000 AXNT20 KNHC 181157 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT SUN SEP 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST OF SENEGAL NEAR 18N16W TO A 1010 MB LOW NEAR 12N24W TO A SECOND 1009 MB LOW NEAR 11N35W ENDING NEAR 9N45W WHERE THE ITCZ CONTINUES TO 4N58W. A CLUSTER OF STRONG CONVECTION IS JUST OFF THE AFRICAN COAST FROM 12N-14N BETWEEN 17W-19W. SIMILAR ACTIVITY IS NEAR THE EASTWARD MOST LOW FROM 12N-14N BETWEEN 22W-26W. SCATTERED MODERATE/STRONG CONVECTION IS NEAR THE WESTWARD MOST LOW FROM 6N-13N BETWEEN 33W-40W...AND FROM 4N-10N BETWEEN 40W-45W. ...DISCUSSION... GULF OF MEXICO... MOSTLY FAIR WEATHER IS ACROSS THE GULF OF MEXICO THIS MORNING WITH LIGHT ANTI-CYCLONIC SURFACE FLOW AROUND HIGH PRESSURE CENTERED OVER NEW ENGLAND. ALOFT...UPPER RIDGING DOMINATES EXTENDING FROM CENTRAL MEXICO TO N FLORIDA. DRY AND SUBSIDENT AIR ACCOMPANIES THE RIDGE WHICH IS HELPING MAINTAIN THE PLEASANT CONDITIONS. HOWEVER...SOME MOISTURE FROM THE E PACIFIC IS BEING WRAPPED AROUND THE WRN SIDE OF THE UPPER RIDGE WHICH HAS MADE ITS WAY TO SRN TEXAS AND THE NW GULF WHERE AN AREA OF SHOWERS/THUNDERSTORMS HAS POPPED UP ALONG THE TEXAS COAST AND WITHIN 90 NM OFFSHORE. DOPPLER RADAR ALSO INDICATES SOME ISOLATED SHOWERS IN THE SE GULF OFF THE COAST OF SW FLORIDA...AND IN THE FAR SRN BAY OF CAMPECHE. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS BESIDES A SLIGHT INCREASE IN THE CHANCE OF RAIN OVER THE SE GULF AS AN AREA OF MOISTURE TO THE E ADVECTS WWD. CARIBBEAN SEA... DEEP LAYER MOISTURE CONTINUES TO IMPACT MUCH OF THE CARIBBEAN WITH THE FIRST AREA SITTING OVER THE WRN HALF OF THE BASIN W OF 79W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE S OF 22N BETWEEN 79W-86W. A SURFACE TROUGH EXTENDS JUST E OF THE YUCATAN INTO NRN HONDURAS SUPPORTING A FEW ISOLATED SHOWERS IN ITS VICINITY. STRONG SHOWERS/THUNDERSTORMS ARE ALSO OVER NRN COLOMBIA AND E OF COSTA RICA/NICARAGUA INFLUENCED BY THE MONSOON TROUGH THAT EXTENDS ACROSS PANAMA TO NRN COLOMBIA. AN UPPER LEVEL LOW IS DOMINATING THE ERN CARIBBEAN CENTERED OVER ERN PUERTO RICO. DRY AIR IS BEING WRAPPED AROUND THE WRN SIDE OF THE UPPER LOW KEEPING THE CENTRAL CARIBBEAN UNDER MOSTLY FAIR CONDITIONS EXCEPT FOR A CLUSTER OF SHOWERS/THUNDERSTORMS S OF HAITI. CLUSTERS HAVE ALSO POPPED UP OVER NRN VENEZUELA AND OVER THE NRN WINDWARD ISLANDS NEAR A SURFACE TROUGH EXTENDING FROM THE VIRGIN ISLANDS TO NRN VENEZUELA NEAR 12N66W. MOST OF THE REMAINING SHOWER/THUNDERSTORM ACTIVITY ASSOCIATED WITH THE UPPER LOW IS N AND E OF THE ISLANDS. EXPECT MOIST CONDITIONS TO REMAIN OVER THE WRN CARIBBEAN AND CENTRAL AMERICA. MOISTURE IN THE ERN CARIBBEAN IS EXPECTED TO DRIFT WWD WHICH SHOULD INCREASE THE SHOWER ACTIVITY OVER THAT PORTION OF THE BASIN. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH OVER THE ERN SEABOARD IS SUPPORTING A STATIONARY FRONT WHICH JUST CLIPS THE AREA AND EXTENDS TO NE FLORIDA NEAR 29N81W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 60 NM SE OF THE FRONT. A SURFACE TROUGH CONTINUES TO SIT OVER THE CENTRAL BAHAMAS FROM 28N75W TO 23N77W. MOST OF THE SHOWER ACTIVITY NEAR THE TROUGH HAS DIED OUT WITH ONLY ISOLATED SHOWERS ALONG THE AXIS. AN UPPER LEVEL LOW SPINNING OVER ERN PUERTO RICO IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS S OF 28N BETWEEN 60W-65W...AND S OF 22N BETWEEN 65W-70W. SIMILAR ACTIVITY IS E OF THE LESSER ANTILLES FROM 15N-20N BETWEEN 60W-63W IN THE AREA OF DIFFLUENCE ALOFT AROUND THE ERN SIDE OF THE UPPER LOW/TROUGH. FARTHER E...A SURFACE TROUGH IS ANALYZED IN THE TROPICAL ATLC ALONG 43W FROM 14N-20N. A CLUSTER OF STRONG SHOWERS/THUNDERSTORMS IS OVER THE TROUGH AXIS FROM 16N-19N BETWEEN 40W-44W. A LOW PRESSURE SYSTEM IS TO THE N SUPPORTED BY AN UPPER LEVEL LOW NEAR 32N39W. A SURFACE TROUGH ASSOCIATED WITH THIS SYSTEM EXTENDS FROM 32N37W TO 27N47W. SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS ARE N OF 27N BETWEEN 34W-40W. SURFACE RIDGING COVERS THE FAR ERN ATLC ANCHORED BY A 1030 MB HIGH NE OF THE AZORES ISLANDS. THE HIGH IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 44N22W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON