000 WTPZ43 KNHC 141446 TCDEP3 TROPICAL STORM CARLOTTA DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032012 800 AM PDT THU JUN 14 2012 DURING THE PAST SEVERAL HOURS...CARLOTTA HAS DEVELOPED A CENTRAL CONVECTIVE FEATURE SURROUNDED BY A COMPLEX OF OUTER RAINBANDS. SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND 35 KT FROM SAB...AND A RECENT AMSU INTENSITY ESTIMATE FROM CIMSS IS 50 KT. THE INITIAL INTENSITY IS RAISED TO 40 KT...AND THIS COULD BE CONSERVATIVE. THE CIRRUS OUTFLOW IS GOOD IN THE NORTH AND SOUTH QUADRANTS. THE INITIAL MOTION IS 325/8. CARLOTTA IS CURRENTLY BEING STEERED BY A MID/UPPER-LEVEL RIDGE OVER THE WESTERN CARIBBEAN AND A SMALL UPPER-LEVEL TROUGH SEEN IN WATER VAPOR IMAGERY TO THE WEST OF THE CYCLONE. THE DYNAMICAL MODELS FORECAST THIS PATTERN TO PERSIST FOR 48 HR OR SO...FOLLOWED BY A MID/UPPER-LEVEL RIDGE BUILDING OVER NORTHERN MEXICO. THIS EVOLUTION SHOULD CAUSE CARLOTTA TO MOVE GENERALLY NORTHWESTWARD FOR 36-48 HR...FOLLOWED BY A MORE WESTWARD MOTION. THE TRACK GUIDANCE HAS SHIFTED WESTWARD SINCE THE LAST ADVISORY AND IS IN FAIR AGREEMENT THAT CARLOTTA SHOULD TRACK NEAR OR ALONG THE COAST OF MEXICO FROM 36-72 HR. THE NEW FORECAST TRACK IS ALSO SHIFTED TO THE WEST...BUT LIES ON THE EASTERN SIDE OF THE GUIDANCE ENVELOPE. AFTER 72 HR...THE MEXICAN RIDGE IS FORECAST TO WEAKEN AS A MID/UPPER-LEVEL TROUGH DEVELOPS OVER THE GULF OF MEXICO. THIS SHOULD LEAVE THE CYCLONE IN AN AREA OF WEAK STEERING CURRENTS WITH A VERY SLOW MOTION. CARLOTTA IS CURRENTLY IN AN ENVIRONMENT OF LIGHT VERTICAL WIND SHEAR AND OVER 30C SEA SURFACE TEMPERATURES. THESE CONDITIONS ARE FAVORABLE FOR STRENGTHENING...AND THE INTENSITY FORECAST NOW CALLS FOR CARLOTTA TO REACH AN INTENSITY OF 80 KT IN 48 HR. THE RAPID INTENSIFICATION INDEX OF THE SHIPS MODEL SHOWS A 50-60 PERCENT CHANCE OF 25-KT STRENGTHENING DURING THE NEXT 24 HR...AND ABOUT A 25 PERCENT CHANCE OF 40-KT STRENGTHENING...SO THE EARLY PART OF THE CURRENT FORECAST COULD BE CONSERVATIVE. AFTER 48 HR...THE INTENSITY IS LIKELY TO BE CONTROLLED BY HOW CLOSE THE CENTER IS TO THE COAST. IF CARLOTTA MOVES INLAND...IT COULD DISSIPATE OVER THE MOUNTAINS OF MEXICO. EVEN IF IT STAYS OFFSHORE...IT IS EXPECTED TO BE CLOSE ENOUGH TO INTERACT WITH THE MOUNTAINS AND WEAKEN AS SHOWN BY THE GFDL AND HWRF MODELS...AND THAT IS THE SCENARIO USED IN THE INTENSITY FORECAST. USERS ARE AGAIN REMINDED NOT TO FOCUS ON THE EXACT FORECAST TRACK AS TYPICAL NHC FORECAST ERRORS AT 48 AND 72 HOURS ARE 80-110 N MI... AND ANY DEVIATION TO THE NORTH AND EAST OF THE FORECAST TRACK WOULD BRING THE CENTER OF CARLOTTA ONTO THE COAST OF MEXICO. FORECAST POSITIONS AND MAX WINDS INIT 14/1500Z 10.9N 93.6W 40 KT 45 MPH 12H 15/0000Z 11.9N 94.5W 50 KT 60 MPH 24H 15/1200Z 13.3N 95.6W 60 KT 70 MPH 36H 16/0000Z 14.6N 96.7W 75 KT 85 MPH 48H 16/1200Z 15.6N 97.7W 80 KT 90 MPH...NEAR COAST 72H 17/1200Z 16.5N 99.5W 60 KT 70 MPH...NEAR COAST 96H 18/1200Z 16.5N 100.0W 45 KT 50 MPH...NEAR COAST 120H 19/1200Z 16.0N 100.0W 45 KT 50 MPH $$ FORECASTER BEVEN