|
Show Selection: |
| #299661 (Received by flhurricane at: 4:55 AM 05.Oct.2009) TCDAT4 TROPICAL STORM GRACE DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL092009 500 AM AST MON OCT 05 2009 DESPITE ITS ENVIRONMENT AND UNUSUAL LOCATION...INFRARED SATELLITE IMAGERY INDICATES THAT GRACE HAS BEEN MAINTAINING A SMALL BUT IMPRESSIVE INNER CORE OF RELATIVELY DEEP CONVECTION. MORE RECENTLY...THERE HAS BEEN AN EXPANSION OF COLD-TOPPED CONVECTION IN A RING SURROUNDING A RAGGED EYE-TYPE FEATURE. BASED ON SUBJECTIVE DVORAK CLASSIFICATIONS AND THE CURRENT TREND OF INCREASING ORGANIZATION...THE INITIAL INTENSITY IS RAISED TO 60 KT. IT IS UNCLEAR WHETHER SURFACE WINDS MATCH THE SATELLITE SIGNATURE... ESPECIALLY SINCE CONVECTIVE TOPS MIGHT LACK SOME VIGOR OVER 20C SSTS. HOWEVER...THERE HAVE BEEN NO RECENT DATA TO CONFIRM OR DENY DVORAK ESTIMATES...OTHER THAN AN ASCAT PASS OF 45-50 KT FROM MUCH EARLIER. RECENT FIXES INDICATE THAT GRACE HAS ACCELERATED WHILE MOVING A LITTLE TO THE LEFT OF ITS PREVIOUS HEADING AND IS NOW MOVING 045/24. THE CYCLONE IS MOVING NORTHEASTWARD IN A DEEP LAYER OF SOUTHWESTERLY FLOW...BUT IS EXPECTED TO TURN NORTH-NORTHEAST AND DECELERATE AS A POTENT SHORTWAVE NEARS IT FROM THE SOUTHWEST. ON THIS TRACK...A STEADY WEAKENING IS FORECAST AS GRACE MOVES OVER SUB-20C WATER TEMPERATURES IN AN ENVIRONMENT OF MODERATE TO STRONG WESTERLY SHEAR. GRACE SHOULD MERGE WITH A LARGER EXTRATROPICAL CYCLONE OR ITS ASSOCIATED COLD FRONT OVER THE NORTHEAST ATLANTIC WITHIN 24 TO 36 HOURS...IF NOT SOONER. FORECAST POSITIONS AND MAX WINDS INITIAL 05/0900Z 43.0N 18.0W 60 KT 12HR VT 05/1800Z 45.5N 16.5W 50 KT 24HR VT 06/0600Z 49.0N 15.0W 45 KT 36HR VT 06/1800Z...DISSIPATED $$ FORECASTER KIMBERLAIN |
