000 AXNT20 KNHC 180558 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN JUL 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC... ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 55W FROM 8N TO 20N MOVING W NEAR 20 KT. A BROAD AREA OF LOW PRESSURE IS ASSOCIATED WITH THIS WAVE CENTERED ABOUT 600 NM EAST OF THE WINDWARD ISLANDS. CURRENTLY...THIS SYSTEM IS PRODUCING VERY LITTLE SHOWER ACTIVITY...AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT DURING THE NEXT COUPLE OF DAYS AS THE AREA OF LOW PRES MOVES WEST-NORTHWESTWARD. THE WAVE IS EMBEDDED IN A REGION OF ELEVATED VALUES IN DEEP LAYER MOISTURE SEEN IN TOTAL PRECIPITABLE WATER IMAGERY. SAHARAN AIR LAYER IN THE VICINITY OF THE WAVE IS SUPPRESSING DEEP CONVECTION FROM DEVELOPING...LEAVING ONLY SCATTERED MODERATE CONVECTION MAINLY NEAR THE NORTHERN END OF THE WAVE AXIS FROM 15N TO 20N BETWEEN 52W AND 58W. THIS WAVE WILL ENTER THE CARIBBEAN SEA TONIGHT BRINGING AN INCREASE IN SHOWER AND TSTM ACTIVITY PARTICULARLY ACROSS THE LEEWARD ISLANDS AND THEN OVER PUERTO RICO AND THE US/UK VIRGIN ISLANDS BY MON. TROPICAL WAVE IS OVER THE EASTERN CARIBBEAN ALONG 69W/70W WITH AXIS EXTENDING FROM EASTERN DOMINICAN REPUBLIC TO WESTERN VENEZUELA NEAR 10N70W MOVING W ABOUT 10 KT. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE NOTED AHEAD OF THE WAVE AXIS AFFECTING THE CARIBBEAN COASTAL WATERS OF HISPANIOLA...WESTERN VENEZUELA AND THE ABC ISLANDS. SCATTERED MODERATE CONVECTION CAN BE ALSO FOUND BETWEEN THE WAVE AXIS AND 75W. THIS WAVE WILL MOVE THROUGH THE CENTRAL CARIBBEAN TODAY AND THROUGH THE W CARIBBEAN MON AND TUE. TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN ALONG 80W FROM 11N TO 20N MOVING W AT ABOUT 5 KT. THE WAVE IS GENERATING SOME SHOWER ACTIVITY OVER THE CAYMAN ISLANDS...AND WILL BECOME ABSORBED INTO A BROAD AREA OF LOW PRES IN W CARIBBEAN TONIGHT. ...ITCZ... THE ITCZ AXIS IS ALONG 10N15W 4N30W 6N40W 9N52W INTO NORTHERN GUYANA. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 4N TO 10N BETWEEN 18W-25W. A CLUSTER OF SIMILAR CONVECTION IS NOTED OVER SENEGAL LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE. ...DISCUSSION... GULF OF MEXICO... THE SURFACE TROUGH THAT HAS BEEN GENERATING SOME SHOWER ACTIVITY ACROSS THE GULF WATERS OVER THE PAST FEW DAYS IS NOW HEADING TO THE WESTERN GULF COAST EXTENDING FROM 29N94W TO THE BAY OF CAMPECHE NEAR 19N95W. ABUNDANT MID/UPPER LEVEL MOISTURE IS STILL NOTED ON WATER VAPOR IMAGERY BETWEEN THE TROUGH AXIS AND AN UPPER-LEVEL LOW SPINNING NOW NEAR SW FLORIDA. A DRYER AIR MASS IS SEEN WEST OF THE SURFACE TROUGH EXPECTED TO WEAKEN TONIGHT. A RIDGE FROM THE ATLC EXTENDS ACROSS THE FLORIDA PENINSULA INTO THE EASTERN GULF. THE RIDGE ALSO DOMINATES THE SE CONUS ANCHORED ON A 1020 MB HIGH LOCATED OVER SW GEORGIA. ANOTHER TROUGH IS FORECAST TO ENTER THE EASTERN GULF LATE MON. CARIBBEAN SEA... VERY UNSTABLE ATMOSPHERIC CONDITIONS PERSIST OVER THE CARIBBEAN SEA DUE TO A PAIR OF TROPICAL WAVES AND THE PRESENCE OF A BROAD AREA OF LOW PRES OVER THE WESTERN CARIBBEAN. SEE TROPICAL WAVE SECTION FOR MORE DETAILS. A DIFFLUENT PATTERN ALOFT BETWEEN AN UPPER LEVEL RIDGE OVER THE CENTRAL CARIBBEAN AND AN UPPER- LEVEL LOW SPINNING N OF PUERTO RICO IS HELPING TO INDUCE CONVECTION ACROSS THE AREA...PARTICULARLY BETWEEN TROPICAL WAVES. ATLANTIC OCEAN... ALOFT...AN UPPER-LEVEL LOW IS SPINNING NEAR SW FLORIDA WITH THE CYCLONIC FLOW COVERING THE PENINSULA AND THE NW BAHAMAS. ANOTHER UPPER-LEVEL LOW IS N OF PUERTO RICO NEAR 25N65W. MOST OF THE CONVECTIVE ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS MOVED N AND AWAY FROM PUERTO RICO LEAVING THE ISLAND UNDER A MORE STABLE AND LESS HUMID ATMOSPHERE. BETWEEN LOWS...THERE IS AN UPPER-LEVEL RIDGE EXTENDING S TO ACROSS EASTERN CUBA AND INTO THE CENTRAL CARIBBEAN. A RIDGE ALSO DOMINATES THE TROPICAL ATLC W OF 32W. AN INVERTED TROUGH IS NOTED OVER THE CAPE VERDE ISLANDS. AT THE SURFACE...THE BERMUDA-AZORE HIGH DOMINATES THE BASIN WITH THE RIDGE EXTENDING SW THEN MAINLY W TO THE SE CONUS INTO THE EASTERN GULF OF MEXICO. TRADE WINDS ON THE SOUTHERN PERIPHERY OF THE RIDGE ARE IN THE 15 TO 20 KT RANGE TRANSPORTING PATCHES OF LOW LEVEL MOISTURE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GR