ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM MARTY DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT SAT SEP 20 2003 THERE IS CONSIDERABLE UNCERTAINTY IN THE CENTER LOCATION. LATEST FIXES FROM TAFB...SAB...AND AFWA SUGGEST LITTLE MOTION. MICROWAVE DATA ARE NOT CONCLUSIVE BUT A TRMM OVERPASS AT 0448Z SUGGESTED THAT THE CENTER MIGHT BE SOUTHEAST OF OUR ESTIMATED LOCATION. IT WOULD BE BEST TO WAIT FOR VISIBLE IMAGES BEFORE DOING ANY SUBSTANTIAL RE-LOCATION. THE MOTION IS SET TO STATIONARY FOR THIS ADVISORY. ENOUGH MID-LEVEL RIDGING SHOULD DEVELOP TO THE NORTHEAST OF THE STORM TO MOVE MARTY NORTHWESTWARD LATER TODAY. THERE IS CONSIDERABLE DIVERGENCE IN THE GUIDANCE MODEL TRACKS. THE GFDL MODEL IS THE EASTERNMOST AND TAKES MARTY TO BAJA CALIFORNIA. THE NOGAPS AND GFDN ARE THE WESTERNMOST AND KEEP MARTY WELL WEST OF BAJA. IT SEEMS THAT THE GFDL DEVELOPS A STRONGER MID-LEVEL RIDGE TO THE EAST-SOUTHEAST OF MARTY WHICH INDUCES THE MORE NORTHWARD MOTION...WHEREAS THE NOGAPS HAS A STRONGER RIDGE TO THE NORTH AND NORTHEAST OF THE TROPICAL CYCLONE. THE OFFICIAL FORECAST IS ROUGHLY IN THE MIDDLE OF THE GUIDANCE SUITE...AND SLIGHTLY TO THE EAST OF THE PREVIOUS NHC TRACK FORECAST. MARTY IS EXHIBITING VERY COLD-TOPPED CONVECTION BUT THE ORGANIZATION IS NOT TOO IMPRESSIVE AT THIS TIME. A BANDING FEATURE MAY BE TRYING TO RE-DEVELOP OVER THE WESTERN AND SOUTHERN PORTIONS OF THE CIRCULATION. DVORAK SATELLITE INTENSITY ESTIMATES FROM AFWA...SAB...AND TAFB ARE 45...45...AND 55 KT RESPECTIVELY. SINCE THERE IS UNCERTAINTY AS TO THE CENTER LOCATION...AND THIS HAS A BEARING ON THE INTENSITY ESTIMATE...WE WILL BE CONSERVATIVE AND KEEP THE CURRENT WIND SPEED AT 45 KT. THERE IS SOME EASTERLY SHEAR OVER THE SYSTEM BUT DYNAMICAL GUIDANCE INDICATES THAT THIS WILL LESSEN OVER THE NEXT 12 TO 24 HOURS. WATER TEMPERATURES UNDER THE CYCLONE SHOULD REMAIN WARM FOR ANOTHER 48 HOURS OR SO. WATER VAPOR IMAGERY SHOWS CONSIDERABLE MID- TO UPPER-LEVEL DRY AIR OVER THE AREA ABOUT 400 N MI TO THE NORTHWEST OF MARTY. WE ARE NOT SURE WHETHER THIS WOULD INHIBIT STRENGTHENING. THE SHIPS MODEL DOES INCLUDE 500 TO 300 MB RELATIVE HUMIDITY AS A PREDICTOR...BUT THE SHIPS OUTPUT HAS NOT BEEN SHOWING A NEGATIVE INTENSITY TENDENCY DUE TO THIS DRYING. THE OFFICIAL FORECAST SHOWS GRADUAL STRENGTHENING...SIMILAR TO THE PREVIOUS ADVISORY. NOTE: A SMALL DEVIATION TO THE NORTHEAST OF THE PROJECTED TRACK WOULD BRING THE TROPICAL CYCLONE CLOSER TO THE SOUTHERN BAJA CALIFORNIA PENINSULA. THEREFORE...INTERESTS IN THAT AREA SHOULD MONITOR THE PROGRESS OF MARTY. FORECASTER PASCH/FORMOSA FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 17.7N 107.7W 45 KT 12HR VT 20/1800Z 18.3N 108.6W 55 KT 24HR VT 21/0600Z 19.3N 110.0W 65 KT 36HR VT 21/1800Z 20.3N 111.3W 70 KT 48HR VT 22/0600Z 21.4N 112.6W 70 KT 72HR VT 23/0600Z 23.5N 114.5W 65 KT 96HR VT 24/0600Z 25.5N 116.0W 55 KT 120HR VT 25/0600Z 27.5N 117.0W 40 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:59 UTC