000 AXNT20 KNHC 232358 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU SEP 23 2010 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... TROPICAL DEPRESSION FIFTEEN WAS UPGRADED TO TROPICAL STORM MATTHEW AT 23/2100 UTC. TROPICAL STORM MATTHEW IS CENTERED NEAR 14.2N 77.7W AT 24/0000 UTC OR ABOUT 330 NM E OF PUERTO CABEZAS NICARAGUA MOVING W AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1005 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT5/WTNT35 KNHC AND THE FULL FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC FOR MORE DETAILS. MATTHEW HAS A LARGE ENVELOPE OF DEEP CONVECTION WITH THE OUTFLOW WELL DEFINED TO THE N AND THE S. SCATTERED MODERATE WITH EMBEDDED CLUSTERS OF SCATTERED STRONG CONVECTION COVERS THE AREA FROM 11N-17N BETWEEN 73W-81W. TROPICAL DEPRESSION LISA WAS UPGRADED TO TROPICAL STORM AT 23/2100 UTC. TROPICAL STORM LISA IS CENTERED NEAR 17.5N 28.6W AT 23/2100 UTC OR ABOUT 280 NM WNW OF THE CAPE VERDE ISLANDS NEAR STATIONARY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/ WTNT24 KNHC FOR MORE DETAILS. SATELLITE IMAGERY SHOWS A SMALL BUT WELL DEFINED SYSTEM BUT THE DEEP CONVECTION IS MOSTLY TO THE NE OF THE LOW LEVEL CENTER. CLUSTERS OF SCATTERED MODERATE/ STRONG CONVECTION ARE WITHIN 60 NM OF LINE FROM THE CENTER NE TO 20N26W. ...ITCZ... THE ITCZ IS ANALYZED SW OF T.S. LISA NEAR 11N32W 14N49W 12N63W. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 4N-10N BETWEEN 27W-38W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER RIDGE COVERS THE NW GULF W OF A LINE FROM VERMILION BAY LOUISIANA TO TAMPICO MEXICO ANCHORED OVER THE MEXICO/TEXAS BORDER NEAR 30N102W AND IS PROVIDING DRY STABLE AIR WITH NE FLOW ALOFT OVER THE NW GULF. A SECOND UPPER RIDGE COVERS THE E GULF E OF A LINE FROM PENSACOLA FLORIDA TO THE YUCATAN PENINSULA NEAR 21N88W ANCHORED IN THE NW CARIBBEAN. THIS UPPER RIDGE IS PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO HEAVY SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS E OF A LINE FROM 27N85W TO THE YUCATAN NEAR 21N90W INCLUDING S FLORIDA AND THE FLORIDA STRAITS/KEYS. THESE UPPER RIDGES ARE INDUCING AN UPPER TROUGH THAT EXTENDS FROM SE LOUISIANA THROUGH AN UPPER LOW NEAR 27N91W TO NEAR VERACRUZ MEXICO. THIS UPPER TROUGH IS SUPPORTING A WEAK SURFACE TROUGH THAT EXTENDS FROM 24N96W TO THE BAY OF CAMPECHE NEAR 19N94W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 120 NM OF LINE FROM 27N89W TO INLAND OVER MEXICO NEAR TAMPICO. A SURFACE RIDGE COVERS THE N GULF N OF 25N E OF 96W ANCHORED IN THE W ATLC. ISOLATED SHOWERS ARE POSSIBLE ACROSS THE REMAINDER OF THE GULF WATERS AND MOVING FROM THE W ATLC ACROSS THE FLORIDA PENINSULA AND N TO INLAND OVER THE GULF COAST W OF MISSISSIPPI/ALABAMA BORDER TO TEXAS. CARIBBEAN SEA... THE MAIN CONCERN THIS EVENING IS NEWLY FORMED TROPICAL STORM MATTHEW...SEE SURFACE FEATURES ABOVE. BROAD UPPER RIDGE COVERS THE CARIBBEAN W OF 73W ANCHORED JUST S OF CUBA NEAR 20N80W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO HEAVY SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS N OF 18N W OF 82W TO OVER CUBA AND THE YUCATAN PENINSULA INCLUDING THE YUCATAN CHANNEL. JUST TO E IS AN UPPER LOW CENTERED ALONG THE NE COAST OF THE DOMINICAN REPUBLIC NEAR 20N69W COVERING THE E CARIBBEAN N OF 15N BETWEEN 65W-73W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE ALONG THE BASE OF THE UPPER TROUGH N OF 12N BETWEEN 65W-69W TO OVER PUERTO RICO AND THE VIRGIN ISLANDS. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS COVER THE REMAINDER OF THE W CARIBBEAN FROM 11N-17N W OF 81W LEAVING ONLY A SMALL AREA OF CLEAR SKIES THIS EVENING...N OF 18N BETWEEN 73W-80W AND OVER THE LESSER ANTILLES. ATLANTIC OCEAN... A CONCERN FOR THE FAR E ATLC IS TROPICAL STORM LISA...SEE SPECIAL FEATURES ABOVE. THE UPPER RIDGE ANCHORED IN THE NW CARIBBEAN EXTENDS AN UPPER RIDGE AXIS NE ALONG 25N80W TO 30N75W PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED TO HEAVY SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS S OF 28N W OF 78W TO INLAND OVER THE FLORIDA PENINSULA AND THROUGH THE FLORIDA STRAITS. JUST TO SE IS AN UPPER LOW CENTERED ALONG THE NE COAST OF THE DOMINICAN REPUBLIC NEAR 20N69W COVERING THE W ATLC S OF 27N BETWEEN 63W-70W. BROAD UPPER RIDGE ANCHORED NEAR 26N51W DOMINATES THE CENTRAL ATLC WITH MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR. A CUTOFF UPPER LOW IS CENTERED NEAR 32N36W SUPPORTING A WEAK 1012 MB SURFACE LOW NEAR 32N28W AND A SURFACE TROUGH EXTENDING FROM 31N37W TO 25N41W WITH ISOLATED SHOWERS WITHIN 75 NM E OF THE SURFACE TROUGH. A PAIR OF UPPER LOWS ARE OVER THE FAR E ATLC CENTERED NEAR 31N23W AND 23N25W WITH A LARGE UPPER RIDGE ANCHORED INLAND OVER AFRICA. THIS SCENARIO IS DRAWING TROPICAL MOISTURE NE FROM T.S. LISA WITH ISOLATED SHOWERS WITHIN 120 NM OF LINE FROM 20N26W TO 30N23W INCLUDING THE WESTERN MOST CANARY ISLANDS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ PAW