000 AXNT20 KNHC 061806 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT JUL 06 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. ...SPECIAL FEATURES... THE 1012 MB LOW PRESSURE ASSOCIATED WITH THE TROPICAL WAVE OVER THE EASTERN ATLC HAS BECOME BETTER ORGANIZED WITHIN THE LAST COUPLE OF HOURS AND HAS A MEDIUM CHANCE OF DEVELOPMENT WITHIN THE NEXT 48 HOURS. SEE THE TROPICAL WAVES SECTION BELOW FOR MORE INFORMATION ABOUT THE WAVE ASSOCIATED WITH THIS LOW. ...TROPICAL WAVES... A TROPICAL WAVE IS MOVING W NEAR 20 KT WITH AXIS EXTENDING FROM 18N39W TO A 1012 MB LOW EMBEDDED WITHIN THE MONSOON TROUGH AXIS. EXCEPT FOR THE PORTION OF THE WAVE ASSOCIATED WITH THE LOW...VERY DRY AIR FROM A SAL OUTBREAK SPREADS OVER ITS ENVIRONMENT WHICH IS HINDERING CONVECTION N OF 9N. A CLUSTER OF MODERATE CONVECTION IS FROM 04N-09N BETWEEN 32W-36W ASSOCIATED WITH THE LOW. A TROPICAL WAVE IS MOVING W-NW NEAR 15 KT ACROSS THE EASTERN CARIBBEAN. CURRENTLY ITS AXIS EXTENDS FROM 21N61W TO 13N68W AND IS EMBEDDED IN A MODERATE MOIST ENVIRONMENT AS DEPICTED IN TOTAL PRECIPITABLE WATER IMAGERY. A MORE MOIST AREA LIES FARTHER EAST WHERE THE WAVE WAS PREVIOUSLY ANALYZED. WIDESPREAD DUST HAS BEEN REPORTED IN THE LESSER ANTILLES AS WELL AS IN DOMINICAN REPUBLIC AND DRY AIR IS OBSERVED SURROUNDING THE WAVE ENVIRONMENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE CONVECTION AND ISOLATED THUNDERSTORMS ARE FROM 18N-20N WITHIN 250 NM E OF THE WAVE AXIS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE FROM AN UPPER CYCLONIC CIRCULATION CENTERED NEAR 23N66W AND AN ANTICYCLONIC CIRCULATION CENTERED 12N58W. RADAR IMAGERY FROM PUERTO RICO SHOW ISOLATED SHOWERS N OF 16N E OF 68W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST COAST OF AFRICA NEAR 19N16W TO 11N23W TO A 1012 MB SURFACE LOW NEAR 06N33W TO 06N36W. THE ITCZ BEGINS NEAR 06N36W AND CONTINUES ALONG 05N49W 06N57W. BESIDES CONVECTION NEAR THE SURFACE LOW ASSOCIATED WITH THE TROPICAL WAVE...SCATTERED MODERATE CONVECTION IS FROM 06N-12N E OF 19W. SIMILAR CONVECTION IS WITHIN 180 NM S OF THE ITCZ AND WITHIN 80 NM N OF THE AXIS W OF 39W. ...DISCUSSION... GULF OF MEXICO... ABUNDANT MOISTURE IS BASIN WIDE WITH A MAXIMUM S OF 27N W OF 90W. THIS MOISTURE IS DUE TO A COMBINATION OF MOIST SOUTHERLY TO SOUTHEASTERLY FLOW AT THE SURFACE THROUGHOUT MUCH OF THE AREA...AND MOIST SOUTHWESTERLY AND DIFFLUENT FLOW ALOFT BETWEEN AN UPPER LEVEL TROUGH OVER THE CENTRAL CONUS THAT IS PUSHING INTO THE NW GULF...AND AN UPPER LEVEL RIDGE OVER THE REMAINDER OF THE BASIN EXTENDING FROM THE BAY OF CAMPECHE TO NORTHERN FLORIDA. THE UPPER LEVEL TROUGH IS SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM SOUTHERN ALABAMA NEAR 30N88W...ACROSS SE LOUISIANA TO 29N91W 26N96W TO TAMPICO MEXICO. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION AND THUNDERSTORMS CONCENTRATE E OF THE SURFACE TROUGH AXIS W OF 90W. SCATTERED MODERATE CONVECTION AND ISOLATED THUNDERSTORMS ARE N OF 21N BETWEEN 84W-90W. OTHERWISE...RETURN FLOW OF 15-25 KT SPREADS EAST OF THE SURFACE TROUGH BEING THE STRONGEST WINDS W OF 90W. ABUNDANT MOISTURE WILL PERSIST OVER THE GULF WITH THE HIGHEST CONCENTRATION BEING OVER THE WESTERN GULF AS RETURN FLOW COMPLETELY BUILDS ACROSS THE BASIN AND THE UPPER LEVEL RIDGE CONTINUES TO SHIFT W-NW. RAINSHOWERS ACROSS THE BASIN ARE EXPECTED UNTIL MONDAY MORNING WHEN DRIER AIR ENTERS THE REGION. CARIBBEAN SEA... MOISTURE FROM THE GULF OF MEXICO IS BEING DRAWN OVER THE NW CARIBBEAN IN NORTHERLY FLOW ALOFT AROUND AN UPPER LEVEL RIDGE OVER THE GULF. ONLY A FEW ISOLATED SHOWERS ARE NORTH OF 18N W OF 73W. SCATTERED MODERATE CONVECTION AND ISOLATED THUNDERSTORMS ARE IN THE SW CARIBBEAN S OF 13N W OF 77W ASSOCIATED WITH THE MONSOON TROUGH AXIS WHICH MOVES ACROSS PANAMA TO A 1008 MB SURFACE LOW OVER NORTHERN COLOMBIA. A TROPICAL WAVE AXIS IS JUST EAST OF PUERTO RICO AND WILL BE MOVING ACROSS THE ISLAND TODAY. CURRENTLY SCATTERED MODERATE CONVECTION AND ISOLATED THUNDERSTORMS ARE FROM 18N-20N WITHIN 250 NM E OF THE WAVE AXIS BEING ENHANCED BY UPPER LEVEL DIFFLUENCE FROM AN UPPER CYCLONIC CIRCULATION CENTERED NEAR 23N66W AND AN ANTICYCLONIC CIRCULATION CENTERED 12N58W. RADAR IMAGERY FROM PUERTO RICO SHOW ISOLATED SHOWERS N OF 16N E OF 68W. DRY AIR AT LOWER AND MIDDLE LEVELS IS ACROSS THE REMAINDER BASIN AS DEPICTED IN TOTAL PRECIPITABLE WATER AND WATER VAPOR IMAGERY. OTHERWISE...TRADEWINDS FLOW OF 15- 20 KT IS THROUGHOUT MUCH OF THE AREA WITH STRONGER WINDS TO 25 KT OVER THE CENTRAL CARIBBEAN AND NEAR THE COAST OF COLOMBIA. THE WAVE OVER THE EASTERN CARIBBEAN IS EXPECTED TO MOVE OFF PUERTO RICO VERY EARLY ON SUNDAY. RAINSHOWERS CAN BE EXPECTED THROUGHOUT THE DAY. HISPANIOLA... CURRENTLY VERY DRY AIR IS ACROSS THE ISLAND AS DEPICTED IN TOTAL PRECIPITABLE WATER AND WATER VAPOR IMAGERY. IN ADDITION...DOMINICAN REPUBLIC HAS BEEN REPORTING WIDESPREAD DUST OVER THE PAST SEVERAL HOURS. HOWEVER RAINSHOWERS COULD BE POSSIBLE THIS AFTERNOON ENHANCED BY DAYTIME HEATING. WEATHER CONDITIONS WILL START TO DEGRADE VERY EARLY ON SUNDAY AS A TROPICAL WAVE MOVES OVER THE WINDWARD PASSAGE TOWARDS THE DOMINICAN REPUBLIC. UPPER LEVEL DIFFLUENT FLOW SHIFTING WESTWARD ALONG WITH THE WAVE AS WELL AS MODERATE MOISTURE ARE LIKELY TO ENHANCE RAINSHOWERS ACROSS THE ISLAND ON SUNDAY. WEATHER CONDITIONS ARE EXPECTED TO IMPROVE EARLY ON MONDAY. ATLANTIC OCEAN... BROAD SURFACE RIDGING DOMINATES THE WEST ATLC AROUND A 1027 MB HIGH NEAR 34N71W. THE RIDGE IS SUPPORTED BY BROAD UPPER RIDGING CENTERED NEAR 35N69W. AN UPPER LEVEL LOW IS CENTERED NEAR 23N66W SUPPORTING A FEW ISOLATED SHOWERS FROM 21N-26N BETWEEN 63W-70W. A TROPICAL WAVE IS TO THE EAST SUPPORTING SCATTERED MODERATE CONVECTION AND ISOLATED THUNDERSTORMS FROM 18N-20N WITHIN 250 NM E OF THE WAVE AXIS. A STATIONARY FRONT TO THE NORTH EXTENDS INTO THE AREA ALONG 30N42W TO 29N46W 29N52W 29N56W 29N59W. SCATTERED MODERATE CONVECTION IS N OF 27N BETWEEN 41W-45W...ISOLATED SHOWERS ARE N OF 28N BETWEEN 58W-63W. VERY DRY AIR IS THROUGHOUT THE EAST ATLC DUE TO A SAHARAN AIR LAYER OUTBREAK. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ RAMOS