000 AXNT20 KNHC 180552 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT THU JUN 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A STRONG PRESSURE GRADIENT EXISTS BETWEEN A 1019 MB HIGH CENTERED EAST OF THE BAHAMAS NEAR 26N70W AND LOWER PRESSURE FOCUSED ON A 1005 MB LOW CENTERED ACROSS NORTHERN COLOMBIA NEAR 10N75W THAT IS RESULTING IN NEAR GALE FORCE E-NE WINDS THIS EVENING WITHIN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. THIS WIND FIELD IS FORECAST TO INCREASE TO GALE FORCE OVERNIGHT AS THE PRESSURE GRADIENT STRENGTHENS SLIGHTLY. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 07N26W TO 15N25W MOVING W AT 15 KT. THE WAVE COINCIDES WITH HIGHER MOISTURE VALUES ON TOTAL PRECIPITABLE WATER IMAGERY BETWEEN 18W-31W. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM 06N64W TO 15N63W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH WEAK 700 MB TROUGHING BETWEEN 60W- 68W EMBEDDED WITHIN A LENGTHY EASTERLY JET STRETCHING FROM 12N36W TO 15N76W. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM 09N78N TO 18N78W MOVING W AT 15-20 KT. THE TOTAL PRECIPITABLE WATER IMAGERY SHOWS THE WAVE EMBEDDED WITHIN INCREASED VALUES OF DEEP MOISTURE ACROSS THE WESTERN CARIBBEAN SEA. NO SIGNIFICANT CONVECTION IS NOTED WITH THE WAVE AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 10N23W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N30W TO 03N51W. SCATTERED MODERATE CONVECTION IS FROM 07N-10N BETWEEN 12W-15W. ISOLATED MODERATE CONVECTION IS FROM 05N-09N BETWEEN 27W-37W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW IS CENTERED OVER THE NORTHERN YUCATAN PENINSULA NEAR 21N87W THAT IS PROVIDING MUCH OF THE GULF WITH EAST-NORTHEASTERLY FLOW ALOFT WHICH ON WATER VAPOR IMAGERY REMAINS RELATIVELY DRY AND STABLE ALOFT. AT THE SURFACE... STABILITY PREVAILS AS WELL DUE TO SURFACE RIDGING ANCHORED BY A 1018 MB HIGH CENTERED IN THE NE GULF NEAR 28N85W. ONLY IN THE FAR NW PORTION OF THE BASIN ARE A FEW SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING N OF 26N W OF 95W. THIS ACTIVITY LIES WITHIN AN AREA OF MODERATE TO FRESH SOUTHERLY FLOW ACROSS THE WESTERN GULF...WHILE CLOSER TO THE HIGH CENTER GENTLE TO OCCASIONAL MODERATE SE WINDS PREVAIL. THE SURFACE RIDGE AXIS IS FORECAST TO REMAIN ALONG 28N FROM THE FLORIDA PENINSULA TO THE SE TEXAS COAST THROUGH FRIDAY AND SHIFT SLIGHTLY NORTH INTO SATURDAY. CARIBBEAN SEA... WITH AN UPPER LEVEL LOW CENTERED OVER THE NORTHERN YUCATAN PENINSULA NEAR 21N87W...MUCH OF THE CARIBBEAN IS UNDER THE INFLUENCE OF WEST-SOUTHWESTERLY FLOW STEMMING FROM THE LOW. MIDDLE TO UPPER LEVEL MOISTURE REMAINS ENHANCED NEAREST TO THE UPPER LEVEL FEATURE WITH POSSIBLE ISOLATED SHOWERS OCCURRING W OF 78W THIS EVENING. LATE EVENING SHOWERS AND TSTM ACTIVITY CONTINUES TO DIMINISH ACROSS PORTIONS OF CUBA WITH A FEW ISOLATED SHOWERS AND TSTMS REMAINING ACROSS HISPANIOLA. OTHERWISE...A PAIR OF TROPICAL WAVES ARE MOVING ACROSS THE CENTRAL AND EASTERN CARIBBEAN...EACH INFLUENCED BY A DRY SAHARAN AIR LAYER ALOFT PROVIDING FOR OVERALL STABLE CONDITIONS FOR THE OVERNIGHT PERIOD. THE PRIMARY IMPACT WILL REMAIN THE STRONG TO NEAR GALE TRADES GENERALLY S OF 18N BETWEEN 65W-83W. GIVEN THE INCREASED PRESSURE GRADIENT ACROSS THE REGION...THESE TRADES ARE EXPECTED TO PERSIST THROUGH THE UPCOMING WEEKEND INTO EARLY NEXT WEEK. ...HISPANIOLA... CURRENTLY...A FEW LINGERING ISOLATED SHOWERS AND TSTMS REMAIN ACROSS THE ISLAND AND THIS ACTIVITY IS EXPECTED TO CONTINUE DIMINISHING THROUGH THE OVERNIGHT HOURS. OTHERWISE...WESTERLY FLOW ALOFT PREVAILS AND THIS WILL LIKELY PROVIDE AMPLE MIDDLE TO UPPER LEVEL DYNAMICS FOR LATE AFTERNOON AND EARLY EVENING SCATTERED SHOWERS AND TSTMS DUE TO DIFFLUENCE ALOFT AND PEAK DAYTIME HEATING AND INSTABILITY IN THE LOWER LEVELS. ATLANTIC OCEAN... A 1019 MB HIGH IS CENTERED EAST OF THE BAHAMAS NEAR 26N70W. FAIR SKIES ARE NOTED ACROSS MUCH OF THE SW NORTH ATLC THIS EVENING. TO THE EAST OF THIS HIGH CENTER...AN UPPER LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY CENTERED NEAR 26N59W. MID-LEVEL MOISTURE AND CLOUDINESS INCREASES IN THE VICINITY OF THE FEATURE BETWEEN 56W- 67W WITH ISOLATED SHOWERS POSSIBLE. THE REMAINDER OF THE CENTRAL AND EASTERN ATLC FALL UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE AND RIDGING WITH OVERALL FAIR CONDITIONS PREVAILING. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN