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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2907. Daveg
Models sure are grouping up more north of the borders. **Sorry if this is a double post**

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Quoting Patrap:
GOM 84 Hour Wave Forecast (using MIKE21)

Note the MENU on the left


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?
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Quoting rareaire:
nite all well see whats up in the morning. Nite Flood and Conch.



...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
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2904. Patrap
Floater - RGB Color Infrared Loop
Member Since: July 3, 2005 Posts: 414 Comments: 125418
2903. Levi32
Quoting leo305:


there's barely any outflow on the west side, but yes the shallow cooler waters aren't fueling it enough, but still if it had better outflow it would be doing better.


It's not perfect yet but far better than this morning...and the west side will be remedied tomorrow.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
2902. jpsb
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.
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.
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2901. Gorty
Edit to my comment. I had WSW, but I meant, WNW for the movement.
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Quoting Patrap:
Another convective Burst near the Sw Corner of the Circulation Mean center begins

Floater - Rainbow Color Infrared Loop

IM-presssive


Kind of late there, sir. *points to previous comments*
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2899. Daveg
Sure are starting to cluster up again more north of the border.

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2898. leo305
Quoting Levi32:


He's breathing far better than this morning when that upper trough was jabbing into his NW quad. It's the cold water I think that will halt this attempt at intensification if it does indeed halt.


there's barely any outflow on the west side, but yes the shallow cooler waters aren't fueling it enough, but still if it had better outflow it would be doing better.
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Quoting KoritheMan:


I doubt that would significantly alter intensity



Scientists spot massive methane rainstorm over Titan
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nite all well see whats up in the morning. Nite Flood and Conch.
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Quoting Gorty:
It looks like Alex is going WSW now.

And maybe the cloud tops are warming because he could be trying to form an eye?


He's brought up cooler waters and that won't help with development. He needs to move or he won't be able to really intensify. Cold water = bad for tropical systems.
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2894. scott39
Quoting Levi32:


He's breathing far better than this morning when that upper trough was jabbing into his NW quad. It's the cold water I think that will halt this attempt at intensification if it does indeed halt.
Levi, Whats your thoughts on the high getting far enough S to turn Alex more W?
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OKay folks, out for the night...play nice, huh?
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2892. Patrap
Another convective Burst near the Se Corner of the Circulation Mean center begins

Floater - Rainbow Color Infrared Loop

IM-presssive
Member Since: July 3, 2005 Posts: 414 Comments: 125418
Quoting atmoaggie:
I was out of school completely for 4 years...it'll come back.

I don't know....I'm 24 now and took Trig/cal 1 in highschool, retaking trig this summer, cal 1 in the fall, and I can't remember a single thing from highschool haha
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Quoting Levi32:


He's breathing far better than this morning when that upper trough was jabbing into his NW quad. It's the cold water I think that will halt this attempt at intensification if it does indeed halt.


Never thought GOM and cold would be used in the same sentence this season. Then again it is still June.
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2889. Gorty
It looks like Alex is going WSW now.

And maybe the cloud tops are warming because he could be trying to form an eye?
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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.


Man, it sucks to be you...but then the last time I took Calc was 32 years ago...adn the last time I used it was 25 years ago

I fear that it will not come back to me easily
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2887. Gorty
Quoting leo305:
Alex isn't breathing well.. may not strengthen much


What are you talking about? Are you looking at Alex? lol.

Alex has amazing outer bands, which means it is breathing very well.
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Quoting Levi32:


I thought it was :)

Managed to make it out with an A....probably won't be so lucky in the next level up.


Math is not about luck. You sound modest. Keep up the hard work, and we should be hearing more about your A's. Calculus is tough but easier once at it for a while.
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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 was out of school completely for 4 years...it'll come back.

Really leaving now...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
2884. Levi32
Quoting leo305:
Alex isn't breathing well.. may not strengthen much


He's breathing far better than this morning when that upper trough was jabbing into his NW quad. It's the cold water I think that will halt this attempt at intensification if it does indeed halt.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
2883. Levi32
Quoting jpsb:
Calculus with no teacher? I feel sorry for you. Curious integral or differential calculus (cat1 or cal 2). FYI never take advanced math without a (good) teacher.


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.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
2882. nolajet
Quoting louisianaweatherguy:


lol know whatcha mean LOL... he still is headed more north than west still, right?



Not quite sure how reliable this is when watching motion, but I MIMIC makes it look as if it is still going pretty much north. If that isn't reliable, hopefully someone will tell me and then I'll know for the future. :)

http://cimss.ssec.wisc.edu/tropic/real-time/marti/2010_01L/webManager/basicGifDisplay.html

Sorry, I don't know the bbcode to make a link here.

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Quoting StormJunkie:
Hey Jerry, good to see ya as always.

Ok, really out now.


My great pleasure to see you!
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2880. leo305
Alex isn't breathing well.. may not strengthen much
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2879. ssmate
Thanks everyone. Have a safe night.

ssmate
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2878. Levi32
Quoting atmoaggie:
Wow. Latest image really shows that core either collapsing or wrapping. Either way losing the cold in the cloud tops.



Could be the still shallow shelf waters catching up to it again....if it's going to explosively deepen I still think it needs to get north of 22N to do it.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
2877. jpsb
Quoting Levi32:


Average I think.....Calculus is kicking my butt, but that's probably more because I'm doing a summer distance course in half the time of a regular fall/winter semester, and this is the last distance course I'll ever do....Calc with just a textbook and no teacher sucks.
Calculus with no teacher? I feel sorry for you. Curious integral or differential calculus (cat1 or cal 2). FYI never take advanced math without a (good) teacher.
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2876. guygee
goodnight atmo, good night all.
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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
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting scott39:
Its hard to tell which way Alex is moving by eyesight when he doesnt have an eye to look back at you!


lol know whatcha mean LOL... he still is headed more north than west still, right?

Looking at the Water Vapor Loop I'm not sure if I see anything thats gonna drasticialy turn it to the NW/WNW anytime soon...

If anybody can help me out on that let me know.. is there something I'm not seeing on the water vapor loop? I see a high but its way far to the north...
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Quoting Levi32:


Average I think.....Calculus is kicking my butt, but that's probably more because I'm doing a summer distance course in half the time of a regular fall/winter semester, and this is the last distance course I'll ever do....Calc with just a textbook and no teacher sucks.


I'm at least on campus for that class...I knew better than to try it on line. But like you said, short summer term makes everything so much tougher.

Ok, for real; I'm out now!
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Quoting Levi32:


Average I think.....Calculus is kicking my butt, but that's probably more because I'm doing a summer distance course in half the time of a regular fall/winter semester, and this is the last distance course I'll ever do....Calc with just a textbook and no teacher sucks.
Use youtube videos, I found them to be very helpful even in Calc 3. I prefer PatrickJMT's videos.
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2871. JLPR2
Quoting rareaire:


look at the african coast, nuff said!


*Looks at satellite imagery*

*raises eyebrow*
Go on... XD
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I think we'll have more progress once the northern bands of Alex start moving through 95W.

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2869. jpsb
Open book! WTH, sheesh
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Hey Jerry, good to see ya as always.

Ok, really out now.
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2867. scott39
Its hard to tell which way Alex is moving by eyesight when he doesnt have an eye to look back at you!
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2866. Patrap
GOM 84 Hour Wave Forecast (using MIKE21)

Note the MENU on the left
Member Since: July 3, 2005 Posts: 414 Comments: 125418
2865. Levi32
Quoting GlobalWarming:
are you good in math, levi?


Average I think.....Calculus is kicking my butt, but that's probably more because I'm doing a summer distance course in half the time of a regular fall/winter semester, and this is the last distance course I'll ever do....Calc with just a textbook and no teacher sucks.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
2864. guygee
Quoting StormJunkie:
That's not right Levi...That's the professor I need...Open book!
Goodnight and good luck SJ! I had to take that class twice, undergrad and grad...
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Quoting StormJunkie:
That's not right Levi...That's the professor I need...Open book!

Ok, night all. See everyone, and Alex tomorrow.

And atmo, don't trust that xtrap model...It's real unreliable from what I hear...lmao
Ooohhh. thanks, SJ.
G'Nite.

And, I'm out too. G'Nite, all.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting GlobalWarming:


Why is the Xtrap model taking it towards Houma, La? Gulp, :(.
No thats where i live. LOL
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Quoting GlobalWarming:
Ooooohhhhhh, thank you, I never knew that, lol.



Hmmm...despite the fact that you've been told like thousands of times? I've told you several hundred myself
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well, that dry air doesn't seem to be having much of an impact. Water's too warm and Alex is moving off the shelf and will get over last year's loop current. Shear's dying, Alex is moistening up the environment in front of it. As I understand it, the more powerful Alex gets now, the more it'll get influenced by that trough - no? Well, having that trough go over us a couple days ago I can tell you it's PLENTY powerful! We got the full monty here - lightning, hail, tornados, the whole gmish - and THIS is in a part of the world where humidity might make it to 10% AFTER a rainstorm. If Alex is going to get influenced by THAT, it's going to NOLA for sure!
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Quoting pipelines:


I'm curious as to why the intensity forecast is so low, landfall isn't forecasted for almost 48 hours yet cat one status is supposed to be maintained the entire time. I don't see any real inhibiting factors in the next 2 days for Alex.
Besides size. but, where does Alex end and the upper trough effects begin?

The early cycle intensity models initialized too low, IMO.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
2858. Levi32
If the G-IV data is in the GFS it looks to have made it trend south.

GFS Parallel 54 hours.

Member Since: November 24, 2005 Posts: 628 Comments: 26452

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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.