000 AXNT20 KNHC 310555 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN JUL 31 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0545 UTC. ...SPECIAL FEATURES... A TROPICAL WAVE IS MOVING ACROSS THE EASTERN TROPICAL ATLC ANALYZED FROM 20N55W TO A 1008 MB LOW CENTERED IN THE SOUTHERN EXTENT OF THE WAVE NEAR 13N50W. THIS WAVE IS EMBEDDED WITHIN A BROAD AREA OF DEEP MOISTURE ON TPW PRODUCT. BROAD CYCLONIC FLOW IS WELL OBSERVED IN THE LOW LEVEL CLOUD PATTERN ON SATELLITE IMAGERY. THE CIRCULATION HAS BECOME BETTER ORGANIZED OVER THE PAST 6-12 HOURS. THUS...THIS SYSTEM IS CLOSE TO BECOMING A TROPICAL DEPRESSION WITH A THREAT TO THE LESSER ANTILLES AND PUERTO RICO. TROPICAL CYCLONE WATCHES OR WARNINGS WOULD LIKELY BE REQUIRED FOR PARTS OF THESE GROUP OF ISLANDS. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM AS IT MOVES WNW AT 15 TO 20 KT. AN AIR FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THIS DISTURBANCE LATER THIS AFTERNOON. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 8N-16N BETWEEN 44W-57W. ...TROPICAL WAVES... A TROPICAL WAVE IN THE ATLC IS ANALYZED FROM 24N36W TO 11N35W MOVING W AT 15 KT. THIS WAVE IS LOCATED ALONG THE LEADING EDGE OF A WEAK LOW LEVEL MOISTURE SURGE DEPICTED ON TOTAL PRECIPITABLE WATER PRODUCT. WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL INVERTED TROUGH IS IN THE VICINITY OF THE WAVE. NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT THIS TIME. A TROPICAL WAVE IS MOVING ACROSS CENTRAL AMERICA AND THE YUCATAN PENINSULA...ANALYZED FROM 23N87W TO 12N85W MOVING W AT 10-15 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF DEEP MOISTURE THAT COVERS MOST OF THE NW CARIBBEAN. BROAD LOW LEVEL CLOUD CYCLONIC CURVATURE IS OBSERVED ON SATELLITE DATA. SCATTERED HEAVY SHOWERS AND THUNDERSTORMS ARE AFFECTING THE W AND NW CARIBBEAN WATERS W OF 80W...WITH THE STRONGEST CONVECTION NOTICED WITHIN 70-130 NM OFF THE COAST OF NORTHERN NICARAGUA AND EASTERN HONDURAS. LOCALLY HEAVY RAINFALL TO PORTIONS OF CENTRAL AMERICA ARE EXPECTED THROUGH OVER THE NEXT 24 HOURS. A TROPICAL WAVE CURRENTLY OVER WEST AFRICA IS EXPECTED TO ENTER THE EAST ATLC WATERS OVER THE NEXT 24-36 HOURS. THE CONVECTION ASSOCIATED TO THIS WAVE IS ALREADY OVER THE EAST TROPICAL ATLC DISCUSSED BELOW. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS GUINEA-BISSAU IN WEST AFRICA ENTERING THE ATLC ALONG 12N16W TO 9N19W TO 11N26W. THE ITCZ CONTINUES FROM THIS POINT ALONG 12N33W 8N40W TO 12N49W...THEN RESUMES S OF THE SPECIAL FEATURE TROPICAL WAVE NEAR 11N51W TO THE COAST OF GUYANA IN SOUTH AMERICA NEAR 7N58W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 140 NM ON EITHER SIDE OF THE ITCZ AXIS BETWEEN 38W-50W. THIS AREA OF CONVECTION IS ALSO ASSOCIATED TO THE SPECIAL FEATURE TROPICAL WAVE. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 7N-13N E OF 22W ASSOCIATED TO THE NEXT TROPICAL WAVE THAT WILL BE ENTERING THE EAST ATLC OVER THE NEXT 24-36 HOURS. ...DISCUSSION... GULF OF MEXICO... EASTERLY FLOW ALOFT IS OBSERVED ACROSS THE GULF WITH MODERATE SUBSIDENCE NOTICED ON WATER VAPOR IMAGERY. THIS FLOW TURNS ANTICYCLONIC AROUND AN UPPER RIDGE CENTERED OVER THE SE CONUS... AND SUPPORTS A 1018 MB HIGH OVER THE NE GULF NEAR 28N87W. THIS PATTERN IS KEEPING FAIR WEATHER CONDITIONS ACROSS THE DISCUSSION AREA N OF 23N. A TROPICAL WAVE IS MOVING OVER CENTRAL AMERICA AND THE YUCATAN PENINSULA ALONG 87W S OF 23N. THIS SYSTEM IS BRINGING SCATTERED SHOWERS AND THUNDERSTORMS TO THE S AND SE GULF WATERS INCLUDING THE YUCATAN CHANNEL AND BAY OF CAMPECHE S OF 23N. AS THE WAVE TRACKS W...MORE CONVECTION IS EXPECTED OVER THE BAY OF CAMPECHE DURING THE NEXT 24-36 HOURS. CARIBBEAN SEA... A TROPICAL WAVE MOVES ACROSS CENTRAL AMERICA AND THE YUCATAN PENINSULA. HOWEVER...SCATTERED HEAVY SHOWERS AND THUNDERSTORMS LAG BEHIND THE WAVE...AFFECTING THE W AND NW CARIBBEAN WATERS W OF 80W. THIS AREA OF CONVECTION AND MOISTURE WILL CONTINUE TO MOVE OVER CENTRAL AMERICA TERRAIN OVER THE NEXT 24 HOURS WITH THE POTENTIAL FOR FLASH FLOODING ACROSS THE AREA. THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN GENERATING SIMILAR CONVECTION TO THE COASTAL WATERS WITHIN 70 NM OF COSTA RICA...PANAMA...AND COLOMBIA. A WEAK UPPER LEVEL TROUGH MOVES ACROSS THE N CENTRAL CARIBBEAN SUPPORTING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OVER THE SOUTHERN COASTAL WATERS OF HISPANIOLA N OF 15N AND OVER THE WINDWARD PASSAGE BETWEEN HAITI AND CUBA N OF 18N. THE REMAINDER OF THE CARIBBEAN BASIN IS EXPERIENCING FAIR WEATHER CONDITIONS WITH ISOLATED MODERATE TO HEAVY SHOWERS EMBEDDED IN THE MODERATE EASTERLY TRADE WINDS. ATLANTIC OCEAN... A WEAK SURFACE TROUGH IS OVER THE W ATLC ANALYZED FROM 34N68W TO 29N71W GENERATING SCATTERED WEAK SHOWERS WITHIN 20 NM ON EITHER SIDE OF THE AXIS. THE REMAINDER OF THE DISCUSSION AREA EXPERIENCES FAIR WEATHER INFLUENCED BY A STRONG 1031 MB HIGH PRESSURE SYSTEM ANCHORED WEST OF THE AZORES NEAR 39N35W AND EXTENDING A RIDGE AXIS SW TO THE BAHAMAS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA