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: 2707 - 2657

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

2706. Patrap
ALEX RECON HH Tail #304 Latest Message

From 199° at 55 knots
(From the SSW at ~ 63.2 mph) 19.3°C
(~ 66.7°F) 17.9°C
(~ 64.2°F) 56 knots
(~ 64.4 mph)
Member Since: July 3, 2005 Posts: 428 Comments: 129902
2705. scott39
Quoting CoopNTexas:


where do you live?
Mobile, AL. Im not blasting the guy, it just suprised me.
Member Since: Posts: Comments:
What really sucks is that tomorrow I have to drive from Houston in to Beaumont, Tx for work. I won't get off work till 5:00pm.

If NHC suddenly says "Cat-2... mandatory evac Galveston, Crystal Beach, Clear Lake, etc..." I'm going to have to fight my way back through hours of evacuation traffic and people running to hardware & grocery stores in order to get home.

If Alex is projected by morning to be moving North to between Matagorda Bay and Galveston landfall... I may just have to call in sick. Call it the Alex Flu. It's better than being 75 miles away from home and fighting back through the traffic.

Member Since: Posts: Comments:
so the bahama low could steer it a little more NE than we expected?
Member Since: Posts: Comments:
2702. Hhunter
Member Since: Posts: Comments:
2701. guygee
Quoting atmoaggie:
Thermal IR with a good color scale for TCs.
I do like that one, especially for the labeled color map with good contrasts. I hate when the color maps are not labeled, then they are different for different satellites in a composite, or shift from day to night, or over/under-saturated...
Member Since: Posts: Comments:
Quoting Levi32:


Sounds like a lot of the data got into the 0z GFS which is about to run. I don't know about the other models.
Yes. They will be incorporated into the 00z runs.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2698. scott39
Quoting MiamiHurricanes09:
OH! I thought you were talking about StormW. Well pretty bad met you got there.
Yea glad I cleared that up! LOL He said it all thru the newscast so i doubt he said it wrong.
Member Since: Posts: Comments:
Just curious... why is there no chance the storm goes East... what factors say no and yes to a West movement? Thanks!
Member Since: Posts: Comments:
2696. Hhunter
Member Since: Posts: Comments:
Quoting scott39:
My local Chief Met said Alex was going NNW at 10.


where do you live?
Member Since: Posts: Comments:
2694. Levi32
Quoting truecajun:
drak, levi, r stormW, has the "data" plane put its info into the models yet. has the "updated" models been released? i'm guessing no. if not, when?


Sounds like a lot of the data got into the 0z GFS which is about to run. I don't know about the other models.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
2691. Drakoen
Quoting truecajun:
drak, levi, r stormW, has the "data" plane put its info into the models yet. has the "updated" models been released? i'm guessing no. if not, when?


They data will be in the 00z model runs.
Member Since: October 28, 2006 Posts: 57 Comments: 30832
2690. hydrus
Quoting StormW:


This turn to the west wont occur soon as forecast. At least when I look at some of those water vapor images. It will drift further north.jmo
Member Since: Posts: Comments:
Quoting scott39:
My local Chief Met said Alex was going NNW at 10.
OH! I thought you were talking about StormW. Well pretty bad met you got there.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
New models will come out at 2 a.m. won't they?
Member Since: Posts: Comments:
2687. MZV
Yeah enough for me. Will have to check it from work tomorrow (and not get too distracted)
Member Since: Posts: Comments:
2686. Drakoen
Excellent Water Vapor Loop to monitor the factors that are steering Alex. You can see the 500mb trough through the Ohio River Valley extending down into the Mississippi River Valley. You can also see the ridge over the northwestern United States that will aid in bring Alex westward.
Member Since: October 28, 2006 Posts: 57 Comments: 30832
Thanks. I am a novice at this so I am trying to learn as I go.
Member Since: September 18, 2007 Posts: 0 Comments: 1074
2684. scott39
Quoting StormW:


????????????????
My local Chief Met said Alex was going NNW at 10.
Member Since: Posts: Comments:
Well, I can't take it anymore. Going to turn in for the night since 0430 comes soon. Guess I'll have to wait for the model runs tomorrow after the high alt . data has been digested. Guess we'll get a better pic by then, and see if the A/B high and Colorado high have met and can steer this monster away from a "possible" upper TX coast smackdown.
Member Since: Posts: Comments:
2682. tillou
2627. StormW 3:30 AM GMT on June 29, 2010 Hide this comment.
00Z Steering Layers forecast maps from PSU e-WALL, Valid 12Z 29 JUN 2010,

Indicate landfall north of NHC forecast track...near Brownsville. I'll be looking at things closely in the a.m.

I think one problem is, the mid layer steering set is not taking into account, that Upper to Mid level low off the Bahamas...It's not showing up on mid layer, and weak on deep layer. It's the A/B high that is supposed to nose in, and help turn Alex more NW-WNW, aiding the other small ridge.

I caught on to that to StormW. That ULL by the Bahama's caught my eye last night.

Tomorrow morning and mid day should tell us more. Nite-all.
Member Since: Posts: Comments:
Quoting RecordSeason:
Hate to tell ya'll noobs, but Alex is going to go north and then hook northeast to east/ENE.

It is inevitable.



What makes you think that?
Member Since: Posts: Comments:
Quoting rareaire:

just got the new cougar paws in the mail today !! The only question is where Flood. Ive been conferring with the conch weather center and we feel the ridge does not make it in time to bump him west. I feel like Corpus Christi... But then I could be wrong. Usually am but never stops me from trying. lol


I'm intuiting some serious shock and surprise in the next 12 hours or so...
Member Since: Posts: Comments:
Quoting scott39:
Im saying that the NHC had already posted the 10 saying N and the MET said NNW when the news came on. I know its not major, just thought it was funny i knew it and he didnt!
Um...Ok?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
drak, levi, r stormW, has the "data" plane put its info into the models yet. has the "updated" models been released? i'm guessing no. if not, when?
Member Since: Posts: Comments:
2677. Levi32
Quoting RitaEvac:
NHC track and models have it turning NW right now and its not doing that, I dont know what to believe.


Well believing no one would be a start lol. Figure it out on your own :)
Quoting pipelines:


Hey Levi, question for you. I've been putting a lot of thought into this and can't figure it out, maybe you have some insight. I understand TCHP is measured by how deep the top layer of warm water is (and the temperature of that water). Shallow continental shelf areas can't have high TCHP due to the fact the water column is just too shallow. Is it safe to assume that the top, warmer layer of water goes all the way down to the sea floor in these areas? And if this is true, how can a storm upwell cold water in these hot/shallow areas when there is no cold water at the seafloor? I understand that the storm will use up a lot of that energy in these areas, but I don't understand how it can upwell anything. I remember Dr.Masters mentioned cold water upwelling in very shallow warm areas last season and it perplexed me then.


It probably is....26C isotherm products show the depth of the 26c isotherm being nearly equal to the depth of the ocean on the Yucatan shelf (only around 100-150 feet in the entire area).

But this isn't upwelling of cold water from the depths, because there are no depths. I suppose it can't technically be called upwelling, but if a storm sits there and churns the water for a long time, the shallow ocean layer cools rapidly by evaporation and rainfall falling into it, as well as the lack of sunlight under storm clouds.
Member Since: November 24, 2005 Posts: 635 Comments: 26700
Quoting HoustonTxGal:
Question.. this may have already been asked and answered but.... Is Alex feeding on what is left of Darby?
System A bringing in system B's "spin" does help system A intensify. (If you want to look up vorticity advection, google, umm, "vorticity advection")

Many of our tougher hurricanes did this.
Member Since: Posts: Comments:
2674. leo305
Quoting Tazmanian:
i think thenhc sould do a hurrican watch for LA this too be safe


so people could panic? Yea sure..
Member Since: Posts: Comments:
Quoting winter123:

I believe he meant funny as in "ironic" because it's been predicted to move into mexico for days now. We all know it wouldn't(won't) be funny if(when) a storm hits the oil spill.
no what would be Ironic is if This storm goes to TX/LA like the GFS predicted 5 days ago as a cat 2 maybe a cat 3....

Taco :o)
Member Since: Posts: Comments:
Quoting StormW:


????????????????
I think he meant forecast of Alex and not direction of Alex.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting PcolaDan:


I bet you still lay on the lawn and see bunnies in the clouds, don't you? :)

The beach, yeah. Been doin that a long long time. You can look at the sky and feel the same way you did decades ago.
Member Since: Posts: Comments:
Quoting RCThunder:
Does anyone have a long-term animated graphic showing the satellite of Alex from his inception as an Invest many days ago?

Quoting P451:
84HR Loop of Alex. Water Vapor.


Member Since: Posts: Comments:
2669. scott39
Quoting MiamiHurricanes09:
Way to start the season. Alex is what I would call a "face-palm system". I think StormW would agree.
Im saying that the NHC had already posted the 10 saying N and the MET said NNW when the news came on. I know its not major, just thought it was funny i knew it and he didnt!
Member Since: Posts: Comments:
Quoting ConchHondros:
I just had the best pear I have EVER had, that and my leftover chicken bones indicate that we may need to wait until the am to see what model the tea leaves will favor...


my pears are never good:(
Member Since: Posts: Comments:
I am just enamored with this product...

Member Since: Posts: Comments:
2666. WxLogic
Quoting Drakoen:
Recon heading in for another pass


Waiting on that pass before I head out for the evening... should be an interesting and insightful pass.
Member Since: Posts: Comments:
2664. Drakoen
Member Since: October 28, 2006 Posts: 57 Comments: 30832
Question.. this may have already been asked and answered but.... Is Alex feeding on what is left of Darby?
Member Since: September 18, 2007 Posts: 0 Comments: 1074
2661. guygee
feeder bands...hmmm.
24 hr CIMMS MIMIC-TC for Alex.
Member Since: Posts: Comments:
Quoting StormW:
00Z Steering Layers forecast maps from PSU e-WALL, Valid 12Z 29 JUN 2010,

Indicate landfall north of NHC forecast track...near Brownsville. I'll be looking at things closely in the a.m.

I think one problem is, the mid layer steering set is not taking into account, that Upper to Mid level low off the Bahamas...It's not showing up on mid layer, and weak on deep layer. It's the A/B high that is supposed to nose in, and help turn Alex more NW-WNW, aiding the other small ridge.



You mention the Bahamian Upper Level Low(ULL). I was asking about it earlier this afternoon but had to get back to work, and this blog goes so fast didn't notice if anyone answered. Do you think it will affect the path of Alex, or will it arrive after Alex has made landfall?
Member Since: Posts: Comments:
Quoting Tazmanian:
woud t it be funny if this storm this kep going N and hit LA be come that what am seeng if it dos not turn soon that where it will end up
Quoting fldude99:


Funny?

I believe he meant funny as in "ironic" because it's been predicted to move into mexico for days now. We all know it wouldn't(won't) be funny if(when) a storm hits the oil spill.
Member Since: Posts: Comments:
Quoting Floodman:


Rare, how you doing? Ready to ride?

just got the new cougar paws in the mail today !! The only question is where Flood. Ive been conferring with the conch weather center and we feel the ridge does not make it in time to bump him west. I feel like Corpus Christi... But then I could be wrong. Usually am but never stops me from trying. lol
Member Since: Posts: Comments:
Quoting RCThunder:
Does anyone have a long-term animated graphic showing the satellite of Alex from his inception as an Invest many days ago?
I'll wager that P451 has posted that a couple of times...that's one of his best contributions here. Keep an eye out...
Member Since: Posts: Comments:

Viewing: 2707 - 2657

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
38 °F
Overcast

JeffMasters's Recent Photos

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