Tropical Storm Don close to landfall; 91L tracks west
Tropical Storm Don continues to make its way west-northwest toward the Texas coast this evening. Don has increased steadily in pressure over the past 18 to 24 hours. Wind speed remained 45 knots in the 5pm EDT advisory. The strongest thunderstorm activity continues to be south of the center, southeast of Brownsville, Texas, but the strongest winds are to the north according to Hurricane Hunter data. A mesoscale vortex developed on the southern end this afternoon with high radar reflectivity. Radar estimated rainfall rates are as much as 5 inches per hour to the south, and around 2 inches on the north side of the storm, but these are likely an overestimate, although rainfall rate is definitely higher on the southern end of this storm. It began raining in Brownsville, Texas in the 2pm CDT hour, and so far the airport has received 0.3 inches of rain. The heaviest thunderstorms still look to be to Brownsville's southeast.
Figure 1. Radar reflectivity from Brownsville, Texas at 5pm CDT.
Forecast for Tropical Storm Don
A Hurricane Hunter is currently in the storm, and center fixes suggest Don will make landfall south of Baffin Bay, Texas, in the next couple of hours. Tropical storm-force winds, should there be any, will most likely be seen in a swath from Baffin Bay to Corpus Christi. Once Don moves inland it is expected to dissipate quickly, and without having produced enough meaningful rainfall to impact any drought conditions. The Hydrometeorological Prediction Center isn't predicting any rainfall that would exceed flash flood guidance, and no flood watches or warnings are in effect.
NHC Invest 91L
Moderate thunderstorm activity continues in Invest 91L this afternoon, and the Hurricane Center estimates that the axis of the wave is located near 42W. Estimates from satellites show that 91L has a moderate circulation at all levels, and the Advanced Scatterometer resolved a surface circulation early this morning.
Figure 2. Advanced Scatterometer pass over 91L at 7am EDT this morning. The wind barbs show a low-level circulation had formed near the most intense thunderstorms—a good sign of potential development.
Some of the reliable models—GFS, UKMET, and CMC—are developing 91L into at least a weak tropical cyclone. The ECMWF continues to show no development, but a more interesting solution, one that takes the wave on a southerly track. The GFDL does not develop Invest 91L, but the HWRF forecasts category 1 hurricane strength by August 1st. The track for 91L is likely a turn to the northwest when it reaches the Caribbean and a curve to the northeast around the Bahamas. The models that are developing the system do not suggest this is a U.S. landfall threat, although it's pretty early in the game to predict that, and I imagine the track will fluctuate over the next few days. Today the Hurricane Center gives the wave a 30% chance of development (now 50% in the 8pm EDT outlook) over the next 48 hours, and I'm around 40-50% over its lifetime.
I'll have a post tomorrow afternoon on the aftermath of Don as well as NHC Invest 91L.
Angela
Reader Comments
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looks like Sunday afternoon.
wait it takes it over puerto rico and north west into the East coast?? interesting..
TS BUSTED FORECAST ALIBI
I can give you some uneducated guesses. I mostly studied hops and hemp in college lol.
Teddy do you think 91L will recurve?
Me too, lol. Trying to understand convergence and divergence as it relates to storms and how to recognize that in satellite imagery.
As the day progresses, I expect that to happen slowly. Could be a TD as soon as tomorrow.
Here is one of the best tutorial blogs I have ever seen on here..
quasigeostropic's WunderBlog
CONVERGENCE and DIVERGENCE, ain't that what happens when you drive your car under the INFLUENCE?
No one goes to TO on purpose.
The current Texas drought is a real bear! Actually, it's the fifth year of drought out of the last seven years. From what I've read this morning, the dry air from the upper high plus the extremely dry lower levels basically evaporated Don out of existence!
Thank you Orca
Seriously though there are some folks on here that seem to be pretty sharp, and they don't seem to mind answering questions.
;-)
Yeah what's up Dude? I remember that prof. lol
I like it. I think have a pretty good handle on the track of this one.
Guess i need to get the plywood... clearly headed right for us.
Neapolitan
Based on satellite imagery, water vapor loops, shear forecasts, the latest model runs, and my own experience with tracking tropical weather, I believe that 91L will most likely follow one or more of the following historical tracks. Unless it doesn't
well, that about covers it....lol
Invest91
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)
Dynamic Models (More sophisticated models)
Very simply stated is that Convergence (Moving Towards) is winds converging on an area of low pressure at the surface and Divergence (Moving Away) is winds diverging at the upper levels away from the low pressure area. A perfect cyclone has surface winds spiraling counterclockwise (Converging) into a low center and winds spiraling clockwise away from the low center (Diverging). Upper level anti-cylcones (High Pressure) on top of a low center create this perfect flow. However, other forms of divergence can also do the job just not as efficient.
Totally flawed. It misses Upper Michigan.
Should just about cover everyone who 'wants' it to come their way too! But you missed out on a few loop tracks to give them multiple strikes!
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm
----- Current Analysis -----
Date : 30 JUL 2011 Time : 133000 UTC
Lat : 16:42:15 N Lon : 132:29:12 E
CI# /Pressure/ Vmax
6.5 / 927.5mb/127.0kt
Final T# Adj T# Raw T#
6.5 6.5 7.4
Estimated radius of max. wind based on IR : 13 km
Center Temp : -1.5C Cloud Region Temp : -81.2C
Scene Type : EYE
Positioning Method : SPIRAL ANALYSIS
that storm in the W pac is on it way too CAT 5
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