[Tropical] Tropical Cyclone Discussion
EMWIN Server
emwin at nashvilleweather.net
Fri Aug 12 21:35:56 CDT 2011
WTNT41 KNHC 130236
TCDAT1
TROPICAL DEPRESSION SIX DISCUSSION NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL AL062011
1100 PM EDT FRI AUG 12 2011
THROUGH 0000 UTC...THE DEPRESSION WAS MAINTAINING A CENTRAL DENSE
OVERCAST...WITH SSM/IS AND TRMM DATA NEAR 2330 UTC SHOWING SOME
CONVECTIVE CURVATURE NEAR THE CENTER. SINCE THEN...THE CONVECTION
HAS DIMINISHED...ALTHOUGH IT IS UNCLEAR WHETHER THIS IS A DIURNAL
MINIMUM OR THE START OF A WEAKENING TREND. SATELLITE INTENSITY
ESTIMATES FROM TAFB AND SAB ARE 30 KT...AND THAT REMAINS THE
INITIAL INTENSITY.
THE INITIAL MOTION IS 065/19. THE DEPRESSION IS MOVING ALONG THE
SOUTHEASTERN EDGE OF THE WESTERLIES AND TO THE NORTHWEST OF THE
SUBTROPICAL RIDGE. ALL GUIDANCE AGREES THAT THE SYSTEM SHOULD MOVE
GENERALLY EAST-NORTHEASTWARD FOR 24 HR OR SO...FOLLOWED BY A MOTION
TOWARD THE EAST THAT SHOULD CONTINUE UNTIL DISSIPATION. THE NEW
FORECAST TRACK IS A LITTLE SOUTH OF THE PREVIOUS TRACK BASED ON THE
INITIAL POSITION AND MOTION...AND IT LIES NEAR THE CENTER OF THE
TRACK GUIDANCE ENVELOPE.
THE DEPRESSION IS JUST SOUTHEAST OF A FRONTAL SYSTEM AND IS MOVING
TOWARD COOLER WATERS. IN ADDITION...VERTICAL WIND SHEAR IS FORECAST
TO INCREASE AFTER 6-12 HOURS. THEREFORE...THERE IS ONLY A SHORT
WINDOW FOR INTENSIFICATION. THE INTENSITY FORECAST CALLS FOR
MODEST STRENGTHENING DURING THE NEXT 12 HOURS...FOLLOWED BY
EXTRATROPICAL TRANSITION AS THE DEPRESSION MERGES WITH THE FRONTAL
SYSTEM. THE CYCLONE IS FORECAST TO DISSIPATE COMPLETELY WITHIN THE
FRONTAL ZONE BY 72 HR...AND THIS COULD EVEN OCCUR EARLIER. THE
INTENSITY FORECAST IS A LITTLE LESS INTENSE THAN THE FORECAST OF
THE SHIPS AND LGEM MODELS.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0300Z 36.6N 61.3W 30 KT 35 MPH
12H 13/1200Z 37.8N 58.4W 35 KT 40 MPH
24H 14/0000Z 39.3N 54.2W 35 KT 40 MPH
36H 14/1200Z 40.3N 50.0W 35 KT 40 MPH...POST-TROP/EXTRATROP
48H 15/0000Z 40.3N 45.6W 35 KT 40 MPH...POST-TROP/EXTRATROP
72H 16/0000Z...DISSIPATED
$$
FORECASTER BEVEN
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