000
WTPZ42 KNHC 281438
TCDEP2
TROPICAL STORM BORIS DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022008
800 AM PDT SAT JUN 28 2008
 
OVERNIGHT MICROWAVE AND FIRST-LIGHT VISIBLE IMAGES SHOW THAT THE
LOW-LEVEL CENTER OF BORIS IS PARTLY EXPOSED TO THE NORTH OF A
CONVECTIVE MASS WITH TOPS COLDER THAN -80C.  THIS IS DUE TO
INCREASING NORTHEASTERLY VERTICAL WIND SHEAR SEEN IN WATER VAPOR
IMAGERY AND ANALYSES FROM CIMSS AT THE UNIVERSITY OF WISCONSIN. 
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN 45 KT...AND
THAT REMAINS THE INITIAL INTENSITY.  THE CIRRUS OUTFLOW REMAINS
FAIR TO GOOD IN THE SOUTHWESTERN SEMICIRCLE BUT IS RESTRICTED
ELSEWHERE.

THE INITIAL MOTION IS 290/11...SOMEWHAT FASTER THAN PREVIOUSLY.  THE
LARGE SCALE MODELS ARE IN GOOD AGREEMENT THAT A MID/UPPER-LEVEL
RIDGE WILL BUILD WESTWARD NORTH OF BORIS THROUGH THE FORECAST
PERIOD...WHICH SHOULD CAUSE A GENERAL WESTWARD MOTION.  HOWEVER...
THE MODEL TRACK FORECASTS FOR BORIS SHOW SOME SPREAD DUE TO
INTERACTION WITH OTHER TROPICAL CYCLONES BOTH REAL...TROPICAL STORM
CRISTINA...AND POTENTIAL...THE LARGE BUT WEAK DISTURBANCE EAST OF
BORIS.  AT THIS TIME...BORIS AND CRISTINA APPEAR TO BE TOO FAR
APART FOR SIGNIFICANT INTERACTION.  ALSO...THE EASTERN DISTURBANCE
APPEARS TO BE TOO WEAK TO CAUSE BORIS TO MOVE EASTWARD NEAR THE END
OF THE FORECAST PERIOD AS INDICATED BY THE ECMWF.  BASED ON THIS...
THE NEW FORECAST TRACK CALLS FOR A GENERALLY WESTWARD MOTION UNDER
THE RIDGE FOR THE NEXT 5 DAYS.  THE NEW TRACK IS A BIT FASTER THAN
THE PREVIOUS FORECAST AND IS IN BEST AGREEMENT WITH THE CONSENSUS
MODELS.

WITH THE SHEAR INCREASING...IT APPEARS THAT BORIS HAS REACHED PEAK
INTENSITY.  THE LARGE-SCALE MODELS FORECAST THE SHEAR TO PERSIST
FOR 36-72 HR BEFORE DECREASING...AND BY THAT TIME BORIS WILL BE
MOVING OVER COOLER SEA SURFACE TEMPERATURES.  BASED ON THIS...THE
CYCLONE IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY FOR 24
HR...FOLLOWED BY A GRADUAL WEAKENING THROUGH THE REST OF THE
FORECAST PERIOD.  THE NEW INTENSITY FORECAST IS IN BEST AGREEMENT
WITH THE SHIPS MODEL.  IT SHOULD BE NOTED THAT THE GFDL AND HWRF
MODELS BOTH FORECAST BORIS TO BECOME A HURRICANE...WHICH LOOKS
UNLIKELY AT THE MOMENT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      28/1500Z 14.5N 113.0W    45 KT
 12HR VT     29/0000Z 14.6N 114.3W    45 KT
 24HR VT     29/1200Z 14.8N 115.9W    45 KT
 36HR VT     30/0000Z 14.9N 117.5W    40 KT
 48HR VT     30/1200Z 15.0N 119.1W    40 KT
 72HR VT     01/1200Z 15.0N 122.5W    35 KT
 96HR VT     02/1200Z 15.0N 126.0W    30 KT
120HR VT     03/1200Z 15.0N 128.5W    25 KT
 
$$
FORECASTER BEVEN