Tropical Storm BORIS

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TROPICAL STORM BORIS DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022008
200 PM PDT FRI JUN 27 2008

BORIS CONTINUES TO PRODUCE A LARGE AREA OF CONVECTION WITH CLOUD TOP
TEMPERATURES COLDER THAN -80C...WITH THE LOW-LEVEL CENTER NEAR THE
NORTHERN EDGE OF THE CONVECTION.  SATELLITE INTENSITY ESTIMATES
FROM TAFB AND SAB ARE 45 KT...AND THAT IS THE INITIAL INTENSITY FOR
THIS ADVISORY.  DATA FROM A QUIKSCAT OVERPASS NEAR 13Z SHOWS THAT
BORIS HAS A BROAD INNER CIRCULATION...WITH THE MAXIMUM WINDS
LOCATED ABOUT 60-75 N MI FROM THE CENTER.  THE CIRRUS OUTFLOW
REMAINS GOOD IN THE SOUTHWESTERN SEMICIRCLE AND POOR ELSEWHERE.  

BORIS HAS JOGGED TO THE RIGHT OVER THE PAST SEVERAL HOURS AND THE
INITIAL MOTION IS NOW 315/8.  THIS HAS RESULTED IN THE FORECAST
TRACK BEING SHIFTED NORTHWARD FROM THE PREVIOUS PACKAGE...BUT
OTHERWISE THERE IS LITTLE CHANGE IN THE TRACK FORECAST PHILOSOPHY. 
BORIS SHOULD GRADUALLY TURN WESTWARD ON THE SOUTH SIDE OF A MID/
UPPER-LEVEL RIDGE BUILDING WESTWARD FROM MEXICO DURING THE NEXT 48
HR WITH A GENERALLY WESTWARD MOTION THEREAFTER.  THE NEW FORECAST
TRACK IS DOWN THE MIDDLE OF THE DYNAMICAL MODEL GUIDANCE IN BEST
OVERALL AGREEMENT WITH THE HWRF.  IT SHOULD BE NOTED THAT THE TRACK
OF BORIS COULD BE INFLUENCED BY INTERACTION WITH OTHER TROPICAL
CYCLONE...THE NEWLY-DEVELOPED TROPICAL DEPRESSION THREE-E TO THE
WEST EARLY IN THE FORECAST PERIOD AND ANOTHER CYCLONE FORECAST BY
THE LARGE-SCALE MODELS EAST OF BORIS LATE IN THE PERIOD.  THE
FORECAST TRACK CURRENTLY DOES NOT TAKE THESE POSSIBLE INTERACTIONS
INTO ACCOUNT.
 
BORIS IS CURRENTLY IN AN ENVIRONMENT OF LIGHT TO MODERATE
EAST-NORTHEASTERLY VERTICAL WIND SHEAR.  AN INVERTED UPPER-LEVEL
TROUGH APPROACHING FROM THE EAST IS EXPECTED TO INCREASE THE
SHEAR...WITH THE LARGE-SCALE MODELS NOW SHOWING AN EARLIER ONSET
AND LONGER DURATION OF THE SHEAR THAN IN THEIR PREVIOUS RUNS.  THIS
IS LIKELY TO HAVE A GREATER IMPACT ON BORIS THAN PREVIOUSLY
FORECAST.  BASED ON THE CURRENT STRENGTHENING TREND...THE NEW
INTENSITY FORECAST NOW CALLS FOR BORIS TO REACH A PEAK INTENSITY OF
60 KT BEFORE THE SHEAR INCREASES.  AFTER 24-36 HR...BORIS SHOULD
GRADUALLY WEAKEN DUE TO A COMBINATION OF CONTINUED SHEAR AND SLOWLY
DECREASING SEA SURFACE TEMPERATURES.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/2100Z 13.3N 109.8W    45 KT
 12HR VT     28/0600Z 13.7N 110.8W    55 KT
 24HR VT     28/1800Z 14.0N 112.4W    60 KT
 36HR VT     29/0600Z 14.2N 114.0W    60 KT
 48HR VT     29/1800Z 14.2N 115.5W    55 KT
 72HR VT     30/1800Z 14.0N 118.5W    45 KT
 96HR VT     01/1800Z 14.0N 121.5W    40 KT
120HR VT     02/1800Z 14.0N 124.5W    35 KT
 
$$
FORECASTER BEVEN
 
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