000 AXNT20 KNHC 222347 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT OCT 22 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...SPECIAL FEATURES... AN AREA OF LOW PRESSURE COVERS THE SW CARIBBEAN FOCUSED NEAR A 1005 MB LOW AT 13N81W. A STATIONARY FRONT CONTINUES TO SIT TO THE N OF THE SYSTEM KEEPING A TROPICAL AIRMASS OVER THE LOW. HOWEVER...SOME DRY AIR ALOFT IS SINKING IN FROM THE ATLC ACROSS THE CENTRAL CARIBBEAN AND AROUND THE NE SIDE OF THE LOW...WHICH COINCIDES WITH AN AREA LACKING CONVECTION. CURRENTLY SCATTERED MODERATE/STRONG CONVECTION IS MAINLY NW OF THE LOW FROM 12N-16N BETWEEN 82W-86W MERGING INTO THE CONVECTION ALONG THE FRONTAL BOUNDARY. SCATTERED MODERATE CONVECTION IS ALSO S OF THE LOW FROM 9N-12N BETWEEN 78W-84W. EVEN THOUGH CONVECTION REMAINS DISORGANIZED...THIS SYSTEM STILL HAS A CHANCE TO FURTHER DEVELOP OVER THE NEXT COUPLE OF DAYS AS IT DRIFTS NWD. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 14N17W ALONG 11N24W 7N34W. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 120 NM N OF THE AXIS...AS WELL AS WITHIN 200 NM S OF THE AXIS BETWEEN 23W-34W. SIMILAR ACTIVITY IS ALSO FROM 2N-6N BETWEEN 33W-38W. ...DISCUSSION... GULF OF MEXICO... A STABLE AND DRY AIRMASS CONTINUES TO SIT OVER THE GULF OF MEXICO PROVIDING FAIR WEATHER BASIN WIDE. ALOFT...MAINLY WLY FLOW DOMINATES...WHILE AT THE SURFACE RIDGING PREVAILS WITH AXIS FROM LOUISIANA TO THE BAY OF CAMPECHE. SATELLITE IMAGERY INDICATES AREAS OF STRATOCUMULUS CLOUDS S OF 26N WITH A FEW ISOLATED SHOWERS OVER THE FAR SRN BAY OF CAMPECHE. SURFACE RIDGING AND MOSTLY FAIR CONDITIONS ARE EXPECTED TO REMAIN ACROSS THE BASIN FOR THE NEXT SEVERAL DAYS. CARIBBEAN SEA... DRY AIR FROM THE GULF OF MEXICO IS SEEPING INTO THE FAR NW CARIBBEAN MAINTAINING FAIR CONDITIONS. HOWEVER...JUST E AND S A STATIONARY FRONT IS PROVIDING UNSTABLE CONDITIONS. THE FRONT EXTENDS FROM ERN CUBA NEAR 21N78W ALONG 19N81W 17N84W. SCATTERED SHOWERS/THUNDERSTORMS ARE MAINLY SE OF THE AXIS WITHIN 100 NM. A FEW SHOWERS/THUNDERSTORMS ARE ALSO NW OF THE FRONT WITHIN 75 NM W OF 80W. ALOFT...AN UPPER LEVEL RIDGE EXTENDS FROM NEAR 18N83W TOWARDS THE NE INTO THE ATLC. TO THE S...A BROAD AREA OF LOW PRESSURE EXISTS AROUND THE MONSOON TROUGH WHICH EXTENDS ACROSS SRN NICARAGUA FROM 12N85W TO 15N77W. THE MONSOON TROUGH EXTENDS THROUGH A 1005 MB SURFACE LOW THAT IS MENTIONED IN THE SPECIAL FEATURES SECTION. AS THE LOW DRIFTS N...POSSIBLE HEAVY SHOWERS COULD OCCUR OVER PORTIONS OF NICARAGUA AND HONDURAS CAUSING THE POTENTIAL FOR FLOODING AND MUDSLIDES. BESIDES THE CONVECTION ASSOCIATED WITH THE LOW...SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 12N-15N BETWEEN 72W-77W. A FEW CLUSTERS OF STORMS ARE ALSO NOTED OVER HISPANIOLA AND PUERTO RICO. ACROSS THE ERN CARIBBEAN...MODERATE DRY AIR ALOFT IN SWLY FLOW IS KEEPING CONDITIONS FAIR EVEN THOUGH A WEAK SURFACE TROUGH EXTENDS FROM 11N63W TO 16N70W. THE SURFACE TROUGH WILL LIKELY DISSIPATE OVER THE NEXT 12-24 HOURS. MOIST CONDITIONS WILL REMAIN OVER THE WRN CARIBBEAN IN ASSOCIATED WITH BOTH THE FRONTAL BOUNDARY AND THE SURFACE LOW. ATLANTIC OCEAN... A BROAD LONGWAVE UPPER TROUGH IS MOVING ACROSS THE ERN CONUS AND FAR WRN ATLC SUPPORTING A STATIONARY FRONT ENTERING THE DISCUSSION AREA NEAR 32N69W CONTINUING TO THE CENTRAL BAHAMAS NEAR 25N76W TO ERN CUBA NEAR 21N78W. STRONG DRY AIR ACCOMPANIES THE UPPER TROUGH MAINTAINING MOSTLY FAIR CONDITIONS W OF THE FRONTAL BOUNDARY BESIDES SOME LOW LEVEL CLOUDINESS AND POSSIBLE ISOLATED SHOWERS THAT EXIST WITHIN 150 NM TO THE W. ISOLATED SHOWERS ARE ALONG THE FRONTAL BOUNDARY AND WITHIN 160 NM E OF THE AXIS. A WEAK UPPER RIDGE IS SANDWICHED BETWEEN THE BROAD UPPER TROUGH AND AN UPPER LEVEL LOW NEAR 25N66W. THIS UPPER LOW IS SUPPORTING A SURFACE TROUGH ALONG 30N68W TO 21N66W. NO SHOWER ACTIVITY IS ALONG THE TROUGH AXIS. HOWEVER...DUE TO DIFFLUENCE ALOFT...SCATTERED SHOWERS/THUNDERSTORMS ARE FARTHER E FROM 21N-25N BETWEEN 60W-65W...AND FROM 27N-31N BETWEEN 57W-62W. AN UPPER LEVEL RIDGE DOMINATES THE CENTRAL AND MOST OF THE ERN ATLC WITH AXIS EXTENDING FROM 10N51W TO 41N40W SUPPORTING A 1026 MB HIGH NEAR 35N46W. TO THE S...E OF THE LESSER ANTILLES AND AROUND THE BASE OF THE UPPER RIDGE...A 1006 MB SURFACE LOW SPINS NEAR 10N56W. ISOLATED SHOWERS/POSSIBLE THUNDERSTORMS ARE WITHIN 150 NM OF THE LOW CENTER. A SECOND WEAKER 1009 MB LOW IS FARTHER E NEAR 16N43W WITH NO ASSOCIATED SHOWER ACTIVITY. HOWEVER...A NARROW UPPER LEVEL TROUGH THAT EXTENDS E OF THE UPPER RIDGE AND WRAPS AROUND THE ERN SIDE OF THE RIDGE IS PROVIDING DIFFLUENCE ALOFT TO SUPPORT AREAS OF SCATTERED SHOWERS/POSSIBLE THUNDERSTORMS FROM 7N-13N BETWEEN 36W-45W...AND FROM 12N-17N BETWEEN 25W-37W. POSSIBLE ISOLATE SHOWERS CONTINUE TO THE NE ACROSS NW AFRICA. THE UPPER TROUGH ALSO SUPPORTS A WEAK 1013 MB SURFACE LOW NEAR 24N23W WITH A SURFACE TROUGH EXTENDING THROUGH IT FROM 26N18W TO 23N26W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON