000 AXNT20 KNHC 200604 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT FRI SEP 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A 1006 MB LOW CENTER IS IN THE BAY OF CAMPECHE NEAR 21N95W. THIS AREA OF LOW PRESSURE IS WITHIN A ZONE OF VERY MOIST AIR AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. HOWEVER...STRONG NORTHWESTERLY WIND SHEAR IN THE VICINITY OF THE LOW IS HINDERING IN PART CONVECTIVE ACTIVITY. MIDDLE-LEVEL DIFFLUENCE WEST OF THE LOW CENTER IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION AND TSTMS INLAND SOUTHERN AND EASTERN MEXICO. ENVIRONMENTAL CONDITIONS ARE ONLY MARGINALLY CONDUCIVE AND SIGNIFICANT DEVELOPMENT OF THIS SYSTEM IS BECOMING LESS LIKELY THUS GIVING IT A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS DISTURBANCE WILL CONTINUE TO PRODUCE LOCALLY HEAVY RAINS OVER PORTIONS OF EASTERN AND SOUTHERN MEXICO DURING THE NEXT FEW DAYS. ...TROPICAL WAVES... THE AXIS OF A TROPICAL WAVE EXTENDS ALONG 23N31W TO 13N32W AND IS MOVING W NEAR 10 KNOTS. TOTAL PRECIPITABLE WATER IMAGERY SHOW MOST OF THE WAVE ENVIRONMENT HAS BEEN UNDERCUT BY VERY DRY AIR WHICH IS LIMITING CONVECTION. SCATTERED MODERATE CONVECTION IS NW OF THE WAVE AXIS FROM 20N-23N BETWEEN 31W-34W AND SE OF THE AXIS FROM 12N-15N BETWEEN 28W-32W. THESE AREAS OF CONVECTION COINCIDE WITH SMALL SECTORS OF VERY MOIST AIR IN TOTAL PRECIPITABLE WATER IMAGERY. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES THROUGH COASTAL WEST AFRICA NEAR 11N15W TO 11N30W 08N37W. THE ITCZ CONTINUES FROM 08N38W TO 09N46W. A SQUALL LINE OF MODERATE TO ISOLATED STRONG CONVECTION IS FROM 08N-13N BETWEEN 16W-19W. BESIDES THE CONVECTION ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED MODERATE CONVECTION IS FROM 07N-12N BETWEEN 27W-36W AND FROM 06N-09N BETWEEN 38W-42W. ...DISCUSSION... GULF OF MEXICO... A VERY MOIST ENVIRONMENT AT THE LOWER LEVELS DOMINATE THE WESTERN GULF WATERS AS DEPICTED IN IMAGERY OF TOTAL PRECIPITABLE WATER. HOWEVER...STRONG NORTHWESTERLY WIND SHEAR ACROSS GREAT PORTIONS OF THE BASIN INHIBITS IN PART CONVECTIVE ACTIVITY THIS MORNING. A 1006 MB LOW CENTER IS IN THE BAY OF CAMPECHE NEAR 21N95W. MIDDLE-LEVEL DIFFLUENCE WEST OF THE LOW CENTER IS SUPPORTING SCATTERED MODERATE/ISOLATED STRONG CONVECTION AND TSTMS INLAND SOUTHERN AND EASTERN MEXICO. THE CONVECTION OVER SOUTHERN MEXICO EXTENDS OFFSHORE TO THE BAY OF CAMPECHE S OF 20N BETWEEN 92W-96W. SEE THE SPECIAL FEATURES SECTION FOR MORE INFORMATION ABOUT THIS DISTURBANCE. SCATTERED SHOWERS ARE NW OF THE BASIN N OF 25N BETWEEN 92W-96W. AN UPPER-LEVEL TROUGH EXTENDS ACROSS THE FLORIDA PENINSULA AND THE STRAITS SUPPORTING ISOLATED SHOWERS OVER THE EASTERN GULF S OF 29N E OF 85W. THE DISTURBANCE IN THE SW GULF HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. THIS SYSTEM WILL CONTINUE TO PRODUCE LOCALLY HEAVY RAINS OVER PORTIONS OF EASTERN AND SOUTHERN MEXICO DURING THE NEXT FEW DAYS. A COLD FRONT IS EXPECTED TO ENTER THE NORTHERN GULF WATERS BY SATURDAY AFTERNOON. CARIBBEAN SEA... TOTAL PRECIPITABLE WATER IMAGERY SHOW A REDUCTION IN MOISTURE ACROSS GREAT PORTIONS OF THE BASIN THIS MORNING. MIDDLE LEVEL DIFFLUENT FLOW IN THE NW CARIBBEAN BASIN ENHANCES SCATTERED SHOWERS N OF 15N W OF 78W. HOWEVER...UPPER-LEVEL DIFFLUENCE FROM THE TROUGH OVER THE N WESTERN ATLC AND A RIDGE COVERING WESTERN- CENTRAL CARIBBEAN SEA SUPPORTS SCATTERED MODERATE CONVECTION OVER THE WINDWARD PASSAGE AND HISPANIOLA. ISOLATED SHOWERS ARE ELSEWHERE IN THE BASIN...EXCEPT BETWEEN 66W-71W WHERE FAIR WEATHER DOMINATES. A SURFACE TROUGH IS EXPECTED TO ENTER THE EASTERN CARIBBEAN SEA EARLY SUNDAY AFTERNOON GENERATING SHOWERS POSSIBLY AFFECTING THE LESSER ANTILLES. HISPANIOLA... UPPER-LEVEL DIFFLUENCE FROM A TROUGH OVER THE N WESTERN ATLC AND A RIDGE COVERING WESTERN-CENTRAL CARIBBEAN SEA SUPPORTS SCATTERED MODERATE CONVECTION OVER THE WINDWARD PASSAGE...HAITI AND WESTERN DOMINICAN REPUBLIC. BESIDES THE TYPICAL AFTERNOON/EARLY EVENING SHOWERS ACTIVITY DUE TO SURFACE HEATING...CONVECTIVE ACTIVITY DUE TO THE UPPER-LEVEL FEATURES MENTIONED ABOVE IS EXPECTED TO CONTINUE UNTIL SATURDAY NIGHT. ATLANTIC OCEAN... AN UPPER-LEVEL TROUGH IN THE N WESTERN ATLC SUPPORTS A FRONTAL SYSTEM THAT ENTERS THE DISCUSSION AREA AS A COLD FRONT FROM 30N52W TO 29N55W WHERE IT TRANSITIONS TO A STATIONARY FRONT TO 29N61W TO 29N68W. IN ADDITION...THE UPPER-LEVEL TROUGH SUPPORTS A SURFACE TROUGH ASSOCIATED WITH A 1011 MB LOW PRESSURE CENTER NEAR 25N70W. DISORGANIZED CLOUDINESS AS WELL AS SCATTERED SHOWERS AND TSTMS ASSOCIATED WITH THE FRONT AND THE LOW ARE FROM 22N-31N BETWEEN 59W-73W. DIFFLUENT FLOW ALOFT FROM THE UPPER- LEVEL TROUGH AND A RIDGE COVERING THE WESTERN-CENTRAL CARIBBEAN SUPPORTS SCATTERED SHOWERS IN THE BAHAMAS. A SURFACE TROUGH EMBEDDED WITHIN A VERY MOIST ENVIRONMENT EXTENDS ALONG 17N53W TO 10N54W. TRAILING SCATTERED MODERATE CONVECTION AND ISOLATED TSTMS IS FROM 12N-18N BETWEEN 46W-53W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS