000 AXNT20 KNHC 122337 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN JUL 12 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. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM ABOUT 09N20W TO 18N18Z MOVING W AT 10 TO 15 KT. THE WAVE HAS A WEAK CONVECTIVE AND SURFACE SIGNATURE...BUT IS EVIDENT IN THE TOTAL PRECIPITABLE WATER IMAGERY...THE SENEGAL RAWINDSONDES...AND THE GFS-BASED 700 MB TROUGH DIAGNOSTICS. NO SIGNIFICANT DEEP CONVECTION IS ASSOCIATED WITH THE WAVE OVER THE ATLANTIC...THOUGH SUBSTANTIAL CONVECTION IS SEEN OVER SENEGAL...GAMBIA...GUINEA-BISSAU...AND GUINEA. TROPICAL WAVE EXTENDS FROM 07N33W TO 17N31W MOVING W AT 10 TO 15 KT. THE WAVE IS EASILY DISTINGUISHED IN VISIBLE IMAGERY FROM THE SWIRL OF LOW-LEVEL CLOUDS...A MAXIMUM OF TPW...AND THE TROUGH DIAGNOSTICS. JUST TO THE NORTH AND THE WEST OF THE WAVE...THERE IS A LARGE AREA OF SAHARAN AIR LAYER AS SEEN FROM THE METEOSAT9 SAL IMAGERY. NO SIGNIFICANT CONVECTION IS PRESENT WITH THE WAVE CURRENTLY. TROPICAL WAVE EXTENDS FROM 06N56W TO 18N52W MOVING W AT AROUND 20 KT. THE WAVE COINCIDES WITH A RELATIVELY BROAD 700 MB GFS MODEL INDICATED TROUGH BETWEEN 48W AND 58W AND THE BARBADOS RAWINDSONDE...BUT WITH LITTLE SIGNATURE AT THE SURFACE. THIS WAVE IS EMBEDDED IN RELATIVELY DRY AIR WITH SAHARAN DUST NORTH OF 10N. NO SIGNIFICANT CONVECTION IS PRESENT WITH THE WAVE CURRENTLY. TROPICAL WAVE EXTENDS FROM 09N77W TO 18N75W MOVING W AT 15 TO 20 KT. THE WAVE IS ONLY OBSERVED WELL FROM THE CARIBBEAN RAWINDSONDES AND THE TROUGH DIAGNOSTICS...AS IT IS QUITE WEAK AT THE SURFACE. THE NORTHERN PORTION OF THIS WAVE IS MOVING UNDER AN UPPER LEVEL LOW. SCATTERED MODERATE ISOLATED STRONG CONVECTION EXISTS OVER EASTERN CUBA AS WELL AS IN THE SOUTHWESTERNMOST CARIBBEAN SEA FROM 09N TO 12N BETWEEN 78W TO 83W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N17W TO 07N30W...WHERE THE ITCZ BEGINS AND CONTINUES THROUGH 06N54W AT THE SOUTH AMERICA COAST. SCATTERED MODERATE CONVECTION IS FROM 04N TO 10N BETWEEN 12W AND 28W. ISOLATED MODERATE CONVECTION IS FROM 04N TO 08N BETWEEN 18W AND 25W. ...DISCUSSION... GULF OF MEXICO... A 1020 MB HIGH IS CENTERED JUST SOUTH OF THE TEXAS-LOUISIANA BORDER. SURFACE WINDS AROUND THE HIGH ARE VERY WEAK...15 KT OR LESS ACROSS THE WHOLE GULF. A SURFACE TROUGH EXTENDS THROUGH THE FLORIDA PENINSULA. MOST OF THE DEEP CONVECTION OVER THE EASTERN GULF EARLIER TODAY HAS NEARLY DISSIPATED...WITH ONLY ISOLATED MODERATE CONVECTION REMAINING NORTH OF 28N EAST OF 85W. THE SURFACE HIGH IS ANTICIPATED TO REMAIN RELATIVE STATIONARY DURING THE NEXT TWO DAYS AND ADDITIONAL SHOWERS AND THUNDERSTORMS MAY OCCUR OVER THE EASTERN GULF OF MEXICO. CARIBBEAN SEA... A MODERATE NORTH-SOUTH PRESSURE GRADIENT IS PRODUCING GENERALLY 10-20 KT TRADEWINDS ACROSS THE CARIBBEAN...WITH A 25 KT MAX OBSERVED JUST NORTH OF COLOMBIA. A STRONG UPPER LOW IS CENTERED OVER THE SOUTHERN BAHAMAS NEAR 22N74W. THE INTERACTION OF THE UPPER LOW AND A TROPICAL WAVE OVER THE CENTRAL CARIBBEAN CONTRIBUTED TOWARD SCATTERED MODERATE AND ISOLATES STRONG CONVECTION OVER EASTERN CUBA. THE PUERTO RICO RADAR INDICATES THAT SCATTERED SHOWERS ALSO ARE OVER WESTERN PUERTO RICO AND THE ADJACENT WATERS. THE DIFFLUENT ZONE IN THE SOUTHEASTERN SEMICIRCLE OF THE UPPER LOW IS CAUSING A LARGE AREA OF UPPER LEVEL DIVERGENCE IN THE NORTHEASTERN CARIBBEAN SEA IN SUPPORT OF THESE SHOWERS. DURING THE NEXT TWO DAYS...LITTLE CHANGE IS EXPECTED TO THE TRADEWINDS. THE UPPER LOW SHOULD LIFT OUT TO THE NORTHEAST...WHILE THE TROPICAL WAVE CONTINUES WESTWARD. THIS LIKELY WILL SHIFT CHANCES FOR DEEP CONVECTION WESTWARD TO THE WESTERN CARIBBEAN. ...HISPANIOLA... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS OCCURRED EARLIER TODAY OVER EASTERN DOMINICAN REPUBLIC. DURING THE AFTERNOON...THERE WERE ISOLATED THUNDERSTORMS OVER NORTHERN HAITI. THE BROAD UPPER LOW OVER THE SOUTHERN BAHAMAS MAY CONTINUE TO PROMOTE SOME DEEP CONVECTION DURING THE NEXT DAY OR SO. THESE COULD RESULT IN HEAVY RAINFALL AND FLASH FLOODING WITH THE POTENTIAL FOR MUDSLIDES. AS THE UPPER LOW PULLS NORTHEASTWARD AND THE TROPICAL WAVE MOVES TO THE WESTERN CARIBBEAN...THE CHANCES FOR DEEP CONVECTION SHOULD DROP ON TUESDAY. ATLANTIC OCEAN... A 1025 MB SURFACE HIGH IS LOCATED AT 32N38W WITH RIDGING EXTENDING WEST-SOUTHWESTWARD. THIS IS RESULTING IN NORTHEASTERLY TRADEWINDS OF GENERALLY 10-20 KT IN THE EASTERN ATLANTIC AND 5-15 KT IN THE WESTERN ATLANTIC. NUMEROUS SHOWERS WITH SCATTERED MODERATE CONVECTION IS OCCURRING NORTH OF PUERTO RICO...FROM 18N TO 25N BETWEEN 65W AND 70W. ISOLATED MODERATE TO DEEP CONVECTION ALSO IS OCCURRING OVER THE BAHAMAS. THIS CONVECTIVE ACTIVITY IS DUE TO THE UPPER LOW CENTERED OVER THE SOUTHERN BAHAMAS. SCATTERED MODERATE CONVECTION IS ALSO OBSERVED FROM 30N TO 32N BETWEEN 76W TO 79W IN ASSOCIATION WITH A WEAK FRONTAL LOW JUST OFFSHORE OF SOUTH CAROLINA. THE SURFACE SYNOPTIC PATTERN DOES NOT CHANGE MUCH DURING THE NEXT TWO DAYS. HOWEVER...THE UPPER LOW SHOULD MOVE NORTHEASTWARD AND FILL SOME. AS IT DOES SO...THE LIKELIHOOD FOR DEEP CONVECTION WILL CONTINUE FOR THE BAHAMAS ON MONDAY BUT DIMINISH ON TUESDAY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LANDSEA