000 AXNT20 KNHC 280545 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE JUL 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...SPECIAL FEATURES... A STRENGTHENED PRESSURE GRADIENT IS NOTED ACROSS THE CENTRAL CARIBBEAN SEA WITH NEAR GALE TO GALE FORCE WINDS OCCURRING FROM 11N-14N BETWEEN 72W-77W. THESE CONDITIONS ARE FORECAST TO DIMINISH BELOW GALE FORCE WARNING CRITERIA BY 28/1200 UTC. SEE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N26W TO 17N25W MOVING W AT 10-15 KT. THE WAVE COINCIDES WITH BROAD AND VERY SUBTLE 700 MB TROUGHING BETWEEN 23W-28W WITH 850 MB RELATIVE VORTICITY FOCUSED NEAR THE SOUTHERN EXTENT OF THE WAVE AXIS. ISOLATED MODERATE CONVECTION IS FROM 05N-13N BETWEEN 21W-29W. TROPICAL WAVE EXTENDS FROM 09N45W TO 18N46W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 43W- 52W WITH GLOBAL MODEL INDICATED 850 MB RELATIVE VORTICITY STRETCHED EAST-WEST FROM 10N-12N WITHIN THE INFLUENCE OF THE LOW TO MIDDLE LEVEL TROUGHING. NO SIGNIFICANT CONVECTION IS OCCURRING WITH THE WAVE AT THIS TIME. TROPICAL WAVE EXTENDS FROM 10N67W TO 18N679W MOVING W AT 20 KT. THE WAVE COINCIDES WITH 700 MB TROUGHING BETWEEN 64W-72W WITH NO SIGNIFICANT CONVECTION OCCURRING AT THIS TIME. TROPICAL WAVE EXTENDS FROM 12N84W TO 22N82W MOVING W AT 20 KT. THE WAVE COINCIDES WITH BROAD 700 MB TROUGHING BETWEEN 80W-88W ON THE WESTERN PERIPHERY OF A MID-LEVEL RIDGE ANCHORED OVER THE CENTRAL ATLC NEAR 24N63W. ISOLATED MODERATE CONVECTION IS WITHIN 75 NM EITHER SIDE OF THE WAVE AXIS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE AFRICAN COAST NEAR 20N16W TO 16N18W TO 11N26W TO 09N44W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N44W TO 07N58W. ISOLATED MODERATE CONVECTION IS FROM 08N-15N BETWEEN 14W-21W. ...DISCUSSION... GULF OF MEXICO... NORTHEAST TO EASTERLY FLOW ALOFT INFLUENCES THE GULF BASIN THIS EVENING ON THE SOUTHERN PERIPHERY OF A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION ANCHORED OVER THE LOWER MISSISSIPPI RIVER VALLEY REGION. WHILE PROVIDING A GENERALLY STABLE ENVIRONMENT ALOFT...A SURFACE WEAKNESS IN THE FORM OF A 1012 MB LOW CENTERED IN THE NE GULF NEAR 29N83W AND SURFACE TROUGHING EXTENDING GENERALLY WESTWARD FROM THE LOW TO 28N87W IS PROVIDING FOCUS FOR ISOLATED SHOWERS AND TSTMS. THIS ACTIVITY IS OCCURRING FROM 26N-29N BETWEEN 83W-86W WITH MID-LEVEL ENERGY NOTED OVER THE EASTERN GULF THAT CONTINUES TO PROVIDE MARGINAL LIFTING DYNAMICS FOR THE CONVECTION. OTHERWISE...A WEAK SURFACE RIDGE ANCHORED BY A 1017 MB HIGH CENTERED NEAR 24N86W WILL MAINTAIN GENTLE TO MODERATE ANTICYCLONIC WINDS THROUGH LATE WEDNESDAY AS THE HIGH DRIFTS GRADUALLY NORTHWESTWARD. CARIBBEAN SEA... WATER VAPOR IMAGERY INDICATES MOSTLY DRY CONDITIONS ALOFT OVER MUCH OF THE CARIBBEAN BASIN THIS EVENING WHICH IS LIMITING ANY WIDESPREAD AREAS OF STRONG AND DEEP CONVECTION. HOWEVER THE PRESENCE OF A TROPICAL WAVE ALONG 84W IS GENERATING A FEW ISOLATED SHOWERS AND TSTMS WITHIN 75 NM EITHER SIDE OF THE AXIS AND ACROSS PORTIONS OF EASTERN HONDURAS AND NICARAGUA. OTHERWISE...THE PRIMARY MARINE IMPACT IS INCREASED TRADES ACROSS CENTRAL PORTIONS REACHING NEAR GALE TO GALE FORCE IN CLOSE PROXIMITY TO THE COAST OF COLOMBIA. WHILE THE GALE IS FORECAST THROUGH 28/1200 UTC...THE AREA OF TRADES IS EXPECTED TO PERSIST IN THE STRONG BREEZE TO NEAR GALE RANGE THROUGH THURSDAY. ...HISPANIOLA... CURRENTLY...MOSTLY CLEAR SKIES AND FAIR CONDITIONS PREVAIL ACROSS THE ISLAND FOR THE OVERNIGHT HOURS. GIVEN DRY AND STABLE AIR ALOFT ALONG WITH RELATIVELY CLEAR SKIES NOTED ON SATELLITE IMAGERY TO THE EAST...NO SIGNIFICANT DEEP CONVECTION IS EXPECTED ACROSS THE ISLAND THROUGH TUESDAY. ATLANTIC OCEAN... WATER VAPOR IMAGERY INDICATED LONGWAVE TROUGHING OVER THE WESTERN NORTH ATLC WITH A FEW EMBEDDED SHORTWAVES NEAR THE BASE OF THE TROUGHING SLIGHTLY NORTH OF THE DISCUSSION BORDER...ONE NEAR 37N50W AND THE OTHER NEAR 36N70W. BOTH SUPPORT WEAK SURFACE LOWS AND FRONTS. THE FIRST LOW IS A 1016 MB LOW CENTERED NEAR 37N48W WITH A COLD FRONT EXTENDING SW TO 30N56W THEN STATIONARY TO 33N61W. THE FRONT CONTINUES AS A WARM FRONT FROM THERE INTO A 1014 MB LOW CENTERED NW OF BERMUDA NEAR 34N68W. THE ASSOCIATED COLD FRONT EXTENDS SW FROM THE 1014 MB LOW TO 33N73W AND BECOMES STATIONARY TO THE FLORIDA COAST NEAR JACKSONVILLE. ISOLATED SHOWERS ARE OCCURRING WITHIN 120 NM EAST OF THE FIRST COLD FRONT MENTIONED...HOWEVER IS RELATIVELY DRIER THAN THE DEEPER SURFACE LOW TO THE WEST. GIVEN THE STRONGER MIDDLE TO UPPER LEVEL DYNAMICS WITH THE WESTERN-MOST LOW PRESSURE AREA...WIDELY SCATTERED SHOWERS AND TSTMS ARE OCCURRING GENERALLY N OF 29N BETWEEN 60W-78W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE AXIS EXTENDING FROM A 1021 MB HIGH CENTERED NEAR 26N62W TO A 1017 MB HIGH CENTERED IN THE SE GULF OF MEXICO NEAR 24N86W. FINALLY...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF ANOTHER SURFACE RIDGE ANCHORED BY A 1026 MB HIGH CENTERED SE OF THE AZORES NEAR 36N30W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN