ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM HURRICANE MIRIAM DISCUSSION NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132012 200 AM PDT TUE SEP 25 2012 MICROWAVE AND INFRARED SATELLITE IMAGERY INDICATE MIRIAM HAS COMPLETED ITS EYEWALL REPLACEMENT CYCLE AND A 30 N MI DIAMETER EYE APPEARS TO HAVE STABILIZED. CLOUD TOPS HAVE COOLED SIGNIFICANTLY AROUND THE EYE OVER THE PAST 4 HOURS...AND UW-CIMSS ADT AND NHC AODT SATELLITE INTENSITY ESTIMATES HAVE INCREASED TO T5.3/97 KT AND T5.6/105 KT...RESPECTIVELY. AS A RESULT...THE INITIAL INTENSITY IS BEING MAINTAINED AT 90 KT...WHICH COULD BE CONSERVATIVE. THE INITIAL MOTION ESTIMATE IS 310/05 KT. MIRIAM IS ON TRACK AND... AS A RESULT...THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. MIRIAM IS EXPECTED TO GRADUALLY TURN TOWARD THE NORTHWEST LATER TODAY AND TURN NORTHWARD IN 24-36 HOURS AS THE CYCLONE BECOMES EMBEDDED IN WEAK SOUTHERLY STEERING FLOW BETWEEN A SUBTROPICAL RIDGE SITUATED TO THE EAST AND A MID- TO UPPER-LEVEL LOW LOCATED TO ITS WEST AND NORTHWEST. THE UKMET MODEL REMAINS A SIGNIFICANT OUTLIER WITH A STRONG WEST BIAS AND HAS... THEREFORE...BEEN DISCOUNTED FOR THIS FORECAST CYCLE. AS A RESULT... THE OFFICIAL FORECAST TRACK REMAINS TO THE EAST OF THE CONSENSUS MODELS TV15 AND TVCE...AND IS FAIRLY CLOSE TO A BLEND OF THE GFS AND ECMWF MODELS...WHICH BETTER DEPICT A STRONGER AND MORE VERTICALLY DEEP CYCLONE AS CURRENTLY ANALYZED. GRADUAL WEAKENING IS FORECAST DURING THE NEXT 24 TO 36 HOURS AS SOUTHWESTERLY SHEAR INCREASES AHEAD OF A SLOWLY ADVANCING MID-/UPPER-LEVEL TROUGH NOTED TO THE WEST AND NORTHWEST OF MIRIAM IN WATER VAPOR IMAGERY. BY DAYS 3-5...THE GLOBAL MODELS ARE FORECASTING A LARGE MID-/UPPER-LEVEL LOW DEVELOPING NEAR 30N 130W. THIS LOW IS EXPECTED TO INCREASE THE VERTICAL SHEAR ABOVE 30 KT... WHICH SHOULD INDUCE MORE RAPID WEAKENING AND POSSIBLE DISSIPATION BEFORE MIRIAM REACHES BAJA CALIFORNIA. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND FOLLOWS A BLEND OF THE SHIPS AND LGEM MODELS. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 18.7N 114.3W 90 KT 105 MPH 12H 25/1800Z 19.3N 114.7W 85 KT 100 MPH 24H 26/0600Z 20.1N 115.0W 80 KT 90 MPH 36H 26/1800Z 21.1N 115.2W 70 KT 80 MPH 48H 27/0600Z 22.1N 115.3W 65 KT 75 MPH 72H 28/0600Z 24.0N 115.3W 50 KT 60 MPH 96H 29/0600Z 25.7N 114.9W 40 KT 45 MPH 120H 30/0600Z 27.2N 114.4W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ FORECASTER STEWART NNNN
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Page last modified: Monday, 31-Dec-2012 12:10:38 UTC