ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM LESLIE DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122012 500 AM AST SAT SEP 01 2012 LESLIE CONTINUES TO PRODUCE A LARGE CENTRAL DENSE OVERCAST WITH A BAND OF DEEP CONVECTION WRAPPING AROUND THE SOUTHERN AND WESTERN SEMICIRCLES. DURING THE PAST FEW HOURS...AN EYE-LIKE FEATURE WAS OBSERVED IN INFRARED SATELLITE IMAGERY EMBEDDED IN THE CENTER OF THE CDO. HOWEVER...THERE HAVE BEEN NO TIMELY MICROWAVE PASSES... AND IT IS UNCLEAR IF THIS FEATURE IS COINCIDENT WITH THE LOW-LEVEL CENTER. STILL...DVORAK ESTIMATES HAVE COME UP TO T4.0 FROM TAFB AND T3.5 FROM SAB...AND THE INITIAL INTENSITY IS RAISED TO 60 KT. DESPITE THE UNCERTAINTY IN THE CENTER LOCATION...THE INITIAL MOTION APPEARS TO BE A LITTLE SLOWER THAN BEFORE AND IS ESTIMATED TO BE 295/15 KT. A DIGGING SHORTWAVE TROUGH OVER THE WESTERN ATLANTIC IS EXPECTED TO DEVELOP A CUT-OFF LOW DURING THE NEXT 24 HOURS...AND THIS SHOULD CAUSE THE RIDGE TO THE NORTH OF LESLIE TO WEAKEN. LESLIE WILL RESPOND BY TURNING NORTHWESTWARD AND THEN NORTHWARD DURING THE NEXT 5 DAYS...BUT THE CYCLONE WILL ALSO SLOW DOWN AS THE STEERING FLOW AROUND IT COLLAPSES. ALTHOUGH THERE IS SOME DIVERGENCE IN THE TRACK GUIDANCE AFTER ABOUT 72 HOURS...THEY ALL SHOW A SLOW MOTION TOWARD THE NORTH OR EVEN NORTH-NORTHEAST BY DAY 5. THE NEW NHC FORECAST LIES ON THE WESTERN SIDE OF THE GUIDANCE ENVELOPE...AND IS NUDGED SLIGHTLY EAST OF THE PREVIOUS FORECAST ON DAYS 4 AND 5. IF LESLIE IS GOING TO STRENGTHEN...IT PROBABLY HAS TO DO IT DURING THE NEXT 24 TO 48 HOURS BEFORE IT ENCOUNTERS STRONG WESTERLY TO NORTHWESTERLY SHEAR. THE UPPER-LEVEL PATTERN COULD THEN BECOME MORE FAVORABLE FOR STRENGTHENING BY DAY 5. THE INTENSITY MODELS DO NOT SUPPORT MUCH INTENSIFICATION DURING THE FORECAST PERIOD...AND THE NEW NHC FORECAST IS LARGELY UNCHANGED FROM THE PREVIOUS ONE BY INDICATING ONLY GRADUAL STRENGTHENING. THIS FORECAST IS HIGHER THAN THAT SHOWN BY THE STATISTICAL GUIDANCE...BUT NOT AS HIGH AS THE INTENSITY CONSENSUS ICON AND HFIP CONSENSUS TV15. FORECAST POSITIONS AND MAX WINDS INIT 01/0900Z 17.8N 53.5W 60 KT 70 MPH 12H 01/1800Z 18.8N 55.5W 65 KT 75 MPH 24H 02/0600Z 20.2N 57.7W 65 KT 75 MPH 36H 02/1800Z 21.6N 59.5W 65 KT 75 MPH 48H 03/0600Z 23.1N 60.8W 70 KT 80 MPH 72H 04/0600Z 25.0N 61.5W 70 KT 80 MPH 96H 05/0600Z 26.5N 61.5W 70 KT 80 MPH 120H 06/0600Z 28.5N 61.0W 75 KT 85 MPH $$ FORECASTER BERG NNNN
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Page last modified: Monday, 31-Dec-2012 12:09:33 UTC