000 AXNT20 KNHC 201047 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SAT SEP 20 2008 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1015 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 30W S OF 17N MOVING W NEAR 10 KT. THIS WAVE IS BENEATH AN UPPER LEVEL RIDGE AND NO CONVECTION IS NOTED WITH THIS FEATURE. A TROPICAL WAVE IS ALONG 52W S OF 19N MOVING W NEAR 10 KT. AN UPPER LEVEL ANTICYCLONE IS CENTERED NEAR 14N57W E OF THE WAVE AXIS AND IS GENERATING SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 14N-19N BETWEEN 51W-60W. A TROPICAL WAVE IS ALONG 65W S OF 19N MOVING W NEAR 5-10 KT. THIS WAVE IS EMBEDDED WITHIN A BROAD AREA OF LOW PRESSURE ACROSS THE ERN CARIBBEAN AND IS GENERATING A LARGE AREA OF CLOUDINESS WITH SCATTERED SHOWERS ACROSS THE LESSER ANTILLES. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 14N-16N BETWEEN 63W-66W. SIMILAR CONVECTION IS FROM 9N-12N BETWEEN 62W-65W. A TROPICAL WAVE IS ALONG 77W S OF 19N MOVING W NEAR 10-15 KT. SATELLITE IMAGERY INDICATES AN INVERTED-V SIGNATURE ACROSS THE WRN CARIBBEAN WITH SCATTERED MODERATE CONVECTION WITHIN 100 NM OF A LINE FROM THE WINDWARD PASSAGE NEAR 20N74W SW TO THE NICARAGUA AND COSTA RICA BORDER NEAR 11N84W. ...THE ITCZ... ITCZ AXIS IS ANALYZED ALONG 11N14W 6N20W 7N27W 8N32W 8N49W 9N54W 11N64. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 1N-9N BETWEEN 21W-27W. A SIMILAR AREA OF CONVECTION IS ACROSS THE SE CARIBBEAN SEA FROM 9N-12N BETWEEN 61W-64W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING IS ACROSS MUCH OF THE GULF THIS MORNING WITH WESTERLY UPPER FLOW DOMINATING FROM NRN MEXICO TO THE FLORIDA PENINSULA. A SURFACE TROUGH EXTENDS FROM 27N93W TO 22N97W ACROSS THE WRN GULF AND COVERS MUCH OF THE GULF WITH A BROAD AREA OF MULTILAYERED CLOUDINESS. EMBEDDED ISOLATED SHOWERS ARE POSSIBLE N OF 21N AND W OF 88W. WITH A DIFFLUENT PATTERN ALOFT IN PLACE ACROSS THE SW GULF...SCATTERED MODERATE TO STRONG CONVECTION IS ACROSS THE SRN BAY OF CAMPECHE AND SRN MEXICO FROM 16N-20N BETWEEN 90W-95W. A SURFACE RIDGE IS ACROSS THE SE CONUS AND EXTENDS WEAK RIDGING INTO THE NE GULF. AN AMPLE AMOUNT OF UPPER LEVEL MOISTURE IS NOTED OVER THE GULF REGION WHILE SUBSIDENCE AND DRY AIR IS ACROSS THE FLORIDA PENINSULA AND THE FAR NW GULF WATERS. CARIBBEAN SEA... TWO TROPICAL WAVES ARE ACROSS THE CARIBBEAN SEA...SEE THE TROPICAL WAVE SECTION FOR MORE DETAILS. WIDESPREAD CLOUDINESS AND SHOWERS ARE OVER PUERTO RICO AND THE LESSER ANTILLES WITH THE NEARBY TROPICAL WAVE ALONG 65W. CLUSTERS OF SCATTERED SHOWERS/TSTMS ARE ACROSS THE WRN CARIBBEAN FROM 10N-20N BETWEEN 74W-83W IN ASSOCIATION WITH THE TROPICAL WAVE ALONG 75W...WHICH INCLUDES THE WINDWARD PASSAGE...ERN HISPANIOLA AND JAMAICA. AN UPPER LEVEL TROUGH EXTENDS FROM THE FAR W ATLC ACROSS CENTRAL CUBA INTO THE WRN CARIBBEAN TO NORTH OF PANAMA AND IS PROVIDING UPPER LEVEL DIFFLUENCE E OF 83W TO FURTHER ENHANCE THE SHOWER AND TSTM ACTIVITY. UPPER LEVEL RIDGING EXTENDS FROM THE SRN GULF OF MEXICO ACROSS THE NW CARIBBEAN W OF 83W PROVIDING UPPER LEVEL DIFFLUENCE TO INDUCE SCATTERED SHOWERS ACROSS THE GULF OF HONDURAS AND INLAND CENTRAL AMERICA. SIMILAR SCATTERED SHOWERS AND TSTMS ARE ACROSS THE SW CARIBBEAN S OF 13N BETWEEN 74W-84W DUE TO THE CLOSE PROXIMITY OF THE ITCZ. MODERATE TRADE WINDS ARE NOTED ACROSS THE BASIN THIS MORNING. ATLANTIC OCEAN... A SURFACE TROUGH EXTENDS SW FROM A 1014 MB LOW CENTERED NEAR 32N73W TO THE CENTRAL BAHAMAS NEAR 24N77W. SCATTERED SHOWERS ARE WITHIN 90 NM EAST OF THE TROUGH. THIS ACTIVITY IS BEING ENHANCED BY SOUTHWESTERLY FLOW AND UPPER LEVEL DIFFLUENCE EAST OF AN UPPER LEVEL TROUGH ALONG THE ERN SEABOARD OF THE US. THIS UPPER TROUGH DIGS INTO THE CARIBBEAN SEA ACROSS ERN CUBA. FARTHER EAST...A BROAD UPPER-LEVEL LOW IS SPINNING OVER THE CENTRAL ATLC NEAR 26N46W. AN UPPER LEVEL HIGH CENTERED OVER THE CAPE VERDE ISLANDS NEAR 17N25W EXTENDS W TO 38W ENVELOPING MUCH OF THE ERN ATLC. AT THE SURFACE...A RIDGE OF HIGH PRESSURE COVERS THE DISCUSSION AREA N OF 20N AND E OF 65W ANCHORED ON A SERIES OF SURFACE HIGHS CENTERED N OF THE REGION. $$ HUFFMAN