000 AXNT20 KNHC 192348 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI JUN 19 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 2215 UTC. ...SPECIAL FEATURES... A TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER THE WESTERN ATLC AND LOWER PRESSURE OVER COLOMBIA IS PRODUCING GALE FORCE WINDS OVER A PORTION OF THE SOUTHERN CARIBBEAN. GALE-FORCE WINDS ARE FORECAST TO CONTINUE FROM 11.5N TO 13.5N BETWEEN 72W AND 77W...AND S OF 12N BETWEEN 70W AND 72W UNTIL 1800 UTC SATURDAY. SEAS OF 10 TO 15 FT IN NE SWELL ARE EXPECTED OVER THE WARNED AREA FROM 72W TO 77W...AND SEAS TO 9 FEET ARE EXPECTED OVER THE WARNED AREA FROM 70W TO 72W...INCLUDING THE GULF OF VENEZUELA. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT2/FZNT02 KNHC...AND THE OFFSHORE FORECAST...MIAOFFNT3/FZNT23 KNHC...FOR MORE DETAILS. ...TROPICAL WAVES... AN EASTERN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 24W FROM 12N TO 04N MOVING WESTWARD AT 10 TO 15 KT. SSMI TPW IMAGERY SHOWS DEEP MOISTURE CONFINED S OF 10 N ALONG THE WAVE...WITH SAHARAN DUST N OF 10 N. ISOLATED MODERATE CONVECTION IS FROM 04N TO 08N BETWEEN 22W AND 27W. A CENTRAL ATLANTIC OCEAN TROPICAL WAVE IS ALONG 42W/43W FROM 12N TO 04N...MOVING WESTWARD AT 10 TO 15 KT. SSMI TPW IMAGERY SHOWS THE WAVE IS EMBEDDED IN A LARGE AREA OF DEEP TROPICAL MOISTURE THAT EXTENDS NORTHWARD ACROSS THE ENTIRE WAVE AXIS. CLUSTERS OF MODERATE CONVECTION ARE FROM 07N TO 12N BETWEEN 40W AND 46W. A CARIBBEAN SEA TROPICAL WAVE IS ALONG 75W/76W FROM 16N TO 08N...MOVING WESTWARD AT 15 KT. SSMI TPW IMAGERY SHOWS THE WAVE IS EMBEDDED IN A MODERATELY MOIST ENVIRONMENT. HOWEVER...NO DEEP CONVECTION IS NOTED WITH THIS WAVE AT THIS TIME. A TROPICAL WAVE IS INLAND IN CENTRAL AMERICA...ALONG 85W/86W FROM HONDURAS TO NICARAGUA AND COSTA RICA...TO OVER THE EASTERN PACIFIC WATERS...MOVING WESTWARD AT 10 KT. ISOLATED MODERATE CONVECTION IS INLAND OVER HONDURAS AND COSTA RICA. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH PASSES ACROSS COASTAL SECTIONS OF AFRICA NEAR 12N16W TO 08N22W. THE ITCZ BEGINS WEST OF AN EASTERN ATLC TROPICAL WAVE NEAR 08N27W TO 08N41W...AND RESUMES EAST OF A CENTRAL ATLC TROPICAL WAVE NEAR 07N46W TO THE COAST OF S AMERICA NEAR 05N53W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 05N TO 11N BETWEEN 27W AND 40W. ...DISCUSSION... THE GULF OF MEXICO... UPPER LEVEL CYCLONIC FLOW COVERS THE BASIN WITH RELATIVELY DRY AIR IN THE MIDDLE TO UPPER LEVELS NOTED ON WATER VAPOR IMAGERY. A SURFACE RIDGE AXIS EXTENDS FROM THE WESTERN ATLC TO CENTRAL FL TO THE TX GULF COAST...RESULTING IN EAST TO SOUTHEAST SURFACE WINDS OVER THE SOUTHERN GULF...AND SOUTH TO SOUTHWESTERLY WINDS OVER THE NORTHERN GULF. WINDS ARE GENERALLY UNDER 15 KT ACROSS THE BASIN. A SURFACE TROUGH EXTENDS OVER THE SOUTHWESTERN GULF FROM 23N94W TO 17N94W. SCATTERED THUNDERSTORMS ARE S OF 23N OVER THE SOUTHWESTERN GULF. OTHER CONVECTION OVER THE NEAR-SHORE WATERS OF THE EASTERN GULF IS ASSOCIATED WITH DAYTIME CONVECTION OVER FL AND CUBA THAT IS MAKING ITS WAY OFFSHORE DURING THE EARLY EVENING. THIS CONVECTION IS EXPECTED TO DIMINISH AROUND SUNSET. OVER THE NEXT 24 HOURS...DEEP MOISTURE COMBINED WITH A NEARLY STATIONARY FRONT WILL SUPPORT CONVECTION OVER THE SW GULF. THE CARIBBEAN SEA... A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A TIGHT PRESSURE GRADIENT BETWEEN WESTERN ATLC HIGH PRESSURE AND LOWER PRESSURE OVER COLOMBIA SUPPORTS GALE FORCE WINDS OVER A PORTION OF THE SOUTHERN CARIBBEAN. PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. UPPER LEVEL RIDGING DOMINATES THE WESTERN CARIBBEAN...WITH CYCLONIC UPPER LEVEL FLOW OVER THE EASTERN CARIBBEAN. A MID LEVEL LOW OVER BELIZE AND THE YUCATAN SUPPORTS CLOUDINESS AND ISOLATED MODERATE CONVECTION FROM 16N TO 22N BETWEEN 84W AND 90W. OTHER CONVECTION NEAR THE SHORES OF CUBA IS ASSOCIATED WITH DIURNAL THUNDERSTORM ACTIVITY THAT WILL WEAKEN AROUND SUNSET. OVER THE NEXT 24 HOURS EXPECT CONVECTION TO REMAIN POSSIBLE OVER THE NW CARIBBEAN. ...HISPANIOLA... MODERATE MOISTURE ACROSS THE ISLAND SUPPORTS SCATTERED THUNDERSTORMS OVER THE ISLAND THIS EVENING. THIS ACTIVITY IS FORECAST TO DIMINISH AROUND SUNSET. ADDITIONAL MOISTURE MOVING SW TOWARD THE ISLAND AROUND THE SUBTROPICAL RIDGE MAY SUPPORT AN INCREASE IN AFTERNOON THUNDERSTORM ACTIVITY FOR THE ISLAND ON SATURDAY. THE ATLANTIC OCEAN... A STATIONARY 1020 MB HIGH IS CENTERED NEAR 28N75W. UPPER LEVEL DIFFLUENCE BETWEEN UPPER LEVEL RIDGING NEAR 21N67W AND UPPER LEVEL TROUGHING OVER THE GULF OF MEXICO SUPPORTS ISOLATED MODERATE CONVECTION FROM 23N TO 28N BETWEEN 67W AND 75W. HIGH PRESSURE CENTERED NEAR THE AZORES SUPPORTS GENERALLY FAIR WEATHER OVER THE CENTRAL AND EASTERN SUBTROPICAL NORTHERN ATLC. OVER THE NEXT 24 HOURS EXPECT CHANCES FOR CONVECTION TO INCREASE ACROSS THE BAHAMAS WITH AN INCREASE IN LOW LEVEL MOISTURE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO