000 AXNT20 KNHC 120542 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE JUL 12 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 0500 UTC. ...TROPICAL WAVES... TROPICAL WAVE IN THE WRN TRPCL ATLC EXTENDS FROM NEAR 15N54W TO 8N58W MOVING WNW NEAR 15 KT. WAVE CONTINUES TO PRECEDE A SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY ALSO INDICATES LOW LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS CONFIRMED BY AN ASCAT SCATTEROMETER PASS FROM 0038 UTC. SCATTERED MODERATE/STRONG CONVECTION IS FROM 11N-13N BETWEEN 54W-59W. TROPICAL WAVE IN THE WRN CARIBBEAN EXTENDS JUST E OF NICARAGUA FROM 18N83W TO 12N83W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF ENHANCED MOISTURE ACROSS THE WRN CARIBBEAN. THE WAVE LIES UNDER DIFFLUENT FLOW ALOFT WHICH IS HELPING ENHANCE CONVECTION. IT IS DIFFICULT TO DETERMINE WHAT CONVECTION IS CAUSED BY THE WAVE...THE UPPER LEVEL INFLUENCE...AND ALSO THE MONSOON TROUGH TO THE S OF THE WAVE. NUMEROUS STRONG CONVECTION IS FROM 8N-13N BETWEEN 82W-84W IMPACTING COSTA RICA. SIMILAR ACTIVITY IS FROM 11N-15N BETWEEN 86W-90W IMPACTING HONDURAS. SCATTERED MODERATE/STRONG CONVECTION IS ELSEWHERE S OF 19N BETWEEN 80W-89W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN AT 23N ALONG 22N11W 14N21W 8N34W. THE ITCZ CONTINUES FROM 8N34W ALONG 6N45W 5N57W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM S OF THE AXIS BETWEEN 26W-34W. ...DISCUSSION... GULF OF MEXICO... LATE AFTERNOON SHOWER/THUNDERSTORM ACTIVITY HAS NOW DIED DOWN ACROSS MUCH OF THE GULF OF MEXICO WHERE WEAK SURFACE RIDGING PREVAILS CENTERED AROUND A 1018 MB HIGH OFF THE W CENTRAL COAST OF FLORIDA NEAR 27N84W...AS 0F 0300 UTC. A WEAK SURFACE TROUGH EXTENDS ACROSS THE FLORIDA PANHANDLE FROM 31N85W TO 29N87W SUPPORTING A FEW REMNANT SHOWERS FROM 27N-29N BETWEEN 87W-89W. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SRN BAY OF CAMPECHE S OF 20N BETWEEN 92W-95W. THE TROPICAL WAVE PREVIOUSLY IN THE BAY OF CAMPECHE HAS NOW DISSIPATED OVER MEXICO. THE REMAINDER OF THE BASIN IS UNDER FAIR WEATHER AND LIGHT WINDS. ALOFT...AN UPPER LEVEL RIDGE COVERS THE NRN GULF N OF 25N CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH COVERS THE SW GULF EXTENDING FROM SRN MEXICO NEAR 18N94W TO 26N89W. WATER VAPOR IMAGERY INDICATES DRY AIR IS WRAPPING AROUND THE SRN EXTENT OF THE UPPER RIDGE WHICH IS FURTHER SUPPORTING THE FAIR WEATHER. TOTAL PRECIPITABLE WATER IMAGERY STILL INDICATES ENHANCED MOISTURE IS ACROSS THE NRN GULF. WITH DAYTIME HEATING THIS WILL LIKELY MEAN SHOWERS/THUNDERSTORMS WILL POP UP LATER IN THE AFTERNOON TODAY. SHOWER/THUNDERSTORM ACTIVITY WILL ALSO LIKELY INCREASE OVER THE SE GULF AS MOISTURE FROM A TROPICAL WAVE IN THE WRN CARIBBEAN FLOWS INTO THE BASIN AS THE WAVE MOVES WWD. WEAK SURFACE RIDGING WILL CONTINUE OVER THE NRN GULF. CARIBBEAN SEA... MOIST SWLY AND DIFFLUENT FLOW ALOFT COVERS THE NW CARIBBEAN AROUND THE ERN SIDE OF INVERTED UPPER TROUGH OVER THE SRN GULF OF MEXICO...AND A NARROW UPPER RIDGE EXTENDING FROM PANAMA TO NEAR 17N83W. THIS AREA OF DIFFLUENCE LIES OVER A TROPICAL WAVE ALONG 83W. THIS COMBINATION IS PRODUCING SHOWERS/THUNDERSTORMS ACROSS THE WRN CARIBBEAN S OF 19N BETWEEN 80W-90W WITH THE STRONGEST ACTIVITY ALONG THE WAVE AXIS....ACROSS COSTA RICA...AND ACROSS WRN HONDURAS AND EL SALVADOR. SOME OF THE ACTIVITY OVER COSTA RICA IS BEING INFLUENCED BY THE MONSOON TROUGH EXTENDING FROM THE ERN PACIFIC ACROSS NRN COSTA RICA TO NRN COLOMBIA WHERE THERE ARE ALSO SHOWERS/THUNDERSTORMS FROM 5N-11N BETWEEN 72W-80W. THE REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR CONDITIONS WITH 15-20 KT ELY TRADEWIND FLOW. A FEW ISOLATED SHOWERS ARE NOTED IN THE NE CARIBBEAN N OF 15N E OF 70W WITH A CLUSTER OF SHOWERS/THUNDERSTORMS OVER HAITI FROM 18N-19N BETWEEN 71W-74W. THIS AREA IS ALSO IN AN AREA OF MODERATE MOISTURE INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY. ALOFT...A HORIZONTALLY ALIGNED UPPER LEVEL TROUGH IS ACROSS THE NRN CARIBBEAN WITH AXIS ALONG 18N. EXPECT SHOWER/THUNDERSTORM ACTIVITY TO PERSIST ACROSS THE WRN CARIBBEAN AS MOISTURE ASSOCIATED WITH THE TROPICAL WAVE REMAINS. ALSO...MUCH OF CENTRAL AMERICA AND SRN MEXICO IS AT THREAT FOR PROLONGED HEAVY RAINFALL THROUGHOUT THE END OF THE WEEK WHICH WILL INCREASE THE CHANCE FOR DEADLY FLOODING AND MUDSLIDES. MODEL GUIDANCE INDICATES THE MONSOON TROUGH WILL STRENGTHEN AND LIFT FARTHER N PLACING ABNORMALLY STRONG WLY FLOW AGAINST CENTRAL AMERICA AND SRN MEXICO. THIS W-SW FLOW WILL DRAW SIGNIFICANT TROPICAL MOISTURE ACROSS THESE AREAS. COMBINED WITH OROGRAPHIC LIFT DUE TO MOUNTAINS THIS CREATES A FORMULA TO EQUAL HEAVY PRECIPITATION. THESE AREAS SHOULD MONITOR THE SITUATION OVER THE NEXT FEW DAYS AND STAY TUNED FOR UPDATES ON THIS POSSIBLY DANGEROUS SCENARIO. ATLANTIC OCEAN... SURFACE RIDGING DOMINATES THE MAJORITY OF THE ATLC TONIGHT ANCHORED BY A 1029 MB HIGH NEAR 36N37W PROVIDING FAIR CONDITIONS BASIN-WIDE. ALOFT AN UPPER LEVEL RIDGE COVERS THE WRN ATLC CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH IS TO THE E ALONG 53W. A SHORTWAVE UPPER TROUGH EXTENDS OFF THE MAIN TROUGH EXTENDING TO THE NW BAHAMAS ALONG 26N. THIS IS PRODUCING SOME UPPER LEVEL CLOUDS FROM 21N-26N. A FEW ISOLATED SHOWERS ARE ALSO FROM 26N-31N BETWEEN 51W-60W. UPPER LEVEL RIDGING COVERS MUCH OF THE ERN ATLC CENTERED NEAR 35N33W. AN UPPER LEVEL TROUGH COVERS THE FAR ERN ATLC EXTENDING ACROSS SPAIN TO THE CANARY ISLANDS. ACROSS THE TROPICAL ATLC S OF 25N...AN UPPER LEVEL RIDGE IS CENTERED OVER THE SRN WINDWARD ISLANDS NEAR 13N61W. AN UPPER LEVEL LOW IS CENTERED NEAR 23N34W...AND AN UPPER LEVEL RIDGE IS CENTERED OFF THE W COAST OF AFRICA NEAR 18N18W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON 000 AXNT20 KNHC 120542 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE JUL 12 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 0500 UTC. ...TROPICAL WAVES... TROPICAL WAVE IN THE WRN TRPCL ATLC EXTENDS FROM NEAR 15N54W TO 8N58W MOVING WNW NEAR 15 KT. WAVE CONTINUES TO PRECEDE A SURGE OF DEEP LAYER MOISTURE EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SATELLITE IMAGERY ALSO INDICATES LOW LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS CONFIRMED BY AN ASCAT SCATTEROMETER PASS FROM 0038 UTC. SCATTERED MODERATE/STRONG CONVECTION IS FROM 11N-13N BETWEEN 54W-59W. TROPICAL WAVE IN THE WRN CARIBBEAN EXTENDS JUST E OF NICARAGUA FROM 18N83W TO 12N83W MOVING W 10-15 KT. WAVE IS EMBEDDED WITHIN A BROAD AREA OF ENHANCED MOISTURE ACROSS THE WRN CARIBBEAN. THE WAVE LIES UNDER DIFFLUENT FLOW ALOFT WHICH IS HELPING ENHANCE CONVECTION. IT IS DIFFICULT TO DETERMINE WHAT CONVECTION IS CAUSED BY THE WAVE...THE UPPER LEVEL INFLUENCE...AND ALSO THE MONSOON TROUGH TO THE S OF THE WAVE. NUMEROUS STRONG CONVECTION IS FROM 8N-13N BETWEEN 82W-84W IMPACTING COSTA RICA. SIMILAR ACTIVITY IS FROM 11N-15N BETWEEN 86W-90W IMPACTING HONDURAS. SCATTERED MODERATE/STRONG CONVECTION IS ELSEWHERE S OF 19N BETWEEN 80W-89W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA FROM THE PRIME MERIDIAN AT 23N ALONG 22N11W 14N21W 8N34W. THE ITCZ CONTINUES FROM 8N34W ALONG 6N45W 5N57W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150 NM S OF THE AXIS BETWEEN 26W-34W. ...DISCUSSION... GULF OF MEXICO... LATE AFTERNOON SHOWER/THUNDERSTORM ACTIVITY HAS NOW DIED DOWN ACROSS MUCH OF THE GULF OF MEXICO WHERE WEAK SURFACE RIDGING PREVAILS CENTERED AROUND A 1018 MB HIGH OFF THE W CENTRAL COAST OF FLORIDA NEAR 27N84W...AS 0F 0300 UTC. A WEAK SURFACE TROUGH EXTENDS ACROSS THE FLORIDA PANHANDLE FROM 31N85W TO 29N87W SUPPORTING A FEW REMNANT SHOWERS FROM 27N-29N BETWEEN 87W-89W. A FEW ISOLATED SHOWERS/THUNDERSTORMS ARE ALSO IN THE SRN BAY OF CAMPECHE S OF 20N BETWEEN 92W-95W. THE TROPICAL WAVE PREVIOUSLY IN THE BAY OF CAMPECHE HAS NOW DISSIPATED OVER MEXICO. THE REMAINDER OF THE BASIN IS UNDER FAIR WEATHER AND LIGHT WINDS. ALOFT...AN UPPER LEVEL RIDGE COVERS THE NRN GULF N OF 25N CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH COVERS THE SW GULF EXTENDING FROM SRN MEXICO NEAR 18N94W TO 26N89W. WATER VAPOR IMAGERY INDICATES DRY AIR IS WRAPPING AROUND THE SRN EXTENT OF THE UPPER RIDGE WHICH IS FURTHER SUPPORTING THE FAIR WEATHER. TOTAL PRECIPITABLE WATER IMAGERY STILL INDICATES ENHANCED MOISTURE IS ACROSS THE NRN GULF. WITH DAYTIME HEATING THIS WILL LIKELY MEAN SHOWERS/THUNDERSTORMS WILL POP UP LATER IN THE AFTERNOON TODAY. SHOWER/THUNDERSTORM ACTIVITY WILL ALSO LIKELY INCREASE OVER THE SE GULF AS MOISTURE FROM A TROPICAL WAVE IN THE WRN CARIBBEAN FLOWS INTO THE BASIN AS THE WAVE MOVES WWD. WEAK SURFACE RIDGING WILL CONTINUE OVER THE NRN GULF. CARIBBEAN SEA... MOIST SWLY AND DIFFLUENT FLOW ALOFT COVERS THE NW CARIBBEAN AROUND THE ERN SIDE OF INVERTED UPPER TROUGH OVER THE SRN GULF OF MEXICO...AND A NARROW UPPER RIDGE EXTENDING FROM PANAMA TO NEAR 17N83W. THIS AREA OF DIFFLUENCE LIES OVER A TROPICAL WAVE ALONG 83W. THIS COMBINATION IS PRODUCING SHOWERS/THUNDERSTORMS ACROSS THE WRN CARIBBEAN S OF 19N BETWEEN 80W-90W WITH THE STRONGEST ACTIVITY ALONG THE WAVE AXIS....ACROSS COSTA RICA...AND ACROSS WRN HONDURAS AND EL SALVADOR. SOME OF THE ACTIVITY OVER COSTA RICA IS BEING INFLUENCED BY THE MONSOON TROUGH EXTENDING FROM THE ERN PACIFIC ACROSS NRN COSTA RICA TO NRN COLOMBIA WHERE THERE ARE ALSO SHOWERS/THUNDERSTORMS FROM 5N-11N BETWEEN 72W-80W. THE REMAINDER OF THE BASIN IS UNDER MOSTLY FAIR CONDITIONS WITH 15-20 KT ELY TRADEWIND FLOW. A FEW ISOLATED SHOWERS ARE NOTED IN THE NE CARIBBEAN N OF 15N E OF 70W WITH A CLUSTER OF SHOWERS/THUNDERSTORMS OVER HAITI FROM 18N-19N BETWEEN 71W-74W. THIS AREA IS ALSO IN AN AREA OF MODERATE MOISTURE INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY. ALOFT...A HORIZONTALLY ALIGNED UPPER LEVEL TROUGH IS ACROSS THE NRN CARIBBEAN WITH AXIS ALONG 18N. EXPECT SHOWER/THUNDERSTORM ACTIVITY TO PERSIST ACROSS THE WRN CARIBBEAN AS MOISTURE ASSOCIATED WITH THE TROPICAL WAVE REMAINS. ALSO...MUCH OF CENTRAL AMERICA AND SRN MEXICO IS AT THREAT FOR PROLONGED HEAVY RAINFALL THROUGHOUT THE END OF THE WEEK WHICH WILL INCREASE THE CHANCE FOR DEADLY FLOODING AND MUDSLIDES. MODEL GUIDANCE INDICATES THE MONSOON TROUGH WILL STRENGTHEN AND LIFT FARTHER N PLACING ABNORMALLY STRONG WLY FLOW AGAINST CENTRAL AMERICA AND SRN MEXICO. THIS W-SW FLOW WILL DRAW SIGNIFICANT TROPICAL MOISTURE ACROSS THESE AREAS. COMBINED WITH OROGRAPHIC LIFT DUE TO MOUNTAINS THIS CREATES A FORMULA TO EQUAL HEAVY PRECIPITATION. THESE AREAS SHOULD MONITOR THE SITUATION OVER THE NEXT FEW DAYS AND STAY TUNED FOR UPDATES ON THIS POSSIBLY DANGEROUS SCENARIO. ATLANTIC OCEAN... SURFACE RIDGING DOMINATES THE MAJORITY OF THE ATLC TONIGHT ANCHORED BY A 1029 MB HIGH NEAR 36N37W PROVIDING FAIR CONDITIONS BASIN-WIDE. ALOFT AN UPPER LEVEL RIDGE COVERS THE WRN ATLC CENTERED OVER NRN ALABAMA. AN UPPER LEVEL TROUGH IS TO THE E ALONG 53W. A SHORTWAVE UPPER TROUGH EXTENDS OFF THE MAIN TROUGH EXTENDING TO THE NW BAHAMAS ALONG 26N. THIS IS PRODUCING SOME UPPER LEVEL CLOUDS FROM 21N-26N. A FEW ISOLATED SHOWERS ARE ALSO FROM 26N-31N BETWEEN 51W-60W. UPPER LEVEL RIDGING COVERS MUCH OF THE ERN ATLC CENTERED NEAR 35N33W. AN UPPER LEVEL TROUGH COVERS THE FAR ERN ATLC EXTENDING ACROSS SPAIN TO THE CANARY ISLANDS. ACROSS THE TROPICAL ATLC S OF 25N...AN UPPER LEVEL RIDGE IS CENTERED OVER THE SRN WINDWARD ISLANDS NEAR 13N61W. AN UPPER LEVEL LOW IS CENTERED NEAR 23N34W...AND AN UPPER LEVEL RIDGE IS CENTERED OFF THE W COAST OF AFRICA NEAR 18N18W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON