000 AXNT20 KNHC 170611 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT SEP 17 2011 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 IS SSE OF THE CAPE VERDE ISLANDS NEAR 10N21W. THE LOW IS EMBEDDED WITHIN THE MONSOON TROUGH AND HAS BECOME SLIGHTLY BETTER ORGANIZED OVER THE PAST SEVERAL HOURS WITH AN AREA OF SCATTERED MODERATE/STRONG CONVECTION NEAR THE LOW CENTER FROM 10N-14N BETWEEN 20W-25W. SOME SLOW DEVELOPMENT IS POSSIBLE OVER THE NEXT COUPLE OF DAYS AS THE LOW MOVES WWD AT 10-15 KT. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF SENEGAL NEAR 14N17W TO A 1012 MB LOW NEAR 10N21W TO A SECOND 1012 M LOW NEAR 9N37W AND ENDING NEAR 8N45W WHERE THE ITCZ BEGINS TO 8N56W. SCATTERED MODERATE/STRONG CONVECTION IS IN THE VICINITY OF THE EASTWARD MOST LOW FROM 10N-14N BETWEEN 20W-25W. ISOLATED MODERATE/STRONG CONVECTION IS S OF THE AXIS FROM 5N-9N BETWEEN 25W-34W...BECOMING MORE SCATTERED FROM 6N-10N BETWEEN 34W-42W. ...DISCUSSION... GULF OF MEXICO... A DISSIPATING STATIONARY FRONT REMAINS ACROSS THE NRN GULF OF MEXICO FROM THE BIG BEND OF FLORIDA NEAR 29N83W TO THE TEXAS COAST NEAR 29N96W. A FEW ISOLATED SHOWERS ARE ALONG THE BOUNDARY WITH ONE LARGER CLUSTER OVER NE FLORIDA POSSIBLY FURTHER INFLUENCED BY DIFFLUENCE AROUND THE BASE OF A SHORTWAVE UPPER TROUGH MOVING OFF THE ERN UNITED STATES COAST. UPPER LEVEL RIDGING ACCOMPANIED BY MOSTLY DRY AIR COVERS THE GULF EXTENDING FROM CENTRAL MEXICO TO NRN FLORIDA. THIS DRY AND STABLE AIR MASS IS SUPPORTING FAIR WEATHER BASIN-WIDE WITH LIGHT ANTI-CYCLONIC FLOW. THE FRONTAL BOUNDARY IS EXPECTED TO CONTINUE TO WEAKEN THROUGHOUT THE NEXT 24 HOURS WITH WEAK ANTI-CYCLONIC SURFACE FLOW REMAINING. CARIBBEAN SEA... A CONTRAST FROM THE GULF OF MEXICO...THE WRN CARIBBEAN IS LADEN WITH DEEP LAYER MOISTURE. A SURFACE TROUGH IS ANALYZED JUST E OF CENTRAL AMERICA ALONG 17N83W TO 11N81W. AN UPPER LEVEL TROUGH EXTENDING FROM HONDURAS ACROSS WRN CUBA IS PROVIDING AN AREA OF DIFFLUENCE OVER THE NW CARIBBEAN WHICH IS HELPING ENHANCE SHOWER/THUNDERSTORM ACTIVITY IN THIS AREA. SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 17N-23N BETWEEN 75W-88W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH AXIS. A STRONG CLUSTER OF STORMS PREVIOUSLY OVER CENTRAL AMERICA HAS NOW BEGUN TO PUSH W INTO THE E PACIFIC. ISOLATED SHOWERS ARE ALSO ALONG THE MONSOON TROUGH WHICH EXTENDS ACROSS COSTA RICA TO NRN COLOMBIA. A CLUSTER OF STRONGER SHOWERS/THUNDERSTORMS IS N OF THE AXIS FROM 11N-13N BETWEEN 75W-77W. AN UPPER LEVEL LOW IS DOMINATING THE ERN CARIBBEAN CENTERED OVER THE VIRGIN ISLANDS. DRY AIR IS BEING WRAPPED AROUND THE WRN SIDE OF THE UPPER LOW KEEPING THE CENTRAL AND ERN CARIBBEAN UNDER MOSTLY FAIR CONDITIONS. HOWEVER...SCATTERED SHOWERS/THUNDERSTORMS ARE POPPING UP NEAR THE LOW CENTER AND AROUND THE ERN SIDE...SOME OF WHICH ARE PUSHING S OVER PUERTO RICO AND ACROSS THE WINDWARD ISLANDS WHERE A SURFACE TROUGH IS ANALYZED FROM 16N60W TO 11N62W. EXPECT MOIST CONDITIONS TO REMAIN OVER THE WRN CARIBBEAN AND CENTRAL AMERICA. THE UPPER LEVEL LOW OVER THE ERN CARIBBEAN IS EXPECTED TO REMAIN SOMEWHAT STATIONARY...WITH THE SURFACE TROUGH EXPECTED TO MOVE WWD WHICH WILL KEEP A CHANCE FOR SHOWERS/THUNDERSTORMS OVER THE WINDWARD ISLANDS AND NRN LEEWARD ISLANDS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH OVER THE FAR WRN ATLC IS SUPPORTING A STATIONARY FRONT WHICH JUST CLIPS THE AREA AND CROSSES ACROSS NRN FLORIDA INTO THE GULF OF MEXICO. A CLUSTER OF SHOWERS/THUNDERSTORMS IS ASSOCIATED WITH THE BOUNDARY ACROSS NE FLORIDA AND THE IMMEDIATE COASTAL WATERS. AN AREA OF DRY AIR IS SANDWICHED BETWEEN THIS FRONTAL BOUNDARY AND A SURFACE TROUGH TO THE E ALONG 32N65W 27N71W ACROSS THE SE BAHAMAS TO 20N73W. CLUSTERS OF SHOWERS/THUNDERSTORMS ARE WITHIN 120 NM OF THE TROUGH WITH MORE CONCENTRATED ACTIVITY FROM 24N-27N BETWEEN 70W-76W...AND BETWEEN CUBA AND THE BAHAMAS FROM 21N-24N BETWEEN 74W-80W. AN UPPER LEVEL LOW SPINNING OVER THE VIRGIN ISLANDS IS SUPPORTING CLUSTERS OF SHOWERS/THUNDERSTORMS N OF THE ISLANDS FROM 18N-24N BETWEEN 61W-68W. ISOLATED SHOWERS ARE ALSO E OF THE WINDWARD ISLANDS TO 54W IN THE DIFFLUENT AREA AROUND THE E SIDE OF THE UPPER LOW/TROUGH. FARTHER E...BROAD SURFACE RIDGING IS COVERING MOST OF THE ERN ATLC ANCHORED BY A 1024 MB HIGH NEAR 34N51W SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 36N51W...AND A 1031 MB HIGH N OF THE AZORES ISLANDS. HOWEVER...AN UPPER LEVEL LOW S OF THE AZORES ISLANDS NEAR 34N32W IS SUPPORTING A SURFACE LOW PRESSURE SYSTEM N OF THE DISCUSSION AREA WHICH HAS A COLD FRONT EXTENDING ALONG 32N32W TO 29N36W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 120 NM SE OF THE FRONTAL BOUNDARY. EXPECT THE SURFACE TROUGH IN THE WRN ATLC TO SLOWLY DRIFT WEST DURING THE NEXT 24 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON