000 AXNT20 KNHC 052338 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT THU JUL 05 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 2245 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 22N36W TO 12N33W MOVING W NEAR 20 KT. THE WAVE LIES ON THE WRN SIDE OF A SURGE OF DEEP LAYER MOISTURE. THE WAVE ALSO LIES ON THE LEADING EDGE OF A LARGE AREA OF SAHARAN DUST THAT EXTENDS EWD TO THE AFRICAN COAST. THE DRY DUST E OF THE WAVE IS LIMITING CONVECTION NEAR THE WAVE. CURRENTLY NO DEEP CONVECTION IS ASSOCIATED WITH THE AXIS. ACTIVE TROPICAL WAVE IS MOVING INTO CENTRAL CARIBBEAN ALONG 22N70W TO 15N75W MOVING W NEAR 20 KT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THE WAVE LIES ON THE WRN SIDE OF A LARGE SURGE OF DEEP LAYER MOISTURE COVERING THE ERN CARIBBEAN AND AREAS TO THE N IN THE ATLC. SATELLITE IMAGERY ALSO SHOWS LOW-LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 19N-25N BETWEEN 61W-68W. SIMILAR ACTIVITY IS FROM 17N-24N BETWEEN 68W-74W...INCLUDING MUCH OF HISPANIOLA...AND FROM 16N-19N BETWEEN 74W-79W...INCLUDING JAMAICA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF GUINEA-BISSAU AT 12N16W CONTINUING ACROSS ATLC WATERS TO 8N37W. THE ITCZ BEGINS AT 8N37W TO 8N62W. SCATTERED MODERATE CONVECTION IS OFF THE W COAST OF AFRICA FROM 7N-11N E OF 18W. ...DISCUSSION... GULF OF MEXICO... WEAK SURFACE RIDGING REMAINS ACROSS THE GULF OF MEXICO TODAY CENTERED AROUND A 1017 MB HIGH S OF LOUISIANA NEAR 28N91W...AS OF 2100 UTC. THE RIDGE IS SUPPORTED BY A BROAD UPPER LEVEL RIDGE COVERING THE NRN GULF. WEAK UPPER TROUGHING IS OVER BOTH THE SE GULF...AND SW GULF...WITH WEAK RIDGING OVER THE S CENTRAL GULF. MOSTLY DRY AIR ALOFT IS EMBEDDED WITHIN THE UPPER LEVEL PATTERN...WHICH IS HELPING MAINTAIN FAIR CONDITIONS ACROSS THE MAJORITY OF THE BASIN. A FEW ISOLATED SHOWERS ARE ACROSS THE SE GULF EMBEDDED WITHIN THE LIGHT ANTI-CYCLONIC SURFACE FLOW AROUND THE RIDGE. ISOLATED SHOWERS/THUNDERSTORMS ALSO DOT MUCH OF THE GULF COAST STATES LIKELY DUE TO DAYTIME HEATING AND INSTABILITY. SIMILAR ACTIVITY IS ACROSS THE YUCATAN PENINSULA AND MEXICO. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. CARIBBEAN SEA... WHILE THE NW CARIBBEAN IS UNDER MOSTLY FAIR CONDITIONS DUE TO DRY AIR ALOFT...THE SW CARIBBEAN IS COVERED IN MOIST CONDITIONS. SHOWERS/THUNDERSTORMS COVER THE AREA S OF 15N BETWEEN 82W-86W...AND S OF 12N BETWEEN 77W-82W...INCLUDING MUCH OF NICARAGUA...COSTA RICA...AND PANAMA. SOME OF THIS ACTIVITY IS INFLUENCED BY THE MONSOON TROUGH EXTENDING THROUGH PANAMA TO NRN COLOMBIA. THIS AREA ALSO LIES UNDERNEATH AN UPPER OF DIFFLUENCE ALOFT AROUND THE BASE OF A BROAD UPPER LEVEL TROUGH COVERING THE NW CARIBBEAN...CUBA...AND THE BAHAMAS. THE UPPER TROUGH IS ALSO ENHANCING CONVECTION NEAR A TROPICAL WAVE IN THE CENTRAL CARIBBEAN. SEE TROPICAL WAVE SECTION ABOVE. THE COMBINATION OF THE WAVE AND THE UPPER TROUGH IS SUPPORTING SHOWERS/THUNDERSTORMS ACROSS MUCH OF HISPANIOLA AND JAMAICA. DRY AIR ALOFT IS BEGINNING TO MAKE ITS WAY ACROSS THE FAR ERN CARIBBEAN BEHIND THE SURGE OF MOISTURE ASSOCIATED WITH THE WAVE PROVIDING FAIR CONDITIONS ACROSS THE LESSER ANTILLES. EXPECT THE WAVE TO CONTINUE TO PUSH WWD DRAWING MOISTURE INTO THE CENTRAL AND WRN CARIBBEAN. ATLANTIC OCEAN... DRY AIR ALOFT OVER THE SW NORTH ATLC IS PROVIDING MOSTLY FAIR CONDITIONS ACROSS THE CENTRAL AND WRN BAHAMAS. A TROPICAL WAVE MOVING THROUGH THE CENTRAL CARIBBEAN IS DRAWING MOISTURE ACROSS THE ERN BAHAMAS WITH SHOWERS/THUNDERSTORMS S OF 25N BETWEEN 73W. SEE TROPICAL WAVE SECTION FOR MORE DETAILS. THE WAVE ALSO LIES UNDERNEATH THE DIFFLUENT SIDE OF AN UPPER LEVEL TROUGH COVERING THE NW CARIBBEAN AND THE BAHAMAS...WHICH IS HELPING ENHANCE THE LARGE AREA OF ACTIVITY. A NARROW UPPER LEVEL TROUGH ALONG 56W CONTINUES TO SUPPORT A WEAK SURFACE TROUGH ALONG 28N49W TO 25N50W. THE REMAINDER OF THE CENTRAL AND ERN ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1033 MB AZORES HIGH. THE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE OVER THE FAR NRN ATLC...AS WELL AS AN UPPER LEVEL RIDGE ACROSS THE TROPICAL ATLC CENTERED NEAR 20N38W. A BROAD UPPER LOW IS CENTERED BETWEEN THE TWO RIDGES NEAR 43N39W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY INDICATE ANOTHER LARGE AREA OF DUST EXTENDS E OF THE TROPICAL WAVE IN THE TROPICAL ATLC. DUST IS ALSO PRESENT W OF THE WAVE TO THE ERN CARIBBEAN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON