000 WTNT44 KNHC 110837 TCDAT4 TROPICAL STORM MARIA DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142011 500 AM AST SUN SEP 11 2011 ALTHOUGH SHEARED...FINALLY MARIA LOOKS LIKE A TROPICAL STORM ON SATELLITE. DEEP CONVECTION HAS INCREASED AND THE UPPER-LEVEL OUTFLOW IS A LITTLE BETTER ESTABLISHED. IN FACT...BOTH TAFB AND SAB INTENSITY ESTIMATES ARE UP TO 3.5 ON THE DVORAK SCALE. AN AIR FORCE PLANE WAS IN MARIA UNTIL AROUND 0600 UTC...AND FOUND THAT THE CIRCULATION WAS BETTER DEFINED WITH THE STRONGEST WINDS IN THE NORTHEASTERN QUADRANT ONLY...AND A MINIMUM CENTRAL PRESSURE OF 1004 MB. SURFACE OBSERVATIONS FROM THE NORTHEASTERN CARIBBEAN ISLANDS ALSO INDICATE THAT THE CYCLONE IS BECOMING BETTER ORGANIZED. THE INITIAL INTENSITY IS NOW 50 KNOTS. HAVING SAID THAT...WATER VAPOR IMAGES STILL SHOW THE STRONG UPPER-LEVEL TROUGH TO THE NORTHWEST OF MARIA PRODUCING SHEAR OVER THE CYCLONE. GLOBAL MODELS HAVE BEEN WEAKENING THIS TROUGH...BUT THIS FEATURE HAS BEEN RESILIENT AND IT HAS NOT GONE YET. ON THIS BASIS...THE OFFICIAL FORECAST CALLS FOR NO SIGNIFICANT CHANGE IN STRENGTH IN THE NEXT 24 TO 36 HOURS...WITH THE POSSIBILITY OF SLIGHT INTENSIFICATION THEREAFTER. THIS FOLLOWS THE LGEM MODEL WHICH APPEARS TO BE THE MOST CONSERVATIVE...BUT IN GENERAL MOST OF THE GUIDANCE MAKES MARIA A HURRICANE OVER THE WATERS BETWEEN BERMUDA AND THE BAHAMAS. MARIA IS MOVING TOWARD THE NORTHWEST OR 315 DEGREES AT 11 KNOTS. THE CYCLONE IS EXPECTED TO BE TRAPPED BETWEEN THE ATLANTIC SUBTROPICAL HIGH AND A TROUGH ALONG THE EASTERN UNITED STATES. THIS IS THE SAME STEERING PATTERN THAT IN GENERAL HAS PREVAILED THIS SEASON... AND MOST LIKELY WILL FORCE MARIA TO MOVE ON A NORTHWEST AND THEN NORTHWARD TRACK FOR THE NEXT TWO TO THREE DAYS. THE CYCLONE SHOULD THEN ACCELERATE TOWARD THE NORTHEAST AS IT BECOMES EMBEDDED WITHIN THE MID-LATITUDE FLOW. THE NHC FORECAST LIES IN MIDDLE OF THE TRACK GUIDANCE WHICH IT IS IN REMARKABLY GOOD AGREEMENT BRINGING MARIA WELL NORTH OF THE BAHAMAS...AND THEN RECURVING IT BETWEEN THE UNITED STATES EAST COAST AND BERMUDA. FORECAST POSITIONS AND MAX WINDS INIT 11/0900Z 19.0N 63.7W 50 KT 60 MPH 12H 11/1800Z 20.0N 65.0W 50 KT 60 MPH 24H 12/0600Z 21.5N 66.5W 50 KT 60 MPH 36H 12/1800Z 22.5N 67.5W 55 KT 65 MPH 48H 13/0600Z 23.5N 68.5W 60 KT 70 MPH 72H 14/0600Z 27.0N 70.0W 65 KT 75 MPH 96H 15/0600Z 33.5N 68.0W 65 KT 75 MPH 120H 16/0600Z 43.0N 58.0W 60 KT 70 MPH $$ FORECASTER AVILA