000
WTNT42 KNHC 161431
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER  54
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
1100 AM EDT WED JUL 16 2008

THE SATELLITE PRESENTATION OF BERTHA HAS DEGRADED SINCE YESTERDAY
WITH AN ELONGATED APPEARANCE.  HOWEVER...A QUIKSCAT PASS AT 0938
UTC SHOWED MAXIMUM WINDS OF ABOUT 60 KT.  THIS ESTIMATE WILL BE
USED FOR THE INITIAL INTENSITY.  LITTLE CHANGE IN STRENGTH IS
FORECAST DURING THE NEXT COUPLE OF DAYS AS THE EFFECTS OF
INCREASING VERTICAL WIND SHEAR ON THE STORM MAY BE TEMPERED BY
INCREASING SSTS.  SHEAR IS FORECAST TO INCREASE BY ALL MODELS IN A
FEW DAYS...SO THE CYCLONE SHOULD WEAKEN MORE IN THE LONG-TERM. 
EXTRATROPICAL TRANSITION SHOULD OCCUR IN 4 OR 5 DAYS DUE TO THE
EFFECTS OF STRONG MID-LATITUDE WINDS AND RAPIDLY COOLING WATERS.

QUIKSCAT DATA HELPED PLACE THE CENTER A LITTLE FARTHER TO THE
NORTHWEST THIS MORNING...YIELDING AN UNCERTAIN MOTION ESTIMATE OF
100/3.  THE TROPICAL CYCLONE IS EXPECTED TO TURN TOWARD THE
SOUTHEAST TODAY AS IT PINWHEELS AROUND A LARGE MIDDLE- TO
UPPER-LEVEL LOW TO THE EAST.  MODEL GUIDANCE REMAINS IN GOOD
AGREEMENT ON AN ARCING PATH TAKING THE SYSTEM FARTHER AWAY FROM
NORTH AMERICA.  IN TWO TO THREE DAYS... A MID-LATITUDE TROUGH WILL
APPROACH BERTHA FROM THE WEST.  THERE IS SOME DISAGREEMENT ON HOW
QUICKLY THE STORM WILL MOVE OUT TO SEA...BUT MODELS ARE GENERALLY
FASTER WITH THE PROGRESSION OF THE STORM.  THE OFFICIAL FORECAST IS
FAIRLY SIMILAR TO THE PREVIOUS ONE AND IS A LITTLE FASTER.  


FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/1500Z 36.6N  60.7W    60 KT
 12HR VT     17/0000Z 36.0N  60.1W    60 KT
 24HR VT     17/1200Z 35.0N  58.7W    60 KT
 36HR VT     18/0000Z 34.7N  56.4W    60 KT
 48HR VT     18/1200Z 35.6N  54.0W    60 KT
 72HR VT     19/1200Z 40.0N  49.0W    50 KT
 96HR VT     20/1200Z 43.5N  44.5W    45 KT...BECOMING EXTRATROPICAL
120HR VT     21/1200Z 47.5N  39.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER BLAKE