ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM TROPICAL STORM IGNACIO DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 8 PM PDT SAT AUG 23 2003 AN AMSU PASS AT 2114Z SHOWED A TINY EYE-TYPE FEATURE...BUT AFTER THAT THE DEEP CONVECTION DECREASED AND MOVED SOUTHEASTWARD EXPOSING THE LOW CLOUD CENTER. OBJECTIVE T NUMBERS WERE NEAR 4.0 AND IGNACIO MAY WELL HAVE REACHED HURRICANE INTENSITY AT THAT TIME...BUT SUBJECTIVE DVORAK T NUMBERS ARE AT 3.5...OR 55 KNOTS FROM BOTH TAFB AND SAB AT 00Z. THE INITIAL INTENSITY IS THUS KEPT AT 60 KNOTS. STILL LATER...WITHIN THE LAST TWO HOURS...A SMALL AREA OF DEEP CONVECTION IS REAPPEARING OVER THE CENTER AND IT IS LIKELY THAT IGNACIO WILL BECOME A HURRICANE IN THE NEXT SIX TO 12 HOURS...IF IT HAS NOT ALREADY BECOME ONE. DEPENDING ON HOW LONG IT TAKES TO REACH LAND...THE WIND SPEED COULD INCREASE TO EVEN HIGHER THAN THE 75-KNOT OFFICIAL FORECAST. THE INITIAL MOTION ESTIMATE IS 320/04. IGNACIO IS LOCATED TO THE SOUTH OF A MID-LEVEL RIDGE CENTERED OVER THE SOUTH-CENTRAL UNITED STATES AND EXTENDING WESTWARD ACROSS CALIFORNIA. THE GLOBAL MODELS SHOW A SHORT WAVE TROUGH APPROACHING FROM THE WEST AND ERODING THE WESTERN PORTION OF THE RIDGE. THE TRACK GUIDANCE RESPONDS BY A GRADUAL TURN TOWARD THE NORTH OVER THE NEXT 3 TO 5 DAYS WITH A CONTINUED VERY SLOW FORWARD SPEED. THE NOGAPS IS SOMEWHAT OF AN OUTLIER WELL TO THE RIGHT OF THE OTHER GLOBAL MODELS. THE OFFICIAL FORECAST IS SHIFTED SLIGHTLY TO THE RIGHT OF THE PREVIOUS ADVISORY AND MOVES THE CENTER OVER BAJA CALIFORNIA FOR 5 DAYS. THE INTENSITY FORECAST IS A LITTLE TRICKY IN THAT A SLIGHT DEVIATION TO THE FORECAST TRACK IN EITHER DIRECTION COULD KEEP THE CIRCULATION MOSTLY OVER WATER WHICH COULD SLOW THE WEAKENING PROCESS. MEANWHILE THE IMMEDIATE THREAT IS TO EXTREME SOUTHERN BAJA CALIFORNIA WHERE HURRICANE FORCE WINDS ARE LIKELY...ALONG WITH STORM SURGE FLOODING AND POSSIBLE TORRENTIAL RAINS RESULTING FROM THE SLOW FORWARD SPEED. DEPENDING ON THE FORWARD SPEED...WATCHES AND WARNINGS WILL LIKELY BE EXTENDED NORTHWARD ON SUNDAY. FORECASTER LAWRENCE FORECAST POSITIONS AND MAX WINDS INITIAL 24/0300Z 22.3N 108.7W 60 KT 12HR VT 24/1200Z 22.9N 109.3W 75 KT 24HR VT 25/0000Z 23.5N 109.9W 70 KT...INLAND 36HR VT 25/1200Z 24.0N 110.3W 60 KT...INLAND 48HR VT 26/0000Z 24.6N 110.9W 50 KT...INLAND 72HR VT 27/0000Z 25.8N 111.9W 40 KT...INLAND 96HR VT 28/0000Z 27.5N 113.0W 30 KT...INLAND 120HR VT 29/0000Z 29.0N 113.5W 25 KT...INLAND NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:57 UTC