000 WTNT45 KNHC 241457 TCDAT5 TROPICAL STORM MATTHEW DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL152010 1100 AM EDT FRI SEP 24 2010 AN AIR FORCE PLANE INVESTIGATING MATTHEW THIS MORNING FOUND THAT THE TROPICAL CYCLONE HAS NOT BECOME ANY STRONGER. EASTERLY SHEAR HAS KEPT THE LOW-LEVEL CENTER NEAR THE NORTHEAST EDGE OF A ROUND BLOB OF VERY DEEP CONVECTION AS INDICATED BY THE AIR FORCE PLANE AND MICROWAVE DATA. SATELLITE INTENSITY ESTIMATES SUPPORT AN INITIAL INTENSITY OF 45 KNOTS...BUT DATA FROM THE RECONNAISSANCE PLANE SO FAR SUGGEST THAT THIS ESTIMATE COULD BE GENEROUS. MATTHEW ONLY HAS 12 HOURS OR LESS TO STRENGTHEN BEFORE LANDFALL...AND GIVEN THAT THE ENVIRONMENT IS ONLY MARGINALLY FAVORABLE FOR INTENSIFICATION DUE TO SHEAR...THE OFFICIAL FORECAST NO LONGER FORECAST MATTHEW TO BECOME A HURRICANE. THE CYCLONE HAS INCREASED ITS FORWARD SPEED AND THE BEST ESTIMATE OF THE INITIAL MOTION IS TOWARD THE WEST OR 275 DEGREES AT 17 KNOTS. MATTHEW IS EMBEDDED WITHIN A STRONG DEEP EASTERLY FLOW AND THERE IS HIGH CONFIDENCE IN THE FORECAST THAT THE CYCLONE WILL CONTINUE WESTWARD OVER CENTRAL AMERICA FOR THE NEXT DAY OR TWO. BEYOND TWO DAYS...MODELS SHOW DIFFERENT SCENARIOS AND THE FORECAST BECOMES HIGHLY UNCERTAIN. THE MOST LIKELY SCENARIO IS THAT THE MID-LEVEL CENTER CONTINUES WESTWARD AND DISSIPATES...WHILE THE LOW-LEVEL CIRCULATION WEAKENS AND BECOMES PART OF A NEARLY STATIONARY BROAD AREA OF LOW PRESSURE OVER CENTRAL AMERICA. SUCH A WEATHER PATTERN WOULD LIKELY PRODUCE DANGEROUS TORRENTIAL RAINS IN CENTRAL AMERICA OVER THE NEXT FEW DAYS. FORECAST POSITIONS AND MAX WINDS INITIAL 24/1500Z 14.4N 82.2W 45 KT 12HR VT 25/0000Z 14.6N 84.2W 35 KT...INLAND 24HR VT 25/1200Z 15.4N 86.5W 30 KT...INLAND 36HR VT 26/0000Z 16.0N 89.0W 30 KT...INLAND 48HR VT 26/1200Z 17.0N 90.0W 25 KT...INLAND 72HR VT 27/1200Z 18.0N 90.5W 20 KT...POST-TROP/REMNT LOW 96HR VT 28/1200Z 18.5N 90.5W 20 KT...POST-TROP/REMNT LOW 120HR VT 29/1200Z 18.5N 90.5W 20 KT...POST-TROP/REMNT LOW $$ FORECASTER AVILA