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| #306352 (Received by flhurricane at: 3:40 AM 06.Nov.2009) TCDAT1 TROPICAL DEPRESSION IDA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112009 400 AM EST FRI NOV 06 2009 THE DEEP CONVECTION IS NOW LARGELY CONFINED TO THE NORTHERN SEMICIRCLE OF THE CIRCULATION...WITH THE COLDEST TOPS FOUND IN A BAND EXTENDING FROM EASTERN HONDURAS INTO THE NORTHWESTERN CARIBBEAN. THE INITIAL INTENSITY IS HELD AT 30 KT FOR THIS ADVISORY...BUT IDA WILL LIKELY WEAKEN A LITTLE MORE TODAY WHILE THE CENTER REMAINS OVER LAND. IT NOW APPEARS THAT THE CENTER OF IDA WILL REMAIN EAST OF THE HIGHEST TERRAIN IN NICARAGUA AND HONDURAS BEFORE IT EMERGES OVER THE NORTHWEST CARIBBEAN SEA IN ABOUT 24 HOURS. IF IDA SURVIVES UNTIL THEN IT WILL HAVE AN OPPORTUNITY TO RESTRENGTHEN. THERE IS SIGNIFICANT SPREAD IN THE INTENSITY GUIDANCE...WITH THE GFDL AND HWRF MODELS SHOWING IDA REACHING HURRICANE INTENSITY AS IT ENTERS THE GULF OF MEXICO IN 3 TO 4 DAYS. CONVERSELY...THE SHIPS MODEL SHOWS ONLY MODEST STRENGTHENING WHILE THE LGEM SHOWS GRADUAL WEAKENING. THE OFFICIAL FORECAST IS CLOSER TO THE LATTER SCENARIO AS THE UPPER-LEVEL ENVIRONMENT DEPICTED BY THE GLOBAL MODELS DOES NOT APPEAR CONDUCIVE FOR SIGNIFICANT INTENSIFICATION ONCE IDA MOVES INTO THE GULF OF MEXICO. THE INITIAL MOTION CONTINUES TO NUDGE TO THE RIGHT AND IS ESTIMATED TO BE 350/05 AS IDA MOVES AROUND THE WESTERN PERIPHERY OF A WEAK MID-LEVEL RIDGE OVER THE CARIBBEAN SEA. A GENERAL NORTHWARD TO NORTH-NORTHWESTWARD MOTION IS EXPECTED OVER THE NEXT 4 DAYS BRINGING IDA INTO THE YUCATAN CHANNEL AND THEN INTO THE CENTRAL GULF OF MEXICO. BY THE END OF THE FORECAST PERIOD...THE GLOBAL MODELS SHOW IDA INTERACTING WITH A MID- TO UPPER-LEVEL TROUGH THAT DIGS INTO THE NORTHERN GULF OF MEXICO...AND MANY OF THE MODELS RESPOND BY TURNING IDA NORTHEASTWARD. THE OFFICIAL TRACK FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE AND REMAINS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. THE BIGGEST IMPACT OF THIS IDA IN THE NEXT DAY OR SO 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 06/0900Z 14.4N 84.1W 30 KT 12HR VT 06/1800Z 15.2N 84.2W 25 KT...INLAND 24HR VT 07/0600Z 16.4N 84.4W 30 KT...OVER WATER 36HR VT 07/1800Z 17.4N 84.8W 35 KT 48HR VT 08/0600Z 18.7N 85.4W 40 KT 72HR VT 09/0600Z 21.5N 86.7W 45 KT 96HR VT 10/0600Z 24.0N 87.5W 45 KT 120HR VT 11/0600Z 27.0N 86.5W 45 KT $$ FORECASTER CANGIALOSI/BRENNAN |
