000 AXNT20 KNHC 281035 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN JUN 28 2015 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURES... ...GALE WARNING IN THE CARIBBEAN SEA... A GALE WARNING IS IN EFFECT FOR AN AREA FROM 11.5N-14N BETWEEN 73W-71W. SEAS OF 12 TO 18 FT CAN BE EXPECTED WITHIN THIS AREA. THESE WINDS ARE BEING GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN A STRONG HIGH PRESSURE OVER THE WESTERN ATLANTIC AND LOWER PRESSURES OVER SW CARIBBEAN SEA AND SOUTH AMERICA. SEE THE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC AND THE OFFSHORE FORECAST...MIAOFFNT3/ FZNT23 FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 11N42W TO 03N43W...MOVING W AT 20 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THIS WAVE IS EMBEDDED IN A DEEP MOIST ENVIRONMENT S OF 11N...WHILE A SAHARAN AIR LAYER PREVAILS N OF 08N. ISOLATED MODERATE CONVECTION IS OBSERVED N OF 08N BETWEEN 42W-44W. A TROPICAL WAVE IS ACROSS THE E CARIBBEAN...WITH AXIS EXTENDING FROM 18N65W TO 10N65W. THIS WAVE IS MOVING W AT 15 TO 20 KT. SSMI TPW IMAGERY SHOWS THIS WAVE ALSO EMBEDDED IN DEEP MOISTURE MAINLY S OF 13N BUT A HIGH CONCENTRATION OF SAHARAN DUST PREVAILS N OF 13N INHIBITING SIGNIFICANT CONVECTION. A TROPICAL WAVE MOVING ACROSS THE CENTRAL CARIBBEAN WITH AXIS EXTENDING FROM 20N74W TO 10N76W...MOVING W AT AROUND 15 KT. WATER VAPOR IMAGERY INDICATES THE NORTHERN PORTION OF THE WAVE IS INTERACTING WITH A MID-LEVEL TROUGH THAT EXTENDS ACROSS THE NORTHERN CARIBBEAN FROM THE SW ATLANTIC. THIS INTERACTION WILL SUPPORT ISOLATED CONVECTION ACROSS PORTIONS OF HISPANIOLA AND THE WINDWARD PASSAGE. NO DEEP CONVECTION IS NOTED S OF THE ISLAND DUE TO THE PRESENCE OF SAHARAN DUST. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA REACHING THE TROPICAL ATLANTIC NEAR 14N17W TO 07N36W...WHERE THE ITCZ BEGINS AND CONTINUES TO 07N41W...THEN RESUMES W OF A TROPICAL WAVE NEAR 07N45W TO 05N53W. SCATTERED MODERATE CONVECTION IS WITHIN 50 NM OF THE ITCZ AND MONSOON TROUGH AXES MAINLY E OF 30W...AND WITHIN 50 NM OF THE ITCZ AXIS BETWEEN 50W-53W. ...DISCUSSION... GULF OF MEXICO... AN UPPER-LEVEL LOW IS CENTERED OVER THE WESTERN GULF NEAR 25N94W WHILE AN UPPER-LEVEL ANTICYCLONE IS CENTERED OVER THE FLORIDA STRAITS. THESE FEATURES ARE GENERATING A DIFFLUENT FLOW ACROSS THE CENTRAL GULF WHICH SUPPORTS CLOUDINESS AND ISOLATED CONVECTION BETWEEN 87W-95W. AT THE SURFACE...A 1018 MB HIGH PRESSURE IS CENTERED NEAR 25N85W SUPPORTING A LIGHT TO GENTLE ANTICYCLONIC FLOW ACROSS THE BASIN. SCATTERED MODERATE CONVECTION IS DEVELOPING ACROSS THE SOUTHERN PORTIONS OF TEXAS...LOUISIANA AND MISSISSIPPI AHEAD OF A FRONTAL SYSTEM THAT IS DIGGING SOUTHWARD ACROSS SOUTHERN US. SOME OF THIS ACTIVITY IS REACHING THE NORTHERN GULF MAINLY N OF 29N. OVER THE NEXT 24 HOURS...EXPECT FOR CONVECTION TO PREVAIL ACROSS THE NORTHERN GULF AS THE FRONT CONTINUES MOVING SE. THE SURFACE HIGH WILL REMAIN STATIONARY OVER THE SE GULF. CARIBBEAN SEA... A DIFFLUENT ENVIRONMENT PREVAILS ACROSS THE W CARIBBEAN SUPPORTING ISOLATED CONVECTION MAINLY W OF 85W. TO THE E...AN UPPER-LEVEL TROUGH ORIGINATED ACROSS THE SW ATLANTIC EXTENDS SW ACROSS THE WINDWARD PASSAGE REACHING THE NW PORTION OF THE BASIN. THIS FEATURE IS GENERATING CLOUDINESS AND ISOLATED CONVECTION ACROSS HISPANIOLA AND N OF THE ISLAND. TWO TROPICAL WAVES ARE OBSERVED ACROSS THE CENTRAL AND E CARIBBEAN...FOR MORE INFORMATION PLEASE REFER TO THE SECTION ABOVE. A STRONG PRESSURE GRADIENT BETWEEN THE HIGH PRESSURE OVER THE WESTERN ATLANTIC AND LOWER PRESSURES OVER S AMERICA SUPPORTS GENTLE TO MODERATE TRADE WINDS OVER THE MAJORITY OF THE CARIBBEAN...WITH AN AREA OF MINIMAL GALE FORCE WINDS PREVAILING OVER THE S-CENTRAL CARIBBEAN. PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS...EXPECT A SLIGHT INCREASE IN CONVECTION OVER THE EASTERN CARIBBEAN AS A TROPICAL WAVE MOVES THROUGH PUERTO RICO AND APPROACHES HISPANIOLA. ...HISPANIOLA... A TROPICAL WAVE IS CURRENTLY OVER THE WINDWARD PASSAGE AND THE MOIST AIRMASS BEHIND IT PREVAILS ACROSS THE AREA. DESPITE THIS...FAIR WEATHER PREVAILS OVER THE ISLAND THIS MORNING. AN UPPER-LEVEL TROUGH EXTENDS FROM THE SW ATLANTIC ACROSS THE WINDWARD PASSAGE. WITH THIS...EXPECT CONVECTION TO DEVELOP THIS AFTERNOON AS THIS FEATURE COMBINES WITH DIURNAL HEATING AND OROGRAPHIC LIFTING. ATLANTIC OCEAN... AN UPPER-LEVEL LOW IS CENTERED ACROSS THE SW ATLANTIC NEAR 26N69W SUPPORTING CLOUDINESS AND ISOLATED MODERATE CONVECTION S OF 26N BETWEEN 64W-72W. A 1026 MB SURFACE HIGH PREVAILS ACROSS THE REMAINDER OF THE BASIN CENTERED NEAR 27N52W. A LARGE SAHARAN AIRMASS ALSO COVERS THE AREA MAINLY N OF 09N. WITH THIS...FAIR WEATHER PREVAILS ACROSS THE BASIN. OVER THE NEXT 24 HOURS... EXPECT CONVECTION TO DEVELOP OFFSHORE FL MAINLY N OF THE BAHAMAS AS AN UPPER-LEVEL TROUGH MOVES OFF THE SE US COAST. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ ERA