000 AXNT20 KNHC 281804 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT SAT JUN 28 2014 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. ...SPECIAL FEATURES... AN ELONGATED MIDDLE LEVEL TROUGH ALONG THE WESTERN ATLC N OF 28N SUPPORTS A WEAK LOW PRESSURE SYSTEM JUST OFF THE COAST OF SOUTH CAROLINA. THIS AREA OF LOW PRESSURE IS SUPPORTING HEAVY SHOWERS AND TSTMS N OF 26N BETWEEN 75W-80W. GRADUAL DEVELOPMENT OF THIS SYSTEM IS EXPECTED IF ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE. PLEASE SEE THE ATLC TROPICAL WEATHER OUTLOOK UNDER AWIPS/WMO HEADERS MIATWOAT/ABNT20 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE IS EMBEDDED IN THE ITCZ WITH AXIS EXTENDING FROM 13N40W TO 5N40W MOVING W NEAR 25 KT. SSMI TPW AND SAHARAN AIR LAYER TRACKING IMAGERY INDICATE THE PRESENCE OF DRY AIR N OF THE ITCZ WHICH IS LIMITING THE CONVECTION TO SCATTERED SHOWERS WITHIN 180 NM OF THE AXIS S OF 11N. TROPICAL WAVE IS WEST OF THE ITCZ WITH AXIS EXTENDING FROM 18N53W TO 5N56W MOVING W-NW NEAR 15-20 KT. SAHARAN AIR LAYER TRACKING IMAGERY SHOW DRY AIR IN THE WAVE ENVIRONMENT N OF 10N. SCATTERED MODERATE CONVECTION IS LIMITED TO THE VICINITY OF THE ITCZ FROM 6N-9N BETWEEN 54W-58W. TROPICAL WAVE IS OVER THE CARIBBEAN WITH AXIS EXTENDING FROM 19N68W TO 6N71W MOVING W NEAR 15 KT. SSMI TPW IMAGERY SHOW DRY AIR IN THE NORTHERN ENVIRONMENT OF THE WAVE WHICH ALONG STRONG DEEP-LAYER WIND SHEAR OVER THE CENTRAL AND EASTERN CARIBBEAN HINDER DEEP CONVECTION. SCATTERED SHOWERS ARE WITHIN 200 NM EITHER SIDE OF THE AXIS S OF 15N. TROPICAL WAVE IS OVER THE YUCATAN PENINSULA WITH AXIS EXTENDING FROM 21N86W TO 14N90W MOVING W-NW NEAR 20 KT. THIS WAVE IS VERY WEAK AND BARELY DISCERNIBLE AS IT MOVES IN THE W-SW PERIPHERY OF A LOW LEVEL RIDGE. THERE IS NO CONVECTION ASSOCIATED WITH THIS WAVE AT THE MOMENT. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE COAST GUINEA NEAR 10N14W TO 8N20W. THE ITCZ BEGINS NEAR 8N20W AND CONTINUES ALONG 7N30W TO E OF A TROPICAL WAVE NEAR 7N38W. IT THEN RESUMES W OF THE WAVE NEAR 6N42W TO 8N54W. SCATTERED MODERATE CONVECTION AND TSTMS ARE FROM 6N-11N E OF 20W. SCATTERED MODERATE CONVECTION IS ALSO FROM 5N-7N BETWEEN 20W-28W AND FROM 4N-9N W OF 42W. ...DISCUSSION... ...THE GULF OF MEXICO... SURFACE RIDGING DOMINATES ACROSS THE GULF BEING SUPPORTED BY A MIDDLE LEVEL ANTICYCLONE COVERING THE WHOLE BASIN. THE SURFACE RIDGE IS ANCHORED BY A 1022 MB HIGH NEAR 28N84W AND PROVIDES THE GULF WITH E-SE WIND FLOW OF 10-15 KT...EXCEPT W OF 91W WHERE WINDS ARE UP TO 20 KT. IN THE UPPER LEVELS...A TROUGH EXTENDS ACROSS OKLAHOMA INTO EASTERN TEXAS TO THE NW GULF WHILE THE EASTERN PERIPHERY OF A RIDGE ANCHORED OVER SW MEXICO COASTAL WATERS COVERS THE BAY OF CAMPECHE. THIS WIND PATTERN ALOFT IS GENERATING DIFFLUENCE TO SUPPORT SCATTERED SHOWERS W OF 92W. HIGH PRESSURE WILL PREVAIL ACROSS THE BASIN FOR THE NEXT COUPLE OF DAYS WHILE A TROPICAL WAVE MOVES ACROSS THE BAY OF CAMPECHE TOWARDS THE SOUTHERN MEXICO AND THE E PACIFIC WATERS. ...THE CARIBBEAN SEA... DRY AIR DOMINATES THE NORTHERN CARIBBEAN BASIN WHICH ALONG STRONG DEEP-LAYER WIND SHEAR SUPPORT FAIR WEATHER N OF 15N. A TROPICAL WAVE IS MOVING ACROSS THE CENTRAL BASIN. SEE THE WAVES SECTION ABOVE FOR MORE DETAILS. OVER THE SW CARIBBEAN...THE MONSOON TROUGH IS SUPPORTING SCATTERED SHOWERS S OF 14N W OF 75W. OTHERWISE...A SURFACE TROUGH IS NW OF THE WINDWARD ISLANDS WITH AXIS EXTENDING FROM 15N61W TO 12N63W GENERATING SHOWERS S OF 15N E OF 64W. THE PRESSURE GRADIENT BETWEEN THE ATLANTIC RIDGE AND THE MONSOON TROUGH IS MAINTAINING 20-25 KT TRADES IN THE CENTRAL CARIBBEAN AND 10-20 KT WINDS IN BOTH THE WESTERN AND EASTERN CARIBBEAN. A NEW TROPICAL WAVE WILL BE ENTERING THE E CARIBBEAN LATE SUNDAY. ...HISPANIOLA... FAIR WEATHER AND CLEAR SKIES RULE OVER THE ISLAND SUPPORTED BY DRY AIR AND STRONG DEEP-LAYER WIND SHEAR. SAHARAN DRY AIR WILL CONTINUE TO MOVE OVER HISPANIOLA OVER THE NEXT COUPLE OF DAYS AND DEVELOPMENT OF AFTERNOON CONVECTION SHOULD BE DELAYED...WITH GENERALLY LESS COVERAGE THAN IS TYPICALLY EXPECTED DURING THE SUMMER MONTHS. ...THE ATLANTIC OCEAN... AN ELONGATED MIDDLE LEVEL TROUGH ALONG THE WESTERN ATLC N OF 28N SUPPORTS A WEAK LOW PRESSURE SYSTEM JUST OFF THE COAST OF SOUTH CAROLINA. THIS AREA OF LOW PRESSURE IS SUPPORTING HEAVY SHOWERS AND TSTMS N OF 26N BETWEEN 75W-80W. SEE THE SPECIAL FEATURES SECTION FOR MORE INFORMATION. AN UPPER LEVEL CYCLONIC CIRCULATION CENTERED OVER THE NW CARIBBEAN EXTENDS A TROUGH AXIS NORTHWARD TO SUPPORT ISOLATED SHOWERS AND TSTMS OVER THE CENTRAL BAHAMAS...THE FLORIDA STRAITS AND PORTIONS OF EASTERN S FLORIDA. FARTHER EAST...A SURFACE TROUGH EXTENDS FROM 28N61W TO 24N67W WITH ISOLATED SHOWERS FROM 26N-28N BETWEEN 60W-65W. OTHERWISE...A BROAD SURFACE RIDGE COVERS THE REMAINDER BASIN...THUS SUPPORTING FAIR WEATHER. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ NR