000 WTNT43 KNHC 140852 TCDAT3 TROPICAL STORM INGRID DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082007 500 AM EDT FRI SEP 14 2007 LATEST CONVENTIONAL SATELLITE IMAGERY AND A 0452 UTC AMSU-B MICROWAVE PASS SUGGEST THAT THE CENTER OF CIRCULATION LIES BENEATH THE LARGE BURST OF DEEP CONVECTION. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB ARE 3.0/45 KT AND 2.5/35 KT RESPECTIVELY. SINCE A NOAA HURRICANE HUNTER PLANE CONDUCTING ANOTHER RESEARCH MISSION IS CURRENTLY EN ROUTE TO INVESTIGATE THE CYCLONE...I WILL HOLD OFF INCREASING THE INITIAL INTENSITY UNTIL A MORE ACCURATE MEASUREMENT CAN BE TAKEN. SO...INGRID WILL BE MAINTAINED AS A 35 KT TROPICAL STORM FOR THIS ADVISORY. THE PRIMARY MECHANISM THAT WILL AFFECT THE FUTURE INTENSITY OF INGRID WILL BE THE AMOUNT OF SHEAR THE CYCLONE ENCOUNTERS OVER THE NEXT 5 DAYS. ABOUT 10-15 KNOTS OF WEST-SOUTHWESTERLY SHEAR IS CURRENTLY AFFECTING INGRID...WHICH SHOULD PERSIST FOR THE NEXT 24-36 HOURS. THEREAFTER...THE SHEAR IS EXPECTED TO STRENGTHEN HAMPERING INGRID FROM INTENSIFYING FURTHER. THE OFFICIAL INTENSITY FORECAST ALLOWS FOR SOME STRENGTHENING IN THE NEAR TERM FOLLOWED BY GRADUAL WEAKENING. THIS FOLLOWS CLOSELY WITH THE PREVIOUS FORECAST AND IS CONSISTENT WITH A BLEND OF THE SHIPS/LGE AND FSSE INTENSITY GUIDANCE. THE INITIAL MOTION IS ESTIMATED AROUND 300/6. INGRID IS IN A WEAK STEERING ENVIRONMENT WITH A WEAK RIDGE POSITIONED TO ITS NORTHEAST AND A MID- TO UPPER-LEVEL LOW LOCATED TO ITS NORTH. MODEL GUIDANCE IS IN OVERALL AGREEMENT THAT THE UPPER LOW WILL CONTINUE TO MOVE SOUTHWESTWARD OVER THE NEXT SEVERAL DAYS AND GRADUALLY WEAKEN. BOTH THE STRENGTH OF THE UPPER-LEVEL LOW AND THAT OF INGRID WILL DETERMINE THE DEGREE OF STEERING THE CYCLONE WILL TAKE TOWARD THE NORTHWEST. SINCE INGRID IS FORECAST TO REMAIN A RELATIVELY WEAK CYCLONE IN A SHEARED ENVIRONMENT...THE OFFICIAL TRACK FORECAST MAINTAINS A WEST-NORTHWEST MOTION THAT IS SLIGHTLY NORTH OF THE PREVIOUS TRACK BUT SOUTH OF THE DYNAMICAL MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 14/0900Z 15.1N 49.2W 35 KT 12HR VT 14/1800Z 15.5N 50.0W 40 KT 24HR VT 15/0600Z 16.1N 51.1W 40 KT 36HR VT 15/1800Z 16.7N 52.3W 40 KT 48HR VT 16/0600Z 17.3N 53.7W 35 KT 72HR VT 17/0600Z 18.5N 56.5W 35 KT 96HR VT 18/0600Z 20.0N 58.5W 30 KT 120HR VT 19/0600Z 21.5N 60.5W 30 KT $$ FORECASTER MAINELLI