000 WTNT41 KNHC 020246 TCDAT1 TROPICAL STORM ERIKA DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL062009 1100 PM AST TUE SEP 01 2009 AN AIR FORCE RECONNAISSANCE PLANE HAS BEEN TRAVERSING ERIKA AND FOUND THAT THE CENTER HAS MOVED VERY LITTLE DURING THE PAST SEVERAL HOURS. THE CIRCULATION HAS BECOME BETTER ESTABLISHED AND THE MINIMUM CENTRAL PRESSURE FROM A DROP WAS 1004 MB. THIS VALUE COULD BE A LITTLE BIT LOWER SINCE THE DROP MEASURED 19 KNOTS AT THE SURFACE. THE SFMR AND THE PLANE MEASURED 55 AND 50 KNOTS... RESPECTIVELY...TO THE NORTHEAST OF THE CENTER. THEREFORE...THE INITIAL INTENSITY IS SET AT 50 KNOTS. THERE HAS BEEN AN INCREASE IN CONVECTION NEAR THE CENTER AND THERE ARE SOME INDICATIONS FROM THE HIGH-CLOUD MOTION THAT THE SHEAR HAS LESSENED A LITTLE BIT. ERIKA COULD STRENGTHEN SOME DURING THE NEXT DAY OR TWO. THEREAFTER...MOST OF THE GLOBAL MODELS HAVE STRONG UPPER-LEVEL WESTERLY WINDS OVER ERIKA...A PATTERN THAT IS NOT FAVORABLE FOR STRENGTHENING. IN FACT...THE OFFICIAL FORECAST CALLS FOR WEAKENING DURING THAT PERIOD AS OPPOSED TO THE GFDL AND HWRF THAT BOTH MAKE ERIKA A STRONG HURRICANE. ERIKA HAS BEEN MOVING VERY LITTLE DURING THE PAST FEW HOURS...BUT THIS COULD BE THE RESULT OF THE CYCLONE BEING IN ITS FORMATIVE STAGE. ERIKA IS LOCATED ON THE SOUTHWESTERN EDGE OF THE AZORES-BERMUDA HIGH AND THE CYCLONE SHOULD BEGIN TO MOVE TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 7 KNOTS ON WEDNESDAY. BECAUSE THE AZORES-BERMUDA HIGH IS FORECAST TO EXPAND WESTWARD A LITTLE BIT...ERIKA SHOULD MAINTAIN THIS WEST-NORTHWEST TO NORTHWEST TRACK. SINCE THE STEERING CURRENTS ARE NOT VERY STRONG....ERIKA SHOULD MOVE SLOWLY. GUIDANCE IS NOT IN GOOD AGREEMENT AND THE CONFIDENCE IN THE FORECAST TRACK IS LOW. BOTH THE UK AND THE GFS TAKE A MORE WESTWARD TRACK WHILE THE OTHER MODELS SHOW A MORE NORTHWESTERLY COMPONENT. THE OFFICIAL FORECAST IS VERY CLOSE TO THE CONSENSUS WHICH IS CENTERED BETWEEN THESE TWO MODEL OPTIONS. FORECAST POSITIONS AND MAX WINDS INITIAL 02/0300Z 17.5N 57.6W 50 KT 12HR VT 02/1200Z 18.0N 58.7W 55 KT 24HR VT 03/0000Z 18.5N 60.2W 60 KT 36HR VT 03/1200Z 19.0N 61.8W 60 KT 48HR VT 04/0000Z 19.5N 63.2W 55 KT 72HR VT 05/0000Z 21.0N 66.0W 50 KT 96HR VT 06/0000Z 22.6N 68.4W 45 KT 120HR VT 07/0000Z 24.5N 71.0W 45 KT $$ FORECASTER AVILA