[Tropical] Tropical Cyclone Discussion

[EMWIN Server]

WTNT44 KNHC 202042
TCDAT4

TROPICAL STORM NADINE DISCUSSION NUMBER  38
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
500 PM AST THU SEP 20 2012

THERE HAS BEEN LITTLE CHANGE TO THE STRUCTURE OF NADINE OVER THE
PAST FEW HOURS. AFTER INCREASING A LITTLE EARLIER...CONVECTIVE TOPS
NEAR THE CENTER HAVE WARMED AND DIMINISHED OVER THE PAST COUPLE OF
HOURS. THE INITIAL INTENSITY IS 45 KT...IN AGREEMENT WITH THE
LATEST DVORAK ESTIMATE FROM TAFB. LITTLE CHANGE IN INTENSITY IS
EXPECTED DURING THE FORECAST PERIOD...AS NADINE WILL BE IN A
MARGINAL THERMODYNAMIC ENVIRONMENT FOR INTENSIFICATION VIA LATENT
HEAT RELEASE WHILE LACKING ANY SIGNIFICANT SOURCE OF BAROCLINIC
INTENSIFICATION. ADDITIONALLY...NADINE COULD BECOME POST-TROPICAL AT
JUST ABOUT ANYTIME DURING THE FORECAST PERIOD IF THE DEEP CONVECTION
DISSIPATES. THE NEW NHC INTENSITY FORECAST IS THE SAME AS THE
PREVIOUS ADVISORY.

NADINE HAS JOGGED EASTWARD THIS AFTERNOON...AND THE LONG TERM
INITIAL MOTION ESTIMATE IS 110/09. OTHER THAN AN EASTWARD
ADJUSTMENT DUE TO THE INITIAL POSITION AND MOTION...THE TRACK
FORECAST THROUGH 48 HOURS REMAINS LARGELY UNCHANGED. DURING THIS
TIME NADINE SHOULD BE STEERED SOUTHEASTWARD AHEAD OF A MID/
UPPER-LEVEL TROUGH OVER THE NORTHEASTERN ATLANTIC. BEYOND THAT
TIME...THERE CONTINUES TO BE LARGE SPREAD IN THE TRACK GUIDANCE AT
DAYS 3 THROUGH 5. THE LATEST GFS NOW SHOWS A QUICKER EASTWARD
MOTION...AS NADINE ACCELERATES AHEAD OF ANOTHER DIGGING MID- TO
UPPER-LEVEL TROUGH. WHILE THE ECMWF ALSO SHOWS AN EASTWARD
MOTION BY DAY 5...THIS MODEL HAS TRENDED ABOUT 500 MILES WESTWARD
COMPARED TO ITS PREVIOUS RUN. ON THE OTHER SIDE OF THE GUIDANCE
ENVELOPE...THE HWRF SHOWS A SOUTHWESTWARD MOTION LATE IN THE PERIOD
WHILE THE UKMET SHOWS A SLOW WESTWARD DRIFT. THE LATEST ECMWF AND
GFS ENSEMBLE MEMBERS REMAIN ALMOST EVENLY SPLIT BETWEEN AN
EASTWARD AND WESTWARD COMPONENT OF MOTION BY DAY 5. GIVEN THE
PERSISTENT UNCERTAINTY...THE NHC FORECAST CONTINUES TO SHOW NO
MOTION BEYOND 72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INIT  20/2100Z 36.1N  28.2W   45 KT  50 MPH
 12H  21/0600Z 35.3N  27.2W   45 KT  50 MPH
 24H  21/1800Z 34.0N  26.3W   45 KT  50 MPH
 36H  22/0600Z 32.9N  25.3W   45 KT  50 MPH...POST-TROPICAL
 48H  22/1800Z 32.5N  24.7W   45 KT  50 MPH...POST-TROPICAL
 72H  23/1800Z 32.5N  24.5W   45 KT  50 MPH...POST-TROPICAL
 96H  24/1800Z 32.5N  24.5W   45 KT  50 MPH...POST-TROPICAL
120H  25/1800Z 32.5N  24.5W   45 KT  50 MPH...POST-TROPICAL

$$
FORECASTER BRENNAN


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