[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 050235
TCDAT1
TROPICAL STORM IDA DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112009
1000 PM EST WED NOV 04 2009

SINCE THE LAST AIRCRAFT PENETRATION OF THE STORM...THE CLOUD PATTERN
OF IDA HAS REMAINED WELL ORGANIZED WITH A PROMINENT COLD-TOPPED CDO
AND SOME BANDING FEATURES OVER THE NORTHERN SEMICIRCLE.  A RECENT
SSMIS OVERPASS REVEALED A BANDING-TYPE EYE IN MICROWAVE IMAGERY.
DVORAK INTENSITY ESTIMATES WERE 45 KT FROM TAFB AND SAB BUT THESE
ARE CONSTRAINED BY THE RULES OF THE TECHNIQUE.  BASED ON THE
EARLIER AIRCRAFT DATA AND CURRENT ORGANIZATION OF THE SYSTEM...THE
CURRENT INTENSITY IS ESTIMATED TO BE 55 KT.  THE UPPER-LEVEL
OUTFLOW IS WELL DEFINED AND THERE REMAINS A SHORT PERIOD PRIOR TO
LANDFALL FOR IDA TO STRENGTHEN A LITTLE MORE.  RAPID WEAKENING IS
LIKELY WHEN THE CYCLONE INTERACTS WITH THE MOUNTAINOUS TERRAIN OF
CENTRAL AMERICA.  IDA IS PROJECTED TO MOVE BACK OVER THE WATERS OF
THE CARIBBEAN SEA IN ABOUT 3 DAYS.  THE INTENSITY FORECAST IN THE
LATTER PART OF THE PERIOD IS HIGHLY UNCERTAIN...HOWEVER...BECAUSE
IT IS NOT CLEAR WHETHER THE TROPICAL CYCLONE WILL SURVIVE ITS
TRANSIT OVER LAND.

THE ESTIMATED INITIAL MOTION IS NOW NORTHWESTWARD OR 315/6.  IDA IS
BEING STEERED BY THE FLOW BETWEEN A WEAK RIDGE OVER THE
NORTH-CENTRAL CARIBBEAN SEA AND A WEAK TROUGH OVER THE SOUTHWESTERN
GULF OF MEXICO.  AS THE RIDGE BUILDS NORTHWARD OVER THE NEXT FEW
DAYS...THE TROPICAL CYCLONE SHOULD GRADUALLY TURN TOWARD THE
NORTH-NORTHWEST.  MOST OF THE TRACK MODELS ARE IN FAIR AGREEMENT ON
A GENERAL NORTHWARD OR NORTH-NORTHWESTWARD MOTION...BUT VARY
SIGNIFICANTLY IN FORWARD SPEED.  THE OFFICIAL FORECAST IS A BLEND
OF THE MODEL CONSENSUS AND THE PREVIOUS NHC TRACK.

THE BIGGEST IMPACT OF THIS SLOW-MOVING SYSTEM WILL LIKELY BE
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES CAUSED BY EXTREMELY
HEAVY RAINS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      05/0300Z 12.5N  83.1W    55 KT
 12HR VT     05/1200Z 12.9N  83.6W    60 KT...INLAND
 24HR VT     06/0000Z 13.5N  84.0W    40 KT...INLAND
 36HR VT     06/1200Z 14.3N  84.4W    30 KT...INLAND
 48HR VT     07/0000Z 15.1N  84.6W    25 KT...INLAND
 72HR VT     08/0000Z 17.0N  85.0W    35 KT...OVER WATER
 96HR VT     09/0000Z 19.5N  85.5W    40 KT
120HR VT     10/0000Z 21.5N  86.5W    45 KT

$$
FORECASTER PASCH/ROBERTS



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