Tropical Storm MARCO

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TROPICAL STORM MARCO DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132008
1100 PM EDT MON OCT 06 2008
 
MINIATURE MARCO HAS MAINTAINED ONE SMALL COLD-TOPPED THUNDERSTORM
CLUSTER...ABOUT THE SIZE OF THE STATE OF DELAWARE...OVER THE
LOW-LEVEL CENTER. THEREFORE...THE INITIAL INTENSITY IS BEING KEPT
AT 55 KT IN LINE WITH THE LAST AIR FORCE RECON DATA...EVEN THOUGH
DVORAK SATELLITE CLASSIFICATIONS ARE T2.0/30 KT FROM BOTH TAFB AND
SAB. I HAVE WORKED SOME TINY TYPHOONS IN THE WESTERN PACIFIC
BEFORE...BUT HORIZONTALLY-CHALLENGED MARCO COULD BE THE SMALLEST
TROPICAL CYCLONE ON RECORD.
 
INITIAL MOTION ESTIMATE 295/06. MARCO HAS REMAINED ON THE PREVIOUS
FORECAST TRACK...SO THERE IS NO CHANGE SIGNIFICANT CHANGE TO THE
PREVIOUS FORECAST TRACK OR REASONING. MARCO IS EXPECTED TO MAINTAIN
A GENERAL WEST-NORTHWESTWARD MOTION TO THE SOUTH OF A STRONG
MID-LEVEL RIDGE PARKED OVER MOST OF THE GULF OF MEXICO...AND MAKE
LANDFALL IN 18 HOURS OR SO. THE OFFICIAL FORECAST TRACK IS ROUGHLY
IN THE MIDDLE OF THE NHC MODEL GUIDANCE SUITE.
 
ALTHOUGH MARCO MAY BE SMALL IN STATURE...IT HAS BEEN ABLE TO
MAINTAIN DEEP CONVECTION NEAR THE SMALL CIRCULATION CENTER THAT
ONLY HAS A RADIUS OF MAXIMUM WINDS OF ABOUT 4 NMI. SMALL SYSTEMS
LIKE MARCO CAN SPIN UP QUICKLY...BUT THEY CAN ALSO SPIN DOWN JUST
AS FAST. VERTICAL SHEAR IS FORECAST TO REMAIN RELATIVELY LOW AND
SSTS ARE EXPECTED TO BE ABOVE 28C UNTIL LANDFALL IN ABOUT 18 HOURS.
THEREFORE...SOME SLIGHT STRENGTHENING IS POSSIBLE. THE SHIPS MODEL
BRINGS MARCO UP TO HURRICANE INTENSITY IN 12 HOURS...AND UP TO 71
KT IN 18 HOURS...WHICH SEEMS A LITTLE TO AGGRESSIVE AT THIS STAGE.
THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE STRONGER HWRF AND
THE WEAKER GFDL...WHICH KEEPS MARCO JUST BELOW HURRICANE STRENGTH.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0300Z 19.8N  95.4W    55 KT
 12HR VT     07/1200Z 20.2N  96.4W    60 KT
 24HR VT     08/0000Z 20.7N  97.8W    25 KT...DISSIPATING INLAND
 36HR VT     08/1200Z...DISSIPATED INLAND OVER EASTERN MEXICO
 
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FORECASTER STEWART
 
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