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#370421 (Received by flhurricane at: 4:46 PM 22.Aug.2010) TCDAT1 TROPICAL STORM DANIELLE DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062010 500 PM AST SUN AUG 22 2010 STRONG SHOWERS AND THUNDERSTORMS...WITH VERY COLD CLOUD TOPS TO NEAR -85C...HAVE RECENTLY FORMED IN ASSOCIATION WITH THE CYCLONE...AND THE LOW-LEVEL CENTER IS NOW EMBEDDED BENEATH THE CONVECTIVE CANOPY. DVORAK FINAL T-NUMBERS FROM TAFB AND SAB ARE NOW BOTH 2.5...35 KT...AND THE MOST RECENT 3-HOUR AVERAGE ADT FROM UW-CIMSS IS 2.7. THE DEPRESSION IS THEREFORE UPGRADED TO A 35-KT TROPICAL STORM. GIVEN THE NORTHWARD MOVEMENT OF THE CENTER OF DANIELLE THROUGH MUCH OF THE DAY...THE ESTIMATED INITIAL MOTION IS 310/10. HOWEVER... RECENT SATELLITE IMAGES SUGGEST THAT THE CENTER IS TURNING BACK TOWARD THE WEST-NORTHWEST...AND THIS MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 72 HOURS AS THE SYSTEM IS STEERED BY THE SUBTROPICAL RIDGE TO ITS NORTH. A BREAK IN THE RIDGE BY DAY 3 COULD ALLOW THE CYCLONE TO TURN TOWARD THE NORTHWEST...BUT DANIELLE IS EXPECTED TO SLOW DOWN AS IT APPROACHES A NEW RIDGE TO ITS NORTH ON DAY 5. THE NEW OFFICIAL FORECAST IS A LITTLE NORTH OF THE PREVIOUS FORECAST DURING THE FIRST 72 HOURS TO ACCOUNT FOR THE INITIAL POSITION...BUT IT CONVERGES BACK WITH THE PREVIOUS FORECAST ON DAYS 4 AND 5. THERE HAS BEEN NO SIGNIFICANT SHIFT IN THE MODEL GUIDANCE SINCE THE LAST ADVISORY...AND THE MULTI-MODEL CONSENSUS TVCN IS EXTREMELY CLOSE TO OFCI. WITH THE EXCEPTION OF THE GFDL...THE INTENSITY GUIDANCE HAS CONTINUED TO SCALE BACK ON THE INTENSIFICATION OF THE CYCLONE. SLOW STRENGTHENING IS ANTICIPATED FOR MUCH OF THE FORECAST PERIOD SINCE VERTICAL SHEAR IS CURRENTLY NOT IDEAL...AND SOME DRY AIR APPEARS TO SURROUND THE SYSTEM. THE STATISTICAL GUIDANCE SEEMS TO SUGGEST THAT THE VERTICAL SHEAR COULD INCREASE AGAIN AFTER DAY 3...AND THE LGEM DOES NOT EVEN STRENGTHEN THE CYCLONE TO A HURRICANE DURING THE FORECAST PERIOD. FOR NOW...THE OFFICIAL INTENSITY FORECAST IS LEFT UNCHANGED OUT OF RESPECT FOR CONTINUITY. FORECAST POSITIONS AND MAX WINDS INITIAL 22/2100Z 13.4N 35.1W 35 KT 12HR VT 23/0600Z 14.0N 36.6W 35 KT 24HR VT 23/1800Z 14.9N 39.2W 40 KT 36HR VT 24/0600Z 16.0N 42.0W 50 KT 48HR VT 24/1800Z 17.3N 44.9W 60 KT 72HR VT 25/1800Z 20.0N 50.0W 70 KT 96HR VT 26/1800Z 23.0N 54.0W 75 KT 120HR VT 27/1800Z 25.5N 57.0W 85 KT $$ FORECASTER BERG |