[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 280900
TCDAT1

TROPICAL DEPRESSION OPHELIA DISCUSSION NUMBER  23
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL162011
500 AM AST WED SEP 28 2011

OPHELIA APPEARS TO BE GRADUALLY ORGANIZING. DEEP CONVECTION HAS
INCREASED IN A CURVED BAND OVER THE SOUTHEASTERN PORTION OF THE
CIRCULATION...AND THE LOW-LEVEL CLOUD LINES HAVE GAINED SOME
CURVATURE TO THE NORTH OF THE CENTER.  ALTHOUGH OPHELIA COULD BE
NEARING TROPICAL STORM STRENGTH...THE INITIAL WIND SPEED IS
HELD AT 30 KT...IN AGREEMENT WITH THE LATEST DVORAK CLASSIFICATIONS.

THE TROPICAL CYCLONE HAS BEEN MEANDERING DURING THE PAST COUPLE OF
HOURS...BUT THE LONGER-TERM INITIAL MOTION ESTIMATE IS 305/3.  A
SLOW NORTH-NORTHWESTWARD TRACK IS FORECAST DURING THE NEXT 12 TO 24
HOURS AS OPHELIA REMAINS NEAR THE SOUTHWESTERN PERIPHERY OF A WEAK
SUBTROPICAL RIDGE.  BEYOND THAT TIME...THE CYCLONE IS EXPECTED TO
GAIN SPEED AND GRADUALLY TURN NORTHWARD AND THEN NORTHEASTWARD AS
IT BECOMES EMBEDDED IN STRONGER FLOW BETWEEN THE STRENGTHENING
SUBTROPICAL HIGH AND A LARGE TROUGH MOVING ACROSS THE EASTERN
UNITED STATES. THIS SYNOPTIC PATTERN SHOULD MOVE OPHELIA AWAY FROM
THE NORTHERN LEEWARD ISLANDS TODAY AND NEAR OR TO THE EAST OF
BERMUDA THIS WEEKEND.  THE OFFICIAL FORECAST IS A TOUCH TO THE
LEFT OF THE PREVIOUS ONE...BUT REMAINS ON THE EASTERN SIDE OF THE
GUIDANCE ENVELOPE IN GOOD AGREEMENT WITH THE GFS AND ECMWF MODELS.

ALTHOUGH THE ATMOSPHERIC ENVIRONMENT IS NOT IDEAL FOR
STRENGTHENING...IT SHOULD ALLOW OPHELIA TO INTENSIFY GRADUALLY. THE
OFFICIAL FORECAST FOLLOWS THE MULTI-MODEL AND HFIP CONSENSUS AIDS...
BRINGING THE CYCLONE TO HURRICANE STRENGTH IN A FEW DAYS.  WEAKENING
IS EXPECTED BY THE END OF THE FORECAST PERIOD AS OPHELIA CROSSES A
SHARP SEA SURFACE TEMPERATURE GRADIENT AND ENCOUNTERS SOME INCREASE
IN SOUTHWESTERLY SHEAR.

FORECAST POSITIONS AND MAX WINDS

INIT  28/0900Z 18.6N  60.0W   30 KT  35 MPH
 12H  28/1800Z 19.2N  60.1W   40 KT  45 MPH
 24H  29/0600Z 20.4N  60.7W   45 KT  50 MPH
 36H  29/1800Z 21.8N  61.5W   50 KT  60 MPH
 48H  30/0600Z 23.4N  62.2W   55 KT  65 MPH
 72H  01/0600Z 27.7N  62.9W   65 KT  75 MPH
 96H  02/0600Z 34.0N  61.0W   75 KT  85 MPH
120H  03/0600Z 43.5N  55.5W   65 KT  75 MPH

$$
FORECASTER CANGIALOSI


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