[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT42 KNHC 182050
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022006
500 PM EDT TUE JUL 18 2006

RECONNAISSANCE DATA AND SATELLITE IMAGERY INDICATE THE DEPRESSION
HAS CONTINUED TO BECOME BETTER ORGANIZED. RECENT DATA FROM THE
AIRCRAFT THAT CAME IN AFTER SOME OF THE FORECAST PRODUCTS WERE
ISSUED INDICATE 1000 FT FLIGHT-LEVEL WINDS OF 46 KT IN THE
SOUTHEASTERN QUADRANT AND A PRESSURE OF 1007 MB. THIS CORRESPONDS
TO AT LEAST 35 KT SURFACE WINDS...AND A TROPICAL CYCLONE UPDATE...
OR TCU PRODUCT... WILL ISSUED SHORTLY INDICATING THAT THE CYCLONE IS
NOW TROPICAL STORM BERYL.

THE INITIAL MOTION ESTIMATE IS 360/05. THE GLOBAL MODELS AT 12Z
AGAIN DID NOT INITIALIZE THE CYCLONE VERY WELL AND...AS A
RESULT ...GRADUALLY SHEAR OUT A VERY WEAK SYSTEM NORTHWARD THROUGH
36-48 HOURS...AND THEN TURN GRADUALLY TURN IT NORTHEASTWARD. UNTIL
THE MODELS SHOW THAT THEY HAVE A BETTER HANDLE ON THE INITIAL STATE
OF THIS SYSTEM...I AM LEANING MORE TOWARD THE ECMWF...GFDL...AND
THE BAM MODELS ON THE CYCLONE MAKING A SLIGHT S-BEND IN THE
FORECAST TRACK THROUGH 48-72 HOURS. THIS SCENARIO IS SUPPORTED BY
ALL THE MODELS WHICH INDICATE A SHORTWAVE TROUGH CURRENTLY OVER THE
GREAT LAKES DIGGING EAST-SOUTHEASTWARD AND ERODING THE EASTERN
PORTION OF THE SUBTROPICAL RIDGE ALONG THE MID-ATLANTIC STATES. THE
MODELS ALSO AGREE THAT THE SUBTROPICAL RIDGE TO THE EAST OF THE
CYCLONE WILL BUILD WESTWARD SLIGHTLY...WHICH APPEARS TO BE ONGOING
RIGHT NOW BASED ON TRENDS NOTED IN WATER VAPOR IMAGERY. THE
COMBINATION OF MID-LEVEL HEIGHT FALLS TO THE WEST AND HEIGHT RISES
TO THE EAST SHOULD IS EXPECTED TO NUDGE THE CYCLONE ON A
NORTH-NORTHWESTWARD TRACK THROUGH 48 HOURS. THE OFFICIAL FORECAST
TRACK IS SIMILAR TO THE PREVIOUS TRACK...BUT WAS SHIFTED SLIGHTLY
TO THE EAST.

UPPER-LEVEL OUTFLOW CONTINUES TO IMPROVE AND BECOME MORE
SYMMETRICAL. THE SHIPS MODEL INDICATES THE VERTICAL SHEAR IS
FORECAST TO BE ONLY 1 KT IN 24 HOURS...WHICH WOULD FAVOR
SIGNIFICANT STRENGTHENING IN MOST CASES. ALTHOUGH SSTS APPEAR TO BE
WARMER THAN WHAT THE SHIPS MODEL IS USING...DRY AIR ENTRAINMENT IN
THE WESTERN SEMICIRCLE MAY MODULATE THE NORMAL INTENSIFICATION
TREND FOR A SYSTEM LIKE THIS. THE SHIPS MODEL NOW BRINGS THE
CYCLONE UP TO 50 KT IN 36 HOURS...AND THE OFFICIAL INTENSITY
FORECAST REMAINS SLIGHTLY HIGHER.

FORECAST POSITIONS AND MAX WINDS

INITIAL      18/2100Z 33.3N  73.3W    30 KT
 12HR VT     19/0600Z 33.7N  73.7W    40 KT
 24HR VT     19/1800Z 34.4N  74.2W    45 KT
 36HR VT     20/0600Z 35.2N  74.6W    50 KT
 48HR VT     20/1800Z 36.0N  74.6W    55 KT
 72HR VT     21/1800Z 37.4N  73.4W    55 KT
 96HR VT     22/1800Z 39.5N  68.5W    50 KT
120HR VT     23/1800Z 42.5N  60.0W    40 KT...BECOMING EXTRATROPICAL

$$
FORECASTER STEWART

This weather bulletin was brought to you by:
www.nashvilleweather.net