Tropical Storm MARTY
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TROPICAL STORM MARTY DISCUSSION NUMBER 6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP162009
800 AM PDT THU SEP 17 2009
THE CLOUD PATTERN HAS BECOME A LITTLE LESS ORGANIZED DURING THE PAST
FEW HOURS AS THE CLOUD TOPS HAVE WARMED SLIGHTLY AND THE OVERALL
SHAPE HAS BECOME ELONGATED. AN AMSR-E MICROWAVE IMAGE FROM 0913
UTC SUGGESTS THAT THE CENTER WAS LOCATED SLIGHTLY SOUTHWEST OF THE
PREVIOUS ESTIMATES. THE INITIAL INTENSITY REMAINS 40 KT...WHICH
COULD BE A LITTLE GENEROUS. MARTY HAS LIKELY REACHED ITS PEAK
INTENSITY. SOUTHWESTERLY SHEAR IS EXPECTED TO INCREASE DURING THE
NEXT DAY OR TWO AND THE CYCLONE WILL BE MOVING INTO A DRIER AND
MORE STABLE AIRMASS. THESE NEGATIVE ENVIRONMENTAL FACTORS SHOULD
TRANSLATE INTO A WEAKENING TROPICAL CYCLONE. THE OFFICIAL FORECAST
IS AT THE LOW END OF THE GUIDANCE AND SHOWS MARTY BECOMING A
REMNANT LOW WITHIN 48 HOURS.
MARTY APPEARS TO BE MOVING SLOWLY NORTH-NORTHWESTWARD. THIS
GENERAL MOTION SHOULD CONTINUE DURING THE NEXT DAY OR TWO. AS
MARTY WEAKENS AND BECOMES A SHALLOW SYSTEM IT IS EXPECTED TO
TURN WESTWARD IN THE LOW-LEVEL FLOW. ALL OF THE TRACK
GUIDANCE...EXCEPT THE HWRF...AGREE WITH THIS SOLUTION. THE HWRF
KEEPS MARTY A DEEP SYSTEM AND MOVES IT INTO THE BAJA PENINSULA.
THIS MODEL IS CONSIDERED AN OUTLIER AT THIS TIME.
FORECAST POSITIONS AND MAX WINDS
INITIAL 17/1500Z 19.7N 113.1W 40 KT
12HR VT 18/0000Z 20.3N 113.4W 35 KT
24HR VT 18/1200Z 21.1N 113.9W 35 KT
36HR VT 19/0000Z 22.0N 114.8W 30 KT
48HR VT 19/1200Z 22.8N 115.8W 25 KT...REMNANT LOW
72HR VT 20/1200Z 23.8N 117.6W 25 KT...REMNANT LOW
96HR VT 21/1200Z 24.0N 119.0W 20 KT...REMNANT LOW
120HR VT 22/1200Z...DISSIPATED
$$
FORECASTER BROWN
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