000 AXNT20 KNHC 050001 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 04 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 2315 UTC. ...SPECIAL FEATURES... ...GALE IN THE CARIBBEAN... A GALE WARNING CONTINUES FOR THE SW CARIBBEAN FROM 11N TO 13N BETWEEN 73W AND 78W THROUGH SUNDAY NIGHT. THESE WINDS ARE GENERATED BY A TIGHT PRESSURE GRADIENT BETWEEN THE STRONG SURFACE RIDGE THAT PREVAILS OVER THE ATLC AND LOWER SURFACE PRESSURE OVER COLOMBIA. SEE THE LATEST NWS HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS MIAHSFAT2/FZNT02 KNHC FOR MORE DETAILS. ...TROPICAL WAVES... A TROPICAL WAVE IS MOVING OVER THE EASTERN TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 16N37W TO 06N39W...MOVING W AT ABOUT 20 TO 25 KT OVER THE PAST 24 HOURS. ALTHOUGH SSMI TPW INDICATES MODERATE TO HIGH MOISTURE S OF 12N IN THE WAVE ENVIRONMENT... CURRENT METEOSAT ENHANCED IMAGERY DEPICTS A BROAD AREA OF SAHARAN DUST SURROUNDING THIS WAVE WHICH IS INHIBITING SIGNIFICANT CONVECTION. A TROPICAL WAVE IS OVER THE CENTRAL TROPICAL ATLANTIC WITH AXIS EXTENDING FROM 13N46W TO 03N49W...MOVING AT 15 TO 20 KT OVER THE PAST 24 HOURS. SSMI TPW SHOWS THIS WAVE IS EMBEDDED IN AN ENVIRONMENT OF HIGH MOISTURE S OF 11N. METEOSAT ENHANCED IMAGERY INDICATES SAHARAN DUST N OF 11N. ISOLATED MODERATE CONVECTION IS FROM 07N TO 11N BETWEEN 44W AND 53W. A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN WITH AXIS EXTENDING FROM 18N75W TO 11N78W...MOVING W AT AROUND 20 KT OVER THE PAST 24 HOURS. SSMI TPW SHOWS THIS WAVE IS EMBEDDED IN A MODERATELY MOIST ENVIRONMENT. CURRENT METEOSAT ENHANCED IMAGERY DEPICTS A BROAD AREA OF SAHARAN DUST PREVAILING ACROSS THE CARIBBEAN AND IN THE ENVIRONMENT OF THIS WAVE WHICH IS INHIBITING CONVECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE TROPICAL ATLANTIC NEAR 17N16W TO 09N24W WHERE THE ITCZ BEGINS AND CONTINUES TO NEAR 09N37W...THEN RESUMES W OF A TROPICAL WAVE NEAR 08N39W TO 08N47W. OTHER THAN CONVECTION ASSOCIATED WITH THE CENTRAL ATLC TROPICAL WAVE...NO CONVECTION IS NOTED. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LOW IS CENTERED OVER THE CENTRAL GULF NEAR 24N88W AND DOMINATES THE MAJORITY OF THE BASIN WITH CYCLONIC FLOW ALOFT. TWO AREAS OF UPPER LEVEL DIFFLUENCE ARE BEING CREATED BY THIS LOW...THE FIRST IS LOCATED ACROSS THE NORTHERN GULF BETWEEN THE BASE OF AN UPPER TROUGH OVER THE SOUTHERN US AND THE UPPER LOW. ISOLATED MODERATE CONVECTION IS N OF 29N BETWEEN 85W AND 94W. THE OTHER AREA OF DIFFLUENCE IS ACROSS THE FL STRAITS AND THE BAHAMAS. ISOLATED SHOWERS ARE E OF 83W S OF 25N OVER THE SE GULF. A 1021 MB HIGH CENTERED ALONG THE FL WEST COAST NEAR 29N83W IS A WESTERN EXTENSION OF A BROAD SURFACE RIDGE FROM THE CENTRAL ATLC TO THE TX COAST. LIGHT ANTICYCLONIC SURFACE WINDS ARE E OF 87W. SE TO SW WINDS OF 10 TO 15 KT COVER THE REMAINDER OF THE BASIN. THE BASE OF THE UPPER TROUGH OVER THE SOUTHERN US WILL DIG EAST-SOUTHEAST TO THE FL PANHANDLE ON SUNDAY. THIS WILL HELP TO ENHANCE SHOWER AND THUNDERSTORM ACTIVITY OVER THE NE GULF TONIGHT THROUGH SUNDAY. CARIBBEAN SEA... THE BASIN IS UNDER THE INFLUENCE OF A LARGE SAHARAN AIRMASS WHICH CONTINUES TO INHIBIT ANY SIGNIFICANT CONVECTION. A TROPICAL WAVE IS OVER THE WESTERN CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. A STRONG PRESSURE GRADIENT BETWEEN STRONG HIGH PRESSURE OVER THE SUBTROPICAL ATLC AND LOWER PRESSURE OVER COLOMBIA IS PRODUCING PERSISTENT GALE FORCE WINDS OVER A PORTION OF THE SW CARIBBEAN. PLEASE SEE THE SPECIAL FEATURES SECTION FOR MORE DETAILS. ELSEWHERE TRADE WINDS OF 20 TO 30 KT EXTEND AS FAR NORTH AS 18N BETWEEN 67W AND 82W WHICH IS PRODUCING SEAS OF 8 TO 14 FEET. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. ...HISPANIOLA... ISOLATED AFTERNOON AND EVENING THUNDERSTORMS OVER INLAND PORTIONS OF HISPANIOLA WILL DIMINISH BY LATE THIS EVENING WITH THE LOSS OF DAYTIME EVENING. THE PRESENCE OF SAHARAN DUST AND LACK OF SIGNIFICANT MOISTURE WILL MAINTAIN ONLY ISOLATED COVERAGE OF AFTERNOON AND EVENING THUNDERSTORMS AGAIN ON SUNDAY. ATLANTIC OCEAN... A WEAK UPPER RIDGE BETWEEN THE UPPER LOW OVER THE GULF OF MEXICO AND AN UPPER LOW OVER THE ATLC NEAR 27N69W IS PRODUCING AN AREA OF UPPER LEVEL DIFFLUENCE SUPPORTING SCATTERED THUNDERSTORMS FROM 24N TO 29N BETWEEN 76W AND THE FL PENINSULA. THE UPPER LOW ITSELF SUPPORTS ISOLATED WEAK CONVECTION FROM 27N TO 31N BETWEEN 70W AND 74W. FARTHER EAST...A CONVECTION FREE SURFACE TROUGH EXTENDS FROM 26N54W TO 23N55W. A 1030 MB HIGH CENTERED NEAR 34N42W ANCHORS A BROAD SUBTROPICAL SURFACE RIDGE THAT DOMINATES THE MAJORITY OF THE SUBTROPICAL NORTHERN ATLC. TWO TROPICAL WAVES ARE OVER THE TROPICAL NORTHERN ATLC. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO