000 AXNT20 KNHC 101802 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT NOV 10 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. ...THE ITCZ/THE MONSOON TROUGH... THE ITCZ EXTENDS FROM SIERRA LEONE AT 8N13W ACROSS THE TROPICAL ATLC ALONG 7N20W 8N26W 7N30W 10N37W 7N60W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 5N-9N BETWEEN 18W-26W...FROM 8N-11N BETWEEN 26W-31W...AND FROM 7N-11N BETWEEN 34W-42W. SCATTERED STRONG CONVECTION IS FROM 11N-12N BETWEEN 19W-28W...AND FROM 13N-17N BETWEEN 26W-33W. AN UPPER LEVEL TROUGH IN THE EASTERN ATLC IS HELPING ENHANCE SOME OF THIS CONVECTION. ...DISCUSSION... THE GULF OF MEXICO... FAIR WEATHER STILL PREVAILS ACROSS THE GULF OF MEXICO WITH ONLY A SLIGHT INCREASE IN CLOUD COVER ACROSS THE SE GULF FROM THE FLORIDA STRAITS TO NORTH OF THE YUCATAN PENINSULA AND IN THE NORTH CENTRAL GULF SOUTH OF LOUISIANA. THE FAIR WEATHER IS ATTRIBUTED TO SURFACE RIDGING AND DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE COVERING THE BASIN WITH AXIS ALONG 93W. EAST TO SOUTHEAST WINDS ARE AROUND THE SURFACE RIDGE RANGING FROM 10-15 KT WITH SOME 20 KT WINDS NOTED NEAR THE FLORIDA STRAITS AND NEAR THE TEXAS COAST. SURFACE RIDGING IS EXPECTED TO REMAIN ACROSS THE BASIN OVER THE NEXT 24 HOURS WITH WINDS INCREASING TO 20-25 KT. A COLD FRONT IS EXPECTED TO EMERGE INTO THE NW GULF MONDAY MORNING. THE CARIBBEAN SEA... DRY AIR ALOFT COVERS A GOOD PORTION OF THE CARIBBEAN TODAY AROUND THE BASE OF AN UPPER LEVEL TROUGH COVERING THE WEST ATLC PROVIDING MOSTLY FAIR WEATHER ACROSS THE BASIN. THE UPPER TROUGH SUPPORTS A COLD FRONT THAT EXTENDS FROM THE W ATLC TO CENTRAL HISPANIOLA TRANSITIONING INTO A SHEAR AXIS IN THE CARIBBEAN ALONG 19N72W 16N78W 13N82W. A RECENT SCATTEROMETER PASS INDICATES THE BOUNDARY IS WEAK WITH ONLY A 5 KT DIFFERENCE ACROSS THE AXIS. NORTHEAST WINDS UP TO 25 KT ARE NW OF THE AXIS WITH NE WINDS UP TO 20 KT TOWARDS THE SE. DESPITE IT BEING WEAK...THE BOUNDARY IS STILL HELPING PRODUCE A FEW ISOLATED SHOWERS/THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF THE AXIS. ISOLATED SHOWERS ARE ALSO NOTED ACROSS PORTIONS OF HONDURAS AS WELL AS HISPANIOLA. ACROSS THE EASTERN CARIBBEAN...MOSTLY CLEAR SKIES ARE PRESENT WITH ONLY A FEW ISOLATED SHOWERS NORTH OF VENEZUELA TIED TO A SMALL AREA OF ENHANCED MOISTURE NEAR A WEAK SURFACE TROUGH WEST OF THE WINDWARD ISLANDS ALONG 16N62W TO 12N63W. STRONG NE WINDS ARE EXPECTED TO REMAIN ACROSS THE WESTERN AND CENTRAL CARIBBEAN WITH LITTLE CHANGE EXPECTED ELSEWHERE. THE ATLANTIC OCEAN... SURFACE RIDGING ACROSS THE EASTERN CONUS CONTINUES INTO THE WEST ATLC MAINTAINING MOSTLY FAIR CONDITIONS ACROSS THE AREA. DRY AIR ALOFT IS ALSO SPREADING INTO THE AREA AS IT WRAPS AROUND AN UPPER LEVEL TROUGH ALONG 70W. THE UPPER TROUGH CONTINUES TO SUPPORT A COLD FRONT THAT HAS NOW PUSHED INTO THE CENTRAL ATLC. IT ENTERS THE DISCUSSION AREA NEAR 32N54W AND CONTINUES TO HISPANIOLA ALONG 24N60W 19N71W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 160 NM EITHER SIDE OF THE AXIS. AN UPPER LEVEL RIDGE COVERS THE CENTRAL ATLC ALONG 50W EXTENDING INTO A LARGER UPPER RIDGE OVER THE NE ATLC SUPPORTING A BROAD SURFACE RIDGE ANCHORED BY A 1035 MB AZORES HIGH. THE RIDGE IS PROVIDING GENERALLY FAIR CONDITIONS ACROSS THE EASTERN ATLC EXCEPT FOR SOME AREAS OF DISTURBED WEATHER IN THE EASTERN TROPICAL ATLC. AN UPPER LEVEL TROUGH SOUTH OF THE LARGE UPPER RIDGE ALONG 38W IS WHAT IS RESPONSIBLE FOR THE DISTURBED WEATHER. IT FIRST SUPPORTS A SURFACE TROUGH ALONG 22N40W TO A WEAK 1010 MB LOW AT 18N41W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE EAST OF THE SYSTEM FROM 18N-24N BETWEEN 33W-38W. AN ASCAT PASS FROM EARLIER THIS MORNING ALSO INDICATES THAT WINDS UP TO 30 KT ARE EAST OF THE TROUGH AXIS FROM 20N-23N. THE UPPER LEVEL TROUGH IS ALSO ENHANCING CONVECTION JUST NORTH OF THE ITCZ REGION WHICH IS DESCRIBED IN THE ITCZ SECTION ABOVE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON