000
WTNT44 KNHC 060001
TCDAT4
TROPICAL STORM COLIN SPECIAL DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042010
730 PM AST THU AUG 05 2010
 
...THIS SPECIAL ADVISORY HAS BEEN ISSUED TO PRIMARILY UPDATE THE
INTENSITY AND WIND RADII FORECASTS.

SHORTLY AFTER THE PREVIOUS ADVISORY HAD BEEN ISSUED...AN AIR FORCE
RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING TROPICAL STORM COLIN
REPORTED A 600-FT FLIGHT-LEVEL WIND OF 71 KT ABOUT 14 NMI NORTHEAST
OF THE CIRCULATION CENTER. IN ADDITION...A SURFACE PRESSURE OF 1005
MB WAS ALSO OBSERVED IN THE GENERAL VICINITY. IT IS UNCERTAIN IF
THESE VALUES WERE ASSOCIATED WITH A SMALL MESOVORTEX LOCATED
NORTHEAST OF THE CENTER...WHICH WOULD NOT BE REPRESENTATIVE OF THE
LARGER-SCALE WIND FIELD. FOR THIS REASON...THE INTENSITY WAS
INITIALIZED AT 40 KT IN AGREEMENT WITH NEARBY SFMR WINDS.
HOWEVER...SINCE THE TIME OF THAT RECON REPORT...DEEP CONVECTION IN
THE NORTHEASTERN QUADRANT OF COLIN HAS CONTINUED TO DEVELOP CLOSER
TO THE LOW-LEVEL CIRCULATION CENTER...WHICH JUSTIFIES INCREASING
THE INTENSITY TO 50 KT BASED ON A BLEND OF THE FLIGHT-LEVEL WINDS
AND SFMR SURFACE WINDS. SINCE A FORECAST INTENSITY OF 50 KT WAS NOT
EXPECTED TO OCCUR UNTIL 48 HOURS IN THE PREVIOUS ADVISORY...A
SPECIAL ADVISORY WAS REQUIRED TO INCREASE THE INTENSITY AND TO
ADJUST THE INTENSITY FORECAST UPWARD DURING THE NEXT 36 HOURS.
ALSO...DROPSONDE DATA INDICATES AN EXPANSION OF THE 34-KT WIND
RADII IN THE SOUTHEASTERN QUADRANT WAS NECESSARY.
 
NO SIGNIFICANT CHANGES TO THE PREVIOUS TRACK FORECAST OR REASONING
WERE MADE.
 
INTERNET PROBLEMS WILL PREVENT THE NHC WEB SITE FROM BEING UPDATED
AT THIS TIME.  PLEASE SEE WEATHER.GOV FOR ADVISORY TEXT PRODUCTS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      05/2330Z 25.6N  66.3W    50 KT
 12HR VT     06/0600Z 26.6N  67.1W    50 KT
 24HR VT     06/1800Z 28.1N  67.3W    50 KT
 36HR VT     07/0600Z 29.6N  67.3W    50 KT
 48HR VT     07/1800Z 31.3N  67.1W    55 KT
 72HR VT     08/1800Z 36.0N  65.0W    55 KT
 96HR VT     09/1800Z 40.0N  61.5W    60 KT
120HR VT     10/1800Z 49.0N  48.0W    50 KT...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART/BROWN