000 AXNT20 KNHC 272357 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUN 27 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2330 UTC. ...SPECIAL FEATURES... ...GALE WARNING IN THE CARIBBEAN SEA... GALE FORCE WINDS ARE FORECAST TO RESUME TONIGHT BEGINNING AT 0600 UTC FROM 11.5N TO 16N BETWEEN 70W AND 78W. SEAS OF 10 TO 15 FT CAN BE EXPECTED DUE TO THE GALE FORCE WINDS. THESE WINDS ARE BEING GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN STRONG HIGH PRESSURE OVER THE WESTERN ATLC...AND LOWER PRESSURES OVER NORTHERN COLOMBIA AND THE SW CARIBBEAN SEA. 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 ATLC WITH AN AXIS EXTENDING FROM 11N39W TO 04N40W...MOVING W AT 20 TO 25 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THIS WAVE IS EMBEDDED IN A DEEP MOIST ENVIRONMENT S OF 11N....WITH A SAHARAN AIR LAYER N OF 11N. SCATTERED MODERATE CONVECTION IS FROM 05N TO 11N BETWEEN 38W AND 43W. ANOTHER TROPICAL WAVE OVER THE CENTRAL TROPICAL ATLC HAS AN AXIS EXTENDING FROM 16N55W TO 06N56W...MOVING W AT 15 TO 20 KT. SSMI TPW IMAGERY SHOWS THIS WAVE IS ALSO EMBEDDED IN DEEP MOISTURE S OF 12N AND A SAHARAN AIR LAYER TO THE N OF 12N. NO DEEP CONVECTION IS CURRENTLY NOTED WITH THIS WAVE. A TROPICAL WAVE MOVING ACROSS THE CENTRAL CARIBBEAN HAS AN AXIS EXTENDING FROM 20N70W TO 10N70W...MOVING W AT AROUND 15 KT. WATER VAPOR IMAGERY INDICATES THE NORTHERN PORTION OF THE WAVE IS INTERACTING WITH A MID LEVEL TROUGH OVER THE WESTERN ATLC AND HISPANIOLA. MODERATE TO DEEP MOISTURE IS ALONG THE WAVE ENVIRONMENT. WEAKENING SCATTERED THUNDERSTORMS ARE OVER HISPANIOLA. OTHERWISE...NO DEEP CONVECTION IS NOTED WITH THIS WAVE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA REACHING THE TROPICAL ATLANTIC NEAR 11N16W TO 08N32W...WHERE THE ITCZ BEGINS AND CONTINUES TO 07N39W AND THEN RESUMES W OF A TROPICAL WAVE NEAR 06N43W TO 07N55W. SCATTERED MODERATE CONVECTION IS WITHIN 50 NM OF THE ITCZ AND MONSOON TROUGH AXIS E OF 32W...AND WITHIN 50 NM OF THE ITCZ AXIS BETWEEN 44W AND 48W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LOW IS CENTERED OVER THE WESTERN GULF NEAR 23N97W WITH AN UPPER LEVEL ANTICYCLONE CENTERED JUST EAST OF FL WITH UPPER LEVEL RIDGE AXIS OVER THE EASTERN GULF. SURFACE HIGH PRESSURE OF 1019 MB IS CENTERED NEAR 25N85W AND IS A WESTERN EXTENSION OF BROAD ATLC SURFACE RIDGING THAT EXTENDS ACROSS FL AND MUCH OF THE GULF OF MEXICO. THE UPPER LOW SUPPORTS ISOLATED MODERATE CONVECTION FROM 25N TO 29N BETWEEN 92W AND 97W. OTHERWISE...NO OTHER NOTABLE CONVECTION IS OVER THE BASIN THIS EVENING. S TO SW WINDS OF 5 TO 15 KT COVER THE WESTERN GULF...WITH SW TO W WINDS OF 5 TO 15 KT OVER THE EASTERN GULF. AN UPPER TROUGH AND ASSOCIATED COLD FRONT DIGGING SOUTHWARD ACROSS THE SOUTHERN US MAY BRING CONVECTION ACROSS THE NORTHERN GULF LATE TONIGHT THROUGH SUNDAY NIGHT. CARIBBEAN SEA... UPPER LEVEL DIFFLUENCE BETWEEN RIDGING OVER THE EASTERN GULF AND AN UPPER LOW OVER THE WESTERN GULF SUPPORTS ISOLATED MODERATE CONVECTION OVER THE NW CARIBBEAN FROM 18N TO 21N BETWEEN 83W AND 89W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE WESTERN ATLC AND LOW PRESSURE OVER N COLOMBIA SUPPORTS 15 TO 20 KT TRADE WINDS OVER THE MAJORITY OF THE CARIBBEAN...WITH A SMALLER AREA OF WINDS TO 25 KT OVER THE SOUTH-CENTRAL CARIBBEAN. THE PRESSURE GRADIENT WILL TIGHTEN LATER TONIGHT WHICH WILL INCREASE WINDS TO GALE FORCE LATE TONIGHT OVER A PORTION OF THE SOUTHERN CARIBBEAN. PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. OVER THE NEXT 24 HOURS CONVECTION MAY INCREASE OVER THE EASTERN CARIBBEAN AS A TROPICAL WAVE CROSSES THE LEEWARD ISLANDS. ...HISPANIOLA... SCATTERED THUNDERSTORMS ARE WEAKENING OVER HISPANIOLA...AS THEY WERE MAINTAINED PRIMARILY DUE TO DAYTIME HEATING. ADDITIONAL SHOWERS WILL BE POSSIBLE OVERNIGHT TONIGHT AS A TROPICAL WAVE PASSES OVER THE ISLAND. SCATTERED AFTERNOON THUNDERSTORMS WILL OCCUR AGAIN ON SUNDAY AS A MOIST AIRMASS REMAINS ACROSS THE ISLAND. ATLANTIC OCEAN... SCATTERED SHOWERS AND THUNDERSTORMS ARE FROM 25N TO 30N BETWEEN 76W AND 81W AND ARE PRIMARILY SUPPORTED BY UPPER LEVEL DIFFLUENCE IN THE PRESENCE OF AN UPPER LEVEL RIDGE. ELSEWHERE...A BROAD LOW LEVEL RIDGE ANCHORED BY A 1027 MB HIGH NEAR 29N51W SUPPORTS GENERALLY FAIR WEATHER ACROSS THE SUBTROPICAL NORTHERN ATLC E OF 75W. TWO TROPICAL WAVES ARE OVER THE CENTRAL TROPICAL NORTHERN ATLC. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A LARGE AREA OF SAHARAN AIR WITH DUST IS LOCATED FROM 11N/12N TO 20N BETWEEN THE AFRICAN COAST AND 60W. OVER THE NEXT 24 HOURS CONVECTION WILL PERSIST OFFSHORE FL MAINLY NORTH OF THE BAHAMAS AS AN UPPER TROUGH MOVES OFF THE SE US COAST. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO