000 AXNT20 KNHC 171802 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT MON AUG 17 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... A TROPICAL WAVE SEVERAL HUNDRED MILES SW OF THE CAPE VERDE ISLANDS IS ASSOCIATED WITH A 1011 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH NEAR 10N31W. CIRA LAYER PRECIPITABLE WATER SHOWS AMPLE LOW TO MID LEVEL MOISTURE IN THE ENVIRONMENT OF THE LOW WITH A SMALL AMOUNT OF DRY AIR ALOFT SURROUNDING THE SYSTEM. SCATTERED MODERATE CONVECTION IS FROM 06N TO 12N BETWEEN 30W AND 35W. THERE IS A MEDIUM CHANCE OF THIS SYSTEM DEVELOPING INTO A TROPICAL CYCLONE OVER THE NEXT 48 HOURS. ...TROPICAL WAVES... A TROPICAL WAVE IS OVER THE EASTERN ATLC WITH AN AXIS EXTENDING FROM 16N32W THROUGH THE SPECIAL FEATURES 1011 MB LOW NEAR 10N31W TO 06N31W. HIGH MOISTURE IS NOTED S OF 13N WITH SAHARAN DUST AND STABLE AIR EVIDENT N OF 13N. OTHER THAN CONVECTION DISCUSSED IN THE SPECIAL FEATURES SECTION...ISOLATED MODERATE CONVECTION IS FROM 12N TO 14N BETWEEN 28W AND 32W. A TROPICAL WAVE IS OVER THE CENTRAL ATLC WITH AN AXIS EXTENDING FROM 15N49W TO 07N51W...MOVING W AT AROUND 15 KT OVER THE PAST 24 HOURS. THE WAVE IS EMBEDDED IN A MOIST ENVIRONMENT S OF 14N WITH A 850 MB VORTICITY MAXIMA INDICATED NEAR 09N50W. CLUSTERS OF SHOWERS AND ISOLATED MODERATE CONVECTION ARE FROM 08N TO 12N BETWEEN 47W AND 53W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN WITH AN AXIS EXTENDING FROM 20N76W TO 11N75W...MOVING W AT 10 TO 15 KT. AN INVERTED 700 MB TROUGH IS NOTED IN MODEL GUIDANCE BETWEEN 73W AND 78W. SUBSIDENCE ALOFT AND DRY AIR IN THE MID LEVELS IS INHIBITING DEEP CONVECTION ALONG THE WAVE AXIS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE WEST AFRICAN COAST NEAR 14N17W AND CONTINUES W-SW THROUGH THE SPECIAL FEATURES 1011 MB LOW NEAR 10N31W TO 08N37W....WHERE THE ITCZ BEGINS AND CONTINUES TO 06N54W. ASIDE FROM THE CONVECTION DISCUSSED WITH THE SPECIAL FEATURES LOW...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION ARE WITHIN 100 NM N AND 200 NM S OF THE MONSOON TROUGH E OF 22W. ISOLATED MODERATE CONVECTION IS ELSEWHERE WITHIN 200 NM OF EITHER SIDE OF THE MONSOON TROUGH AND ITCZ E OF 47W. ...DISCUSSION... GULF OF MEXICO... A SHARP UPPER TROUGH EXTENDS FROM THE CENTRAL US SW ACROSS TX AND MEXICO. AN UPPER LEVEL ANTICYCLONE EXTENDS FROM THE YUCATAN PENINSULA NE ACROSS CENTRAL FL. A SURFACE TROUGH EXTENDS FROM 29N94W TO 30N89W. THE COMBINATION OF UPPER LEVEL SUPPORT DOWNSTREAM OF THE UPPER TROUGH...LOW LEVEL CONVERGENCE NEAR THE SURFACE TROUGH...AND DEEP MOISTURE OVER THE GULF SUPPORTS ISOLATED MODERATE CONVECTION AND SCATTERED THUNDERSTORMS NW OF A LINE FROM 23N96W TO 24N89W TO 29N85W. SURFACE RIDGING OVER THE W ATLC EXTENDS AN AXIS TO THE EASTERN US. ANTICYCLONIC FLOW AROUND THIS RIDGE IS RESULTING IN SE WINDS MAINLY BETWEEN 10 TO 15 KT OVER THE SOUTHERN HALF OF THE GULF AND THE NE GULF. GENTLE VARIABLE WINDS COVER THE NW GULF...EXCEPT GUSTY NEAR CONVECTION. THE UPPER TROUGH OVER TX WILL WEAKEN AND LIFT AWAY FROM THE GULF OVER THE NEXT 24 HOURS. THIS WILL RESULT IN AN OVERALL DECREASE IN CONVECTION OVER THE NW GULF THROUGH TUESDAY. AN ATLC SURFACE TROUGH APPROACHING THE FL STRAITS WILL BRING AN INCREASE IN SHOWERS AND THUNDERSTORMS TO THE SE GULF BY TUESDAY NIGHT. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE YUCATAN PENINSULA WHILE AN UPPER LOW IS CENTERED BETWEEN HISPANIOLA AND CUBA. SUBSIDENCE BETWEEN THESE TWO FEATURES INHIBITS CONVECTION OVER THE NW CARIBBEAN. THE UPPER LOW SUPPORTS SCATTERED THUNDERSTORMS FROM 16N TO 20N BETWEEN 68W AND 77W. UPPER LEVEL DIFFLUENCE AND THE THE PRESENCE OF THE E PACIFIC MONSOON TROUGH OVER PANAMA SUPPORTS SCATTERED MODERATE TO STRONG CONVECTION S OF 12N W OF 78W. A TROPICAL WAVE IS OVER THE CENTRAL CARIBBEAN. PLEASE SEE THE TROPICAL WAVES SECTION FOR MORE DETAILS. MODERATE TO FRESH TRADE WINDS ARE OVER THE CENTRAL CARIBBEAN S OF 16N BETWEEN 70W AND 78W. GENTLE TO MODERATE TRADE WINDS COVER THE REMAINDER OF THE CARIBBEAN WITH THE LIGHTEST WINDS OVER THE W CARIBBEAN N OF 18N. OVER THE NEXT 24 HOURS THE UPPER LOW WILL MOVE W WITH CONVECTION LIKELY OVER THE N CARIBBEAN E OF 85W AND W OF 75W. ONGOING CONVECTION CAN BE EXPECTED OVER THE EXTREME SW CARIBBEAN. A TROPICAL WAVE OVER THE CENTRAL ATLC SHOULD BEGIN TO IMPACT THE LESSER ANTILLES WITH INCREASING SHOWERS AND ISOLATED THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY. ...HISPANIOLA... AN UPPER LOW IN THE AREA SUPPORTS SCATTERED THUNDERSTORMS OVER THE ISLAND TODAY. SOME OF THESE STORMS WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL WITH POSSIBLE MUDSLIDES AND FLASH FLOODING IN MORE PERSISTENT STORMS THROUGH THIS EVENING. THUNDERSTORM ACTIVITY OVER LAND IS FORECAST TO WEAKEN OVERNIGHT. BY TUESDAY IT APPEARS THAT SOME DRIER AIR WILL MOVE OVER THE ISLAND FROM THE EAST...DECREASING THE COVERAGE OF THUNDERSTORMS. HOWEVER...IT APPEARS SUFFICIENT MOISTURE MAY REMAIN OVER THE WESTERN PORTION OF THE ISLAND TO SUPPORT ISOLATED THUNDERSTORMS TUESDAY AFTERNOON. ATLANTIC OCEAN... A SURFACE TROUGH EXTENDS FROM 25N73W TO 21N76W ANS IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WITHIN 150 NM OF THE TROUGH AXIS...INCLUDING THE CENTRAL BAHAMAS. ASCENT ASSOCIATED WITH AN WESTERN ATLC UPPER LOW N OF OUR AREA OF DISCUSSION SUPPORTS SCATTERED THUNDERSTORMS FROM 28N TO 31N BETWEEN 65W AND 71W. A SURFACE TROUGH IS OVER THE CENTRAL ATLC FROM 29N56W TO 23N59W. THIS TROUGH IS INTERACTING WITH AN UPPER LOW NEAR 28N59W ISOLATED MODERATE CONVECTION WITHIN 100 NM OF THE SURFACE TROUGH AXIS. TWO TROPICAL WAVES...INCLUDING THE SPECIAL FEATURES LOW...ARE OVER THE TROPICAL N ATLC. PLEASE REFER TO THE SPECIAL FEATURES SECTION AND TROPICAL WAVES SECTION FOR MORE DETAILS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ LATTO