[Tropical] Tropical Cyclone Discussion

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WTNT42 KNHC 170244
TCDAT2
TROPICAL STORM BERTHA DISCUSSION NUMBER  56
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
1100 PM EDT WED JUL 16 2008

BERTHA'S SATELLITE APPEARANCE HAS CONTINUED TO GRADUALLY DEGRADE
DURING THE PAST 24 HOURS.  THE CYCLONE IS PRODUCING VERY LITTLE
DEEP CONVECTION AND THERE ARE VIRTUALLY NO CLOUD TOPS COLDER THAN
-50 DEGREES C.  DVORAK INTENSITY ESTIMATES HAVE DECREASED TO
45 KT...HOWEVER A QUIKSCAT OVERPASS AT 2156 UTC SUGGESTS THAT THE
WINDS REMAIN 55-60 KT...SO THE INITIAL INTENSITY IS UNCHANGED.
ALL OF THE INTENSITY GUIDANCE PREDICTS LITTLE CHANGE IN BERTHA'S
STRENGTH DURING THE NEXT DAY OR TWO...FOLLOWED BY GRADUAL WEAKENING
AS SSTS ALONG THE FORECAST TRACK COOL AND THE SHEAR INCREASES.
BERTHA IS FORECAST TO BECOME EXTRATROPICAL IN ABOUT 4 DAYS.

BERTHA IS MOVING A LITTLE FASTER TO THE SOUTHEAST...140/7.  LITTLE
CHANGE HAS BEEN MADE TO THE FORECAST TRACK THROUGH 36 HOURS AS
BERTHA IS PREDICTED TO MOVE SOUTHEASTWARD...THEN EASTWARD AROUND
THE SOUTHWESTERN PERIPHERY OF A LARGE MID- TO UPPER-LEVEL LOW.
THEREAFTER...THE TRACK MODELS ARE IN GOOD AGREEMENT ON A
NORTHEASTWARD MOTION...BUT AT VARYING FORWARD SPEEDS.
HOWEVER...THE MOST RECENT TRACK GUIDANCE IS IN A LITTLE BETTER
AGREEMENT THAN 6 HOURS AGO.  THE NEW NHC TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY AND IS IN BEST AGREEMENT WITH THE FSU
SUPERENSEMBLE...12Z UKMET...AND GFDL...BUT IS SLOWER THAN THE MODEL
CONSENSUS.

THE 34 AND 50 KT WIND RADII OVER THE EASTERN SEMICIRCLE WERE
EXPANDED BASED ON THE SCATTEROMETER DATA.

FORECAST POSITIONS AND MAX WINDS

INITIAL      17/0300Z 35.4N  59.8W    60 KT
 12HR VT     17/1200Z 34.6N  58.9W    60 KT
 24HR VT     18/0000Z 34.5N  56.8W    60 KT
 36HR VT     18/1200Z 35.5N  54.4W    55 KT
 48HR VT     19/0000Z 37.6N  51.7W    55 KT
 72HR VT     20/0000Z 42.5N  45.7W    50 KT
 96HR VT     21/0000Z 48.0N  39.0W    45 KT...EXTRATROPICAL
120HR VT     22/0000Z 54.5N  30.0W    45 KT...EXTRATROPICAL

$$
FORECASTER BROWN

WWWW
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