000 WTNT42 KNHC 271435 TCDAT2 TROPICAL STORM GUSTAV DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008 1100 AM EDT WED AUG 27 2008 GUSTAV HAS BEEN SLOW TO DEPART THE SOUTHWEST PENINSULA OF HAITI. HOWEVER RECENT HIGH-RESOLUTION VISIBLE SATELLITE IMAGES AND RADAR OBSERVATIONS FROM GRAN PIEDRA CUBA SUGGEST THAT THE TROPICAL CYCLONE IS GRADUALLY BECOMING BETTER ORGANIZED. THE LAST AERIAL RECONNAISSANCE OBSERVATIONS IN THE STORM DID NOT ACTUALLY SUPPORT AN INTENSITY OF 50 KT...BUT BASED ON THE TREND SEEN IN THE SATELLITE PRESENTATION WE ASSUME THAT GUSTAV IS PROBABLY VERY NEAR THAT INTENSITY BY NOW. CIRRUS MOTIONS INDICATE SOME MODEST NORTHERLY SHEAR OVER THE SYSTEM BUT OTHERWISE THE ENVIRONMENT SEEMS TO BE FAVORABLE FOR STRENGTHENING...ONCE GUSTAV PULLS AWAY FROM HAITI. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE THROUGH DAY 3. GLOBAL MODELS SHOW SOME INCREASE IN SOUTHWESTERLY SHEAR AT DAYS 4 AND 5... SO WE SHOW LITTLE CHANGE IN STRENGTH IN THE LATTER PART OF THE FORECAST PERIOD. NOTWITHSTANDING...THERE IS VERY LITTLE...IF ANY...SKILL IN INTENSITY PREDICTIONS AT THESE EXTENDED RANGES. INDEED...IF ONE LOOKS AT THE LATEST WIND SPEED PROBABILITY PRODUCT INCLUDED IN THIS PACKAGE...IT CAN BE SEEN THAT THERE IS NEARLY AN EQUAL CHANCE THAT GUSTAV WILL BE A CATEGORY 1...CATEGORY 2...OR CATEGORY 3 HURRICANE AT THE END OF THE FORECAST PERIOD. THE CENTER HAS BEEN WOBBLING AS IT INTERACTED WITH THE MOUNTAINOUS LANDMASS OF SOUTHWESTERN HAITI. HOWEVER A SLOW WEST-NORTHWESTWARD MOTION...290/4...APPEARS TO HAVE RESUMED THIS MORNING. A 500 MB HIGH CENTERED NEAR FLORIDA WITH AN ASSOCIATED RIDGE EXTENDING EASTWARD AND WESTWARD IS EXPECTED TO DRIVE THE STORM TOWARD THE WEST OR WEST-NORTHWEST OVER THE NEXT COUPLE OF DAYS. BEGINNING AROUND DAY 3...THE GLOBAL MODELS SHOW SOME WEAKENING OF THE THE RIDGE OVER THE EAST-CENTRAL GULF OF MEXICO. THIS SHOULD CAUSE GUSTAV TO GRADUALLY TURN TOWARD THE NORTHWEST IN 4 TO 5 DAYS. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS NHC TRACK THROUGH 72 HOURS AND IS SHIFTED A LITTLE TO THE RIGHT BY DAY 5. ONE SHOULD NOT READ MUCH INTO SUCH SHIFTS OF THE FORECAST TRACK SINCE THE TYPICAL ERROR OF A 5-DAY PREDICTION IS OVER 300 MILES. FORECAST POSITIONS AND MAX WINDS INITIAL 27/1500Z 18.8N 74.0W 50 KT 12HR VT 28/0000Z 19.0N 74.8W 55 KT 24HR VT 28/1200Z 19.2N 76.0W 60 KT 36HR VT 29/0000Z 19.3N 77.5W 70 KT 48HR VT 29/1200Z 19.9N 79.4W 80 KT 72HR VT 30/1200Z 21.5N 83.0W 100 KT 96HR VT 31/1200Z 24.5N 86.0W 100 KT 120HR VT 01/1200Z 28.5N 88.5W 100 KT $$ FORECASTER PASCH/RHOME