000
WTNT44 KNHC 201456
TCDAT4
 
TROPICAL STORM NADINE DISCUSSION NUMBER  37
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
1100 AM AST THU SEP 20 2012

NADINE CONTINUES TO HAVE A TROPICAL-TYPE APPEARANCE ON SATELLITE
IMAGERY.  IN FACT...THE INNER-CORE CONVECTION HAS INCREASED
SOMEWHAT AND BECOME BETTER ORGANIZED WITH AN EYE-LIKE FEATURE
BECOMING APPARENT ON ENHANCED IR IMAGES.  THE CURRENT INTENSITY IS
KEPT AT 45 KT WHICH IS ABOVE THE SUBJECTIVE DVORAK ESTIMATES FROM
TAFB AND SAB...BUT IN GOOD AGREEMENT WITH DROPSONDE DATA FROM THE
NASA GLOBAL HAWK AIRCRAFT AND AMSU ESTIMATES.  ALTHOUGH THE SYSTEM
CONTINUES TO EXPERIENCE SIGNIFICANT SOUTHWESTERLY SHEAR...THE
UPPER-LEVEL OUTFLOW REMAINS WELL DEFINED OVER THE NORTHERN PORTION
OF THE CIRCULATION.  CONSIDERABLE COLD AIR STRATOCUMULUS ARE
EVIDENT OVER THE NORTHWESTERN QUADRANT OF THE CYCLONE...AND THE GFS
SHOWS SOME COLD AIR ADVECTION OVER THIS REGION DURING THE NEXT FEW
DAYS.  THE SYSTEM WILL LIKELY BE DRAWING SOME ENERGY FROM
BAROCLINIC SOURCES AS WELL AS FROM LATENT HEAT...AND SHOULD BE ABLE
TO AT LEAST MAINTAIN ITS INTENSITY THROUGH THE FORECAST PERIOD
EITHER AS A TROPICAL OR A POST-TROPICAL CYCLONE.  THE OFFICIAL WIND
SPEED FORECAST IS THE SAME AS THE PREVIOUS ONE.

NADINE HAS BEEN MOVING EAST-SOUTHEASTWARD...OR 120/9...IN THE FLOW
ON THE SOUTHWEST SIDE OF A STRONG MID-TROPOSPHERIC TROUGH OVER THE
NORTHEAST ATLANTIC.  THIS TROUGH IS FORECAST TO LIFT NORTHEASTWARD
OVER THE NEXT SEVERAL DAYS...AND LEAVE NADINE IN A REGION OF WEAKER
STEERING WINDS.  THE LONGER-RANGE TRACK OF THIS SYSTEM REMAINS
UNCLEAR...AS THE NORMALLY-RELIABLE DYNAMICAL MODELS HAVE BEEN VERY
INCONSISTENT.  AS HAS BEEN THE CASE FOR SOME TIME NOW...THERE IS
CONSIDERABLE SPREAD IN THE TRACK GUIDANCE IN THE 3-5 DAY TIME
FRAME.  THE LATEST GFS RUN LIES WELL WEST OF THE GFDL...HWRF...AND
ECMWF MODEL POSITIONS AT 4 AND 5 DAYS.  IN THESE SITUATIONS IT IS
USUALLY BEST TO MOVE THE SYSTEM VERY SLOWLY IN THE LATTER PART OF
THE FORECAST PERIOD. THEREFORE THE OFFICIAL TRACK FORECAST...LIKE
THE PREVIOUS ONE...SHOWS NO MOTION BEYOND 72 HOURS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/1500Z 36.2N  29.4W   45 KT  50 MPH
 12H  21/0000Z 35.4N  27.9W   45 KT  50 MPH
 24H  21/1200Z 34.1N  26.7W   45 KT  50 MPH
 36H  22/0000Z 32.9N  25.8W   45 KT  50 MPH...POST-TROPICAL
 48H  22/1200Z 32.3N  25.1W   45 KT  50 MPH...POST-TROPICAL
 72H  23/1200Z 32.0N  25.0W   45 KT  50 MPH...POST-TROPICAL
 96H  24/1200Z 32.0N  25.0W   45 KT  50 MPH...POST-TROPICAL
120H  25/1200Z 32.0N  25.0W   45 KT  50 MPH...POST-TROPICAL
 
$$
FORECASTER PASCH