[Tropical] Tropical Cyclone Discussion
EMWIN Server
emwin at nashvilleweather.net
Tue Aug 11 09:45:51 CDT 2009
WTNT42 KNHC 111445
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER 2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
1100 AM AST TUE AUG 11 2009
THE DEPRESSION IS A LITTLE THIN ON DEEP CONVECTION AT THE
MOMENT...BUT IT STILL HAS A SMALL WELL-DEFINED LOW-LEVEL
CIRCULATION. AN 1114 UTC ASCAT PASS INDICATED THAT MAXIMUM WINDS
ARE 25 KT...LIMITED TO THE WESTERN SIDE OF THE CIRCULATION...AND
THE INITIAL INTENSITY IS HELD AT THAT INTENSITY FOR THIS ADVISORY.
IN GENERAL...THE NUMERICAL GUIDANCE IS NOT ALL THAT AGGRESSIVE IN
SHOWING INTENSIFICATION OF THIS SYSTEM. SEA SURFACE TEMPERATURES
ALONG THE FORECAST TRACK WILL BE MARGINALLY WARM...AND THE
DEPRESSION WILL HAVE TO ENDURE SOME DRY AIR IN THE MID-LEVELS.
NONETHELESS...VERTICAL SHEAR IS EXPECTED TO BE LIGHT ENOUGH DURING
THE FIRST FOUR DAYS OR SO TO ALLOW SOME SLOW STRENGTHENING. THE
SYSTEM COULD MOVE FAR ENOUGH NORTH BY DAY 5 THAT IT BEGINS TO FEEL
THE EFFECTS OF UPPER-LEVEL WESTERLY WINDS...AND THE OFFICIAL
FORECAST INDICATES SOME WEAKENING BY THEN. IT MUST BE STATED AGAIN
THAT IF THE DEPRESSION TAKES A MORE SOUTHERN TRACK...IT WOULD STAY
AWAY FROM THE INCREASING SHEAR AND COULD POSSIBLY BECOME STRONGER
THAN INDICATED HERE.
THE DEPRESSION IS MOVING AT 275/11. LITTLE CHANGE TO THIS MOTION IS
EXPECTED OVER THE NEXT 3 DAYS DUE TO A MID-LEVEL SUBTROPICAL RIDGE
FORECAST TO PERSIST NORTH OF THE DEPRESSION. BY DAYS 4 AND 5...A
WEAKNESS IS EXPECTED TO DEVELOP IN THE RIDGE OVER THE CENTRAL
ATLANTIC AND CAUSE THE SYSTEM TO TURN SLIGHTLY TO THE WEST-
NORTHWEST. THE NEW OFFICIAL FORECAST IS SHIFTED A LITTLE TO THE
SOUTH BUT STILL LIES NORTH AND EAST OF THE GFDL...HWRF...AND THE
MODEL CONSENSUS TVCN.
FORECAST POSITIONS AND MAX WINDS
INITIAL 11/1500Z 14.6N 29.6W 25 KT
12HR VT 12/0000Z 14.7N 31.3W 30 KT
24HR VT 12/1200Z 14.8N 33.6W 35 KT
36HR VT 13/0000Z 14.9N 35.8W 35 KT
48HR VT 13/1200Z 15.1N 38.2W 40 KT
72HR VT 14/1200Z 16.0N 43.0W 45 KT
96HR VT 15/1200Z 17.5N 47.5W 50 KT
120HR VT 16/1200Z 20.0N 52.0W 45 KT
$$
FORECASTER BERG
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