000 AXNT20 KNHC 211753 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 205 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... TROPICAL WAVE EXTENDS FROM 14N47W TO 22N51W MOVING W-NW AT 5-10 KT. A 1012 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 19N50W AS NOTED ON METEOSAT-9 VISIBLE SATELLITE IMAGERY WITH ISOLATED MODERATE CONVECTION OCCURRING FROM 19N-25N BETWEEN 48W-54W. THIS CONVECTION IS LIKELY ENHANCED BY A MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 20N49W. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. TROPICAL WAVE EXTENDS FROM 11N74W TO 20N76W MOVING W AT 5 KT. A 1008 MB LOW IS ANALYZED ALONG THE WAVE AXIS NEAR 15N76W WITH BROAD LOW-LEVEL CYCLONIC FLOW LOCATED ACROSS MUCH OF THE WESTERN CARIBBEAN. TOTAL PRECIPITABLE WATER IMAGERY ALSO INDICATES MAXIMUM VALUES OF DEEP LAYER MOISTURE ACROSS THE CENTRAL CARIBBEAN BETWEEN 70W-80W. UNORGANIZED SCATTERED MODERATE AND ISOLATED STRONG CONVECTION ACCOMPANIES THE WAVE OVER A LARGE AREA FROM 12N-18N BETWEEN 70W-77W. A WEAK UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER THE TROPICAL WAVE NEAR 16N73W WITH ENVIRONMENTAL CONDITIONS CONTINUING TO BECOME MORE FAVORABLE FOR DEVELOPMENT DURING THE NEXT DAY OR TWO AS THE DISTURBANCE MOVES SLOWLY WESTWARD. THIS SYSTEM HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. ...TROPICAL WAVES... SEE SPECIAL FEATURES SECTION ABOVE FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO 11N20W TO 11N33W TO 09N40W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N40W TO 05N50W. SCATTERED MODERATE CONVECTION IS FROM 02N-07N BETWEEN 09W-15W...FROM 04N-13N BETWEEN 18W-29W...AND FROM 08N-11N BETWEEN 35W-45W. ...DISCUSSION... GULF OF MEXICO... A DEEP LAYERED LOW IS CENTERED OVER EASTERN CANADA AND PROVIDES MIDDLE TO UPPER LEVEL TROUGHING ALONG THE EASTERN U.S. SEABOARD. THE TROUGH AXIS DIPS SOUTHWARD INTO THE SE GULF WITH A BASE OVER THE YUCATAN CHANNEL AND WATER VAPOR IMAGERY INDICATING VERY DRY AND STABLE NW FLOW ALOFT BETWEEN THE TROUGHING AND AN UPPER LEVEL RIDGE OVER MEXICO AND THE CENTRAL PLAINS. WHILE A LINGERING DISSIPATING STATIONARY FRONT IS ANALYZED FROM THE STRAITS OF FLORIDA TO NORTH OF THE YUCATAN PENINSULA NEAR 22N90W...THE ENTIRE GULF IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED OVER NORTHERN ALABAMA NEAR 34N86W. THE RIDGE AXIS EXTENDS FROM THE HIGH S-SW TO THE SW GULF NEAR 20N96W AND IS EXPECTED TO MAINTAIN CLEAR SKIES AND FAIR WEATHER CONDITIONS THROUGH LATE MONDAY. CARIBBEAN SEA... WITH AN UPPER LEVEL TROUGH OVER THE EASTERN U.S SEABOARD DIPPING SOUTHWARD OVER PORTIONS OF THE SW NORTH ATLC AND THE SE GULF OF MEXICO...THE WESTERN CARIBBEAN FINDS ITSELF SOUTH OF THE BASE OF THIS TROUGH AND BENEATH A BROAD AREA OF OVERALL DIFFLUENCE AND RELATIVELY UNSETTLED WEATHER. THE MAIN FEATURE IMPACTING THE CENTRAL AND WESTERN CARIBBEAN IS THE TROPICAL WAVE AND ASSOCIATED AREA OF LOW PRESSURE ALONG 76W AND IN THE VICINITY OF 15N76W. SCATTERED SHOWERS AND WIDELY SCATTERED STRONG TSTMS ARE OCCURRING FROM 12N-18N BETWEEN 70W-80W. TO THE WEST OF THIS TROPICAL WAVE...THE UPPER LEVEL DIFFLUENCE ALONG WITH PERSISTENT NORTHEASTERLY WINDS ARE PROVIDING FOR LOW-LEVEL MOISTURE CONVERGENCE ALONG A SURFACE TROUGH ANALYZED ALONG 13N83W TO 16N84W TO 19N88W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 13N-21N BETWEEN 80W-88W...INCLUDING PORTIONS OF THE GULF OF HONDURAS. THE DEVELOPMENT OF ORGANIZED DEEP CONVECTION AND THE FORMATION OF A CONSOLIDATED LOW LEVEL CIRCULATION CENTER WILL BE SLOW TO OCCUR OVER THE NEXT FEW DAYS AS MANY OF THE GLOBAL MODELS SUGGEST A RATHER BROAD AREA OF LOW PRESSURE ACROSS THE CENTRAL AND WESTERN CARIBBEAN PERSISTING INTO MID-WEEK. IN THE MEANTIME...HEAVY RAINS FROM THIS SYSTEM ARE LIKELY TO CONTINUE OVER JAMAICA...HISPANIOLA...AND EASTERN CUBA OVER THE NEXT SEVERAL DAYS AND COULD PRODUCE LIFE- THREATENING FLASH FLOODS AND MUD SLIDES...ESPECIALLY IN AREAS OF HIGH TERRAIN. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL TROUGH IS OVER THE EASTERN U.S SEABOARD THAT SUPPORTS A COLD FRONT EXTENDING INTO THE DISCUSSION AREA NEAR 32N70W SW ACROSS THE NW BAHAMAS TO 25N80W IN THE FLORIDA STRAITS WHERE IT BECOMES STATIONARY INTO THE SE GULF OF MEXICO W OF 80W. WATER VAPOR IMAGERY INDICATES SOUTHWESTERLY FLOW ALOFT NEAR AND EAST OF THE TROUGH AXIS IS PROVIDING FOR SUFFICIENT DIFFLUENCE TO FURTHER SUPPORT ISOLATED SHOWERS AND TSTMS OCCURRING WITHIN 360 NM EAST OF THE FRONT. FARTHER EAST...MOST OF THE REMAINDER OF THE CENTRAL AND EASTERN ATLC...OUTSIDE OF THE TROPICAL WAVE MENTIONED ABOVE IN THE SPECIAL FEATURES SECTION...IS INFLUENCED BY A SURFACE RIDGE THAT IS STRETCHED THIN IN AN EAST-WEST ORIENTATION AND ANCHORED BY A 1017 MB HIGH CENTERED NEAR 30N14W AND A 1023 MB HIGH CENTERED NORTH OF THE AREA NEAR 41N50W. BETWEEN THESE TWO HIGH CENTERS...A COLD FRONT IS LOCATED ALONG 31N/32N BETWEEN 28W-45W AND IS EXPECTED TO CONTINUE A GRADUAL SOUTHWARD DRIFT WHILE DISSIPATING AS AN UPPER LEVEL SHORTWAVE TROUGH CURRENTLY NEAR 30N30W PROGRESSES E-SE OVER THE NE ATLC DISCUSSION WATERS DURING THE NEXT 24 TO 36 HOURS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN