000 WTNT44 KNHC 121447 TCDAT4 TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092007 1100 AM EDT WED SEP 12 2007 RADAR...SATELLITE...AND BUOY OBSERVATIONS INDICATE THAT THE AREA OF LOW PRESSURE IN THE WESTERN GULF OF MEXICO HAS BECOME BETTER ORGANIZED THIS MORNING. NWS RADAR IMAGERY FROM CORPUS CHRISTI AND HOUSTON SHOW A LOOSE BANDING STRUCTURE IN THE SOUTHEAST AND NORTHWEST QUADRANTS...WHILE THE NORTHWEST WINDS FROM NOAA BUOY 42019 INDICATE THAT THE SYSTEM LIKELY HAS A WELL-DEFINED SURFACE CIRCULATION. CONSEQUENTLY... TROPICAL CYCLONE ADVISORIES ARE BEING INITIATED. WITH 38 KT WINDS REPORTED FROM SHIP V7DI7...THE SYSTEM MIGHT ALREADY BE A TROPICAL STORM...BUT FOR THE MOMENT THOSE WINDS ARE JUDGED AS UNREPRESENTATIVE OF THE CYCLONE SCALE. THE INITIAL INTENSITY IS ESTIMATED TO BE 30 KT FOR NOW...WITH A BETTER READ ON THE INTENSITY EXPECTED WHEN A RECONNAISSANCE AIRCRAFT ARRIVES IN THE AREA WITHIN THE NEXT HOUR OR SO. THE DEPRESSION IS IN A LIGHT-SHEAR ENVIRONMENT WITH ANTICYCLONIC FLOW ALOFT...AND SOME INTENSIFICATION IS THEREFORE ANTICIPATED. THE PRIMARY INHIBITING FACTOR FOR DEVELOPMENT WILL BE THE SHORT PERIOD OF TIME THE SYSTEM WILL HAVE OVER WATER. THE OFFICIAL FORECAST REPRESENTS A BLEND OF THE SHIPS AND GFDL GUIDANCE. THE INITIAL MOTION ESTIMATE IS 350/5. THE DEPRESSION IS ROUNDING THE WESTERN PERIPHERY OF MID-LEVEL HIGH PRESSURE THAT EXTENDS FROM THE ATLANTIC ACROSS FLORIDA INTO THE CENTRAL GULF OF MEXICO. A MID-LATITUDE SHORT-WAVE TROUGH OVER THE SOUTHWESTERN UNITED STATES IS FORECAST TO DIG SOUTHEASTWARD OVER THE NEXT COUPLE OF DAYS AND INDUCE A GRADUAL TURN OF THE CYCLONE TOWARD THE NORTHEAST. MODEL GUIDANCE IS IN PRETTY GOOD AGREEMENT ON THIS SCENARIO IN THE SHORT TERM...ALTHOUGH WHAT HAPPENS WITH THE REMNANTS OF THE CYCLONE AFTER DAY 2 IS LESS CLEAR. MOST OF THE GUIDANCE MODELS DETACH THE SYSTEM FROM THE WESTERLIES AND LINGER IT ALONG THE GULF COAST...WHERE IT COULD REPRESENT A PROLONGED RAINFALL THREAT. FORECAST POSITIONS AND MAX WINDS INITIAL 12/1500Z 28.1N 95.2W 30 KT 12HR VT 13/0000Z 28.6N 95.3W 40 KT 24HR VT 13/1200Z 29.8N 95.0W 40 KT...INLAND 36HR VT 14/0000Z 31.4N 94.0W 30 KT...INLAND 48HR VT 14/1200Z 32.7N 91.5W 20 KT...REMNANT LOW 72HR VT 15/1200Z...DISSIPATED $$ FORECASTER FRANKLIN