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Tropical Storm NADINE (Text)

ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
 
TROPICAL STORM NADINE DISCUSSION NUMBER  67
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL142012
500 AM AST SAT SEP 29 2012
 
IT APPEARS THAT VERTICAL SHEAR IS STARTING TO WEAKEN NADINE. ALMOST
ALL OF DEEP CONVECTION IS NOW LOCATED NORTH OF THE CENTER...AND
MICROWAVE IMAGES SHOW AN INCREASING SEPARATION BETWEEN THE LOW AND
MID-LEVEL CENTERS.  WITH THE DEGRADATION IN THE CLOUD PATTERN...THE
INITIAL WIND SPEED IS REDUCED TO 60 KT...A BLEND OF THE T AND CI
NUMBERS FROM TAFB AND SAB.  WHILE THE SHEAR IS EXPECTED TO REMAIN
MODERATE OVER THE NEXT DAY OR TWO...SSTS SHOULD DECREASE AS NADINE
GAINS LATITUDE.  NORMALLY THIS PATTERN WOULD CALL FOR ADDITIONAL
WEAKENING...BUT UPPER-LEVEL TEMPERATURES ARE ALSO FORECAST TO
COOL...WHICH COULD HELP THE CYCLONE KEEP ITS STRENGTH.  VERY LITTLE
CHANGE WAS MADE TO THE PREVIOUS FORECAST AFTER ACCOUNTING FOR THE
SLIGHTLY WEAKER INITIAL STATE. 

A SERIES OF MICROWAVE PASSES GIVE A CONFIDENT INITIAL MOTION OF
340/10.  THIS GENERAL MOTION IS EXPECTED FOR A DAY OR SO UNTIL
STEERING CURRENTS BREAK DOWN TO THE NORTHWEST OF A SUBTROPICAL
RIDGE.  MODEL GUIDANCE OVERNIGHT IS GENERALLY SHOWING MORE
INTERACTION BETWEEN NADINE AND A MID- TO UPPER-LEVEL TROUGH OVER
THE CENTRAL ATLANTIC...WHICH CAUSES NADINE TO UNDERGO A CYCLONIC
LOOP IN 2 TO 4 DAY TIME FRAME.  THE ECMWF MODEL HAS BEEN FAIRLY
CONSISTENTLY SHOWING THIS LOOP...AND NOW MOST OF THE MODELS SHOW IT
BESIDES THE GFS AND GFS ENSEMBLE.  THE OFFICIAL FORECAST IS TRENDED
TOWARD THE MODEL CONSENSUS...SHOWING LITTLE CHANGE IN THE FIRST DAY
OR SO...AND A SMALL SOUTHWARD LOOP IN THE MEDIUM RANGE.  A RATHER
LARGE TROUGH IS EXPECTED TO DEVELOP OVER THE NORTHERN ATLANTIC
OCEAN AT BY DAY 5...WHICH WILL HOPEFULLY CAUSE NADINE TO FINALLY
LEAVE THE SUBTROPICS.  MOST OF THE MODELS ARE NOW SHOWING THE STORM
BECOMING POST-TROPICAL BY DAY 5 DUE TO COLDER WATERS AND STRONGER
SHEAR...BUT GIVEN PAST EXPERIENCE...I HAVE ELECTED NOT TO SHOW THIS
TRANSITION YET.  
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z 31.9N  35.9W   60 KT  70 MPH
 12H  29/1800Z 33.5N  36.5W   60 KT  70 MPH
 24H  30/0600Z 35.4N  37.2W   60 KT  70 MPH
 36H  30/1800Z 36.4N  37.8W   60 KT  70 MPH
 48H  01/0600Z 36.2N  38.0W   55 KT  65 MPH
 72H  02/0600Z 35.5N  37.5W   50 KT  60 MPH
 96H  03/0600Z 35.5N  36.5W   45 KT  50 MPH
120H  04/0600Z 37.5N  33.5W   40 KT  45 MPH
 
$$
FORECASTER BLAKE
 
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