000 WTNT43 KNHC 050246 TCDAT3 TROPICAL STORM HANNA DISCUSSION NUMBER 33 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008 1100 PM EDT THU SEP 04 2008 A RECONNAISSANCE AIRCRAFT MEASURED A MINIMUM PRESSURE OF 987 MB AND 60 KNOTS AT FLIGHT LEVEL ON ITS WAY HOME A FEW HOURS AGO. SINCE THEN SATELLITE IMAGES HAVE SHOWN AN INCREASE IN THUNDERSTORM ACTIVITY AND THERE ARE SOME INDICATIONS THAT THE CENTER COULD BE UNDER THE CONVECTION OR VERY NEAR THE SOUTHERN EDGE. THE CLOUD PATTERN ON IR IMAGES INDICATE THAT HANNA LOOKS A LITTLE MORE TROPICAL THAN EARLIER TODAY BUT THE CYCLONE STILL HAS A LARGE WIND FIELD AND LACKS AN INNER CORE. INITIAL INTENSITY IS KEPT AT 55 KNOTS AND ANOTHER PLANE WILL BE IN THE AREA IN A FEW HOURS TO CHECK IF THE WINDS HAVE INCREASED. NONE OF THE GUIDANCE INDICATE SIGNIFICANT STRENGTHENING AND THE OFFICIAL FORECAST BRINGS HANNA TO 60 KNOTS BEFORE IT REACHES THE UNITED STATES COAST. PEOPLE ARE REMINDED THAT THERE IS VERY LITTLE DIFFERENCE BETWEEN A STRONG TROPICAL STORM AND A MINIMAL HURRICANE...ONLY A FIVE KNOT DIFFERENCE. SURFACE DATA AND EXTRAPOLATION FROM EARLIER RECONNAISSANCE FIXES INDICATE THAT HANNA IS MOVING TOWARD THE NORTHWEST OR 320 DEGREES AT 12 KNOTS...STEERED BY STRONG SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC. THE WESTERN EDGE OF THE RIDGE IS FORECAST TO BE ERODED BY AN APPROACHING SHORT WAVE. THIS PATTERN SHOULD FORCE HANNA TO MOVE ON A MORE NORTHERLY TRACK DURING THE NEXT 24 TO 48 HOURS WITH AN INCREASE IN FORWARD SPEED. THEREAFTER...HANNA IS EXPECTED TO BE FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES AND RACE TO THE NORTHEAST WHILE BECOMING EXTRATROPICAL. THIS IS BASICALLY THE SOLUTION PROVIDED BY MOST OF THE GUIDANCE. IF HANNA BECOMES MORE TROPICAL AS SUGGESTED BY THE INCREASE IN CONVECTION...THE WIND FIELD MOST LIKELY WILL CONTRACT A LITTLE BIT. FORECAST POSITIONS AND MAX WINDS INITIAL 05/0300Z 26.5N 76.3W 55 KT 12HR VT 05/1200Z 28.5N 77.7W 55 KT 24HR VT 06/0000Z 31.5N 78.5W 60 KT 36HR VT 06/1200Z 35.0N 78.0W 50 KT...INLAND 48HR VT 07/0000Z 39.0N 75.0W 40 KT...INLAND 72HR VT 08/0000Z 46.0N 62.0W 40 KT...EXTRATROPICAL 96HR VT 09/0000Z 50.5N 44.5W 40 KT...EXTRATROPICAL 120HR VT 10/0000Z 51.2N 27.0W 40 KT...EXTRATROPICAL $$ FORECASTER AVILA