Tropical Storm BORIS

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TROPICAL STORM BORIS DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022008
200 PM PDT SAT JUN 28 2008
 
THERE HAS BEEN LITTLE CHANGE IN THE STRUCTURE OR MOTION OF BORIS
DURING THE PAST SIX HOURS.  THE LOW-LEVEL CENTER REMAINS PARTLY
EXPOSED ON THE NORTH SIDE OF THE CONVECTION DUE TO 20 KT OF
NORTHEASTERLY VERTICAL WIND SHEAR.  THE INITIAL MOTION IS 290/10...
LITTLE CHANGE SINCE THE LAST ADVISORY...AND THE INITIAL INTENSITY
REMAINS 45 KT IN AGREEMENT WITH SATELLITE INTENSITY ESTIMATES FROM
TAFB AND SAB.

FOR THE TRACK FORECAST...THE LARGE SCALE MODELS REMAIN IN GOOD
AGREEMENT THAT A MID/UPPER-LEVEL RIDGE WILL BUILD WESTWARD NORTH OF
BORIS THROUGH THE FORECAST PERIOD...WHICH SHOULD STEER THE CYCLONE
GENERALLY WESTWARD.  HOWEVER...SOME SPREAD REMAINS IN THE
ASSOCIATED TRACK FORECASTS DUE TO POSSIBLE INTERACTION WITH
TROPICAL STORM CRISTINA...A POTENTIAL CYCLONE FORMING EAST OF
BORIS...OR...IN THE CASE OF THE GFS...LIKELY SPURIOUS CYCLONES IN
THE MODEL ALONG THE ITCZ.  CURRENTLY...THERE ARE NO INDICATIONS OF
BORIS ACTUALLY INTERACTING WITH CRISTINA OR THE EASTERN
DISTURBANCE.  THEREFORE... THE FORECAST TRACK CALLS FOR A STEADY
WESTWARD MOTION SOUTH OF THE RIDGE.  THE NEW TRACK IS SLIGHTLY
FASTER THAN AND A LITTLE TO THE NORTH OF THE PREVIOUS FORECAST AND
IS IN BEST AGREEMENT WITH THE CONSENSUS MODELS.
 
THE LARGE-SCALE MODELS FORECAST THE SHEAR TO INCREASE FURTHER DURING
THE NEXT 24 HOURS.  AFTER THAT...THE GFS AND NOGAPS FORECAST
DECREASING SHEAR...WHILE THE UKMET...ECMWF...AND CANADIAN MODELS
CONTINUE STRONG UPPER-LEVEL EASTERLY FLOW OVER BORIS.  EVEN IF
THE SHEAR DECREASES...BORIS SHOULD APPROACH COOLER SEA SURFACE
TEMPERATURES AFTER 48 HR.  BASED ON THIS...BORIS IS FORECAST
TO SLOWLY WEAKEN THROUGH THE FORECAST PERIOD AND BECOME A
NON-CONVECTIVE REMNANT LOW BY 120 HOURS.  THE NEW INTENSITY
FORECAST IS AGAIN IN BEST AGREEMENT WITH THE SHIPS MODEL.  IT
SHOULD BE NOTED THAT THE GFDL...HWRF...AND GFDN ALL CALL FOR BORIS
TO STRENGTHEN TO 60 KT OR GREATER...WHICH LOOKS UNLIKELY AT THE
MOMENT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/2100Z 14.8N 113.9W    45 KT
 12HR VT     29/0600Z 14.9N 115.0W    45 KT
 24HR VT     29/1800Z 15.0N 116.8W    40 KT
 36HR VT     30/0600Z 15.1N 118.4W    40 KT
 48HR VT     30/1800Z 15.3N 120.3W    35 KT
 72HR VT     01/1800Z 15.5N 123.5W    30 KT
 96HR VT     02/1800Z 15.5N 127.0W    30 KT
120HR VT     03/1800Z 15.5N 129.5W    25 KT...REMNANT LOW
 
$$
FORECASTER BEVEN
 
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