000 AXNT20 KNHC 231806 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT FRI AUG 23 2013 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 1715 UTC. ...TROPICAL WAVES... A TROPICAL WAVE ASSOCIATED WITH A SURFACE LOW PRESSURE CAME OFF THE AFRICAN COAST THIS MORNING. ITS AXIS EXTENDS FROM 17N19W TO A 1011 MB LOW EMBEDDED IN THE MONSOON TROUGH NEAR 10N20W TO 07N21W. THE WAVE IS EMBEDDED IN A HIGH MOIST ENVIRONMENT WHICH ALONG UPPER LEVEL DIFFLUENCE SUPPORTS SCATTERED MODERATE CONVECTION FROM 07N-14N BETWEEN 18W-31W. A TROPICAL WAVE IS WEST OF THE ITCZ AXIS AND ABOUT 450 NM SE OF THE LESSER ANTILLES. ITS AXIS EXTENDS FROM 16N46W TO 07N59W AND IS MOVING W-NW NEAR 15 KT. THE WAVE IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT IN THE LOWER LEVELS AND THERE IS NO CONVECTION ASSOCIATED WITH IT. A TROPICAL WAVE IS OVER THE FAR WESTERN CARIBBEAN WITH AXIS EXTENDING FROM 23N86W IN THE YUCATAN CHANNEL TO 12N86W IN NICARAGUA. THIS WAVE HAS BEEN MOVING WESTWARD NEAR 5 KT AND IT IS FOUND IN A HIGH MOIST ENVIRONMENT. AN UPPER LEVEL LOW CENTERED N OF THE YUCATAN PENINSULA AS WELL AS UPPER LEVEL DIFFLUENCE OVER THE WESTERN CARIBBEAN SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM 12N-22N BETWEEN 80W-89W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 16N16W TO A 1011 MB LOW NEAR 10N20W TO 11N28W 11N35W 11N42W. THE ITCZ AXIS EXTENDS FROM 11N42W TO 12N49W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVES ALREADY DISCUSSED...SCATTERED MODERATE CONVECTION IS FROM 07N-14N BETWEEN 36W-48W. ...DISCUSSION... GULF OF MEXICO... SURFACE TROUGHINESS DOMINATES THE GULF WATERS WITH WINDS RANGING FROM 5-15 KT. AN UPPER LEVEL TROUGH EXTENDING SW ALONG THE EASTERN CONUS TO LOUISIANA SUPPORTS A SURFACE TROUGH FROM SOUTHERN ALABAMA NEAR 30N88W TO 24N92W. NUMEROUS MODERATE CONVECTION AND TSTMS ASSOCIATED WITH THIS TROUGH ARE N OF 26N E OF 89W. SCATTERED MODERATE CONVECTION IS OVER THE WESTERN GULF S OF 26N W OF 96W. ISOLATED SHOWERS AND TSTMS ARE OVER THE YUCATAN CHANNEL ASSOCIATED WITH A TROPICAL WAVE THAT IS EXPECTED TO MOVE ACROSS THE PENINSULA LATER TODAY. THE TROUGH OVER THE CENTRAL GULF WILL CONTINUE TO MOVE W-NW AND IS EXPECTED TO MOVE INLAND FROM SOUTHERN TEXAS TO NEAR TAMPICO MEXICO BY EARLY SUNDAY. THE TROPICAL WAVE WILL MOVE ACROSS THE YUCATAN PENINSULA TONIGHT...IT WILL BE OVER THE BAY OF CAMPECHE ON SUNDAY AND IS EXPECTED TO ENTER EASTERN MEXICO EARLY ON MONDAY. RAINSHOWERS ARE EXPECTED OVER THE CENTRAL AND WESTERN GULF THROUGHOUT THIS PERIOD. CARIBBEAN SEA... A TROPICAL WAVE IS EMBEDDED IN A HIGH MOIST ENVIRONMENT OVER THE FAR WESTERN CARIBBEAN WITH AXIS EXTENDING FROM 23N86W IN THE YUCATAN CHANNEL TO 12N86W IN NICARAGUA. AN UPPER LEVEL LOW CENTERED N OF THE YUCATAN PENINSULA AND DIFFLUENCE OVER THE WESTERN CARIBBEAN SUPPORT SCATTERED MODERATE CONVECTION AND TSTMS FROM 12N-22N BETWEEN 80W-89W. SIMILAR CONVECTION ASSOCIATED WITH THE WAVE IS WITHIN SOUTHERN CUBA AND JAMAICA BETWEEN 75W-78W. OVER THE SOUTHERN CARIBBEAN...ISOLATED SHOWERS ASSOCIATED WITH THE MONSOON TROUGH ARE S OF 11N BETWEEN 78W-83W. AN ELONGATED UPPER LEVEL LOW CENTERED OVER THE MONA PASSAGE EXTENDS ACROSS THE EASTER CARIBBEAN SUPPORTING A SURFACE TROUGH ALONG 20N63W TO 18N66W 14N68W. THIS SYSTEM OR THE REMNANTS OF ERIN IS GENERATING RAINSHOWERS AND TSTMS AS IT MOVES ACROSS PUERTO RICO THIS AFTERNOON. THESE SHOWERS EXTENDS 90 NM FROM THE SOUTHERN COAST OF THE ISLAND. PRECIPITATION ACTIVITY IS EXPECTED TO CONTINUE ACROSS PUERTO RICO UNTIL EARLY THIS EVENING. WEATHER CONDITIONS IMPROVE FOR SATURDAY AND SUNDAY AS A DRY AIRMASS IS EXPECTED TO ENTER THE EASTERN CARIBBEAN. THE TROPICAL WAVE OVER THE WESTERN BASIN IS EXPECTED TO CROSS NORTHERN CENTRAL AMERICA AND THE YUCATAN PENINSULA TONIGHT. HISPANIOLA... FAIR WEATHER IS ACROSS THE ISLAND THIS AFTERNOON BEING SUPPORTED BY LOW MOISTURE IN THE LOWER LEVELS AND DRY AIR SUBSIDENCE FROM THE MIDDLE LEVELS. RAINSHOWERS WILL DEVELOP LATE IN THE AFTERNOON/EARLY EVENING ASSOCIATED WITH THE SURFACE TROUGH/REMNANTS OF ERIN CURRENTLY MOVING ACROSS PUERTO RICO. ATLANTIC OCEAN... A WEAK UPPER LEVEL RIDGE CENTERED OVER THE NE GULF WHICH EXTENDS INTO THE SW N ATLC SUPPORTS A 1017 MB HIGH NEAR 30N72W. FURTHER EAST A SURFACE TROUGH EXTENDS FROM 29N56W TO 25N61W WITH NO CONVECTION ASSOCIATED WITH IT. IN THE CENTRAL TROPICAL ATLC...A 1014 MB LOW IS ANALYZED NEAR 15N37W WITH NO CONVECTION ASSOCIATED WITH IT. THIS LACK OF CONVECTION IS ASSOCIATED IN PART TO SAHARAN DRY AIR SPREADING OVER ITS ENVIRONMENT. OTHER THAN THAT...BESIDES THE TROPICAL WAVES ALREADY DISCUSSED...SURFACE RIDGING AND FAIR WEATHER DOMINATE THE REMAINDER BASIN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR