000 WTNT44 KNHC 241458 TCDAT4 TROPICAL STORM DEBBY DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042012 1000 AM CDT SUN JUN 24 2012 IT IS A VERY DIFFICULT AND HIGHLY UNCERTAIN FORECAST THIS MORNING. DEBBY HAS BEEN MOVING VERY SLOWLY TOWARD THE NORTHEAST...040 AT 3 KNOTS...WHILE THE WIND RADII HAVE BEEN EXPANDING IN THE EASTERN SEMICIRCLE. THIS HAS PROMPTED ADDITIONAL TROPICAL STORM WARNINGS AND WATCHES FOR PORTIONS OF THE FLORIDA COAST. DEBBY CONTINUES TO BE SHEARED WITH MOST OF THE THUNDERSTORM ACTIVITY NORTH AND EAST OF THE CENTER. THIS SHEAR IS EXPECTED TO CONTINUE FOR THE NEXT DAY OR SO...ALTHOUGH SOME DECREASE IN THE SHEAR IS POSSIBLE AFTER THAT...PARTICULARLY IF THE ECMWF VERIFIES. THE OFFICIAL FORECAST IS A LITTLE LESS AGGRESSIVE THAN THE PREVIOUS FORECAST...BUT REMAINS ABOVE MOST OF THE EXPLICIT INTENSITY GUIDANCE. THE TRACK FORECAST IS EVEN MORE COMPLEX. THE GFS INSISTS ON A TRACK TOWARD THE NORTHEAST AS DEBBY BECOMES EMBEDDED WITHIN A LARGE MID-LATITUDE TROUGH. HOWEVER...THE ECMWF AND THE HWRF BUILD A RIDGE TO THE NORTH OF DEBBY AND FORECAST A WESTWARD TRACK. GIVEN THE WESTWARD TURN INHERITED FROM THE PREVIOUS FORECAST...AS WELL AS THE HISTORICAL STRONG RECORD OF THE ECMWF...THE NEW OFFICIAL FORECAST MOVES DEBBY INITIALLY A LITTLE BIT TO THE NORTHEAST TO REFLECT CURRENT TRENDS BUT THEN TURNS THE CYCLONE BACK TOWARD THE WEST OR WEST-NORTHWEST IN 24 TO 36 HOURS. A MAJORITY OF THE GFS ENSEMBLE MEMBERS NOW ARE CONSISTENT WITH THE DETERMINISTIC RUN...WHICH WAS NOT THE CASE YESTERDAY...MAKING A STRONGER CASE FOR THE EASTWARD SOLUTION. WE MUST BE READY TO MAKE A CHANGE OF THE FORECAST TRACK AT ANY TIME. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 28.0N 86.2W 50 KT 60 MPH 12H 25/0000Z 28.5N 85.8W 50 KT 60 MPH 24H 25/1200Z 28.5N 85.8W 50 KT 60 MPH 36H 26/0000Z 28.5N 86.2W 55 KT 65 MPH 48H 26/1200Z 28.7N 87.0W 60 KT 70 MPH 72H 27/1200Z 29.0N 88.4W 65 KT 75 MPH 96H 28/1200Z 29.5N 90.5W 45 KT 50 MPH 120H 29/1200Z 30.0N 91.5W 30 KT 35 MPH $$ FORECASTER AVILA