000 WTNT44 KNHC 260849 TCDAT4 TROPICAL STORM NADINE DISCUSSION NUMBER 55 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142012 500 AM AST WED SEP 26 2012 RECENT SATELLITE IMAGES SHOW THAT A SMALL BURST OF DEEP CONVECTION HAS FORMED IN THE NORTHEASTERN QUADRANT OF THE STORM...ALTHOUGH THE BANDING HAS BECOME LESS WELL-DEFINED. THE CURRENT WIND SPEED IS KEPT AT 40 KT...WHICH AGREES WELL WITH EARLIER OSCAT DATA. PERHAPS THIS NEW BURST IS A SIGN THAT NADINE IS ENTERING A MORE FAVORABLE ENVIRONMENT FOR STRENGTHENING AS IT MOVES OVER WARMER SSTS AND THE SHEAR STAYS MODEST. HOWEVER...THE STORM WILL LIKELY BE FIGHTING SOME DRY STABLE AIR AS SUGGESTED BY A NEARBY STRATIFORM CLOUD DECK. MOST OF THE GUIDANCE SHOWS SOME STRENGTHENING OVER THE NEXT COUPLE OF DAYS...AND SO DOES THE OFFICIAL FORECAST. AT LONG RANGE...THE SHEAR IS FORECAST TO INCREASE ALONG WITH A DECREASE IN SSTS...SO THE OFFICIAL FORECAST WILL REDUCE THE WINDS SOMEWHAT AFTER DAY 3. NADINE CONTINUES MOVING TO THE SOUTH-SOUTHWEST AT ABOUT 4 KT. GLOBAL GUIDANCE IS COMING INTO BETTER AGREEMENT ON THE STORM GRADUALLY TURNING FROM A SOUTH-SOUTHWESTWARD TO A NORTHWESTWARD HEADING OVER THE NEXT FEW DAYS AS IT MOVES AROUND A RIDGE BUILDING OVER THE NORTHEASTERN ATLANTIC OCEAN. HOWEVER...IMPORTANT SPEED DIFFERENCES BECOME VERY CLEAR...WITH THE GFS MODEL AND GFS ENSEMBLE MEAN NOT MOVING NADINE AS FAR SOUTH AS SOME OF THE GUIDANCE IN THE SHORT TERM. THIS SOLUTION TRANSLATES INTO NADINE BEING FAR ENOUGH TO THE NORTH BY DAY 4 TO AVOID BEING CAUGHT BY YET ANOTHER RIDGE...AND FINALLY LOSING TROPICAL CHARACTERISTICS OVER COLD WATERS BY DAY 5. OTHER MODELS...SUCH AS THE UKMET AND ECMWF...SHOW THE STORM BECOMING TRAPPED UNDER A RIDGE...AGAIN...WITH LITTLE MOTION BY 120H. THE GFS-BASED GUIDANCE SEEM OPTIMISTIC GIVEN THE PAST PERFORMANCE OF NADINE...BUT OVERALL THE GUIDANCE SUITE IS MOVING THE STORM A LOT FASTER THAN PREVIOUS CYCLES. THE NHC FORECAST HAS BEEN SPED UP FROM THE PREVIOUS ONE...BUT IS SLOWER THAN THE MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 30.9N 30.5W 40 KT 45 MPH 12H 26/1800Z 30.2N 30.8W 40 KT 45 MPH 24H 27/0600Z 29.2N 31.5W 45 KT 50 MPH 36H 27/1800Z 28.6N 32.8W 50 KT 60 MPH 48H 28/0600Z 28.8N 34.0W 50 KT 60 MPH 72H 29/0600Z 30.8N 35.7W 50 KT 60 MPH 96H 30/0600Z 33.5N 36.5W 45 KT 50 MPH 120H 01/0600Z 35.5N 37.0W 45 KT 50 MPH $$ FORECASTER BLAKE