ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM NORMA DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 AM PDT MON SEP 26 2005 DEEP CONVECTION HAS DECREASED SIGNIFICANTLY OVER THE PAST SEVERAL HOURS...AND IS NOW OCCURRING IN ONLY A FEW PATCHES NEAR THE CENTER AND OVER PARTS THE SOUTHERN SEMICIRCLE OF THE CIRCULATION. THIS DECREASE IS LIKELY DUE TO A COMBINATION OF COOLER SEA SURFACE TEMPERATURES AND MORE STABLE LAPSE RATES. EASTERLY SHEAR CONTINUES TO BE AN INHIBITING INFLUENCE AS WELL. NORMA APPEARS TO BE WEAKENING MORE RAPIDLY THAN EARLIER FORECAST...BUT IT REMAINS TO BE SEEN WHETHER THE DEEP CONVECTION WILL MAKE A SUBSTANTIAL COMEBACK. IF THIS DOES NOT OCCUR...THE SYSTEM COULD DISSIPATE EVEN SOONER THAN SHOWN IN THE FORECAST. GIVEN THE CURRENT DOWNWARD TREND...THE OFFICIAL INTENSITY FORECAST IS A LITTLE BELOW THE LATEST SHIPS AND GFDL GUIDANCE. INITIAL MOTION...310/7...IS ABOUT THE SAME AS IN THE PREVIOUS ADVISORY...AS IS THE TRACK FORECAST. A LARGE MID-TROPOSPHERIC HIGH PRESSURE SYSTEM CENTERED NEAR THE WESTERN TEXAS-MEXICO BORDER CONTINUES TO STEER NORMA NORTHWESTWARD. THE TROPICAL CYCLONE SHOULD GRADUALLY TURN TOWARD THE WEST DURING THE NEXT COUPLE OF DAYS AS THE MID-LEVEL RIDGE DEVELOPS WESTWARD AND TO THE NORTH OF NORMA. IN 3-5 DAYS...THE PRIMARY STEERING INFLUENCE SHOULD BE THE EAST-NORTHEASTERLY TRADE FLOW ASSOCIATED WITH A SUBTROPICAL HIGH CENTERED TO THE NORTHWEST OF NORMA'S REMNANT LOW. FORECASTER PASCH FORECAST POSITIONS AND MAX WINDS INITIAL 26/1500Z 19.6N 114.2W 35 KT 12HR VT 27/0000Z 20.2N 115.0W 35 KT 24HR VT 27/1200Z 21.0N 116.1W 30 KT 36HR VT 28/0000Z 21.2N 117.1W 25 KT...DISSIPATING 48HR VT 28/1200Z 21.0N 118.2W 20 KT...REMNANT LOW 72HR VT 29/1200Z 20.5N 120.0W 20 KT...REMNANT LOW 96HR VT 30/1200Z 20.0N 122.0W 20 KT...REMNANT LOW 120HR VT 01/1200Z 20.0N 124.0W 20 KT...REMNANT LOW $$ NNNN
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Page last modified: Monday, 26-Sep-2005 14:40:20 UTC