000
WTNT44 KNHC 180257
TCDAT4
 
TROPICAL STORM NADINE DISCUSSION NUMBER  27
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
1100 PM AST MON SEP 17 2012
 
AN AREA OF DEEP CONVECTION THAT FORMED NEAR THE CENTER OF NADINE
THIS AFTERNOON HAS WEAKENED THIS EVENING.  RECENT MICROWAVE DATA
INDICATE THAT THE LOW-LEVEL CENTER IS NEAR THE SOUTHERN EDGE OF
COLDER CLOUD TOPS...TO THE SOUTH OF THE MID-LEVEL CENTER.  ONCE
AGAIN THIS EVENING NADINE WAS NOT SAMPLED BY THE ASCAT INSTRUMENT
SO THE INITIAL INTENSITY OF 50 KT IS A BLEND OF THE LATEST DVORAK
ESTIMATES FROM SAB AND TAFB.

NADINE CONTINUES TO SLOW DOWN AS EXPECTED...AND IT IS NOW MOVING
NORTHEASTWARD OR 045 DEGREES AT 8 KT.  THE CYCLONE IS FORECAST TO
TURN NORTHWARD DURING THE NEXT 24 TO 36 HOURS AS IT MOVES BETWEEN A
DEVELOPING CUT-OFF LOW TO THE WEST AND A MID-LEVEL RIDGE TO THE
NORTHEAST.  AFTER THAT TIME...A LARGE MID-LATITUDE TROUGH IS
PREDICTED TO MOVE SOUTHEASTWARD OVER THE NORTHEASTERN ATLANTIC.
THIS SHOULD CAUSE NADINE TO MOVE VERY SLOWLY FOR A DAY OR SO TO THE
SOUTHWEST OF THE AZORES.  THE NHC TRACK THROUGH 72 HOURS IS NEAR
THE MIDDLE OF THE GUIDANCE ENVELOPE AND IS CLOSE TO THE PREVIOUS
ADVISORY.  THE GLOBAL MODEL GUIDANCE HAS CONTINUED THE TREND OF
SHOWING LESS DIRECT INTERACTION BETWEEN NADINE AND THE TROUGH LATER
IN THE FORECAST PERIOD.  AS THE TROUGH MOVES EAST OF NADINE IN 
3 TO 4 DAYS...THE CYCLONE IS EXPECTED TO TURN SOUTHWARD....THEN
SOUTHWESTWARD AROUND THE SOUTHEASTERN SIDE OF A DEVELOPING
DEEP-LAYER RIDGE OVER THE NORTH-CENTRAL ATLANTIC.  THE GFS AND
ECMWF ARE IN GENERAL AGREEMENT ON THIS SCENARIO...BUT THERE ARE
SIGNIFICANT DIFFERENCES LATE IN THE PERIOD AS TO HOW FAR SOUTH THE
CYCLONE MOVES.  THE NHC FORECAST HAS BEEN ADJUSTED TO THE SOUTHWEST
OF THE PREVIOUS ADVISORY AT DAYS FOUR AND FIVE AND LEANS TOWARD THE
GFS...WHICH HAS PERFORMED QUITE WELL WITH NADINE SO FAR.

NADINE WILL BE MOVING OVER A LITTLE COOLER SSTS DURING THE NEXT
COUPLE OF DAYS...BUT MOST OF THE GLOBAL MODELS KEEP THE STORM ABOUT
THE SAME STRENGTH AS THE CYCLONE DERIVES SOME ENERGY FROM MID-
LATITUDE SOURCES.  WITHIN 2 TO 3 DAYS...A PUSH OF COOLER AND DRIER
AIR BEHIND THE AFOREMENTIONED TROUGH IS EXPECTED TO CAUSE NADINE TO
TRANSITION TO AN EXTRATROPICAL CYCLONE.  HOWEVER...NEAR THE END OF
THE FORECAST PERIOD WHEN NADINE MOVES SOUTHWARD...THE SYSTEM IS
EXPECTED TO BEGIN LOSING ITS FRONTAL CHARACTERISTICS AND NADINE
COULD BEGIN THE TRANSITION BACK INTO A TROPICAL CYCLONE.    
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0300Z 33.9N  34.2W   50 KT  60 MPH
 12H  18/1200Z 34.6N  33.4W   50 KT  60 MPH
 24H  19/0000Z 35.9N  32.9W   50 KT  60 MPH
 36H  19/1200Z 36.9N  32.9W   50 KT  60 MPH
 48H  20/0000Z 37.2N  32.6W   50 KT  60 MPH
 72H  21/0000Z 36.7N  30.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  22/0000Z 35.0N  30.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  23/0000Z 32.0N  32.0W   50 KT  60 MPH...POST-TROPICAL
 
$$
FORECASTER BROWN