000 AXNT20 KNHC 212355 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN OCT 21 2012 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 2315 UTC. ...SPECIAL FEATURES... A TROPICAL WAVE CONTINUES TO MOVE THROUGH THE WESTERN CARIBBEAN EXTENDING FROM EASTERN CUBA NEAR 20N78W TO NORTH OF COLOMBIA AT 13N75W. A 1006 MB LOW IS ALONG THE WAVE AXIS NEAR 15N77W. TOTAL PRECIPITABLE WATER IMAGERY INDICATES A LARGE AREA OF MAXIMUM MOISTURE VALUES COVER MUCH OF THE SW AND CENTRAL CARIBBEAN. THE SYSTEM REMAINS DISORGANIZED AT THIS TIME WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION RANGING FROM 12N-18N BETWEEN 67W-75W...FROM 11N-18N BETWEEN 75W-80W...AND FROM 20N-22N BETWEEN 74W-79W. ENVIRONMENT CONDITIONS REMAIN CONDUCIVE FOR FURTHER DEVELOPMENT OF THE SYSTEM. A TROPICAL WAVE EXTENDS FROM 24N52W TO 15N47W MOVING W-NW AT 5-10 KT. A 1011 MB LOW IS ANALYZED ALONG THE WAVE AXIS NEAR 20N51W THAT CAN BE SEEN CLEARLY IN SATELLITE IMAGERY. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS NEAR THE LOW CENTER FROM 20N-22N BETWEEN 49W-53W...AND TO THE EAST FROM 21N-24N BETWEEN 44W-49W. THE WAVE IS INTERACTING WITH AN UPPER LEVEL LOW...WHICH IS HELPING ENHANCE THE CONVECTION TO THE EAST. SOME STRENGTHENING IS POSSIBLE OVER THE NEXT COUPLE OF DAYS BEFORE THE UPPER LEVEL CONDITIONS BECOME HARSHER. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 16N34W TO 11N36W MOVING WEST AT 10-15 KT. BROAD CYCLONIC FLOW IS AROUND THE WAVE AXIS EVIDENT IN SATELLITE IMAGERY. SCATTERED MODERATE CONVECTION IS MAINLY EMBEDDED WITHIN THE MONSOON TROUGH AXIS FROM 7N-10N BETWEEN 36W-41W. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE COAST OF GUINEA-BISSAU AT 11N16W CONTINUING ALONG 12N30W 9N40W. THE ITCZ BEGINS AT 9N40W AND GOES TO 6N50W. SCATTERED STRONG CONVECTION IS FROM 8N-13N BETWEEN 20W-24W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 2N-4N BETWEEN 14W-18W. SIMILAR ACTIVITY IS FROM 10N-13N BETWEEN 43W-44W. ...DISCUSSION... GULF OF MEXICO... SURFACE RIDGING DOMINATES THE GULF OF MEXICO TONIGHT IN THE WAKE OF A COLD FRONT THAT MOVED OUT OF THE BASIN YESTERDAY. LIGHT ANTI-CYCLONIC FLOW IS AROUND THE RIDGE EXCEPT FOR SOME STRONGER WINDS UP TO 15 KT ACROSS THE SE GULF AND ALONG THE TEXAS COAST. CLEAR SKIES ARE PRESENT OVER THE MAJORITY OF THE AREA WITH A FEW LOW-LEVEL CLOUDS AND POSSIBLE SHOWERS ACROSS THE FLORIDA STRAITS AND OVER THE FAR WESTERN GULF. ALOFT...AN UPPER LEVEL RIDGE IS MOVING ACROSS THE GULF FROM THE WEST AND CURRENTLY EXTENDS FROM SOUTHERN MEXICO TO THE GREAT LAKES REGION. AN UPPER LEVEL TROUGH CONTINUES TO MOVE OUT TO THE EAST. DRY AIR AND SUBSIDENCE ALSO COVER THE AREA HELPING SUPPORT THE FAIR CONDITIONS. SURFACE RIDGING IS EXPECTED TO REMAIN ACROSS THE GULF FOR THE NEXT SEVERAL DAYS. WINDS WILL INCREASE OVER THE SE GULF AND FLORIDA STRAITS AS THE PRESSURE GRADIENT INCREASES DUE TO A LOW PRESSURE SYSTEM IN THE CARIBBEAN. CARIBBEAN SEA... ABUNDANT MOISTURE COVERS A GOOD PORTION OF THE CARIBBEAN ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE AROUND A TROPICAL WAVE. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. SCATTRED SHOWERS/THUNDERSTORMS ALSO DOT MUCH OF CENTRAL AMERICA AS MOISTURE FROM THE E PACIFIC WRAPS AROUND AN UPPER LEVEL RIDGE COVERING THE MAJORITY OF THE BASIN. THE MOISTURE IS HELPING SUPPORT ISOLATED SHOWERS IN BOTH THE NW CARIBBEAN AS WELL AS ACROSS THE CENTRAL AND EASTERN CARIBBEAN. THE LOW PRESSURE SYSTEM IS EXPECTED TO REMAIN SOMEWHAT STATIONARY AS IT CONSOLIDATES BEFORE GAINING A MORE NORTH-NORTHEAST MOTION. REGARDLESS OF DEVELOPMENT INTO TROPICAL CYCLONE...HEAVY SHOWERS/THUNDERSTORMS WILL CONTINUE ACROSS MUCH OF THE CENTRAL AND WESTERN CARIBBEAN...AND COULD POSE THE RISK OF FLOODING ACROSS THE NORTHERN CARIBBEAN ISLANDS. ATLANTIC OCEAN... AN UPPER LEVEL TROUGH COVERING THE WESTERN ATLC SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION AREA NEAR 32N67W TO THE CENTRAL BAHAMAS AT 25N75W WHERE IT BECOMES STATIONARY AND BEGINS TO DISSIPATE ACROSS WESTERN CUBA TO THE YUCATAN PENINSULA AT 22N88W. SCATTERED SHOWERS/THUNDERSTORMS ARE SE OF THE FRONT ACROSS THE BAHAMAS AND EASTERN CUBA. ISOLATED SHOWERS ARE WITHIN 250 NM EAST OF THE REMAINDER OF THE FRONT. AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE W ATLC EXTENDING FROM THE EASTERN CARIBBEAN TO NEAR 32N60W. A TROPICAL WAVE WITH AN ASSOCIATED SURFACE LOW IS SUPPORTING AN AREA OF SHOWERS/THUNDERSTORMS IN THE CENTRAL ATLC. SEE SPECIAL FEATURES FOR MORE DETAILS. THE SURFACE LOW IS INTERACTING WITH AN UPPER LEVEL LOW CENTERED NEAR 21N49W. THE REMAINDER OF THE EASTERN ATLC IS COVERED BY AN UPPER LEVEL RIDGE CENTERED OVER THE TROPICAL ATLC NEAR 11N35W. MOSTLY FAIR WEATHER IS PRESENT EXCEPT FOR A FEW SHOWERS NEAR A SURFACE TROUGH ALONG 23N33W TO 20N35W. AN UPPER LEVEL TROUGH TO THE NORTH OF THE AREA ALSO SUPPORTS A COLD FRONT THAT SKIMS THE NORTHERN BORDER OF THE DISCUSSION AREA ALONG 32N25W 30N34W 31N42W. ISOLATED SHOWERS ARE WITHIN 30 NM EITHER SIDE OF THE AXIS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON