000 AXNT20 KNHC 211747 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT JUL 21 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1645 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 12N23W TO 22N20W MOVING W AT 10 KT. THE WAVE IS ALONG THE LEADING EDGE OF A DEEP LAYER MOISTURE MAXIMUM AS INDICATED ON TOTAL PRECIPITABLE WATER IMAGERY. THE WAVE COINCIDES WITH A BROAD 700 MB TROUGH THAT IS CENTERED ON THE SOUTHERN TIP OF THE WAVE AXIS NEAR 12N23W. ISOLATED MODERATE CONVECTION IS FROM 13N-16N BETWEEN 15W-21W...AND FROM 09N-13N BETWEEN 22W-25W. TROPICAL WAVE EXTENDS FROM 08N58W TO 17N58W MOVING W AT 15 KT. CYCLONIC TURNING IS EVIDENT IN THE LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE WAVE AXIS BETWEEN 55W-61W. EASTERLY UPPER LEVEL FLOW DOMINATES ALOFT OVER THE WAVE AS IT REMAINS DRY AND FREE OF MOISTURE IN THE MIDDLE AND UPPER LEVELS. POSSIBLE ISOLATED SHOWERS ARE WITHIN 75 NM EITHER SIDE OF A LINE FROM 15N54W TO 17N61W. TROPICAL WAVE EXTENDS FROM 14N84W TO 21N87W MOVING W AT 15 KT. THE WAVE EXHIBITS BROAD CYCLONIC TURNING ACROSS THE WESTERN CARIBBEAN AND IS NOW LOCATED ON THE WESTERN PERIPHERY OF AN UPPER LEVEL LOW CENTERED OVER THE NW CARIBBEAN SEA NEAR 19N81W. LOW-LEVEL MOISTURE CONVERGENCE IS GENERATING SCATTERED MODERATE CONVECTION NORTH OF COASTAL HONDURAS FROM 16N-18N BETWEEN 82W-87W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 18N16W TO 15N23W TO 10N37W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N37W TO 05N45W TO 06N56W. NO SIGNIFICANT CONVECTION IS NOTED ON SATELLITE IMAGERY. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE MISSISSIPPI RIVER DELTA REGION WITH AXIS THAT STRETCHES FROM SOUTHERN ALABAMA NEAR 32N87W TO 28N93W. THIS UPPER LEVEL TROUGHING IS SUPPORTING A SURFACE TROUGH ANALYZED FROM 30N89W TO 28N92W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE SCATTERED SHOWERS AND ISOLATED TSTMS N OF 26N BETWEEN 86W-94W. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF NE FLOW ALOFT ON THE SOUTHEASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONE CENTERED OVER THE CENTRAL PLAINS. THIS UPPER LEVEL RIDGING SUPPORTS A SURFACE RIDGE WITH AXIS EXTENDING FROM THE SW NORTH ATLC NEAR 30N70W TO 26N97W AND ACROSS PORTIONS OF THE SW GULF WHERE A 1019 MB HIGH IS CENTERED OVER COASTAL EAST-CENTRAL MEXICO NEAR 19N96W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER THE WESTERN BAY OF CAMPECHE S OF 20N W OF 94W WHERE LOW-LEVEL MOISTURE CONVERGENCE IS MAXIMIZED. FINALLY...A BROAD UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN SEA NEAR 19N81W AND IS PROVIDING ISOLATED SHOWERS AND TSTMS TO THE FLORIDA STRAITS AND SE GULF S OF 26N BETWEEN 79W-86W. THE RIDGE AXIS IS FORECAST TO SLIDE NORTHWARD BY SUNDAY AND LOCATE ALONG 30N WITH EAST-SOUTHEAST WINDS PREVAILING INTO EARLY NEXT WEEK. CARIBBEAN SEA... AS MENTIONED ABOVE...A TROPICAL WAVE IS PROGRESSING WESTWARD ACROSS THE WESTERN CARIBBEAN SEA. WHILE SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF COASTAL HONDURAS FROM 16N-18N BETWEEN 82W-87W...AN UPPER LEVEL LOW CENTERED NEAR 19N81W CONTINUES TO PROVIDE AMPLE MIDDLE TO UPPER LEVEL ATMOSPHERIC LIFT TO GENERATE ISOLATED SHOWERS AND TSTMS IN THE VICINITY OF JAMAICA AND OVER PORTIONS OF WESTERN CUBA. LOW-LEVEL MOISTURE LINGERS FARTHER TO THE EAST ACROSS THE NE CARIBBEAN WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 16N BETWEEN 65W-72W...INCLUDING PUERTO RICO AND THE US/UK VIRGIN ISLANDS. ELSEWHERE...THE MONSOON TROUGH AXIS EXTENDS FROM THE EAST PACIFIC REGION ALONG 10N/11N WITH A 1009 MB LOW CENTERED NEAR 11N81W. AN UPPER LEVEL DIFFLUENT ENVIRONMENT EXISTS ALOFT DUE TO AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 06N89W. SCATTERED SHOWERS AND TSTMS ARE OCCURRING FROM 10N-13N BETWEEN 78W-85W...INCLUDING INLAND PORTIONS OF PANAMA...COSTA RICA...AND SOUTHEASTERN NICARAGUA. ATLANTIC OCEAN... A BROAD UPPER LEVEL LOW IS CENTERED IN THE NW CARIBBEAN SEA NEAR 19N81W AND CONTINUES TO DRAW LOW TO MID-LEVEL MOISTURE W-NW AND GENERATE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE TURKS AND CAICOS ISLANDS...AND BAHAMAS WITHIN 150 NM EITHER SIDE OF A LINE FROM 18N62W TO 25N79W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC N OF 26N...THE CENTRAL...AND EASTERN ATLC ARE UNDER THE INFLUENCE OF A ELONGATED E-NE TO W SURFACE RIDGE ANCHORED BY A 1026 MB HIGH AND A 1025 MB HIGH CENTERED NEAR 35N28W AND 31N49W RESPECTIVELY. FINALLY OF NOTE...EXAMINING GOES-R PROVING GROUND DUST IMAGERY...A LARGE PORTION OF THE CENTRAL AND EASTERN ATLC HAS SUSPENDED SAHARAN DUST LOCATED N OF 13N E OF A LINE FROM 32N28W TO 15N51W AND FROM 17N-30N BETWEEN 51W-78W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN