000 AXNT20 KNHC 072352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 07 2012 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 24N50W TO 14N49W MOVING W NEAR 15 KT. THE WAVE LIES ON THE WRN SIDE OF AN AREA OF ENHANCED MOISTURE. THE WAVE ALSO LIES ON THE LEADING EDGE OF A LARGE AREA OF SAHARAN DUST THAT EXTENDS EWD TO THE AFRICAN COAST. THE DUST IS SUPPRESSING MOST CONVECTION NEAR THE WAVE EXCEPT FOR A SMALL AREA OF MODERATE CONVECTION FROM 22N-24N BETWEEN 51W-53W. ACTIVE TROPICAL WAVE IS MOVING TOWARDS THE YUCATAN PENINSULA ALONG 22N85W TO 17N88W MOVING W NEAR 15 KT. THE NRN PORTION OF THE WAVE SPLIT FROM IT EARLIER TODAY AND IS NOW ANALYZED AS A SURFACE TROUGH EXTENDING FROM THE NE BAHAMAS AT 27N78W TO 24N82W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THE WAVE LIES ON THE WRN SIDE OF A LARGE SURGE OF DEEP LAYER MOISTURE COVERING THE SE GULF OF MEXICO AND THE WRN CARIBBEAN. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 300 NM E...AND 240 NM W...OF THE AXIS WHICH INCLUDES MUCH OF WRN CUBA...THE YUCATAN PENINSULA...BELIZE...AND NRN GUATEMALA. SIMILAR CONVECTION IS ALSO S OF THE WAVE FROM 12N-16N BETWEEN 81W-88W ACROSS PORTIONS OF NICARAGUA AND HONDURAS. SOME OF THE ACTIVITY ACROSS CUBA IS ALSO ENHANCED BY THE PRESENCE OF A BROAD UPPER LEVEL TROUGH ACROSS THE SRN GULF OF MEXICO. AREAS THAT ARE RECEIVING HEAVY RAINFALL ARE AT RISK FOR LOCALIZED FLOODING AND MUDSLIDES AND SHOULD MONITOR THE ACTIVITY ASSOCIATED WITH THE WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF SENEGAL AT 14N17W TO 8N30W. THE ITCZ BEGINS AT 8N30W AND CONTINUES TO NEAR 7N59W. A WEAK 1011 MB SURFACE LOW IS ANALYZED ALONG THE ITCZ AXIS NEAR 8N40W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MOVING OFF THE COAST OF AFRICA FROM 10N-15N BETWEEN 12W-18W WITH ISOLATED MODERATE CONVECTION FROM 7N-13N BETWEEN 18W-26W. THIS IS LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE. ISOLATED MODERATE CONVECTION IS ALSO FROM 6N-10N BETWEEN 48W-58W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER LEVEL RIDGE COVERS MUCH OF THE ERN CONUS INCLUDING THE NRN GULF OF MEXICO SUPPORTING A WEAK 1019 MB HIGH CENTERED NEAR 29N83W. A SHORTWAVE PERTURBATION ALOFT HAD BEEN SUPPORTING AN AREA OF CONVECTION WITH AN OUTFLOW BOUNDARY THAT HAD BEEN EXTENDING INTO THE GULF...BUT HAS NOW DISSIPATED. HOWEVER...SHOWERS/THUNDERSTORMS CONTINUE TO DOT MUCH OF THE GULF COAST STATES WITH MORE CONCENTRATED ACTIVITY OVER LOUISIANA AND ERN TEXAS. THESE SHOWERS/THUNDERSTORMS ARE LIKELY THE RESULT OF DAYTIME HEATING AND INSTABILITY TYPICAL OF SUMMER. A TROPICAL WAVE APPROACHING THE YUCATAN PENINSULA IS DRAWING MOISTURE ACROSS THE SE GULF SUPPORTING WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS THE YUCATAN PENINSULA AND THE COASTAL WATERS. THE SE GULF ALSO LIES UNDER AN AREA OF DIFFLUENCE ALOFT AROUND A BROAD AND HORIZONTALLY ALIGNED UPPER TROUGH THAT COVERS THE SRN GULF. NO STRONG SHOWERS/THUNDERSTORMS ARE NOTED OVER WATER AT THIS TIME...BUT A FAVORABLE ENVIRONMENT IS THERE. ELSEWHERE ACROSS THE BASIN...SKIES ARE MOSTLY CLEAR WITH MAINLY LIGHT E-SE WINDS. WEAK SURFACE RIDGING IS EXPECTED TO REMAIN OVER THE WEEKEND WHILE MOISTURE ASSOCIATED WITH A TROPICAL WAVE WILL BRING SHOWERS/THUNDERSTORMS TO THE SRN GULF. CARIBBEAN SEA... A TROPICAL WAVE APPROACHING THE YUCATAN PENINSULA IS CAUSING WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS THE WRN CARIBBEAN INCLUDING MUCH OF CUBA...NICARAGUA...HONDURAS...BELIZE...NRN GUATEMALA...AND THE YUCATAN PENINSULA. SEE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. THERE ARE ALSO SHOWERS/THUNDERSTORMS ACROSS COSTA RICA...PANAMA...AND NRN COLOMBIA DUE TO A PORTION OF THE MONSOON TROUGH THAT EXTENDS ACROSS SRN PANAMA TO NRN COLOMBIA. AFTERNOON CONVECTION IS ALSO ACROSS PORTIONS OF ERN CUBA AND HISPANIOLA. ELSEWHERE ACROSS THE BASIN...FAIR WEATHER IS MAINTAINED BY DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE CENTERED NEAR THE NRN LESSER ANTILLES. A WEAK UPPER TROUGH IS ACROSS THE CENTRAL CARIBBEAN BETWEEN THIS UPPER RIDGE AND A SECOND UPPER RIDGE COVERING THE WRN CARIBBEAN. THE UPPER TROUGH IS NOT CAUSING ANY SIGNIFICANT WEATHER. TRADEWIND FLOW OF 15-20 KTS IS PRESENT ACROSS MUCH OF THE BASIN REACHING 25 KTS IN THE CENTRAL CARIBBEAN. EVEN THOUGH THE TROPICAL WAVE WILL EXIT THE CARIBBEAN SHORTLY...MOISTURE WILL LIKELY REMAIN OVER THE WRN PORTION OF THE BASIN FOR AT LEAST THE NEXT 24 HOURS. ATLANTIC OCEAN... DRY AIR ALOFT AROUND A BROAD UPPER LEVEL RIDGE IS PROVIDING FAIR CONDITIONS ACROSS MUCH OF THE WRN ATLC. SHOWERS/THUNDERSTORMS ARE IMPACTING THE ERN BAHAMAS DUE TO A SURFACE TROUGH THAT ORIGINATED AS A SPLIT PORTION OF THE TROPICAL WAVE IN THE WRN CARIBBEAN. THE TROUGH EXTENDS FROM THE NE BAHAMAS NEAR 27N78W TO 24N82W. AN UPPER LEVEL TROUGH IS TO THE E ALONG 53W...BUT IS NOT CAUSING ANY ACTIVE WEATHER. AN UPPER LEVEL RIDGE TO THE N IN THE NRN ATLC IS SUPPORTING AN AZORES HIGH NEAR 43N33W...WHICH IS PROVIDING FAIR CONDITIONS ACROSS MUCH OF THE ATLC. UPPER LEVEL RIDGING ALSO COVERS THE TROPICAL ATLC CENTERED NEAR 20N40W. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE A LARGE AREA OF DUST EXTENDING FROM THE AFRICAN COAST TO THE TROPICAL WAVE IN THE TROPICAL ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON