000 AXNT20 KNHC 122348 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN AUG 12 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N18W TO 20N17W MOVING W AT 15-20 KT. THE WAVE EMERGED OFF THE COAST OF W AFRICA AFTER 12/1200 UTC EARLIER THIS MORNING AND COINCIDES WITH A 700 MB LOW NEAR THE SOUTHERN EXTENT OF THE WAVE AXIS NEAR 10N17W. THE 700 MB TROUGHING EXTENDS NORTHWARD ALONG 18N TO 21N. ALSO...TOTAL PRECIPITABLE WATER IMAGERY INDICATES DEEP LAYERED MOISTURE IS LOCATED FROM 06N-17N E OF 22W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 07N-13N BETWEEN 12W-22W. TROPICAL WAVE EXTENDS FROM 17N38W TO 25N36W MOVING WNW AT 15-20 KT. A 1013 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 21N37W AND COINCIDES WITH AN AREA OF MAXIMUM DEEP LAYERED MOISTURE NOTED IN TOTAL PRECIPITABLE WATER IMAGERY FROM 18N-24N BETWEEN 35W-42W. HOWEVER...DRY AIR AND DUST SURROUND THE WAVE LIMITING DEEP CONVECTION AT THIS TIME. ISOLATED SHOWERS ARE POSSIBLE FROM 20N-24N BETWEEN 37W-42W. TROPICAL WAVE EXTENDS FROM 12N69W TO 18N67W MOVING W AT 20 KT. THE REMNANTS OF T.D. SEVEN...SATELLITE PRESENTATION AND ASSOCIATED SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC FLOW IN THE VICINITY OF THE AXIS. THIS WAS CONFIRMED EARLIER BY A 12/1438 UTC ASCAT PASS IN THE WATERS SOUTH OF PUERTO RICO ALONG 67W. SCATTERED MODERATE CONVECTION IS FROM 13N-19N BETWEEN 65W-71W...AND IS LIKELY ENHANCED DUE TO MIDDLE TO UPPER LEVEL DIFFLUENCE MAXIMIZED OVER THE EASTERN CARIBBEAN SEA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 11N19W TO 11N36W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 11N36W TO 10N49W TO 08N59W. NO SIGNIFICANT CONVECTION IS NOTED AT THIS TIME. ...DISCUSSION... GULF OF MEXICO... SOUTHERLY FLOW ALOFT DOMINATES OVER MUCH OF THE GULF BASIN THIS EVENING BETWEEN AN UPPER LEVEL LOW CENTERED OVER NE MEXICO NEAR 24N99W AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED OVER THE NW BAHAMAS NEAR 25N78W. THIS SYNOPTIC SETUP CONTINUES TO ADVECT MOISTURE FROM SOUTHERN MEXICO AND THE YUCATAN PENINSULA ACROSS THE EASTERN GULF AND FLORIDA PENINSULA. DIFFLUENCE IS MAXIMIZED OVER THIS AREA AND CURRENTLY IS GENERATING SCATTERED SHOWERS AND TSTMS OVER THE FLORIDA PENINSULA AND ADJACENT COASTAL WATERS N OF 25N E OF 84W...AND OVER NORTHERN GUATEMALA AND THE YUCATAN PENINSULA...INCLUDING ADJACENT GULF COAST OFFSHORE WATERS. ELSEWHERE...ISOLATED SHOWERS AND TSTMS ARE OCCURRING E OF 90W AND ACROSS THE SW GULF S OF 24N W OF 90W. THIS ACTIVITY IS LARGELY OVERRIDING THE FACT THAT A WEAK SURFACE RIDGE AXIS EXTENDS FROM THE SW NORTH ATLC ALONG 27N TO THE NW GULF NEAR 27N97W. HELPING TO WEAKEN THIS RIDGE SLIGHTLY IS AN UPPER LEVEL TROUGH AXIS MOVING OFF THE EASTERN SEABOARD THAT SUPPORTS A STATIONARY FRONT FROM SOUTH CAROLINA NEAR 33N82W TO THE FLORIDA PANHANDLE NEAR 30N85W TO SOUTHERN MISSISSIPPI NEAR 31N90W. CARIBBEAN SEA... MUCH OF THE CARIBBEAN SEA IS UNDER THE INFLUENCE OF UPPER LEVEL TROUGHING WITH AXIS EXTENDING ALONG 76W. ALOFT W OF 76W... NORTHEASTERLY FLOW DOMINATES AND IS PROVIDING AN OVERALL STABLE ENVIRONMENT AND CLEAR SKIES THIS EVENING. THE DRY AIR NOTED ON WATER VAPOR IMAGERY IS EXPECTED TO CONTINUE SPREADING WESTWARD THROUGH LATE MONDAY INTO TUESDAY ACROSS THE WESTERN CARIBBEAN. E OF 76W...SOUTHERLY FLOW ALOFT IS ADVECTING MOISTURE INTO THE TROPICAL WAVE ALONG 68W. AS MENTIONED ABOVE...SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER MUCH OF THE EASTERN CARIBBEAN N OF 13N IN ASSOCIATION WITH THE TROPICAL WAVE...BUT DUE TO UPPER LEVEL DIFFLUENCE AND THE BASE OF UPPER LEVEL TROUGHING N OF 18N BETWEEN 55W-66W...SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE ACROSS THE LEEWARD ISLANDS...PUERTO RICO...AND THE US/UK VIRGIN ISLANDS THIS EVENING. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH IS BEGINNING TO EMERGE OFF THE EASTERN SEABOARD THIS EVENING AND SUPPORTS A WEAK AREA OF SURFACE TROUGHING IN THE FORM OF A STATIONARY FRONT DRAPED FROM THE NEW ENGLAND STATES SOUTHWARD TO THE FLORIDA PANHANDLE. MOSTLY UPPER LEVEL DIFFLUENCE BETWEEN THIS TROUGH AXIS AND AN UPPER LEVEL ANTICYCLONIC CIRCULATION CENTERED NEAR 25N78W IS GENERATING SCATTERED SHOWERS AND TSTMS OVER MUCH OF THE FLORIDA PENINSULA AND ADJACENT COASTAL ATLC WATERS FROM 26N-31N W OF 78W. ELSEWHERE OVER THE REMAINDER OF THE SW NORTH ATLC...ISOLATED SHOWERS AND TSTMS ARE OCCURRING N OF 23N W OF 68W. WHILE A SURFACE RIDGE AXIS EXTENDS FROM BERMUDA NEAR 32N65W TO 27N80W AND INTO THE GULF OF MEXICO...IT REMAINS RATHER WEAK AND INFLUENTIAL ACROSS THE SW NORTH ATLC THIS EVENING DUE TO MAXIMUM INSTABILITY. E OF 65W HOWEVER...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC FALL UNDER THE INFLUENCE OF A BROAD SURFACE RIDGE ANCHORED BY A 1025 MB HIGH CENTERED NEAR 33N37W WHERE PRIMARILY STABLE CONDITIONS AND FAIR WEATHER ARE OCCURRING. THE ONLY WEAKNESS FOUND WORKING TO ERODE THE RIDGING IS THE TROPICAL WAVE ALONG 37N MENTIONED ABOVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN