ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ALVIN DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP012013 200 PM PDT THU MAY 16 2013 THERE IS SOME QUESTION WHETHER ALVIN STILL HAS A CLOSED LOW-LEVEL CIRCULATION. THE STORM IS STILL FULLY EMBEDDED WITHIN THE ITCZ AND IS SOMEWHAT DIFFICULT TO DISTINGUISH FROM ANOTHER CLUSTER OF DEEP CONVECTION A FEW HUNDRED NAUTICAL MILES TO ITS SOUTHWEST. SINCE THE SATELLITE APPEARANCE HAS WORSENED SINCE THIS MORNING...AND DVORAK INTENSITY ESTIMATES ARE T3.0 FROM TAFB AND T2.5 FROM SAB...THE INITIAL INTENSITY IS LOWERED TO 40 KT. THIS COULD BE OVERLY GENEROUS. ALVIN ACCELERATED A BIT THIS MORNING BUT HAS AN AVERAGE MOTION OF 285/10 KT. SINCE THE STORM HAS BEEN UNABLE TO DETACH ITSELF FROM THE ITCZ...IT IS DOUBTFUL THAT ALVIN WILL MAKE MUCH NORTHWARD PROGRESS. IN DIRECT CONTRAST TO YESTERDAY...THE TRACK GUIDANCE IS NOW IN FULL AGREEMENT ON A GENERAL WEST-NORTHWESTWARD MOTION DURING THE 5-DAY FORECAST PERIOD WITH VERY LITTLE SPREAD AMONG THE INDIVIDUAL MODELS. THE UPDATED NHC TRACK FORECAST IS ESSENTIALLY UNCHANGED FROM THE PREVIOUS ONE. THE UW-CIMSS SHEAR ANALYSIS INDICATES THAT ALVIN IS BEING AFFECTED BY 20-25 KT OF WESTERLY SHEAR...AND IT IS UNLIKELY THAT THE SHEAR WILL ABATE DURING THE NEXT FEW DAYS. THE CURRENT STRUCTURE OF THE STORM DOES NOT SUGGEST THAT STRENGTHENING IS LIKELY...AND THE NEW NHC INTENSITY FORECAST HAS AGAIN BEEN LOWERED. THIS FORECAST ESSENTIALLY FOLLOWS THE SHIPS...LGEM...AND FSU SUPERENSEMBLE MODELS. ALVIN IS FORECAST TO DEGENERATE TO A REMNANT LOW IN ABOUT 4 DAYS. HOWEVER...ADVISORIES COULD BE TERMINATED AT ANY TIME IF IT IS DETERMINED THAT THERE IS NO LONGER A CLOSED CIRCULATION. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 9.5N 109.1W 40 KT 45 MPH 12H 17/0600Z 9.8N 110.5W 40 KT 45 MPH 24H 17/1800Z 10.8N 112.0W 35 KT 40 MPH 36H 18/0600Z 11.5N 113.3W 35 KT 40 MPH 48H 18/1800Z 12.0N 114.7W 35 KT 40 MPH 72H 19/1800Z 13.0N 117.5W 30 KT 35 MPH 96H 20/1800Z 13.0N 120.0W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 21/1800Z 13.0N 122.5W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ FORECASTER BERG NNNN
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Page last modified: Monday, 07-Apr-2014 23:29:14 UTC