TROPICAL DEPRESSION NINETEEN DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL192010
1100 PM EDT WED OCT 20 2010

SATELLITE IMAGES INDICATE THAT THE CENTER OF THE LOW PRESSURE SYSTEM
OVER THE NORTHWESTERN CARIBBEAN SEA IS NOW LOCATED CLOSER TO THE
MAIN MASS OF DEEP CONVECTION THAN IT WAS EARLIER TODAY.  THE OVERALL
CLOUD PATTERN HAS BECOME SLIGHTLY BETTER ORGANIZED...RESULTING IN
DVORAK DATA T-NUMBERS OF 1.5 FROM BOTH TAFB AND SAB.  DEEP
CONVECTION HAS ALSO BEEN ON THE INCREASE DURING THE LAST SEVERAL
HOURS.  BASED PRIMARILY ON THE FACT THAT THE CIRCULATION CENTER IS
NOW MORE INVOLVED WITH THE DEEP CONVECTION...THE SYSTEM IS BEING
DESIGNATED AS A TROPICAL CYCLONE AT THIS TIME.  RECONNAISSANCE DATA
FROM EARLIER TODAY INDICATED AN INTENSITY NEAR 30 KT...AND IT IS
ASSUMED THAT THERE HAS BEEN LITTLE CHANGE IN STRENGTH SINCE THE
TIME OF THOSE OBSERVATIONS.

SINCE THE CENTER APPEARS TO HAVE REFORMED DURING THE LAST FEW
HOURS...THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 100/02.  THE
CYCLONE IS CURRENTLY LOCATED IN A COL REGION AT THE BASE OF A
MID-LEVEL TROUGH OVER THE EASTERN UNITED STATES AND TO THE WEST OF
A SUBTROPICAL RIDGE OVER THE CENTRAL ATLANTIC.  GLOBAL MODELS BUILD
THE SUBTROPICAL RIDGE TO NORTH OF THE TROPICAL CYCLONE AS THE TROUGH
LIFTS OUT OF THE REGION AFTER ABOUT 36 HOURS.  THE MAJORITY OF THE
TRACK GUIDANCE SHOWS A SLOW LOOPING MOTION TOWARD THE SOUTHEAST...
SOUTH...AND THEN SOUTHWEST DURING THE NEXT DAY OR TWO.  AFTER
THAT...A WESTWARD TO WEST-NORTHWESTWARD MOTION WITH SOME INCREASE
IN FORWARD SPEED IS INDICATED DUE TO THE BUILDING RIDGE TO THE
NORTH.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO...
EXCEPT FOR THE HWRF WHICH TAKES THE CYCLONE TOWARD THE YUCATAN
CHANNEL AND THEN TURNS IT NORTHEASTWARD TOWARD FLORIDA.  ALTHOUGH
THE LATTER SOLUTION CANNOT BE COMPLETELY DISCOUNTED...THE
OFFICIAL NHC TRACK FORECAST LEANS TOWARDS A CONSENSUS OF THE OTHER
DYNAMICAL MODELS.

UW-CIMSS ANALYSES INDICATE THAT THE DEPRESSION IS BEING AFFECTED BY
MODERATE SOUTHWESTERLY SHEAR ASSOCIATED WITH THE EASTERN UNITED
STATES TROUGH.  AS THIS FEATURE LIFTS OUT OF THE AREA IN ABOUT 36
HOURS...THE SHIPS MODEL OUTPUT INDICATES A REDUCTION IN THE SHEAR IN
A DAY OR TWO WHICH SHOULD FAVOR GRADUAL INTENSIFICATION OVER THE
WARM WATERS OF THE NORTHWESTERN CARIBBEAN.  LATER IN THE FORECAST
PERIOD...THE INTENSITY FORECAST IS COMPLICATED BY UNCERTAINTIES IN
THE FUTURE INTERACTION WITH LAND.  THE OFFICIAL FORECAST IS IN
REASONABLE AGREEMENT WITH THE INTENSITY MODEL CONSENSUS AND THE
STATISTICAL-DYNAMICAL LGEM GUIDANCE.
About these ads