000 AXNT20 KNHC 281751 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... THE PRESSURE GRADIENT BETWEEN A 1027 MB HIGH CENTERED IN THE CENTRAL ATLC NEAR 28N57W AND LOWER PRESSURE ANALYZED ACROSS NORTHERN COLOMBIA AND PANAMA IS GENERATING NEAR GALE TO GALE FORCE CONDITIONS ACROSS A LARGE PORTION OF THE SOUTH-CENTRAL CARIBBEAN SEA. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 06N47W TO 14N45W MOVING W AT 20 KT. THE WAVE COINCIDES WITH A 700 MB GLOBAL MODEL INDICATED TROUGH BETWEEN 39W-48W. DUE TO THE SAHARAN AIR LAYER ACROSS MUCH OF THE TROPICAL NORTH ATLC...NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM 10N70W TO 19N69W MOVING W AT 15-20 KT. SSMI TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE ON THE WESTERN EXTENT OF DEEP-LAYERED MOISTURE MAINLY S OF 20N BETWEEN 66W-70W. WHILE MOISTURE IS NOTED IN THE VICINITY OF THE WAVE AXIS...SAHARAN DUST PREVAILS ALOFT OVER MUCH OF THE CARIBBEAN SEAS INHIBITING ANY SIGNIFICANT CONVECTION AT THIS TIME. TROPICAL WAVE EXTENDS FROM 10N79W TO 18N78W MOVING W AT 15 KT. THE WAVE COINCIDES WITH A DEEP-LAYERED MOISTURE MAXIMUM ACROSS THE WESTERN CARIBBEAN SEA AS NOTED ON TOTAL PRECIPITABLE WATER IMAGERY. WHILE SUFFICIENT LOW TO MID-LEVEL MOISTURE IS IN PLACE TO SUPPORT CONVECTION...WATER VAPOR IMAGERY INDICATES NORTHWESTERLY FLOW OVER THE WESTERN CARIBBEAN PROMOTING AN OVERALL STABLE ENVIRONMENT RESULTING IN NO SIGNIFICANT CONVECTION AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W TO 09N20W TO 08N32W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N32N TO 06N46W TO 06N54W. SCATTERED MODERATE CONVECTION IS FROM 06N-10N BETWEEN 14W-31W. ...DISCUSSION... GULF OF MEXICO... A MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE NE CONUS THAT EXTENDS AN AXIS SW FROM WESTERN NEW YORK TO SW LOUISIANA. THIS TROUGHING SUPPORTS A COLD FRONT EXTENDING FROM THE CAROLINAS SW ACROSS THE SE CONUS INTO A 1015 MB LOW CENTERED ACROSS EASTERN TEXAS NEAR 32N94W. THE FRONT ALONG WITH MIDDLE TO UPPER LEVEL DIFFLUENCE SOUTHEAST OF THE UPPER LEVEL TROUGH AXIS IS GENERATING AN AREA OF SCATTERED SHOWERS AND TSTMS N OF 28N BETWEEN 84W-95W. THE CONVECTION IS OCCURRING ON THE NORTHERN PERIPHERY OF A SURFACE RIDGE ANCHORED BY A 1018 MB HIGH CENTERED NEAR 25N87W WHICH COVERS A MAJORITY OF THE BASIN. A WEAKNESS IN THE RIDGING IS NOTED OFF THE COAST OF MEXICO AS A SURFACE TROUGH EXTENDS FROM 22N97W TO 18N95W. THE TROUGH AXIS IS PROVIDING FOCUS FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING FROM 19N-23N BETWEEN 94W-98W. THE RIDGE IS FORECAST TO REMAIN ANCHORED ACROSS THE NE GULF THROUGH WEDNESDAY. CARIBBEAN SEA... MOST OF THE CARIBBEAN SEA REMAINS UNDER RELATIVELY STABLE CONDITIONS THIS AFTERNOON AS MOSTLY NORTHWEST TO WESTERLY FLOW ALOFT PREVAILS. NEAR THE SURFACE...AN EXTENSIVE SAHARAN AIR LAYER IS PROVIDING THE LOW-LEVEL STABILITY AS NO NOTABLE CONVECTION IS OCCURRING AT THIS TIME. LOW-LEVEL MOISTURE AND CLOUDINESS ARE NOTED IN THE VICINITY OF A PAIR OF TROPICAL WAVES...HOWEVER THEY REMAIN GENERALLY BENIGN AND LACK CONVECTION. A FEW ISOLATED SHOWERS AND TSTMS ARE OCCURRING S OF 11N W OF 80W WITHIN CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS EXTENDING FROM COSTA RICA WESTWARD INTO THE EAST PACIFIC REGION. OTHERWISE...THE MAIN IMPACT ACROSS THE BASIN REMAINS THE STRONG TRADES GENERALLY S OF 18N BETWEEN 65W-82W...INCLUDING NEAR GALE TO GALE FORCE CONDITIONS NOTED WITHIN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THE TRADES ARE FORECAST TO PERSIST THROUGH THE UPCOMING WEEK DUE TO A FAIRLY STATIONARY RIDGE ACROSS THE CENTRAL ATLC AND LOWER PRESSURE VALUES ANCHORED ACROSS NORTHERN COLOMBIA. ...HISPANIOLA... CURRENTLY...MOSTLY CLEAR SKIES PREVAIL AS A TROPICAL WAVE CONTINUES TO MOVE THROUGH THE REGION S OF 19N ALONG 70W. WHILE TOTAL PRECIPITABLE WATER VALUES REMAIN HIGHER THAN NORMAL WITH THE PASSAGE OF THE TROPICAL WAVE...VERY LITTLE PRECIPITATION IS OCCURRING WITH THE WAVE AT THIS TIME. EXAMINING THE 28/1200 UTC SAN JUAN PUERTO RICO SOUNDING...THE LOWER-LEVELS OF THE ATMOSPHERE ARE UNDER THE INFLUENCE OF A SAHARAN AIR LAYER INHIBITING ANY SIGNIFICANT CONVECTION. HOWEVER...GIVEN AMPLE DAYTIME HEATING AND INSTABILITY...ISOLATED SHOWERS AND TSTMS ARE POSSIBLE THROUGH THE LATE AFTERNOON AND EARLY EVENING HOURS. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE AXIS EXTENDS OVER A PORTION OF THE SW NORTH ATLC FROM 32N75W TO OVER WESTERN CUBA NEAR 23N81W. THIS RIDGING IS PROVIDING AN OVERALL DIFFLUENT ENVIRONMENT W OF 76W AND ALONG WITH A SURFACE TROUGH ANALYZED FROM 27N79W TO 32N77W IS GENERATING SCATTERED SHOWERS AND TSTMS N OF 25N BETWEEN 74W-79W. FARTHER SOUTHEAST...AN UPPER LEVEL LOW IS CENTERED NEAR 24N69W SUPPORTING POSSIBLE ISOLATED SHOWERS AND TSTMS FROM 23N-26N BETWEEN 65W-73W. OTHERWISE...A 1027 MB SURFACE HIGH PREVAILS ACROSS THE EASTERN AND CENTRAL ATLC CENTERED NEAR 28N57W WITH MOSTLY CLEAR SKIES AND FAIR CONDITIONS NOTED. 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