000
WTNT44 KNHC 192048
TCDAT4
 
TROPICAL STORM NADINE DISCUSSION NUMBER  34
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
500 PM AST WED SEP 19 2012

NADINE HAS NOT CHANGED MUCH SINCE EARLIER TODAY...AS IT CONTINUES TO
MAINTAIN MINIMAL DEEP CONVECTION...MAINLY TO THE NORTH OF THE
CENTER.  THE DVORAK TECHNIQUE CONTINUES TO UNDERESTIMATE THE
INTENSITY OF THIS MARGINAL TROPICAL CYCLONE...AS THE LATEST CI
NUMBERS FROM TAFB AND SAB ONLY SUPPORT 35 KT.  AN ASCAT PASS FROM
THIS MORNING SHOWED THAT THE MAXIMUM WINDS WERE NEAR 45 KT...AND
SINCE THE CONVECTION HAS NOT CHANGED SIGNIFICANTLY FROM THAT
TIME...THE ADVISORY WIND SPEED IS KEPT AT THE LATTER VALUE.  AMSU
ESTIMATES SUGGEST THAT THE CYCLONE MIGHT EVEN BE A LITTLE STRONGER. 
SINCE NADINE HAS BEEN ABLE TO MAINTAIN ITS INTENSITY WITH SO LITTLE
DEEP CONVECTION AND SUBSTANTIAL SHEAR...IT IS PROBABLY DERIVING
SOME ENERGY FROM BAROCLINIC SOURCES.  THE INTENSITY FORECAST
ASSUMES THAT THIS REGIME WILL CONTINUE...SO LITTLE CHANGE IN
STRENGTH IS FORECAST FOR THE NEXT SEVERAL DAYS.  IT IS PRESUMED
THAT WITHIN A DAY OR SO NADINE WILL LOSE MOST OF ITS DEEP
CONVECTION AND THEREFORE BECOME A POST-TROPICAL CYCLONE.  GLOBAL
MODEL FORECASTS SUGGEST THAT THE SYSTEM COULD STRENGTHEN SOMEWHAT
AROUND THE END OF THE FORECAST PERIOD.

THE CENTER HAS BEEN MEANDERING ABOUT FOR MOST OF THE DAY...AND THE
INITIAL MOTION ESTIMATE IS STATIONARY.  FORECASTING THE TRACK OF
THIS SYSTEM CONTINUES TO BE EXTREMELY CHALLENGING.  A PROMINENT
BLOCKING PATTERN IS EXPECTED TO EVOLVE AT MID-TROPOSPHERIC LEVELS
OVER THE NORTH ATLANTIC...RESULTING IN A COMPLICATED STEERING
PATTERN.  THE DYNAMICAL TRACK MODELS HAVE HARDLY BEEN A MODEL OF
CONSISTENCY FOR NADINE.  FOR EXAMPLE...THE 5-DAY FORECAST POSITION
FROM THE 1200 UTC RUN OF THE GFS HAS SHIFTED A MERE 900 N MI TO THE
SOUTHWEST OF THE 0600 UTC RUN.  THE TRACK OF THE CYCLONE IN THE 3-
TO 5-DAY RANGE IS APPARENTLY VERY SENSITIVE TO HOW NADINE INTERACTS
WITH A STRONG TROUGH OVER THE NORTHEAST ATLANTIC AND A MASSIVE
ANTICYCLONE OVER THE NORTH-CENTRAL ATLANTIC.  IN ONE SCENARIO...THE
SYSTEM IS PULLED EASTWARD BY THE TROUGH... AND IN ANOTHER IT MOVES
SOUTHWARD AND WESTWARD ALONG THE SOUTHEASTERN FLANK OF THE
ANTICYCLONE.  IT IS NOT CLEAR WHICH SCENARIO SHOULD BE FAVORED AT
THIS TIME.  AS A COURSE OF LEAST REGRET...THE OFFICIAL FORECAST
SLOWS THE MOTION TO A CRAWL IN 4 TO 5 DAYS.  THIS IS A LITTLE SOUTH
OF THE PREVIOUS FORECAST AND NORTH OF THE LATEST MODEL CONSENSUS.      
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/2100Z 37.1N  32.0W   45 KT  50 MPH
 12H  20/0600Z 36.7N  31.2W   45 KT  50 MPH
 24H  20/1800Z 35.9N  29.8W   45 KT  50 MPH...POST-TROPICAL
 36H  21/0600Z 34.6N  28.1W   45 KT  50 MPH...POST-TROPICAL
 48H  21/1800Z 33.5N  26.5W   45 KT  50 MPH...POST-TROPICAL
 72H  22/1800Z 33.5N  24.0W   45 KT  50 MPH...POST-TROPICAL
 96H  23/1800Z 33.5N  23.0W   45 KT  50 MPH...POST-TROPICAL
120H  24/1800Z 33.5N  22.0W   55 KT  65 MPH...POST-TROPICAL
 
$$
FORECASTER PASCH/ZELINSKY