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Tropical Storm MATTHEW


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TROPICAL STORM MATTHEW DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 PM EDT FRI OCT 08 2004
 
THE AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT INVESTIGATING THE
AREA OF LOW PRESSURE IN THE WESTERN GULF OF MEXICO FOUND A
REASONABLY WELL-DEFINED CIRCULATION WITH STRONG WINDS...48 KT AT A
FLIGHT LEVEL OF 600 FT...NEAR THE CENTER.  WHILE THE CONVECTIVE
ORGANIZATION OF THE SYSTEM IS POOR AND HIGHLY ASYMMETRIC...THE CORE
CIRCULATION DICTATES THAT TROPICAL CYCLONE ADVISORIES BE INITIATED
AT THIS TIME.  ALTHOUGH THE FLIGHT-LEVEL WINDS WOULD SUPPORT AN
INTENSITY ESTIMATE OF 40 KT...THESE WINDS WERE OBSERVED OVER A VERY
SMALL AREA AND MIGHT NOT BE REPRESENTATIVE.  THE INITIAL INTENSITY
IS SET TO 35 KT FOR THIS ADVISORY.
 
THE INITIAL MOTION IS 085/9...WITH THE CENTER FOLLOWING THE DEEP
CONVECTION THROUGH MUCH OF THE DAY TODAY. THERE IS CONSIDERABLE
UNCERTAINTY REGARDING THE FUTURE COURSE AND STRENGTH OF MATTHEW.
GLOBAL MODEL GUIDANCE INDICATES THE FORMATION OF A SEPARATE
BAROCLINICALLY FORCED LOW CENTER IN THE NORTHWESTERN GULF OF
MEXICO...AND THE BEGINNINGS OF THIS LOW ARE ALREADY APPARENT IN THE
SURFACE OBSERVATIONS. IF THIS OCCURS...AND MATTHEW SURVIVES AS A
SEPARATE ENTITY...IT COULD TAKE A GENTLY CURVING PATH AROUND THE
PERIPHERY OF THE NEW LOW. THIS IS THE SCENARIO INDICATED BY THE
SIMPLER STEERING MODELS SUCH AS THE BAM FAMILY OF MODELS. THE GFDL
SHOWS A MUCH SHARPER TURN TO THE NORTH...WHILE THE
GFS...UKMET...AND CANADIAN MODELS SHOW ONLY THE DEVELOPING
BAROCLINIC LOW...WHICH SPENDS MOST OF THE NEXT 2-3 DAYS OVER
LOUISIANA. THE OFFICIAL FORECAST LEANS TOWARDS THE BAM
GUIDANCE...IN PART BECAUSE THIS GUIDANCE APPEARS TO BE MORE
CONSISTENT WITH CURRENT TRENDS...BUT I AM NOT REAL COMFORTABLE
BEING SO FAR AWAY FROM THE NORMALLY GOOD-PERFORMING GLOBAL
GUIDANCE.

THERE IS MODERATE SHEAR OVER MATTHEW NOW...AND GLOBAL GUIDANCE
INDICATES THAT THIS SHEAR WILL INCREASE...AT LEAST OVER THE WESTERN
GULF.  IF THE TRACK FORECAST IS WRONG AND MATTHEW ENDS UP MOVING
MORE TO THE NORTH...IT WOULD LIKELY FIND ITSELF IN AN ENVIRONMENT
UNFAVORABLE FOR STRENGTHENING.  A MORE LEISURELY TRACK ACROSS THE
CENTRAL OR EASTERN GULF WOULD AFFORD MORE OF AN OPPORTUNITY FOR
DEVELOPMENT.
 
FORECASTER FRANKLIN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 24.2N  93.8W    35 KT
 12HR VT     09/0600Z 24.6N  92.6W    35 KT
 24HR VT     09/1800Z 25.3N  91.1W    35 KT
 36HR VT     10/0600Z 26.3N  89.2W    35 KT
 48HR VT     10/1800Z 28.0N  87.5W    35 KT
 72HR VT     11/1800Z 32.0N  86.0W    20 KT...INLAND
 96HR VT     12/1800Z...DISSIPATED
 
 
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