Hurricane IGNACIO

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TROPICAL STORM IGNACIO DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 AM PDT TUE AUG 26 2003
 
CONVECTION HAS WAXED AND WANED DURING THE PAST 12 HOURS AND ANOTHER
BURST OF COLD TOPPED CONVECTION HAS DEVELOPED OVER THE LOW-LEVEL
CENTER. HOWEVER...EACH SUCCESSIVE CONVECTIVE BURST HAS DECREASED IN
AREAL COVERAGE...SO THE INITIAL INTENSITY HAS BEEN DECREASED TO 60
KT BASED ON A BLEND OF SATELLITE INITIAL INTENSITY ESTIMATES OF 65
KT FROM TAFB AND 55 KT FROM SAB.

SATELLITE AND LIMITED SURFACE OBSERVATIONS SUGGEST THAT IGNACIO HAS
MOVED VERY LITTLE DURING THE PAST 6 HOURS...WITH PERHAPS A SLOW
NORTHWESTWARD DRIFT. STEERING CURRENTS REMAIN WEAK AND 26/00Z
UPPER-AIR OBSERVATIONS ACROSS MEXICO AND THE SOUTHWESTERN UNITED
STATES STILL SHOW NO CHANGE TO THE OVERALL SYNOPTIC-SCALE FLOW
PATTERN DURING THE PAST 72 HOURS. A MID-LEVEL HIGH PRESSURE CELL
CENTERED OVER THE U.S. DESERT SOUTHWEST SHOULD INHIBIT MUCH
NORTHWARD MOTION AND KEEP IGNACIO MOVING SLOWLY NORTHWESTWARD OR
WEST-NORTHWESTWARD OVER THE BAJA PENINSULA. THE FUTURE TRACK OF THE
CYCLONE WILL DEPEND HEAVILY ON WHAT KIND OF VERTICAL CIRCULATION
REMAINS AFTER THE SYSTEM TANGLES WITH THE BAJA CALIFORNIA
MOUNTAINS. ONLY THE UKMET MODEL TAKES IGNACIO QUICKLY ACROSS THE
PENINSULA AND INTO THE PACIFIC OCEAN. THE REST OF THE NHC MODEL
GUIDANCE KEEPS A WEAK IGNACIO MOVING NORTHWESTWARD ALONG THE LENGTH
OF THE PENINSULA. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS TRACK...EXCEPT SLIGHTLY SLOWER...AND IS VERY CLOSE TO THE
GFDL MODEL WHICH HAS PERFORMED THE BEST THE PAST FEW MODEL RUNS.
 
BOTH THE INTENSITY FORECAST AND TIME OF DISSIPATION HAVE BEEN
DECREASED SINCE IGNACIO IS EXPECTED TO INTERACT WITH THE BAJA
MOUNTAINS FOR A LONGER LENGTH OF TIME OWING TO THE SLOWER FORWARD
SPEED. IT IS QUITE POSSIBLE THAT IGNACIO COULD COMPLETELY DISSIPATE
AS A TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS. HOWEVER...THE
CONTINUED SLOW MOTION MEANS THAT EXCESSIVE AMOUNTS OF RAINFALL WILL
STILL POSE SERIOUS FLASH FLOODING AND MUD SLIDE THREATS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0900Z 24.6N 110.7W    60 KT
 12HR VT     26/1800Z 24.7N 111.0W    50 KT...INLAND
 24HR VT     27/0600Z 25.1N 111.5W    40 KT...INLAND
 36HR VT     27/1800Z 25.5N 111.8W    30 KT...DISSIPATING INLAND
 48HR VT     28/0600Z 26.0N 112.2W    25 KT...DISSIPATING INLAND
 72HR VT     29/0600Z 26.5N 113.0W    25 KT...REMNANT LOW
 96HR VT     30/0600Z 27.0N 113.5W    20 KT...REMNANT LOW
120HR VT     31/0600Z 28.0N 114.5W    20 KT...REMNANT LOW
 
 
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