094
WTNT42 KNHC 121433
TCDAT2
TROPICAL STORM FRED DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
1100 AM AST SAT SEP 12 2009
SATELLITE IMAGERY INDICATES THAT FRED IS NOW A TIGHT SWIRL OF
LOW-LEVEL CLOUDS...DEVOID OF DEEP CONVECTION. AN EARLIER QUIKSCAT
PASS DID SHOW SEVERAL REALISTIC 35-40 KT WINDS...MOSTLY IN THE
NORTHERN SEMICIRCLE. DVORAK T-NUMBERS HAVE DROPPED TO 1.5 AND 2.0
FROM SAB AND TAFB...RESPECTIVELY. ASSUMING THAT THERE HAS BEEN SOME
ADDITIONAL WEAKENING...THE INITIAL INTENSITY IS LOWERED TO 35 KT.
FURTHER WEAKENING IS FORECAST...AS FRED IS EXPECTED TO ENCOUNTER A
RATHER HOSTILE ENVIRONMENT OF SOUTH-SOUTHWESTERLY SHEAR...MARGINAL
WATER TEMPERATURES...AND DRY MID-LEVEL AIR. IN ALL LIKELIHOOD...
FRED WILL BECOME A REMNANT LOW LATER TODAY OR TONIGHT. GLOBAL
MODELS CONTINUE TO INDICATE SOME CHANCE...ALBEIT REMOTE...OF
REGENERATION TOWARD THE END OF THE FORECAST PERIOD. HOWEVER...THEIR
REPRESENTATION OF FRED SEEMS TOO STRONG GIVEN ITS CURRENT
APPEARANCE...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME
EVEN MORE ADVERSE THAN THEY ARE NOW OVER THE NEXT DAY OR TWO. THE
OFFICIAL FORECAST ASSUMES THAT THE REMNANT CIRCULATION OF FRED WILL
DISSIPATE IN A FEW DAYS.
FRED HAS BEEN MOVING LITTLE DURING THE PAST FEW HOURS. HOWEVER...
RECENT SATELLITE FIXES DO YIELD AN INITIAL MOTION OF 180/03. SINCE
FRED HAS NOW BECOME A SHALLOW SYSTEM...THE EXPECTATION IS THAT IT
WILL MOVE VERY LITTLE DURING THE NEXT 12-24 HOURS WITHIN A RATHER
WEAK LOW-LEVEL FLOW. THEREAFTER...THE REMNANTS OF FRED SHOULD TURN
TOWARD THE NORTHWEST OR EVEN WEST-NORTHWEST...SOUTH OF A BUILDING
LOW-LEVEL RIDGE...WITH SOME INCREASE IN FORWARD SPEED. THE OFFICIAL
FORECAST IS SIMILAR TO THE PREVIOUS PACKAGE BUT SLIGHTLY SLOWER IN
THE SHORT-TERM.
FORECAST POSITIONS AND MAX WINDS
INITIAL 12/1500Z 17.5N 33.7W 35 KT
12HR VT 13/0000Z 17.7N 33.7W 25 KT
24HR VT 13/1200Z 18.4N 34.4W 20 KT...REMNANT LOW
36HR VT 14/0000Z 19.3N 36.4W 20 KT...REMNANT LOW
48HR VT 14/1200Z 20.5N 38.6W 20 KT...REMNANT LOW
72HR VT 15/1200Z 22.5N 44.0W 20 KT...REMNANT LOW
96HR VT 16/1200Z...DISSIPATED
FORECASTER KIMBERLAIN
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