000 AXNT20 KNHC 210000 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE JUL 20 2010 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2350 UTC... ...SPECIAL FEATURES... AN AREA OF DISTURBED WEATHER REMAINS ACROSS HISPANIOLA...PUERTO RICO...AND NORTHERN LEEWARD ISLANDS ASSOCIATED WITH A TROPICAL WAVE THAT HAS NOW MOVED OVER EASTERN CUBA. SEE THE TROPICAL WAVE SECTION FOR MORE DETAILS ABOUT THE WAVE. A SURFACE TROUGH IS LEFT IN ITS WAKE EXTENDING FROM 22N67W TO 16N66W. STRONG SURFACE CONVERGENCE NEAR THE TROUGH ALONG WITH DIFFLUENCE ALOFT ARE ENHANCING SCATTERED MODERATE TO STRONG CONVECTION FROM 15N-23N BETWEEN 60W-70W. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE FAVORABLE FOR TROPICAL CYCLONE FORMATION AS THE SYSTEM MOVES WEST-NORTHWESTWARD AT ABOUT 10 MPH DURING THE NEXT DAY OR SO. LOCALLY HEAVY RAINFALL AND GUSTY WINDS WILL LIKELY CONTINUE TO AFFECT THE NORTHERN LEEWARD ISLANDS ISLANDS...PUERTO RICO... HISPANIOLA...EASTERN CUBA...THE TURKS AND CAICOS ISLANDS...AND THE BAHAMAS DURING THE NEXT COUPLE OF DAYS. THE HEAVY RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES IN MOUNTAINOUS AREAS WHERE TERRAIN HAS BECOME SATURATED. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 36W/37W S OF 25N MOVING W 15-20 KT. SATELLITE IMAGERY INDICATES CLEAR LOW-LEVEL CYCLONIC FLOW ABOUT THE WAVE AXIS WITH AN INVERTED-V STRUCTURE. A SURGE OF DEEP LAYER MOISTURE IS ALSO PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED WEAK CONVECTION IS FROM 20N TO 30N BETWEEN 35W AND 42W. TROPICAL WAVE IS ACROSS EASTERN CUBA ALONG 75W S OF 21N MOVING W NEAR 15 KT. MID-LEVEL CYCLONIC FLOW IS IN THE VICINITY OF THE WAVE AXIS. THIS WAVE PASSED OVER PUERTO RICO AND THE DOMINICAN REPUBLIC OVER THE PAST DAY OR SO...PRODUCING SIGNIFICANT CONVECTION AS IT INTERACTED WITH AN UPPER LEVEL LOW. THIS CONVECTION REMAINS OVER THOSE AREAS AND IS NOW ASSOCIATED WITH A SURFACE TROUGH. SEE SPECIAL FEATURES ABOVE. THE WAVE IS NOW ENHANCING ISOLATED MODERATE/STRONG CONVECTION WITHIN 90 NM EITHER SIDE OF THE AXIS. TROPICAL WAVE IS IN THE CENTRAL GULF AND ACROSS THE YUCATAN PENINSULA ALONG 89W S OF 28N TO NORTHERN GUATEMALA MOVING W NEAR 10 KT. WAVE LIES EMBEDDED WITHIN A LARGE AREA OF DEEP LAYER MOISTURE THAT IS MOVING ACROSS THE NW CARIBBEAN AND CENTRAL AMERICA. MID-LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS INDICATED BY VISIBLE SATELLITE IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 17N-25N BETWEEN 76W-91W...INCLUDING INLAND PORTIONS OF CUBA AND THE YUCATAN PENINSULA. TROPICAL WAVE IS OVER THE FAR SW GULF OF MEXICO EXTENDING FROM 23N96W TO 17N94W MOVING W NEAR 8 KT. WAVE LIES EMBEDDED WITHIN A MAXIMUM IN DEEP LAYER MOISTURE THAT COVERS THE WRN GULF EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS S OF 22N W OF 93W ACROSS THE WESTERN BAY OF CAMPECHE. THIS WAVE IS EXPECTED TO WEAKEN AS IT MOVES OVER HIGHER TERRAIN IN MEXICO. ...ITCZ... THE ITCZ AXIS IS ANALYZED FROM THE WESTERN AFRICAN COASTLINE OF GUINEA NEAR 10N14W...WESTWARD ALONG 8N20W 10N30W 8N40W 9N50W 10N60W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS WITHIN 180 NM ON EITHER SIDE OF THE ITCZ AXIS BETWEEN 14W AND 26W. SCATTERED WEAK CONVECTION IS WITHIN 100 NM ON EITHER SIDE OF THE ITCZ WEST OF 26W. ...DISCUSSION... GULF OF MEXICO... TWO TROPICAL WAVES ARE ANALYZED IN THE GULF OF MEXICO. ONE IN THE FAR SW GULF AND THE OTHER ONE OVER THE CENTRAL GULF. THESE TWO SYSTEMS ARE BRINGING SIGNIFICANT MOISTURE TO THE GULF AND ENHANCING HEAVY SHOWERS AND THUNDERSTORMS ACROSS THE SOUTHERN HALF OF THE BASIN S OF 25N. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE N OF 25N. SEE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. ELSEWHERE ALOFT...AN UPPER LEVEL LOW IS OVER THE WESTERN GULF 24N94W ENHANCING CONVECTION NEAR THE TROPICAL WAVE IN THE FAR WEST GULF. EXPECT SHOWERS AND THUNDERSTORMS TO CONTINUE ACROSS MUCH OF THE BASIN AS THE TROPICAL WAVES MOVE WWD. CARIBBEAN SEA... SIGNIFICANT MOISTURE AND UNSTABLE CONDITIONS ARE OBSERVED ACROSS MUCH OF THE NORTHERN CARIBBEAN..ASSOCIATED WITH A SERIES OF TROPICAL WAVES AND A SURFACE TROUGH. SEE TROPICAL WAVES SECTION ABOVE FOR MORE DETAILS. THE SURFACE TROUGH IS LOCATED ACROSS THE EASTERN COAST OF DOMINICAN REPUBLIC ENHANCING NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS HISPANIOLA...PUERTO RICO...AND THE NORTHERN LEEWARD ISLANDS. THIS AREA OF DISTURBED WEATHER HAS THE POTENTIAL TO DEVELOP INTO A TROPICAL DEPRESSION OR STORM DURING THE NEXT FEW DAYS. SEE SPECIAL FEATURES ABOVE FRO MORE INFO. WATER VAPOR IMAGERY INDICATES AN AREA OF DRY AIR OVER THE S CENTRAL AND SE CARIBBEAN WHICH IS KEEPING CONDITIONS FAIR ACROSS THESE AREAS. EXPECT CONTINUED SHOWER ACTIVITY ACROSS MUCH OF THE N CENTRAL AND WRN CARIBBEAN AS THE TROPICAL WAVES MOVE WWD. THE NE CARIBBEAN IS ALSO EXPECTED TO CONTINUE TO RECEIVE SIGNIFICANT RAINFALL AS THE AREA OF DISTURBED WEATHER MENTIONED IN THE SPECIAL FEATURES MOVES WNW. ATLANTIC OCEAN... MODERATE DRY AIR ALOFT COMBINED WITH SURFACE RIDGING IS MAINTAINING FAIR WEATHER ACROSS THE WESTERN ATLC W OF 70W. AN AREA OF DISTURBED WEATHER ACROSS THE NE CARIBBEAN EXTENDS INTO THE ATLC ASSOCIATED WITH A SURFACE TROUGH EXTENDING FROM NEAR 22N67W ACROSS THE EASTERN COAST OF DOMINICAN REPUBLIC INTO THE CARIBBEAN. SATELLITE IMAGERY INDICATES SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS COVERING FROM 18N TO 27N BETWEEN 61W AND 70W...ESPECIALLY WITHIN 160 NM NORTH OF PUERTO RICO NOTED BY DOPPLER RADAR IMAGERY. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS ON THIS AREA OF DISTURBED WEATHER. THE REMAINDER OF THE BASIN IS DOMINATED BY SURFACE RIDGING AROUND A 1027 MB NEAR 35N40W. A WEAK SURFACE TROUGH IS EMBEDDED WITHIN THE RIDGE ALONG 32N49W TO 28N51W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 90 NM NW OF THE AXIS. A TROPICAL WAVE OVER THE CENTRAL TROPICAL ATLANTIC SPREADS SOME WEAK CONVECTION NORTHWARD FROM 20N TO 30N BETWEEN 35W AND 42W. SEE TROPICAL WAVES DISCUSSION FOR MORE INFO REGARDING THIS WAVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA