000 AXNT20 KNHC 201731 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI JUL 20 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 08N53W TO 17N47W MOVING W AT 15 KT. CYCLONIC TURNING IS EVIDENT IN THE LOW-LEVEL CLOUD FIELD IN THE VICINITY OF THE WAVE AXIS BETWEEN 45W-54W. EASTERLY UPPER LEVEL FLOW DOMINATES ALOFT OVER THE WAVE AS IT REMAINS FAIRLY FREE OF MOISTURE IN THE MIDDLE AND UPPER LEVEL. POSSIBLE ISOLATED SHOWERS ARE FROM 09N-16N BETWEEN 45W-52W. TROPICAL WAVE EXTENDS FROM 14N72W TO 22N75W MOVING W AT 15 KT. LARGELY EMBEDDED WITHIN THE CLIMATOLOGICAL CYCLONIC CIRCULATION ACROSS NORTHERN COLOMBIA...THE WAVE DOES EXHIBIT BROAD CYCLONIC TURNING ACROSS THE CENTRAL CARIBBEAN. IT CONTINUES MOVING INTO A MORE FAVORABLE DIFFLUENT AREA AS AN UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN SEA NEAR 19N78W. LOW-LEVEL MOISTURE CONVERGENCE ALONG WITH THE AMPLE MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED MODERATE CONVECTION FROM 15N-17N BETWEEN 68W-73W...AND FROM 16N-20N BETWEEN 75W-80W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO 12N31W TO 08N39W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N39W TO 07N45W TO 10N51W. SCATTERED MODERATE CONVECTION IS FROM 07N-09N BETWEEN 11W-16W...AND FROM 09N-12N BETWEEN 16W-21W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH IS NOTED ON WATER VAPOR IMAGERY OVER THE MISSISSIPPI RIVER DELTA REGION IN THE VICINITY OF 30N89W. THIS UPPER LEVEL TROUGHING IS SUPPORTING A SURFACE TROUGH ANALYZED FROM MOBILE BAY NEAR 30N88W TO 29N91W. MOSAIC DOPPLER RADAR IMAGERY AND LIGHTNING DATA INDICATE WIDESPREAD SHOWERS AND SCATTERED TSTMS ARE OCCURRING N OF 26N BETWEEN 84W-93W. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF NE FLOW ALOFT ON THE SOUTHEASTERN PERIPHERY OF AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED EAST OF THE TROUGHING NEAR 29N94W. THIS UPPER LEVEL RIDGING SUPPORTS A SURFACE RIDGE ACROSS THE WESTERN GULF ANCHORED BY A 1019 MB HIGH CENTERED NEAR 27N93W. THE RIDGE AXIS EXTENDS ALONG 27N INTO THE SW NORTH ATLC REGION AS WELL AS TO THE SOUTHWEST WHERE A 1020 MB HIGH IS CENTERED OVER COASTAL EAST-CENTRAL MEXICO NEAR 21N98W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING OVER THE WESTERN BAY OF CAMPECHE S OF 21N W OF 95W WHERE LOW-LEVEL MOISTURE CONVERGENCE IS MAXIMIZED. FINALLY...A BROAD UPPER LEVEL LOW IS CENTERED OVER THE NW CARIBBEAN SEA NEAR 20N78W AND IS PROVIDING ISOLATED SHOWERS TO THE FLORIDA STRAITS AND SE GULF S OF 25N BETWEEN 80W-86W. THE RIDGE AXIS IS FORECAST TO SLIDE NORTHWARD BY SUNDAY AND LOCATE ALONG 30N WITH LIGHT EAST-SOUTHEASTERLY WINDS PREVAILING INTO EARLY NEXT WEEK. CARIBBEAN SEA... AS MENTIONED ABOVE...A TROPICAL WAVE IS PROGRESSING WESTWARD ACROSS THE CENTRAL CARIBBEAN SEA. WHILE SCATTERED SHOWERS AND TSTMS ARE OCCURRING N OF 15N WITHIN 300 NM EITHER SIDE OF THE WAVE AXIS...AN UPPER LEVEL LOW CENTERED NEAR 20N78W CONTINUES TO PROVIDE SOUTHWESTERLY DIFFLUENT FLOW WEST OF THE WAVE WHICH IS ENHANCING THE CONVECTION THIS AFTERNOON. LOW-LEVEL MOISTURE LINGERS FARTHER TO THE EAST ACROSS THE NE CARIBBEAN WITH ISOLATED SHOWERS AND TSTMS OCCURRING N OF 14N E OF 68W... INCLUDING PUERTO RICO...THE US/UK VIRGIN ISLANDS...AND THE LEEWARD ISLANDS. ELSEWHERE...THE MONSOON TROUGH AXIS EXTENDS FROM THE EAST PACIFIC REGION ALONG 10N TO A 1007 MB LOW CENTERED NEAR 09N77W. AN UPPER LEVEL DIFFLUENT ENVIRONMENT EXISTS ALOFT DUE TO AN UPPER LEVEL ANTICYCLONE CENTERED NEAR 07N78W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING S OF 12N BETWEEN 78W-85W...INCLUDING INLAND PORTIONS OF PANAMA AND COSTA RICA. ATLANTIC OCEAN... A BROAD UPPER LEVEL LOW IS CENTERED IN THE NW CARIBBEAN SEA NEAR 20N78W AND CONTINUES TO DRAW LOW TO MID-LEVEL MOISTURE WESTWARD AND GENERATE WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ACROSS THE TURKS AND CAICOS ISLANDS...AND SE BAHAMAS S OF 24N BETWEEN 68W-74W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC N OF 25N...THE CENTRAL AND EASTERN ATLC ARE UNDER THE INFLUENCE OF A ELONGATED E-NE TO W SURFACE RIDGE ANCHORED BY A 1027 MB HIGH CENTERED NEAR 32N46W. FINALLY OF NOTE...EXAMINING GOES-R PROVING GROUND DUST IMAGERY...A LARGE PORTION OF THE CENTRAL AND EASTERN ATLC HAS SUSPENDED SAHARAN DUST N OF 13N E OF A LINE FROM 32N29W TO 18N47W AND FROM 16N-30N BETWEEN 47W-72W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN