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| #378612 (Received by flhurricane at: 4:35 AM 25.Sep.2010) TCDAT5 TROPICAL STORM MATTHEW DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 500 AM EDT SAT SEP 25 2010 SATELLITE IMAGERY SHOWS LITTLE CHANGE IN THE STRUCTURE OF MATTHEW DURING THE PAST SEVERAL HOURS...WITH A LARGE AREA OF CONVECTION WITH TOPS COLDER THAN -80C CONTINUING TO THE WEST AND SOUTHWEST OF THE CENTER. LA CEIBA HONDURAS RECENTLY REPORTED A PRESSURE OF 1002.7 MB...SUGGESTING THAT THE CENTRAL PRESSURE IS STILL BELOW 1000 MB. BASED ON THESE FACTORS...THE INITIAL INTENSITY IS HELD AT 45 KT...WITH THOSE WINDS LIKELY OCCURRING OVER WATER TO THE NORTH OF THE CENTER. THE CENTER IS NOT EASY TO FIND...AND THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 285/14. THE TRACK FORECAST REASONING AGAIN REMAINS UNCHANGED...AS A STRONG MID-LEVEL RIDGE OVER THE GULF OF MEXICO WILL GENERALLY STEER MATTHEW WEST-NORTHWESTWARD FOR THE NEXT 36 HOURS OR SO. BY THE TIME MATTHEW MOVES INTO GUATEMALA AND EASTERN MEXICO...THE STEERING FLOW WILL WEAKEN AS THE RIDGE BREAKS DOWN...AND A SLOW MOTION TOWARD THE WEST-NORTHWEST OR NORTHWEST IS EXPECTED UNTIL DISSIPATION. THE NEW TRACK FORECAST IS AGAIN SHIFTED A LITTLE TO THE NORTH AND NOW LIES NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE. MATTHEW COULD STRENGTHEN A LITTLE AS THE CENTER CROSSES THE GULF OF HONDURAS...BUT IT IS UNLIKELY TO BE OVER WATER LONG ENOUGH FOR SIGNIFICANT STRENGTHENING. THE CYCLONE SHOULD WEAKEN STEADILY AFTER LANDFALL IN BELIZE AND BECOME A REMNANT LOW BY 48 HR. AFTER 72 HR...THE REMNANTS ARE EXPECTED TO BE ABSORBED INTO A LARGE MONSOON LOW PRESSURE AREA FORECAST TO FORM OVER CENTRAL AMERICA AND THE ADJACENT WATERS. THE LARGEST THREAT FROM MATTHEW IS HEAVY RAINS. IT SHOULD BE NOTED THAT A HEAVY RAIN THREAT WILL CONTINUE AFTER MATTHEW DISSIPATES DUE TO THE MONSOONAL FLOW ACROSS CENTRAL AMERICA. FORECAST POSITIONS AND MAX WINDS INITIAL 25/0900Z 15.7N 86.3W 45 KT 12HR VT 25/1800Z 16.2N 88.0W 45 KT...OVER WATER 24HR VT 26/0600Z 16.8N 89.8W 35 KT...INLAND 36HR VT 26/1800Z 17.2N 90.8W 30 KT...INLAND 48HR VT 27/0600Z 17.5N 91.4W 25 KT...POST-TROP/REMNT LOW 72HR VT 28/0600Z 18.0N 92.0W 20 KT...POST-TROP/REMNT LOW 96HR VT 29/0600Z...DISSIPATED $$ FORECASTER BEVEN |
