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#151034 (Received by flhurricane at: 10:31 PM 15.Sep.2007) TCDAT3 TROPICAL DEPRESSION INGRID DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082007 1100 PM EDT SAT SEP 15 2007 THE CENTER OF INGRID IS MOSTLY EXPOSED ON NIGHT VISIBLE SATELLITE PICTURES DURING THE PAST FEW HOURS...BUT THERE ARE TWO AREAS OF CONVECTION IN THE CIRCULATION. A BAND OF THUNDERSTORMS IS IN THE WESTERN SEMICIRCLE OF THE DEPRESSION...AND A MUCH LARGER AREA OF THUNDERSTORMS IS TO THE EAST AND SOUTHEAST OF THE CENTER. OVERALL...STRONG WESTERLY SHEAR CONTINUES TO AFFECT INGRID AND CAUSE A DISORGANIZED CLOUD PATTERN. QUIKSCAT SHOWS MAXIMUM WINDS IN THE 25-30 KT RANGE...SO THE INITIAL INTENSITY WILL STAY 30 KT. MOST GLOBAL MODELS ARE SHOWING A RATHER HOSTILE ENVIRONMENT FOR THE NEXT FEW DAYS AND IT SEEMS LIKELY THAT THE SYSTEM WILL CONTINUE TO SLOWLY WEAKEN. THEREAFTER...THE SHEAR MAY LESSEN...BUT THERE PROBABLY WON'T BE MUCH LEFT OF THE SYSTEM TO TAKE ADVANTAGE OF THE IMPROVED ENVIRONMENTAL CONDITIONS. IN FACT...THE GFDL DISSIPATES THE SYSTEM AFTER 48 HOURS AND THE GFS DOES THE SAME BY 96 HOURS. FOR NOW...THE OFFICIAL FORECAST WILL GO WITH THE IDEA OF A WEAK SYSTEM PERSISTING FOR SEVERAL DAYS BEFORE DISSIPATING...BUT THE FORECAST MAY BE A LITTLE OPTIMISTIC ON THE SURVIVAL CHANCES OF INGRID. THE SYSTEM HAS BEEN MOVING TO THE WEST-NORTHWEST THIS EVENING... ESTIMATED AT 285/9. A GRADUAL TURN TO THE NORTHWEST AND A DECREASE IN FORWARD SPEED IS EXPECTED OVER THE NEXT FEW DAYS AS THE LOW- TO MIDDLE-LEVEL RIDGING TO THE NORTH OF INGRID IS SLOWLY ERODED AWAY BY A TROUGH. IN GENERAL...MODEL GUIDANCE HAS SHIFTED WESTWARD THIS EVENING...PERHAPS DUE TO THE MODELS RECOGNIZING THE SHALLOW DEPTH OF THE DEPRESSION. THE OFFICIAL FORECAST IS SHIFTED TO THE WEST FOR THIS ADVISORY BUT IS NOT TOO FAR AWAY FROM THE MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 16/0300Z 16.9N 55.7W 30 KT 12HR VT 16/1200Z 17.4N 57.1W 25 KT 24HR VT 17/0000Z 18.2N 58.6W 25 KT 36HR VT 17/1200Z 19.0N 59.9W 25 KT 48HR VT 18/0000Z 19.8N 60.8W 25 KT 72HR VT 19/0000Z 21.5N 62.0W 25 KT 96HR VT 20/0000Z 23.0N 63.0W 20 KT...DISSIPATING 120HR VT 21/0000Z...DISSIPATED $$ FORECASTER BLAKE |