000 AXNT20 KNHC 191749 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 19 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 1745 UTC. ...TROPICAL WAVES... TROPICAL WAVE MOVES ACROSS THE CENTRAL TROPICAL ATLC WITH AXIS ANALYZED FROM 19N40W TO THE MONSOON TROUGH AXIS NEAR 11N38W. WAVE IS MOVING W AT ABOUT 15-20 KT. LOW TO MID LEVEL MOISTURE COVERS A GREAT AREA OF THE WAVE S OF 15N. HOWEVER...A LAYER OF DRY/SAHARAN AIR CONTINUES TO OVERTAKE THE WAVE LIMITING THE CONVECTIVE ACTIVITY AROUND THE WAVE AXIS. TROPICAL WAVE MOVES WEST OF THE LESSER ANTILLES WITH AXIS EXTENDING FROM 20N67W TO 12N62W MOVING W AT 15-20 KT. THE WAVE PRECEDES A NARROW SURGE OF MOISTURE NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. WAVE IS INTERACTING WITH AN UPPER LEVEL LOW MOVING CENTERED OVER THE WINDWARD PASSAGE NEAR 19N75W. CLUSTERS OF MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS N OF 13N E OF THE MONA PASSAGE. TROPICAL WAVE MOVES ACROSS THE BAY OF CAMPECHE WITH AXIS EXTENDING FROM 22N91W TO INLAND OVER WRN GUATEMALA NEAR 15N91W MOVING W AT ABOUT 10 KT. SCATTERED SHOWERS AND THUNDERSTORMS ARE ACROSS MOST OF THE BAY S OF 22N. THE ACTIVITY IS ENHANCED BY A WEAK UPPER LOW CENTERED NEAR 20N91W. THE WAVE WILL CONTINUE TO TRACK WESTWARD WITH SCATTERED THUNDERSTORM ACTIVITY AFFECTING MAINLY THE COASTAL WATERS NEAR VERACRUZ AND TAMPICO OVER THE NEXT 24 HOURS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS INLAND ACROSS WEST AFRICA...ENTERING THE ATLC THROUGH THE COAST OF GUINEA NEAR 10N14W TO 8N22W 12N35W TO 8N46W...WHERE THE ITCZ CONTINUES WEST TO THE COAST OF GUYANA NEAR 8N59W. SCATTERED WEAK TO ISOLATED MODERATE CONVECTION IS FROM 7N-13N BETWEEN 35W-40W AND WITHIN 130 NM S OF THE MONSOON TROUGH E OF 30W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL CYCLONIC CIRCULATION CENTERED OVER ERN GEORGIA CONTINUES TO DOMINATE THE WEATHER ACROSS THE NE AND N-CENTRAL GULF WATERS THIS AFTERNOON. MID TO UPPER LEVEL LIFT ASSOCIATED TO IT IS HELPING TO MAINTAIN CLUSTERS OF SCATTERED SHOWERS AND THUNDERSTORMS N OF 26N E OF 91W. A BROAD UPPER LEVEL LOW CONTINUES TO DRIFT W ACROSS NRN SIERRA MADRE MOUNTAINS WITH LESS INFLUENCE IN THE SHOWER ACTIVITY OVER THE WRN GULF WATERS COMPARED TO 24 HOURS AGO. JUST A FEW ISOLATED SHOWERS ARE DEPICTED ON RADAR IMAGERY W OF 94W N OF VERACRUZ MEXICO. A TROPICAL WAVE MOVES ACROSS THE BAY OF CAMPECHE GENERATING SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE BAY IN COLLABORATION WITH A WEAK UPPER LOW CENTERED NEAR 20N91W. FAIR WEATHER CONDITIONS ARE ELSEWHERE ACROSS THE AREA THIS AFTERNOON. AS THE UPPER LOW OVER THE SE CONUS REMAINS NEARLY STATIONARY... SHORT RANGE COMPUTER MODELS SUGGEST THE RAIN ACTIVITY OVER THE NE AND N-CENTRAL GULF WILL REMAIN IN PLACE DURING THE NEXT 24 HOURS. THE TROPICAL WAVE WILL CONTINUE TO TRACK WESTWARD WITH SCATTERED THUNDERSTORM ACTIVITY AFFECTING MAINLY THE COASTAL WATERS NEAR VERACRUZ AND TAMPICO DURING THE FORECAST PERIOD. CARIBBEAN SEA... THE MAIN AREA OF ACTIVE WEATHER IS FOUND OVER THE ERN CARIBBEAN BASIN...AS A TROPICAL WAVE MOVES W OF THE LESSER ANTILLES WITH SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS N OF 13N E OF THE MONA PASSAGE. DOPPLER RADAR IMAGERY INDICATES THE OVERALL ACTIVITY IS MOVING WESTWARD AT ABOUT 15-20 KT AND IS EXPECTED TO REACH THE WATERS S OF HISPANIOLA LATER THIS EVENING. THE WAVE IS INTERACTING WITH AN UPPER LEVEL LOW MOVING WEST ACROSS THE WINDWARD PASSAGE. SIMILAR ACTIVITY IS FOUND OVER THE SOUTH WEST CARIBBEAN...WITHIN 90 NM OFF THE COAST OF WRN PANAMA AND COSTA RICA...ASSOCIATED TO THE MONSOON TROUGH AXIS EXTENDING ACROSS NRN COLOMBIA TO THE SRN COASTAL WATERS OF PANAMA AND WRN COSTA RICA. THE REMAINDER OF THE DISCUSSION AREA IS UNDER FAIR WEATHER WITH A FEW ISOLATED FAST MOVING SHOWERS EMBEDDED IN THE MODERATE TO FRESH EASTERLY TRADE WINDS. WATER VAPOR IMAGERY SHOWS DRY AIR ALOFT COVERING A GREAT PORTION OF THE DISCUSSION AREA WITH SAHARAN DUST NOTED ON MOST UPPER AIR SOUNDINGS AND VISIBLE IMAGERY DATA. ATLANTIC OCEAN... AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY MOVING WEST ACROSS THE WINDWARD PASSAGE. AN UPPER INVERTED TROUGH EXTENDS NW FROM THE LOW CENTER TO NEAR 32N60W. THIS FEATURE IS CURRENTLY NOT HAVING ANY SIGNIFICANT IMPACTS AT SURFACE. OTHERWISE...A LARGE AREA OF HIGH PRESSURE DOMINATES THE REMAINDER OF THE ATLC DISCUSSION AREA ANCHORED BY A 1030 MB HIGH CENTERED NEAR 33N34W. THE FAIR WEATHER IN THIS REGION IS FURTHER ENHANCED BY A BROAD LAYER SAHARAN DUST ALOFT NOTED ON METEOSAT-9. WITH SAHARAN DUST ALOFT PRESENT ACROSS THE AREA AND STRONG SURFACE RIDGING EXTENDING WESTWARD...LITTLE CHANGE IS EXPECTED ACROSS THE DISCUSSION AREA FOR AT LEAST THE NEXT 24 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ GARCIA