000 WTPZ43 KNHC 150845 TCDEP3 TROPICAL STORM CARLOTTA DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032012 200 AM PDT FRI JUN 15 2012 THE INNER CORE CONVECTIVE PATTERN HAS CONTINUED TO IMPROVE...AND A SMALL BUT RAGGED CDO HAS FORMED OVER THE LOW-LEVEL CENTER. THE INITIAL INTENSITY HAS BEEN INCREASED TO 60 KT BASED ON CONSENSUS SATELLITE ESTIMATES OF T3.5/55 KT FROM TAFB AND SAB...AND THE APPEARANCE OF AT LEAST HALF AN EYEWALL IN A 15/0348Z AMSU OVERPASS. THE INITIAL MOTION ESTIMATE IS 320/09 KT. CARLOTTA REMAINS ON THE PREVIOUS FORECAST TRACK. THE MID-LEVEL RIDGE TO THE EAST OF THE CYCLONE IS EXPECTED TO KEEP CARLOTTA MOVING IN A NORTHWESTWARD DIRECTION FOR THE NEXT 24 HOURS OR SO. AFTERWARDS...A BLOCKING RIDGE IS FORECAST TO BUILD TO THE NORTH OF CARLOTTA ACROSS CENTRAL AND NORTHERN MEXICO...WHICH SHOULD GRADUALLY FORCE THE STORM ON A WEST-NORTHWESTWARD TRACK BY 36 HOURS...AND WESTWARD BY 48 HOURS BUT AT A MUCH SLOWER FORWARD SPEED. AT 72 HOURS AND BEYOND...THE BLOCKING RIDGE IS FORECAST BY ALL OF THE MODELS TO BREAK DOWN AND GIVE WAY TO A BROAD TROUGH DROPPING SOUTHWARD FROM THE U.S. SOUTHERN PLAINS AND NORTHWESTERN GULF OF MEXICO...WHICH WILL RESULT IN WEAK STEERING CURRENTS. AS A RESULT...CARLOTTA IS EXPECTED TO MEANDER NEAR OR JUST OFFSHORE OF THE SOUTHERN COAST OF MEXICO DURING DAYS 3-5. THE GLOBAL MODELS ARE IN GOOD AGREEMENT ON THIS DEVELOPING TRACK SCENARIO...ALTHOUGH THE GUIDANCE HAS SHIFTED EASTWARD COMPARED TO PREVIOUS RUNS. HOWEVER...GIVEN THE LACK OF ANY SIGNIFICANT DEEP-LAYER SOUTHERLY OR SOUTHWESTERLY STEERING FLOW THAT WOULD FORCE CARLOTTA INLAND OVER THE HIGH MOUNTAIN RANGE OF SOUTHERN MEXICO...THE OFFICIAL FORECAST TRACK KEEPS THE CENTER OF CARLOTTA JUST OFFSHORE AS INDICATED IN PREVIOUS ADVISORIES. RAPID INTENSIFICATION NOW APPEARS LESS LIKELY GIVEN THE RAGGED AND ELONGATED APPEARANCE OF THE CDO FEATURE ALONG WITH MODEST EASTERLY VERTICAL WIND SHEAR EXPECTED FOR THE NEXT 36 HOURS. HOWEVER...THE CURRENT UPPER-LEVEL OUTFLOW PATTERN AND OTHER FAVORABLE OCEANIC AND ENVIRONMENTAL FACTORS SHOULD ALLOW FOR STEADY STRENGTHENING AT A NORMAL RATE OF AT LEAST ONE T-NUMBER PER DAY...AND THAT EXPECTATION IS REFLECTED IN THE OFFICIAL FORECAST TRACK. IT IS POSSIBLE THAT CARLOTTA COULD PEAK AT 85-90 KT BETWEEN THE 24- AND 36-HOUR FORECAST PERIODS BEFORE WEAKENING BEGINS WHEN THE CYCLONE INTERACTS WITH THE MOUNTAINOUS TERRAIN OF SOUTHERN MEXICO BY 36 HOURS. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE SHIPS...LGEM... HWRF...AND FLORIDA STATE SUPERENSEMBLE MODELS. USERS SHOULD NOT FOCUS ON THE EXACT FORECAST TRACK...AS ANY DEVIATION TO THE NORTH AND EAST OF THE ADVISORY TRACK WOULD BRING THE CENTER OF CARLOTTA ONTO THE COAST OF MEXICO. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 13.2N 95.3W 60 KT 70 MPH 12H 15/1800Z 14.1N 96.1W 70 KT 80 MPH 24H 16/0600Z 15.2N 97.3W 80 KT 90 MPH 36H 16/1800Z 15.9N 98.3W 80 KT 90 MPH...NEAR COAST 48H 17/0600Z 16.3N 99.1W 60 KT 70 MPH...NEAR COAST 72H 18/0600Z 16.5N 99.7W 45 KT 50 MPH...NEAR COAST 96H 19/0600Z 16.2N 99.8W 35 KT 40 MPH...NEAR COAST 120H 20/0600Z 16.0N 99.5W 35 KT 40 MPH...NEAR COAST $$ FORECASTER STEWART