000 AXNT20 KNHC 140400 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE OCT 13 2009 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 2200 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 15N56W TO 8N57W MOVING W NEAR 15 KT. THE WAVE COINCIDES WITH A DEEP LAYER MOISTURE MAXIMUM OBSERVED IN TOTAL PRECIPITABLE WATER IMAGERY. AN UPPER LEVEL LOW NEAR 16N55W CONTINUES TO PROVIDE A SHEARED ENVIRONMENT. DUE TO THE SHEAR...ISOLATED MODERATE CONVECTION IS MAINLY E OF THE WAVE AXIS FROM 10N-14N BETWEEN 51W-59W. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 10N12W 9N24W 7N36W 10N44W 10N56W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG 10N26W TO 6N26W. A SECOND EMBEDDED SURFACE TROUGH IS EXTENDS FROM 13N44W 7N46W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 4N-7N BETWEEN 20W-23W...FROM 5N-10N BETWEEN 23W-28W NEAR THE TROUGH ALONG 26W...AND FROM 4N-8N BETWEEN 29W-34W. SIMILAR CONVECTION IS NEAR THE SECOND SURFACE TROUGH FROM 5N-12N BETWEEN 44W-49W...AND FROM 7N-11N BETWEEN 49W-55W. ...DISCUSSION... GULF OF MEXICO... A DYING STATIONARY FRONT LINES THE NE GULF OF MEXICO COASTLINE FROM NEAR THE FLORIDA BIG BEND AT 29N83W TO SE LOUISIANA NEAR NEW ORLEANS AT 30N89W CONTINUING AS A WARM FRONT INLAND OVER LOUISIANA. ISOLATED SHOWERS/THUNDERSTORMS ARE NW OF LINE FROM 26N97W TO 30N88W. THESE SHOWERS/THUNDERSTORMS ARE SUPPORTED BY DIFFLUENT FLOW ALOFT AROUND THE NW PERIPHERY OF AN UPPER LEVEL RIDGE CENTERED OVER THE CENTRAL GULF NEAR 26N90W WITH AN AXIS EXTENDING ALONG 24N ACROSS S FLORIDA AND IN THE WRN ATLC. A SMALL CLUSTER OF SHOWERS/THUNDERSTORMS IS NOTED IN THE CENTRAL GULF NEAR 26N87W. THE REMAINDER OF THE GULF IS EXPERIENCING GENERALLY FAIR WEATHER THIS EVENING AS A WEAK SURFACE RIDGE EXTENDS S OF THE FRONT FROM NE TO SW TO THE BAY OF CAMPECHE. EXPECT THE SURFACE RIDGE TO PERSIST THROUGH THU...FOLLOWED BY A COLD FRONT PUSHING OFF THE NW COAST LATE THU. CARIBBEAN SEA... THE CARIBBEAN REMAINS FAIRLY CALM UNDER THE INFLUENCE OF A LARGE MASS OF DRY STABLE AIR ALOFT EVIDENT ON WATER VAPOR IMAGERY. AN UPPER LEVEL RIDGE COVERING THE GULF OF MEXICO AND THE WRN ATLC IS PROVIDING E TO NE UPPER LEVEL FLOW OVER THE BASIN. MODERATE TRADE WINDS ARE ACROSS THE CENTRAL AND WRN CARIBBEAN WITH STRONGER WINDS IN THE E CARIBBEAN AND NEAR THE COAST OF COLOMBIA. LOW-LEVEL SPEED CONVERGENCE IS SUPPORTING A FEW ISOLATED SHOWERS SHOWERS/THUNDERSTORMS ACROSS PORTIONS OF THE NRN AND NW PORTIONS OF THE CARIBBEAN NW OF A LINE FROM PUERTO RICO NEAR 18N67W TO NICARAGUA NEAR 15N83W. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SW CARIBBEAN S OF 11N W OF 78W DUE TO SURFACE CONVERGENCE NEAR THE E PACIFIC ITCZ. EXPECT A TROPICAL WAVE CURRENTLY NEAR 57W TO ENTER THE E CARIBBEAN TOMORROW. ATLANTIC OCEAN... A COLD FRONT ENTERS THE DISCUSSION AREA NEAR 32N72W CONTINUING TO THE N FLORIDA COAST NEAR 29N81W CONTINUING AS A DYING STATIONARY FRONT ACROSS THE NRN GULF COAST. THE FRONT IS SUPPORTED BY A SHORTWAVE UPPER LEVEL TROUGH N OF THE AREA. MOST OF THE ASSOCIATED SHOWER ACTIVITY HAS SPED AHEAD OF THE FRONTAL SYSTEM AND DIED OUT. HOWEVER...DIFFLUENT FLOW ALOFT TO THE E OF THE UPPER LEVEL SHORTWAVE TROUGH IS SUPPORTING ISOLATED SHOWERS OVER THE AREA N OF 27N BETWEEN 43W-68W. FARTHER E...A 1011 MB LOW IS ANALYZED NEAR 31N35W. A SURFACE TROUGH EXTENDS FROM THE LOW CENTER ALONG 30N33W 28N34W 25N46W. SCATTERED SHOWERS ARE N OF 27N BETWEEN 30W-32W. ISOLATED SHOWERS ARE FROM 28N-30N BETWEEN 35W-37W...AND ARE POSSIBLE ALONG THE TROUGH AXIS. A SECOND SURFACE TROUGH EXTENDS FROM 32N23W ALONG 29N25W TO 27N28W. SCATTERED SHOWERS ARE WITHIN 120 NM E OF THE TROUGH AXIS. AN UPPER LEVEL TROUGH BETWEEN 15W-40W IS SUPPORTING THE SURFACE LOW AND SURFACE TROUGHS. A WEAK 1015 MB HIGH IS CENTERED NEAR 25N25W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE CENTERED OVER WRN AFRICA IS SUPPORTING SHOWER ACTIVITY ALONG THE ERN ITCZ. A SECOND UPPER LEVEL RIDGE WITH AXIS ALONG 26W IS SUPPORTING SHOWER ACTIVITY ALONG THE WRN ITCZ. $$ WALTON