164
WTNT41 KNHC 052038
TCDAT1
TROPICAL STORM IDA DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112009
400 PM EST THU NOV 05 2009
THE SATELLITE PRESENTATION OF IDA HAS GRADUALLY DEGRADED SINCE IT
MADE LANDFALL THIS MORNING...AND THE INITIAL INTENSITY HAS BEEN
LOWERED TO 50 KT.
IDA APPEARS TO HAVE SLOWED AND TURNED MORE NORTH-NORTHWESTWARD WITH
AN INITIAL MOTION ESTIMATE OF 330/3. THE FORECAST REASONING HAS
NOT CHANGED SINCE THIS MORNING AND THE TRACK GUIDANCE REMAINS IN
REASONABLY GOOD AGREEMENT ON A NORTH-NORTHWESTWARD TO NORTHWARD
MOTION DURING THE NEXT COUPLE DAYS. THE GUIDANCE HAS SHIFTED A
LITTLE EASTWARD AND IS A LITTLE FASTER DURING THE FIRST 48 HOURS.
AFTER THAT...THE MODELS SHOW A GENERAL NORTH-NORTHWESTWARD TRACK
INTO THE SOUTHERN GULF OF MEXICO. THERE REMAINS A LARGE SPREAD IN
THE GUIDANCE AFTER 72 HOURS. THE GFDL AND GFS ARE ALONG THE EASTERN
SIDE OF THE GUIDANCE ENVELOPE...WHILE THE NOGAPS IS ALONG THE
WESTERN EDGE. THE OFFICIAL FORECAST IS NEAR THE MIDDLE THE
ENVELOPE...BUT REMAINS A LITTLE SLOWER THAN THE MODEL CONSENSUS.
IDA SHOULD CONTINUE TO WEAKEN AS IT MOVES OVER NORTHEASTERN
NICARAGUA AND EASTERN HONDURAS DURING THE NEXT DAY OR SO. SOME
RESTRENGTHENING IS FORECAST AFTER THE CENTER EMERGES INTO THE
NORTHWEST CARIBBEAN SEA. HOWEVER...CONDITIONS DO NOT APPEAR TO BE
EXTREMELY FAVORABLE FOR INTENSIFICATION AS UPPER-LEVEL SOUTHWESTERLY
WINDS ARE EXPECTED TO PRODUCE MODERATE SHEAR OVER THE SYSTEM.
LATER IN THE PERIOD WESTERLY WINDS BECOME QUITE STRONG AND SHOULD
ARREST FURTHER STRENGTHENING. THERE REMAINS A LARGE DEGREE OF
UNCERTAINTY IN THE LONGER-RANGE FORECAST...SINCE IDA MAY NOT
SURVIVE ITS PASSAGE OVER LAND.
THE BIGGEST IMPACT OF THIS SLOW-MOVING SYSTEM DURING THE NEXT COUPLE
OF DAYS WILL LIKELY BE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES
CAUSED BY EXTREMELY HEAVY RAIN OVER PORTIONS OF NICARAGUA AND
HONDURAS.
FORECAST POSITIONS AND MAX WINDS
INITIAL 05/2100Z 13.3N 83.7W 50 KT
12HR VT 06/0600Z 13.9N 83.9W 40 KT...INLAND
24HR VT 06/1800Z 14.9N 84.1W 30 KT...INLAND
36HR VT 07/0600Z 16.0N 84.3W 35 KT...OVER WATER
48HR VT 07/1800Z 17.1N 84.6W 40 KT
72HR VT 08/1800Z 19.6N 85.7W 45 KT
96HR VT 09/1800Z 22.5N 87.0W 45 KT
120HR VT 10/1800Z 25.0N 87.0W 45 KT
FORECASTER BROWN
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