ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION ALETTA DISCUSSION NUMBER 15 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012012 800 PM PDT THU MAY 17 2012 DEEP CONVECTION INCREASED OVER AND AROUND THE CENTER OF ALETTA A FEW HOURS AGO...BUT NOW APPEARS TO BE ON THE WANE. THE SYSTEM CONTINUES TO LACK BANDING FEATURES...AND DVORAK CLASSIFICATIONS FROM BOTH TAFB AND SAB GIVE AN INTENSITY ESTIMATE OF 30 KT. THE CYCLONE SHOULD CONTINUE TO BE UNDER THE INFLUENCE OF STRONG SOUTHERLY SHEAR FOR THE NEXT DAY OR TWO...AND VERY DRY AIR LIES JUST TO THE NORTHWEST OF THE DEPRESSION. AS THIS AIR BECOMES MORE ENTRAINED INTO THE CIRCULATION OF ALETTA...CONVECTION SHOULD DIMINISH ENOUGH TO CAUSE THE SYSTEM TO DEGENERATE INTO A REMNANT LOW IN A DAY OR SO. THE OFFICIAL WIND SPEED FORECAST FOLLOWS THE LGEM GUIDANCE AND IS THE SAME AS THE PREVIOUS NHC INTENSITY FORECAST. THE CYCLONE SHOULD LOSE ITS IDENTITY IN 3-4 DAYS OR SOONER AS IT BECOMES ABSORBED INTO A DEVELOPING CIRCULATION TO ITS EAST. THE HEADING OF THE DEPRESSION HAS CONTINUED TO VEER TO THE RIGHT... WITH THE INITIAL MOTION ESTIMATE NOW ABOUT 020/5. STEERING CURRENTS ARE WEAK AND THE TRACK MODEL GUIDANCE IS FAIRLY DIVERGENT. HOWEVER...THERE IS GENERAL AGREEMENT AMONG THE MODELS THAT ALETTA OR ITS REMNANT WILL TURN EASTWARD DUE TO LOW-LEVEL WESTERLY FLOW AND THEN BEGIN TO MOVE SOUTHEASTWARD AS IT INTERACTS WITH A LARGER CYCLONIC CIRCULATION TO ITS EAST IN 2-3 DAYS. THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE AND IS CLOSE TO THE MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 18/0300Z 13.6N 114.3W 30 KT 35 MPH 12H 18/1200Z 13.9N 114.2W 25 KT 30 MPH 24H 19/0000Z 14.1N 113.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 19/1200Z 14.1N 113.2W 20 KT 25 MPH...POST-TROP/REMNT LOW 48H 20/0000Z 13.7N 112.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 21/0000Z 12.8N 112.0W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 22/0000Z...DISSIPATED $$ FORECASTER PASCH NNNN
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Page last modified: Monday, 31-Dec-2012 12:10:04 UTC