Hurricane MARTY

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HURRICANE MARTY DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 PM PDT SUN SEP 21 2003

MARTY HAS BECOME MUCH BETTER ORGANIZED DURING THE PAST 6 HOURS. DEEP
CONVECTION HAS RE-DEVELOPED OVER THE LOW-LEVEL CENTER AND A RAGGED
CLOUD-FILLED EYE HAS BRIEFLY APPEARED IN BOTH VISIBLE AND INFRARED
SATELLITE IMAGERY. HOWEVER...A 21/1926Z TRMM OVERPASS SHOWED A
WELL-DEFINED LOW- TO MID-LEVEL EYE...SUGGESTING THAT THE INNER-CORE
WIND FIELD REMAINED WELL ORGANIZED DRUING THE EARLIER WEAKENING
PHASE. THE INITIAL INTENSITY OF 75 KT IS BASED ON A BLEND SATELLITE
INTENSITY ESTIMATES OF 90/77/55 KT FROM TAFB/SAB/AFWA...
RESPECTIVELY. OUTFLOW CONTINUES TO IMPROVE ALONG WITH THE
DEVELOPMENT OF A DISTINCT EQUATORWARD OUTFLOW CHANNEL. OUTER
BANDING FEATURES ALSO CONTINUE TO DEVELOP AND IMPROVE.

THE INITIAL MOTION ESTIMATE IS 345/9. THERE IS NO SIGNIFICANT CHANGE
TO THE PREVIOUS FORECAST TRACK OR REASONING. IT APPEARS THAT MARTY
IS NOW BEGINNING TO MAKE A TURN MORE TOWARD THE NORTH...AND THE NHC
MODEL GUIDANCE IS TIGHTLY CLUSTERED ABOUT THE PREVIOUS FORECAST
TRACK. THERE IS LESS THAN 90 NMI DIFFERENCE EAST-WEST IN THE
GUIDANCE ENVELOPE AT 24 HOURS...SO A DIRECT HIT ON THE SOUTHERN
PORTION OF THE BAJA PENINSULA APPEARS INEVITABLE DURING THE NEXT 12
TO 18 HOURS. AFTER CROSSING OVER INTO THE SEA OF CORTES IN ABOUT 24
HOURS OR SO...MARTY IS EXPECTED TO CONTINUE MOVING NORTHWARD TOWARD
MAINLAND MEXICO AND EVENTUALLY INLAND AND DISSIPATE OVER EXTREME
NORTHWESTERN MEXICO AND SOUTHERN ARIZONA.
 
THE AFOREMENTIONED TRMM OVERPASS INDICATED A TIGHT INNER-CORE WIND
FIELD AS SUGGESTED BY THE SMALL...WELL-DEFINED LOW-LEVEL EYE AND
TIGHT BANDING FEATURES. THIS SUGGESTS THAT THE WIND FIELD SHOULD BE
ABLE TO SPIN UP FAIRLY QUICKLY ONCE THE CENTRAL DEEP CONVECTION HAS
BEEN MAINTAINED. THE INITIAL INTENSITY WAS HELD BELOW THE TAFB 90
KT DVORAK ESTIMATE AND THE 80-85 OBJECTIVE DVORAK INTENSITY
ESTIMATES. HOWEVER...THESE VALUES ARE LIKELY A GOOD INDICATION OF
THE 12 HOUR INTENSITY ESTIMATE...WHICH IS ALSO CLOSE TO THE 12-HOUR
INTENSITY AVERAGE BETWEEN THE SHIPS AND GFDL MODELS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 21.4N 109.7W    75 KT
 12HR VT     22/1200Z 23.1N 110.2W    90 KT
 24HR VT     23/0000Z 25.5N 110.8W    75 KT
 36HR VT     23/1200Z 27.9N 111.6W    65 KT
 48HR VT     24/0000Z 29.9N 112.0W    50 KT...INLAND
 72HR VT     25/0000Z 32.5N 112.0W    30 KT...DISSIPATING INLAND
 96HR VT     26/0000Z 34.5N 111.5W    20 KT...REMNANT LOW INLAND
120HR VT     27/0000Z...DISSIPATED INLAND
 
 
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