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| #220610 (Received by flhurricane at: 10:34 PM 06.Oct.2008) TCDAT3 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 $$ FORECASTER STEWART |
