[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 060345
TCDAT4
TROPICAL STORM COLIN DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042010
1100 PM AST THU AUG 05 2010

COLIN HAS MAINTAINED A SATELLITE CLOUD SIGNATURE SIMILAR TO WHEN A
RECONNAISSANCE AIRCRAFT INVESTIGATED THE SYSTEM 6 HOURS AGO. SINCE
THEN...A STRONG BURST OF DEEP CONVECTION HAS DEVELOPED IN THE
NORTHEASTERN QUADRANT...ALTHOUGH THE CONVECTION HAS WANED A LITTLE
DURING THE PAST COUPLE OF HOURS. HOWEVER...THE STRONG PRESSURE
GRADIENT IN THE EASTERN SEMICIRCLE BETWEEN THE CENTER OF COLIN AND
NOAA BUOY 41049 LOCATED 225 NMI TO THE NORTHEAST SUPPORTS KEEPING
THE INTENSITY AT 50 KT.

THE INITIAL MOTION ESTIMATE IS 340/12. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. COLIN IS
EXPECTED TO GRADUALLY SLOW DOWN AND TURN NORTHWARD TOWARD A
DEVELOPING WEAKNESS IN THE SUBTROPICAL RIDGE OVER THE NEXT 48
HOURS...AND THEN RECURVE TO THE NORTHEAST OVER THE NORTH ATLANTIC
BY 72 HOURS AHEAD OF AN EASTWARD-MOVING MID-LATITUDE SHORTWAVE
TROUGH CURRENTLY MOVING ACROSS GREAT LAKES AND OHIO VALLEY REGIONS.
THE MODELS REMAIN IN GOOD AGREEMENT ON THIS SCENARIO...AND THE
FORECAST TRACK WAS ONLY NUDGED SLIGHTLY TO THE EAST THROUGH 48
HOURS DUE TO THE MORE EASTWARD INITIAL POSITION. COLIN IS EXPECTED
TO PASS JUST WEST OF BERMUDA IN 36-48 HOURS...BUT ONLY A SLIGHT
DEVIATION TO THE EAST COULD BRING THE CENTER OVER BERMUDA.

SOUTHWESTERLY VERTICAL SHEAR OF 20-25 KT CONTINUES TO HINDER
SIGNIFICANT INTENSIFICATION OF COLIN...AND THESE UNFAVORABLE
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE NEXT 24 HOURS.
HOWEVER...FROM 36 TO 48 HOURS...ALL OF THE GLOBAL MODELS ARE
FORECASTING THE VERTICAL SHEAR TO WEAKEN SIGNIFICANTLY AS COLIN
PASSES BETWEEN TWO UPPER-LEVEL LOWS AND MOVES UNDER A SMALL
RIDGE...WHICH PROVIDES A BRIEF WINDOW OF OPPORTUNITY FOR COLIN TO
STRENGTHEN. THE SHIPS AND LGEM MODELS BRING COLIN TO NEAR 60 KT BY
48 HOURS...WHEN THE CYCLONE IS NEAR BERMUDA...AND THIS TREND WAS
FOLLOWED FOR THIS ADVISORY PACKAGE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      06/0300Z 26.3N  66.6W    50 KT
 12HR VT     06/1200Z 27.4N  66.9W    50 KT
 24HR VT     07/0000Z 29.1N  67.0W    50 KT
 36HR VT     07/1200Z 30.7N  66.8W    55 KT
 48HR VT     08/0000Z 32.6N  66.1W    60 KT
 72HR VT     09/0000Z 37.2N  63.5W    60 KT
 96HR VT     10/0000Z 43.0N  57.0W    55 KT
120HR VT     11/0000Z 50.5N  45.0W    50 KT...POST-TROP/EXTRATROP

$$
FORECASTER STEWART



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