barely. But still if I could remember enough for that 15 years out of HS you'll be fine. :) I did get a 780 on the verbal. Way back when it was out of 800. Back in the stone age. Lol.


Isn't it still? Each section of my SAT was 800 total possible points with 2400 total for the entire test.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Quoting TexasHurricane:


Hi Homeless.....anything new?


Hey Tex. Not really. Still look south of the boarder.
Member Since: Posts: Comments:
2929. xcool



update
Member Since: Posts: Comments:
2928. scott39
Levi, look at post 2894
Member Since: Posts: Comments:
Quoting Levi32:


I'm retaking Calc I....so derivatives and integrals. I have to retake it because they don't count what I took in high school as college credit, and I did that 2 years ago as a Junior, so I've forgotten most of it now....hadn't touched a single advanced math problem in those 2 years.


I'm sure you'll do well in it. Math was never my strong suit. Didn't take the SAT until I was 34 and I passed the math part barely. But still if I could remember enough for that 15 years out of HS you'll be fine. :) I did get a 780 on the verbal. Way back when it was out of 800. Back in the stone age. Lol.
Member Since: Posts: Comments:
2926. guygee
Quoting Floodman:

...to sleep, perchance to dream...but what dreams may come in that sleep of death...

Wait, that last one is a bit morbid
Hey Flood...I know that is Shakespeare, never too morbid..., but it also reminds me of that Hunter-Garcia song, "Althea" - Hunter stole it from the bard. I'm goin' now, have a good one.
Member Since: Posts: Comments:
Goodnight, all.
Member Since: Posts: Comments:
2924. Levi32
Quoting Gorty:
@levi

I think Alex is trying to form an eye. Look closely at that satalite picture...


It may be wrapping, which can lead to an eye, but there is none forming yet, and there is evidence this burst of convection may be dying down...it needs to be replenished and sustained if it's going to punch up to a hurricane and form an eye.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
Think I heard a pin drop

Hey Pat, any idea what the wind/wave forecast is based on. Any particular model?
Member Since: Posts: Comments:
Quoting homelesswanderer:


Wow. Thanks for the link. Not sure I'm reading them right looked like high winds and wave up by TX/LA. I think. are the winds at water level on that model?


Hi Homeless.....anything new?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
**cue computer generated voice**

We are all hu-man be-ings...

okay, I will take my inconsequential posts and exit, stage left
Member Since: Posts: Comments:
2919. Gorty
@levi

I think Alex is trying to form an eye. Look closely at that satalite picture...
Member Since: Posts: Comments:
Quoting atmoaggie:
Wow. Latest image really shows that core either collapsing or wrapping. Either way losing the cold in the cloud tops.



From here: http://rammb.cira.colostate.edu/ramsdis/online/rmtc.asp#Sector%205



Dinurmal min?
Member Since: Posts: Comments:
2917. jpsb
Quoting ElConando:
Adios. See how this shapes up tomorrow.
Me too, see yall in the AM. go west Alex go west!
Member Since: Posts: Comments:
2916. scott39
Quoting Patrap:
Yup..

To infinity and beyond we go...as well.

Whats your thoughts on the high forecasted to block Alex back W?
Member Since: Posts: Comments:
2915. Gorty
The cooler waters plus isnt Alex in D-MIN right now? That could also be why the cloud tops are warming.
Member Since: Posts: Comments:
2914. Torgen
I'm convinced some of you are either multiple persons using the same handle, or a perl script running on a college meteorology server somewhere.

Don't you ever sleep? ;)
Member Since: Posts: Comments:
2913. Levi32
This site isn't working for the moment but I managed to get this one image through from 04:15z....the cloud tops are warming but still pretty cold, and you can see it wrapping around the center. We'll have to see if this burst dies down or gets reinforced by new cells.

Member Since: November 24, 2005 Posts: 628 Comments: 26455
Tomorrow guys! good nite! :)
Member Since: July 9, 2008 Posts: 8 Comments: 334
2911. Patrap
Quoting homelesswanderer:


Wow. Thanks for the link. Not sure I'm reading them right looked like high winds and wave up by TX/LA. I think. are the winds at water level on that model?


winds are surface winds
Member Since: July 3, 2005 Posts: 414 Comments: 125594
2910. Patrap
Yup..

To infinity and beyond we go...as well.

Member Since: July 3, 2005 Posts: 414 Comments: 125594
Adios. See how this shapes up tomorrow.
Member Since: Posts: Comments:
2908. Levi32
Quoting jpsb:
Ok, well you will probably get thru it ok since it's a retake. Math is the foundation of all science, please give it your all and next advanced math class make sure you get a good teacher. My education in math and physics gave me a big advantage in .... computer programming. lol, good luck, you will make a great met one of these day.


Well thanks....I certainly look forward to having a live math teacher. Being home-schooled/self-taught has disadvantages in such courses.
Member Since: November 24, 2005 Posts: 628 Comments: 26455
2907. Daveg
Models sure are grouping up more north of the borders. **Sorry if this is a double post**

Member Since: Posts: Comments:

Viewing: 2957 - 2907

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 JeffMasters

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