Tropical Storm IGNACIO

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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
 
 
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