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| #306482 (Received by flhurricane at: 3:49 PM 06.Nov.2009) TCDAT1 TROPICAL DEPRESSION IDA DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL112009 400 PM EST FRI NOV 06 2009 THERE HAS BEEN LITTLE CHANGE WITH IDA DURING THE DAY. SATELLITE IMAGES STILL SHOW A RATHER ASYMMETRIC SYSTEM...WITH MOST OF THE SIGNIFICANT BANDING ACTIVITY TO THE NORTH OF THE CENTER. THE INITIAL INTENSITY WILL BE MAINTAINED AT 30 KT. NOW THAT IDA IS OFFSHORE OVER VERY WARM WATERS...THE SYSTEM HAS A CHANCE TO RE- INTENSIFY. THE BEST OPPORTUNITY FOR THE TROPICAL CYCLONE TO STRENGTHEN IS OVER THE NORTHWESTERN CARIBBEAN SEA...WHERE VERTICAL WIND SHEAR IS FORECAST TO BE MODERATE BY THE GLOBAL MODELS. SHEAR IS LIKELY TO GET RATHER STRONG BY THE TIME THE SYSTEM ENTERS THE CENTRAL GULF OF MEXICO...WITH COOLER WATERS PRESENT...SO WEAKENING WILL BE SHOWN AT THAT TIME. WHILE THE DYNAMICAL GUIDANCE REMAINS HIGHER THAN THE STATISTICAL GUIDANCE...THERE IS A LITTLE LESS SPREAD THAN EARLIER. THE NHC FORECAST SHOWS SLIGHTLY HIGHER WINDS IN THE CARIBBEAN SEA THAN THE PREVIOUS FORECAST DID...AND REDUCES THE INTENSITY AT THE END OF THE FORECAST PERIOD. IDA CONTINUES MOVING TOWARD THE NORTH...360/7. THE DEPRESSION SHOULD MOVE TOWARD THE NORTH-NORTHWEST TOMORROW DUE TO SHORTWAVE RIDGING OVER THE SOUTHEASTERN UNITED STATES. MOST OF THE MODELS ARE IN GOOD AGREEMENT ON THE SYSTEM PASSING OVER OR JUST TO THE EAST OF THE YUCATAN PENINSULA IN A COUPLE OF DAYS. AFTER IDA ENTERS THE GULF OF MEXICO...IT WILL LIKELY TAKE A TRACK TOWARD THE NORTH OR NORTHEAST AS IT BECOMES STEERED BY AN APPROACHING MID-LEVEL TROUGH. THE FORECAST TRACK IS VERY COMPLEX IN THE LONG RANGE WITH SIGNIFICANT UNCERTAINTY IN HOW IDA WILL INTERACT WITH THAT TROUGH. MOST OF THE MODELS ARE SHOWING THE CYCLONE APPROACHING THE NORTHERN GULF COAST...THEN TURNING EASTWARD OR EVEN SOUTH OF EAST. A COMPLICATING FACTOR IS THAT IDA WILL LIKELY BE TRANSITIONING INTO AN EXTRATROPICAL CYCLONE AT THAT TIME...AND THE GLOBAL MODELS HAVE QUITE VARYING SOLUTIONS FOR THIS TRANSITION. THE NHC FORECAST IS ADJUSTED NORTHWARD AT THE LONG RANGE...BUT REMAINS SOUTH OF THE MODEL CONSENSUS. IT IS OF NOTE THAT MOST OF THE GLOBAL MODELS ARE SHOWING A LARGE PRESSURE GRADIENT BETWEEN A HIGH OVER THE SOUTHEASTERN UNITED STATES AND THE TROPICAL CYCLONE. THIS COULD CONTRIBUTE TO A LARGE AREA OF STRONG WINDS OVER THE GULF OF MEXICO NOT DIRECTLY ATTRIBUTABLE TO IDA. FORECAST POSITIONS AND MAX WINDS INITIAL 06/2100Z 15.7N 83.9W 30 KT 12HR VT 07/0600Z 16.7N 84.1W 30 KT 24HR VT 07/1800Z 17.9N 84.7W 35 KT 36HR VT 08/0600Z 19.1N 85.4W 45 KT 48HR VT 08/1800Z 20.6N 86.3W 50 KT 72HR VT 09/1800Z 24.5N 88.0W 45 KT 96HR VT 10/1800Z 27.5N 87.5W 45 KT 120HR VT 11/1800Z 27.5N 85.5W 35 KT...EXTRATROPICAL $$ FORECASTER BLAKE |
