000 AXNT20 KNHC 012348 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST SAT DEC 01 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 1008 MB SURFACE LOW CONTINUES TO SPIN IN THE CENTRAL ATLC NEAR 27N41W. THE CENTER REMAINS EXPOSED AS DRY AIR ALOFT SINKS AROUND THE WEST SIDE OF A NARROW UPPER LEVEL TROUGH ALONG 33N48W TO 24N38W. STRONG DIFFLUENCE ALOFT AROUND THE EAST SIDE OF THE UPPER TROUGH IS HELPING PRODUCE SCATTERED MODERATE/STRONG CONVECTION BOTH EAST AND NORTH OF THE LOW CENTER FROM 23N-31N BETWEEN 35W-40W...AND NORTH OF 28N BETWEEN 40W-44W. A SURFACE TROUGH ALONG EXTENDS THROUGH THE LOW CENTER ALONG 31N41W 27N41W 15N46W. THIS SYSTEM IS BEING MONITORED CLOSELY FOR FURTHER DEVELOPMENT WITH A MEDIUM CHANCE OF BECOMING A TROPICAL OR SUBTROPICAL CYCLONE OVER THE NEXT 48 HOURS AS THE LOW MOVES NORTHWARD AND THEN MERGES WITH A FRONTAL BOUNDARY. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS WEST AFRICA TO THE NORTHERN COAST OF SIERRA LEONE AT 9N13W TO 7N17W. THE ITCZ BEGINS AT 7N17W AND CONTINUES ALONG 9N31W 7N41W 9N49W 7N59W. TWO SURFACE TROUGHS ARE EMBEDDED WITHIN THE ITCZ. THE FIRST IS ALONG 11N30W TO 7N35W. THE SECOND IS ALONG 12N47W TO 7N50W. A 1010 MB SURFACE LOW IS ALSO ALONG THE TROUGH AXIS AT 9N49W. SCATTERED MODERATE/STRONG CONVECTION IS FROM 5N-7N BETWEEN 15W-18W. ISOLATED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 20W-28W. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO IS UNDER PLEASANT CONDITIONS DUE TO A DRY AIRMASS COVERING THE BASIN. MAINLY WEST TO NORTHWEST FLOW COVERS THE AREA AROUND A BROAD UPPER TROUGH THAT EXTENDS ACROSS CENTRAL FLORIDA INTO THE SOUTH CENTRAL GULF. AT THE SURFACE...WEAK SURFACE RIDGING EXTENDS ACROSS THE AREA FROM THE SE CONUS TOWARDS THE SW GULF WHERE A 1022 MB HIGH IS ANALYZED OVER INLAND MEXICO. EAST TO SOUTHEAST FLOW IS AROUND THE RIDGE WITH SPEEDS OF 20 KT IN THE SE GULF BECOMING LIGHTER TO 10 KT ACROSS THE NW GULF. ONLY A SMALL LINE OF SHOWERS IS MOVING WESTWARD THROUGH THE BASIN ALONG 28N92W 23N90W. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. CARIBBEAN SEA... MAINLY SOUTHWEST TO WEST FLOW COVERS THE CARIBBEAN AROUND A BROAD UPPER LEVEL RIDGE COVERING THE AREA AND CONTINUING INTO PORTIONS OF THE SW NORTH ATLC. WHILE MOSTLY DRY AIR ALOFT IS HELPING MAINTAIN FAIR CONDITIONS BASIN-WIDE...A FEW PATCHES OF SHOWERS ARE OVER THE NORTHERN CARIBBEAN ISLANDS INCLUDING EASTERN CUBA...HISPANIOLA...AND PUERTO RICO. A FEW ISOLATED SHOWERS ARE ALSO ACROSS COSTA RICA AND PANAMA. RATHER LIGHT TRADEWIND FLOW OF 10-15 KT IS PRESENT ACROSS THE AREA. LITTLE CHANGE IS EXPECTED OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... A WEAK UPPER LEVEL TROUGH EXTENDS OVER THE FAR WESTERN SW NORTH ATLC. MOSTLY FAIR CONDITIONS ARE SEEN AT THE SURFACE...ALTHOUGH SOME UPPER LEVEL CLOUD COVER IS TO THE EAST NEAR THE AREA OF MOIST SOUTHWESTERLY FLOW BETWEEN THE UPPER TROUGH AND AN UPPER LEVEL RIDGE COVERING THE REMAINDER OF THE WEST ATLC ALONG 60W. A SHEAR AXIS...REMNANTS OF A FRONTAL BOUNDARY EXTENDS FROM NEAR 28N51W ALONG 25N60W 24N69W 21N76W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE MAINLY NORTH OF THE AXIS FROM 23N-29N BETWEEN 61W-70W WITH A FEW ISOLATED SHOWERS/THUNDERSTORMS WITHIN 75 NM OF THE AXIS ELSEWHERE. A SURFACE TROUGH IS SOUTH OF THE SHEAR AXIS ALONG 23N68W TO 19N67W. ISOLATED SHOWERS ARE WITHIN 200 NM EAST OF THE AXIS. FARTHER EAST...A SURFACE LOW AND SURFACE TROUGH ALONG WITH AN UPPER LEVEL TROUGH ARE CAUSING AN AREA OF DISTURBED WEATHER. SEE SPECIAL FEATURES FOR MORE DETAILS. A NARROW UPPER LEVEL RIDGE IS IMMEDIATELY TO THE EAST ALONG 22N30W 37N37W CONTINUING TOWARDS THE NORTHEAST. THE UPPER RIDGE SUPPORTS A SURFACE RIDGE AROUND A 1032 MB AZORES HIGH WHICH IS HELPING PROVIDE FAIR CONDITIONS ACROSS THE EASTERN ATLC. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON