000 AXNT20 KNHC 142340 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE AUG 14 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. ...SPECIAL FEATURES... A SURFACE TROUGH EXTENDS FROM 21N54W TO 29N52W MOVING NW AT 15-20 KT WITH A 1016 MB LOW ANALYZED ALONG THE SURFACE TROUGH NEAR 25N52W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES MAXIMUM DEEP LAYERED MOISTURE FROM 22N-29N BETWEEN 48W-55W AND ISOLATED MODERATE CONVECTION OCCURRING OVER THIS AREA AS WELL. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME MORE CONDUCIVE FOR TROPICAL CYCLONE DEVELOPMENT OVER THE NEXT COUPLE OF DAYS AS IT MOVES AROUND THE SOUTHWESTERN PERIPHERY OF SURFACE RIDGING TO THE NORTH. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N30W TO 20N32W MOVING W AT 20 KT. ENERGY FROM THE WAVE CONTINUES TO ROTATE AROUND A BROAD LOW- LEVEL MONSOON GYRE CENTERED NEAR A 1012 MB LOW EMBEDDED WITHIN THE MONSOON TROUGH NEAR 11N30W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT MOST OF THE DEEP LAYERED MOISTURE IS LOCATED EAST OF THE WAVE AXIS FROM 08N-17N E OF 28W. SAHARAN DUST HAS WRAPPED AROUND AND ENGULFED THIS WAVE THUS LIMITING ANY DEEP CONVECTION AT THIS TIME. THE DUST IS NOTED ON SATELLITE IMAGERY PRIMARILY W OF 48W. TROPICAL WAVE EXTENDS FROM 10N58W TO 16N56W MOVING W AT 15-20 KT. THE WAVE REMAINS RATHER WEAK DUE TO THE FACT THAT MOST OF THE ENERGY IS LOCATED TO THE NORTH AND TIED IN WITH THE SPECIAL FEATURE SURFACE TROUGH AND LOW PRESSURE AREA. GLOBAL MODEL DATA AT 700 MB DOES INDICATE THAT A 700 MB TROUGH AXIS EXTENDS FROM EAST OF THE LESSER ANTILLES TO THE NORTH BETWEEN 50W-60W WHICH COINCIDES WITH BOTH THE WAVE AND SPECIAL FEATURE. NO DEEP CONVECTION IS NOTED ON SATELLITE IMAGERY...HOWEVER ISOLATED SHOWERS ARE OCCURRING WEST OF THE AXIS FROM 12N-16N BETWEEN 55W-61W. TROPICAL WAVE EXTENDS FROM 11N82W TO 21N85W MOVING W AT 15-20 KT. SATELLITE IMAGERY ALONG WITH SURFACE OBSERVATIONS INDICATE SHARP CYCLONIC SURFACE FLOW IS LOCATED IN THE VICINITY OF THE WAVE ACROSS THE WESTERN CARIBBEAN SEA. THE WAVE ALSO LIES NEAR AN AREA DIFFLUENCE ALOFT...WHICH IS ENHANCING SCATTERED MODERATE CONVECTION OCCURRING FROM 10N-18N BETWEEN 75W-86W. ISOLATED MODERATE CONVECTION IS ELSEWHERE FROM 18N-23N BETWEEN 81W-88W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 17N16W TO 14N20W TO 11N30W TO 06N40W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N40W TO 02N51W. DUE TO THE LARGE AREA OF SAHARAN DUST ACROSS THE EASTERN AND CENTRAL ATLC...ONLY ISOLATED MODERATE CONVECTION IS FROM 10N-16N BETWEEN 14W-21W. ...DISCUSSION... GULF OF MEXICO... A BROAD MIDDLE TO UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY ACROSS THE EASTERN CONUS THAT EXTENDS A TROUGH AXIS FROM OVER WESTERN NORTH CAROLINA NEAR 36N81W S-SW TO THE NE GULF NEAR 28N87W AND INTO A WEAK UPPER LEVEL LOW CENTERED NEAR 24N89W. WEST OF THIS TROUGH AXIS RELATIVELY DRY AIR ALOFT IS IN PLACE PROVIDING MUCH OF THE WESTERN GULF WITH FAIR SKIES THIS EVENING. THE ONLY EXCEPTION IS A FEW ISOLATED SHOWERS S OF 25N W OF 94W. EAST OF THE UPPER LEVEL TROUGH AXIS...PLENTY OF MOISTURE CONTINUES TO ADVECT NORTHWARD ON THE WESTERN PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED OVER THE SW NORTH ATLC NEAR 24N76W. UPPER LEVEL DIFFLUENCE IS MAXIMIZED E OF 90W AND ALONG WITH MAXIMUM DAYTIME INSTABILITY IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS E OF 91W. COVERAGE OF TSTMS INCREASES OVER THE FLORID PENINSULA BUT THIS ACTIVITY IS EXPECTED TO DRIFT E-NE OVER THE NEXT FEW HOURS. OTHERWISE...A WEAK SURFACE RIDGE ALONG 27N IS EXPECTED TO REMAIN OVER THE GULF THROUGH LATE THURSDAY. CARIBBEAN SEA... A TROPICAL WAVE IN COMBINATION WITH DIFFLUENCE ALOFT AROUND AN INVERTED UPPER TROUGH OVER CENTRAL AMERICA IS GENERATING SCATTERED SHOWERS AND TSTMS ACROSS MUCH OF THE WESTERN CARIBBEAN W OF 75W THIS EVENING. THE WAVE IS FORECAST TO CONTINUE TRACKING WESTWARD ACROSS CENTRAL AMERICA AND SOUTHERN MEXICO OVER THE NEXT FEW DAYS WITH EXPECTED PRECIPITATION INCREASING THE CHANCE FOR LOCALLY HEAVY RAINFALL...FLOODING...AND THE POTENTIAL FOR MUDSLIDES OVER THE HIGHER TERRAIN. THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING MOSTLY FAIR WEATHER DUE TO AN AREA OF DRY AIR ALOFT MOVING WESTWARD FROM THE TROPICAL ATLC. EASTERLY TRADES ARE FORECAST TO PERSIST IN THE RANGE OF 15 TO 20 KT THROUGH THURSDAY. ATLANTIC OCEAN... UPPER LEVEL DIFFLUENCE IS MAXIMIZED ACROSS THE SW NORTH ATLC THIS EVENING BETWEEN A BROAD MIDDLE TO UPPER LEVEL TROUGH ACROSS THE EASTERN CONUS AND AN ANTICYCLONIC CIRCULATION CENTERED OVER THE CENTRAL BAHAMAS NEAR 25N76W. LOW-LEVEL CONVERGENCE FOCUSED ALONG A SURFACE TROUGH ANALYZED FROM THE SOUTHERN FLORIDA PENINSULA NEAR 26N81W TO 32N75W CONTINUES TO GENERATE SCATTERED SHOWERS AND TSTMS WITHIN 240 NM E OF THE SURFACE TROUGH AND ACROSS THE FLORIDA PENINSULA AND ADJACENT COASTAL WATERS W OF 79W. FARTHER EAST...THE SPECIAL FEATURES SURFACE TROUGH AND LOW PRESSURE AREA ARE CONTINUING TO MOVE AROUND THE SOUTHWESTERN PERIPHERY OF A BROAD SURFACE RIDGE ACROSS THE CENTRAL AND EASTERN ATLC ANCHORED BY A PAIR OF 1024 MB HIGHS NEAR 33N41W AND 33N50W. FINALLY OVER THE NORTHERN PORTION OF THE EASTERN ATLC... A COLD FRONT IS ANALYZED FROM 33N20W TO 32N26W TO 33N35W AND CONTINUES TO WEAKEN AS IT PUSHES S-SE. ISOLATED SHOWERS ARE POSSIBLE WITH 120 NM SOUTH OF THE FRONT. 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