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Tropical Depression Dorian


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The 18z SHIPS and LGEM bring Dorian up to 53kt and 60 kt, respectively, by 120 hours. If Dorian can survive the next 36 hours, conditions should become quite favorable in the Bahamas.

Most of the guidance from yesterday that maintained Dorian as a TC had an uptick in intensity around day 5-6.

 

Looking at the current state I'm not sure it will survive the next 48 hours.

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The 18z SHIPS and LGEM bring Dorian up to 53kt and 60 kt, respectively, by 120 hours. If Dorian can survive the next 36 hours, conditions should become quite favorable in the Bahamas.

 

Completely disregarding the fact that Dorian's mid and low level circulations are pretty much disjointed from one another and that satellite derived winds show that the system is in serious danger of opening up into a wave at least within the next 12 hours...

 

I'm still not seeing an environment that's "quite favorable" for any type of intensification or even redevelopment before this runs into Hispaniola and possibly even western Cuba.

 

RH vales stay below 50% through 120 hours, shear averages greater than 15 knots throughout the entire period, and the upper level environment provided by the TUTT will probably inhibit any convective organization that Dorian, or it's remnants, try to pull off. 

 

It's time to put this one down. It had a good run since it left Africa and it got lucky a few times, but conditions just aren't right to sustain this type of system. 

 

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Completely disregarding the fact that Dorian's mid and low level circulations are pretty much disjointed from one another and that satellite derived winds show that the system is in serious danger of opening up into a wave at least within the next 12 hours...

 

I'm still not seeing an environment that's "quite favorable" for any type of intensification or even redevelopment before this runs into Hispaniola and possibly even western Cuba.

 

RH vales stay below 50% through 120 hours, shear averages greater than 15 knots throughout the entire period, and the upper level environment provided by the TUTT will probably inhibit any convective organization that Dorian, or it's remnants, try to pull off. 

 

It's time to put this one down. It had a good run since it left Africa and it got lucky a few times, but conditions just aren't right to sustain this type of system. 

 

attachicon.gif20130726.1845.goes13.x.vis1km_high.04LDORIAN.40kts-1010mb-176N-448W.100pc.jpg

I am well aware that Dorian may dissipate over the next few hours, that's why I made note of such in my post.

 

If we take a look at satellite imagery, the TUTT northeast of the Bahamas is very convective this afternoon. Those storms are producing latent heat and warming the troposphere, which should allow the feature to weaken over the coming days. The GFS has been predicting this ever since Dorian formed. In addition, the GFS shows the system retaining its anticyclone as it enters the region. But again, it's all dependent on whether Dorian remains a tropical cyclone. With warm waters and above-average vertical instability, I wouldn't expect dry air to be as detrimental as it has been if Dorian enters the Bahamas.

 

As far as track, it's not set in stone this is moving into Hispaniola or Cuba. The National Hurricane Center official track forecast takes this north of the Greater Antilles, and the ECMWF takes this into southern Florida before being picked up by the trough. If anything, this is more likely than the GFS's southwest dive into the aforementioned locations (unless, again, it dissipates).

 

I mean, I don't what else to say other than we'll see. If Dorian dies out, then yeah, it's probably not of concern.

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FWIW...the 12Z GFS Ensemble tracks.

 

 

If one looks at GEFS means SLP, it would appear AP18, the curver, is the only one that ever becomes a 1008 mb or below system.

 

Judging from GFS operational at 12Z, there won't be enough left in a week for redevelopment to occur in the Gulf.  12Z FIM 9 at 168 still has a suggestion of a wave.  It still has near 30 knot winds on the Northern edge of the open wave until it hits Cuba, but a weak 850 mb wind shift and RH max is past Cuba at 168 hours, so 1/64ths optimistic on at least a lemon in the Gulf next 7-10 days.

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TROPICAL STORM DORIAN DISCUSSION NUMBER 11
NWS NATIONAL HURRICANE CENTER MIAMI FL AL042013
500 PM AST FRI JUL 26 2013

UNDER THE INFLUENCE OF WESTERLY SHEAR AND DRIER AIR...DORIAN HAS
BECOME EVEN LESS ORGANIZED THAN IT WAS EARLIER TODAY. VISIBLE
SATELLITE IMAGES INDICATE THAT THE LOW-LEVEL CENTER HAS BECOME
DISPLACED TO THE WEST OF AN AREA OF WEAKENING DEEP CONVECTION.
ALSO...ANIMATION OF THE IMAGERY SHOWS THAT CIRCULATION IS BARELY
CLOSED AT THIS TIME. USING A BLEND OF DVORAK ESTIMATES FROM SAB
AND TAFB...THE ADVISORY INTENSITY IS REDUCED TO 40 KT. THE
OFFICIAL WIND SPEED FORECAST NOW SHOWS GRADUAL WEAKENING WITH
DISSIPATION BY DAY 5...IN GENERAL AGREEMENT WITH THE GFDL AND HWRF
GUIDANCE. GIVEN THE CURRENT TRENDS...HOWEVER...THE SYSTEM COULD
DEGENERATE INTO AN OPEN WAVE MUCH SOONER THAN THAT.

THE LATEST CENTER FIXES INDICATE THAT DORIAN IS MOVING RAPIDLY
WESTWARD...SLIGHTLY TO THE SOUTH OF THE PREVIOUS TRACK. A STRONG
LOW- TO MID-LEVEL HIGH PRESSURE SYSTEM TO THE NORTH OF DORIAN IS
FORECAST TO BUILD WESTWARD WITH TIME BY THE GLOBAL MODELS. THIS
SHOULD MAINTAIN A GENERALLY WESTWARD MOTION FOR THE NEXT SEVERAL
DAYS. THE OFFICIAL TRACK FORECAST IS SHIFTED A BIT TO THE SOUTH OF
THE PREVIOUS ONE AND IS ABOUT IN THE MIDDLE OF THE GUIDANCE
ENVELOPE. THE LATEST ECMWF MODEL TRACK IS A LITTLE FARTHER NORTH
BUT THAT MODEL DOES NOT INITIALIZE NOR FORECAST A CLOSED SURFACE
CIRCULATION.



FORECAST POSITIONS AND MAX WINDS

INIT 26/2100Z 17.8N 45.8W 40 KT 45 MPH
12H 27/0600Z 18.2N 48.8W 40 KT 45 MPH
24H 27/1800Z 18.6N 52.8W 35 KT 40 MPH
36H 28/0600Z 19.0N 56.7W 35 KT 40 MPH
48H 28/1800Z 19.5N 60.5W 30 KT 35 MPH
72H 29/1800Z 20.0N 67.0W 30 KT 35 MPH
96H 30/1800Z 20.5N 74.0W 25 KT 30 MPH
120H 31/1800Z...DISSIPATED

$
FORECASTER PASCH

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DORIAN APPEARS TO STILL HAVE A VIGOROUS LOW- TO MID-LEVEL
CIRCULATION IN CONVENTIONAL SATELLITE IMAGERY WITH 30 TO 35 KNOTS
MEASURED BY A RECENT ASCAT PASS...BUT IT HAS BEEN DEVOID OF DEEP
CONVECTION FOR SEVERAL HOURS. I WAS TEMPTED TO DECLARE DORIAN A
REMNANT LOW IN THIS ADVISORY...BUT GIVEN THE FACT THAT THE
CIRCULATION IS MOVING OVER WARMER WATERS AND SHEAR IS FORECAST TO
LESSEN...NEW CONVECTION COULD REDEVELOP. THE BEST OPTION IS TO KEEP
THE CYCLONE FOR A COUPLE OF MORE ADVISORY CYCLES AND MONITOR THE
EVOLUTION OF THE CONVECTION. SHIPS AND LGEM RE-INTENSIFY THE
CYCLONE A LITTLE BIT BY THE END OF THE FORECAST PERIOD.
HOWEVER...THE OFFICIAL FORECAST IS BIASED TOWARD THE GFS AND THE
ECMWF GLOBAL MODELS WHICH GRADUALLY WEAKEN DORIAN.

 
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Stick a fork in it!

This is making quite a comeback tonight. The strongest convection yet is refiring directly over the LLC just a mere hours after being written off by the NHC and many others.

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http://www.ssd.noaa.gov/PS/TROP/floaters/04L/imagery/avn-animated.gif

 

Intensity forecasting is a b****, no doubt.

 

Still little to no banding features. Odds are this falls apart again tomorrow given all the dry air that surrounds the circulation. This is more likely a last hurrah rather than a comeback. 

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NHC discussion throws Dorian under the bus and concludes "WILL PROBABLY DIE OUT IN FOUR DAYS ... OR HOPEFULLY SOONER."

 

You'd want to be very confident of that outcome given the sort of publicity that would follow if the thing decides to blow up into a hurricane near Florida.

 

All of which is just a preamble to this friendly reminder to tropical contest entrants to post an August forecast and update.

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This is making quite a comeback tonight. The strongest convection yet is refiring directly over the LLC just a mere hours after being written off by the NHC and many others.

True, I was more referring to sticking a fork in it while it's dying so that it doesn't come back. I'd rather it die within half a day than over 4 days. Even the NHC noted they have similar feelings.

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