000 AXNT20 KNHC 010004 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 31 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 2345 UTC. ...SPECIAL FEATURE... A TROPICAL WAVE IS SW OF THE CAPE VERDE ISLANDS ALONG 27W SOUTH OF 15N. THIS WAVE IS EMBEDDED WITHIN AN AREA OF A HIGH AMPLITUDE MOISTURE MAXIMUM. A WELL DEFINED LOW TO MID LEVEL CYCLONIC FLOW SURROUNDS THE WAVE AXIS EVIDENT ON INFRA RED SATELLITE DATA. WHILE AMPLE MOISTURE IS NOTED IN THE LOW LEVELS...A SAHARAN AIR LAYER IS PREVENTING ANY SIGNIFICANT CONVECTION IN ASSOCIATION WITH THE WAVE. THEREFORE...MOST OF THE CONVECTION NEAR BY THIS SYSTEM IS DUE TO INTERACTION WITH AN ELONGATED AREA OF LOW PRESSURE EMBEDDED IN THE ITCZ. ALTHOUGH THIS ENTIRE AREA OF DISTURBED WEATHER REMAINS DISORGANIZED...SHOWER AND THUNDERSTORM ACTIVITY HAS INCREASED DURING THE DAY. CONDITIONS APPEAR FAVORABLE FOR SOME SLOW DEVELOPMENT AS THE DISTURBANCE MOVES SLOWLY WESTWARD...AND THERE IS A MEDIUM CHANCE OF TROPICAL CYCLONE FORMATION DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS ALONG 53W S OF 18N MOVING W AT 10-15 KT. WEAK CYCLONIC FLOW IS IN THE VICINITY OF THE WAVE NOTED ON SATELLITE DERIVED WINDS. THE WAVE AXIS COINCIDES WITH A MID-LEVEL TROUGH AXIS THAT CONTINUES TO GENERATE SCATTERED MODERATE AND ISOLATED STRONG CONVECTION FROM 8N TO 13N BETWEEN 50W AND 58W. TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN SEA EXTENDING ALONG 17N72W TO 10N76W MOVING W 5-10 KT. THE WAVE REMAINS EMBEDDED WITHIN AN AREA OF MAXIMUM TOTAL PRECIPITABLE WATER. VERY WEAK LOW-LEVEL CYCLONIC TURNING IS NOTED ON VISIBLE SATELLITE IMAGERY. HOWEVER...BROAD AREA OF UPPER LEVEL CYCLONIC CIRCULATION NOTED ON WATER VAPOR IMAGERY IS GIVING SUPPORT TO THE TROPICAL WAVE PRODUCING SCATTERED MODERATE TO ISOLATED STRING CONVECTION BETWEEN 66W AND 80W. ...ITCZ... ITCZ AXIS IS ANALYZED ALONG 13N16W 10N28W 8N40W 7N50W. A SURFACE LOW/TROUGH IS EMBEDDED IN THE ITCZ FROM 06N TO 12N ALONG 36W WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION COVERING A LARGE AREA FROM 4N TO 12N BETWEEN 25W AND 50W. MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OFF THE COAST OF SENEGAL...THE GAMBIA AND GUINEA-BISSAU. ...DISCUSSION... GULF OF MEXICO... A SURFACE 1007 MB LOW IS OVER THE NORTHERN FLORIDA PENINSULA NEAR 30N82W. ALTHOUGH THE CONVECTION GENERATED BY THIS SYSTEM IS MOSTLY INLAND...A FEW SHOWERS AND ISOLATED THUNDERSTORMS ARE REACHING THE FLORIDIAN COAST FROM CEDAR KEY TO MIRAMAR BEACH. ALSO...A SURFACE TROUGH ASSOCIATED WITH THE SURFACE LOW EXTENDS FROM THE FLORIDA BIG BEND INTO THE GULF ALONG 30N84W TO 23N90W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WEST OF THE SURFACE TROUGH FROM 24N-28N BETWEEN THE SURFACE TROUGH AND 91W. ELSEWHERE ACROSS THE REMAINDER OF GULF...DRY/STABLE AIR ALOFT IS NOTED ON WATER VAPOR IMAGERY. A 1015 MB HIGH IS CENTERED OVER THE WESTERN GULF NEAR 24N95W KEEPING FAIR WEATHER CONDITIONS OVER THIS REGION WEST OF 91W. CARIBBEAN SEA... SATELLITE IMAGERY SHOWS SCATTERED SHOWERS AND THUNDERSTORMS OVER MOST OF THE CENTRAL CARIBBEAN SEA BETWEEN 66W AND 80W. THE ACTIVITY IS ASSOCIATED WITH A BROAD AREA OF UPPER LEVEL CYCLONIC CIRCULATION NOTED ON WATER VAPOR IMAGERY...GIVING SUPPORT TO A TROPICAL WAVE WITH AXIS FROM 17N72W TO 10N76W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER THE SW CARIBBEAN S OF 12N W OF 75W...INCLUDING PORTIONS OF PANAMA AND COSTA RICA...DUE TO CLOSE PROXIMITY OF THE ITCZ AXIS ALONG 10N. THE PRESENCE OF A SAHARAN AIR LAYER ROUGHLY LOCATED FROM 850 MB TO 600 MB OVER THE FAR EAST CARIBBEAN...IS PROVIDING STABLE AIR AND GENERALLY CLEAR SKIES OVER PUERTO RICO...AND THE LEEWARD ISLANDS THIS EVENING. ATLANTIC OCEAN... A BROAD UPPER LEVEL LONGWAVE/TROUGH IS OVER THE NORTHWEST ATLC AREA OF DISCUSSION. THIS UPPER LEVEL FEATURE SUPPORTS A NEARLY STATIONARY FRONT THAT ENTERS OUR REGION THROUGH 32N70W AND CONTINUES WEST ALONG 29N76W 30N81W. AN AREA OF CONVERGENT LOW-LEVEL WINDS IS ALSO LOCATED 100 NM SOUTHEAST OF THE FRONT DEPICTED AS A SURFACE TROUGH FROM FROM THE NORTHERN BAHAMAS NEAR 25N TO 29N. THE COMBINATION OF THESE SURFACE FEATURES ARE GENERATING SCATTERED MODERATE TO ISOLATED STRONG CONVECTION WEST OF 64W NORTH OF 25N. THE LEADING EDGE OF THE UPPER LEVEL FEATURE IS GENERATING STRONG UPPER LEVEL DIFFLUENCE FLOW...FURTHER SUPPORTING THE CONVECTIVE WEATHER IN THIS REGION. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1032 MB HIGH CENTERED WELL NORTH OF THE DISCUSSION AREA NEAR 45N31W. ALSO...DRY SAHARAN AIR EMBEDDED IN THE BROAD UPPER LEVEL RIDGE OF HIGH PRESSURE IS FURTHER KEEPING CONDITIONS FAIR ACROSS THIS REGION. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA