[Tropical] Tropical Cyclone Discussion

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WTNT44 KNHC 072032
TCDAT4
TROPICAL STORM COLIN DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042010
500 PM AST SAT AUG 07 2010

IT HAS BEEN INTERESTING TO OBSERVE THE EVOLUTION OF THE LOW-LEVEL
CENTER AND THE DEEP CONVECTION TODAY. DURING THE MORNING THE
LOW-LEVEL CENTER WAS COMPLETELY EXPOSED AND AS NEW CONVECTION
FORMED...THE CENTER SHIFTED EASTWARD AND BECAME TUCKED INTO THE
THUNDERSTORM ACTIVITY. EVEN THE OUTFLOW BEGAN TO EXPAND...GIVING THE
IMPRESSION THAT THERE WAS A DEVELOPING TREND. HOWEVER...DATA
FROM THE AIR FORCE RECONNAISSANCE PLANE INDICATE THAT THE CENTRAL
PRESSURE HAS RISEN AND THE WINDS HAVE NOT INCREASED. IN FACT...THE
INITIAL INTENSITY IS KEPT GENEROUSLY AT 35 KNOTS BASED ON ONE
SFMR OBSERVATION OF 34 KNOTS. SHIPS MODEL AS WELL AS THE GFDL/HWRF
PAIR SUGGEST THAT COLIN WILL AT LEAST KEEP ITS TROPICAL STORM
STATUS. GIVEN THE EXPECTED LOW SHEAR FOR A DAY OR SO...THE OFFICIAL
FORECAST ALSO KEEPS COLIN AS A TROPICAL STORM A LITTLE LONGER.
HOWEVER...THIS FORECAST IS HIGHLY UNCERTAIN.  AFTER 48
HOURS...COLIN IS EXPECTED TO BECOME EXTRATROPICAL AND ABSORBED BY A
LARGER MID-LATITUDE LOW.  IN FACT...MOST OF THE MODELS DO NOT EVEN
TRACK COLIN BEYOND 3 DAYS.

THE CENTER HAS BEEN MEANDERING ALL MORNING BUT LATEST VISIBLE IMAGES
AND DATA FROM THE RECONNAISSANCE PLANE INDICATE THAT COLIN IS
BEGINNING A SLOW NORTHERLY TRACK AT ABOUT 6 KNOTS OR LESS. THE
CYCLONE IS EXPECTED TO CONTINUE AROUND THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE FOR THE NEXT DAY OR TWO. IT SHOULD THEN ACCELERATE
TO THE NORTHEAST EMBEDDED WITHIN THE SOUTHWESTERLY FLOW AHEAD OF A
TROUGH OVER THE EASTERN UNITED STATES. THE TRACK GUIDANCE
CONSISTENTLY TAKES COLIN NORTHWARD AND INDEED ALL MODELS BRING THE
CENTER JUST WEST OF BERMUDA IN ABOUT 24 HOURS...AND SO DOES THE
OFFICIAL FORECAST. ON THIS TRACK...MOST OF THE SHOWERS AND SQUALLS
ASSOCIATED WITH COLIN WILL BE AFFECTING BERMUDA SINCE THEY ARE IN
THE EASTERN SEMICIRCLE.


FORECAST POSITIONS AND MAX WINDS

INITIAL      07/2100Z 29.4N  65.7W    35 KT
 12HR VT     08/0600Z 30.3N  65.5W    35 KT
 24HR VT     08/1800Z 32.2N  65.3W    40 KT
 36HR VT     09/0600Z 35.0N  65.0W    45 KT
 48HR VT     09/1800Z 38.5N  62.5W    45 KT
 72HR VT     10/1800Z 45.0N  50.0W    45 KT...POST-TROP/EXTRATROP
 96HR VT     11/1800Z...DISSIPATED

$$
FORECASTER AVILA

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