000 AXNT20 KNHC 160540 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED SEP 16 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 1012 MB LOW MIDWAY BETWEEN THE CAPE VERDE ISLANDS AND THE LESSER ANTILLES IS CENTERED NEAR 13N43W ALONG A TROPICAL WAVE THAT EXTENDS FROM 7N-17N MOVING W-NW 5-10 KT OVER THE PAST 24 HOURS. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE FROM 12N-17N BETWEEN 38W-45W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 7N-12N BETWEEN 40W-47W. ACTIVITY ASSOCIATED WITH THIS SYSTEM HAS BECOME BETTER ORGANIZED THIS EVENING AND IT COULD BECOME A TROPICAL DEPRESSION BEFORE UPPER LEVEL WINDS BECOME LESS FAVORABLE. THERE IS A HIGH CHANCE OF TROPICAL FORMATION OVER THE NEXT 48 HOURS. A 1011 MB LOW S-SW OF THE CAPE VERDE ISLANDS IS CENTERED NEAR 11N27W ALONG A TROPICAL WAVE THAT EXTENDS FROM 7N-15N MOVING W- NW 10-15 KT OVER THE PAST 24 HOURS. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 7N-14N BETWEEN 24W- 31W. THE ACTIVITY HAS BECOME LESS ORGANIZED AND ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE CONDUCIVE FOR FURTHER DEVELOPMENT. THERE IS A MEDIUM CHANCE OF TROPICAL FORMATION OVER THE NEXT 48 HOURS. ...TROPICAL WAVES... TROPICAL WAVE IN THE E CARIBBEAN EXTENDS ALONG 66W/67W FROM 11N- 21N MOVING W NEAR 10 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATES THE WAVE IS EMBEDDED WITHIN SURGE OF DEEP MOISTURE. SCATTERED TO NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 210 NM E OF THE WAVE AXIS N OF 20N AND WITHIN 120 NM E OF THE WAVE AXIS S OF 20N. TROPICAL WAVE ANALYZED IN THE W CARIBBEAN EXTENDS ALONG 85W FROM 23N IN THE YUCATAN CHANNEL TO OVER HONDURAS MOVING NW 10-15 KT OVER THE PAST 24 HOURS. SSMI TPW INDICATES THE CARIBBEAN AND GULF OF MEXICO ARE COVERED IN MODERATE TO DEEP MOISTURE. CLUSTERS OF SCATTERED TO NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 16N-21N BETWEEN 63W-70W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL ATLC NEAR 18N16W THROUGH THE 1011 MB LOW IN THE SPECIAL FEATURES TO 12N36W. THE ITCZ BEGINS W OF THE SECOND WAVE NEAR 10N45W AND CONTINUES ALONG 9N51W TO SOUTH AMERICA NEAR 9N61W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120 NM ALONG THE COAST OF W AFRICA FROM 9N-15N AND WITHIN 60 NM BOTH SIDES OF THE ITCZ BETWEEN 56W-59W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM ALONG THE COAST OF W AFRICA S OF 9N W OF 11W AND FROM 13N-15N BETWEEN 31W-35W. THE REMAINDER OF THE CONVECTION IS ASSOCIATED WITH THE LOWS/TROPICAL WAVES IN THE SPECIAL FEATURES. ...DISCUSSION... GULF OF MEXICO... A SHORTWAVE UPPER TROUGH EXTENDS FROM N MISSISSIPPI ACROSS SE LOUISIANA TO OVER THE N GULF BETWEEN 84W-94W. THIS IS CLEARING SKIES OVER THE NW GULF N OF 27N W OF 90W. AN UPPER RIDGE EXTENDS FROM OVER MEXICO NEAR TUXPAN TO S FLORIDA COVERING THE REMAINDER OF THE GULF OF MEXICO INTO THE W ATLC AND NW CARIBBEAN. A SURFACE TROUGH...REMNANTS OF GRACE...IS IN THE SE GULF EXTENDING FROM 27N83W TO 24N84W GENERATING SCATTERED TO NUMEROUS SHOWERS/ ISOLATED THUNDERSTORMS E OF THE TROUGH TO OVER S FLORIDA AND THROUGH THE STRAITS OF FLORIDA WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS WITHIN 150 NM W OF THE TROUGH. CLUSTERS OF SCATTERED TO NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ARE OVER THE SW GULF S OF 22N W OF 93W WITH SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS OVER THE NE GULF N OF 27N E OF 90W AND S OF 27N BETWEEN 86W-92W. THE SURFACE TROUGH...REMNANTS OF GRACE...WILL STALL ALONG 88W BY WED NIGHT THEN STRETCH FROM THE NE GULF INTO THE S/CENTRAL GULF BEGINNING FRI. CARIBBEAN SEA... AN UPPER RIDGE OVER THE GULF OF MEXICO COVERS THE NW CARIBBEAN N OF 15N W OF 76W. A SECOND UPPER RIDGE EXTENDS FROM THE W ATLC OVER THE E CARIBBEAN TO 70W. AN UPPER LOW IS OVER THE HAITI AND THE WINDWARD PASSAGE EXTENDING A UPPER TROUGH S ALONG 16N76W TO OVER W PANAMA NEAR 9N81W. THESE UPPER RIDGES ARE PROVIDING DIFFLUNCE ALOFT TO ENHANCE THE ACTIVITY ASSOCIATED WITH THE TWO TROPICAL WAVES. ISOLATED SHOWERS/THUNDERSTORMS DOT THE AREA BETWEEN JAMAICA AND CUBA FROM 76W-78W AND WITHIN 45 NM ALONG THE COAST OF W PANAMA W OF 80W...W HONDURAS W OF 86W...AND GUATEMALA. W CARIBBEAN TROPICAL WAVE WILL REACH THE YUCATAN PENINSULA BY WED. E CARIBBEAN TROPICAL WAVE WILL REACH THE CENTRAL CARIBBEAN EARLY WED AND THE W CARIBBEAN THU. WEAKENED RIDGE OVER THE W ATLC WILL DIMINISH WINDS IN THE CENTRAL CARIBBEAN THU THROUGH FRI. ...HISPANIOLA... SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE MOVING OVER THE DOMINICAN REPUBLIC E OF 70W ASSOCIATED WITH THE E CARIBBEAN TROPICAL WAVE. THE UPPER LOW OVER HAITI/WINDWARD PASSAGE WILL SHIFT NE WED AND OPEN INTO AN UPPER TROUGH THAT WILL PERSIST THROUGH THU MORNING BEFORE SHIFTING EASTWARD THROUGH FRI. MOISTURE AND SHOWER/THUNDERSTORM ACTIVITY WILL INCREASE ACROSS THE REMAINDER OF THE ISLAND TONIGHT AND WED AS THE TROPICAL WAVE MOVES FROM OVER PUERTO RICO ACROSS THE ISLAND OF HISPANIOLA. THIS WILL SPREAD SHOWERS/THUNDERSTORMS ACROSS THE REMAINDER OF THE ISLAND THROUGH WED THEN DIMINISHING THU AND FRI. ATLANTIC OCEAN... A BROAD UPPER TROUGH OVER THE NW ATLC EXTENDS TO 30N AND IS SUPPORTING A COLD FRONT N OF THE AREA. A REMNANT DYING STATIONARY FRONT EXTENDS FROM 31N71W TO 29N80W. SCATTERED TO NUMEROUS SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 24N-32N W OF 77W TO THE COAST OF FLORIDA AND GEORGIA. A WEAK SURFACE TROUGH IS IN THE W/CENTRAL ATLC EXTENDING FROM 28N61W TO 24N63W. THE UPPER RIDGE OVER THE E CARIBBEAN EXTENDS A RIDGE AXIS FROM THE UPPER ANTICYCLONE NEAR 15N58W TO 25N67W AND IS PROVIDING DIFFLUNCE ALOFT TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS FROM 22N-26N BETWEEN 51W-67W. AN UPPER LOW IS IN THE E/CENTRAL ATLC NEAR 25N43W GENERATING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS FROM 25N-29N BETWEEN 40W-49W. A SURFACE RIDGE DOMINATES THE ATLC E OF 55W AND IS ANCHORED BY A 1022 MB HIGH N OF THE AREA NEAR 33N37W. W ATLC STATIONARY FRONT WILL DISSIPATE OVERNIGHT. THE E CARIBBEAN TROPICAL WAVE WILL REACH THE WINDWARD PASSAGE WED AND THE STRAITS OF FLORIDA THU. WEAK HIGH PRESSURE N OF THE AREA WILL DOMINATE THE REGION THROUGH THU. 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