000 WTPZ42 KNHC 272037 TCDEP2 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