000 AXNT20 KNHC 072346 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST WED NOV 07 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. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 12N16W TO 09N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 09N20W TO 06N33W TO 09N50W. SCATTERED MODERATE CONVECTION IS FROM 03N-05N BETWEEN 15W-21W...AND FROM 04N-09N BETWEEN 21W-28W. ISOLATED MODERATE CONVECTION IS FROM 05N-10N BETWEEN 36W-48W. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES WEST-NORTHWESTERLY WINDS PREVAIL ALOFT WITHIN A VERY DRY AND STABLE AIRMASS CURRENTLY LOCATED OVER THE GULF BASIN THIS EVENING. THE NORTHERLY FLOW IN THE MIDDLE TO UPPER LEVELS IS FURTHER SUPPORTING A BROAD SURFACE RIDGE ANCHORED BY A 1022 MB HIGH CENTERED NEAR BROWNSVILLE TEXAS. THE SURFACE RIDGE AXIS EXTENDS NORTHWARD ACROSS THE CENTRAL PLAINS AND IS EXPECTED TO BUILD SOUTHEASTWARD THROUGH LATE FRIDAY INTO THE SE CONUS. NORTHERLY SURFACE WINDS IN THE RANGE OF 10 TO 20 KT ARE EXPECTED TO VEER NORTHEASTERLY BY LATE THURSDAY AND BECOME EAST-SOUTHEASTERLY BY EARLY SATURDAY. FOR THE UPCOMING WEEKEND...GLOBAL MODELS INDICATE AS THE SURFACE HIGH EXTENDS INFLUENCE OVER THE EASTERN GULF...FLORIDA PENINSULA...AND AREAS SOUTH OF 23N...THE PRESSURE GRADIENT WILL STRENGTHEN AND PROVIDE FOR STRONGER WINDS ACROSS THE FLORIDA STRAITS AND PORTIONS OF THE SE GULF. THE STRONGER WINDS ARE EXPECTED TO SPREAD WESTWARD BY MONDAY AS THE NEXT COLD FRONT MOVES ACROSS THE MID-MISSISSIPPI RIVER VALLEY AND PORTIONS OF EASTERN TEXAS INTO THE FAR NW GULF WATERS. CARIBBEAN SEA... A BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED NEAR 15N68W OVER THE EASTERN CARIBBEAN AND EXTENDS INFLUENCE AS FAR WEST AS 85W OVER PORTIONS OF CENTRAL AMERICA. THE WESTERN CARIBBEAN IS INFLUENCED BY MIDDLE TO UPPER LEVEL SOUTHWESTERLY WINDS ALOFT N OF 15N AND A COLD FRONT ANALYZED FROM WESTERN CUBA NEAR 23N80W TO 19N90W GENERATING ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF THE COLD FRONT AND WITHIN 120 NM EITHER SIDE OF A LINE FROM 21N76W TO 15N88W DUE TO MAXIMUM MIDDLE TO UPPER LEVEL DIFFLUENCE. FARTHER SOUTH OVER THE SW CARIBBEAN...THE MONSOON TROUGH AXIS EXTENDS FROM WESTERN PANAMA NEAR 09N82W TO NORTHERN COLOMBIA NEAR 11N75W AND IS PROVIDING FOCUS FOR SCATTERED SHOWERS AND ISOLATED TSTMS FROM 08N-15N BETWEEN 74W-85W. THE REMAINDER OF THE EASTERN CARIBBEAN IS UNDER THE INFLUENCE OF A VERY DRY AIRMASS ALOFT WHICH IS RESULTING IN VERY DRY CONDITIONS AND CLEAR SKIES AT THE SURFACE E OF 73W. ATLANTIC OCEAN... A BROAD AND DEEP MIDDLE TO UPPER LEVEL LOW IS CENTERED OVER THE MID-ATLC STATES THAT CONTINUES TO SUPPORT BROAD TROUGHING OVER THE FLORIDA PENINSULA AND SW NORTH ATLC N OF 22N W OF 65W. WATER VAPOR IMAGERY INDICATES A FAIRLY DRY AIRMASS IS LOCATED ON THE SOUTHERN PERIPHERY OF THE UPPER LEVEL LOW AND IS LIMITING ANY SIGNIFICANT DEEP CONVECTION EVEN WITH THE PRESENCE OF A COLD FRONT AND WAVE OF ENERGY ASSOCIATED WITH A SECONDARY SURFACE TROUGH. THE COLD FRONT IS ANALYZED FROM 32N68W SW TO THE CENTRAL BAHAMAS NEAR 25N76W TO WESTERN CUBA NEAR 23N80W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE FRONT... HOWEVER THESE ARE REMAINING LOW-TOPPED AND QUICKLY MOVING TO THE NORTHEAST. THE FRONT CONTINUES TO BECOME MORE AND MORE DIFFUSE WITH THE SECONDARY WAVE OF ENERGY IN THE FORM OF A SURFACE TROUGH FROM 32N73W TO 28N80W POISED TO BECOME THE DOMINATE FEATURE IN 24 TO 36 HOURS. A PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 28N65W TO 23N73W AND IS PROVIDING LOW-LEVEL MOISTURE CONVERGENCE TO SUPPORT ISOLATED SHOWERS FROM 21N-29N BETWEEN 54W-70W. THIS CONVECTION CONTINUES TO BE ENHANCED BY STRONG MIDDLE TO UPPER LEVEL DIFFLUENCE AND SPREADS NORTHEAST COVERING THE ADDITIONAL AREA OF SCATTERED SHOWERS AND TSTMS FROM 26N-36N BETWEEN 52W-62W. ELSEWHERE OVER THE REMAINDER OF THE EASTERN ATLC...SURFACE RIDGING DOMINATES ANCHORED BY A 1035 MB HIGH CENTERED WEST OF THE AZORES NEAR 40N33W. HOWEVER...A WEAK SURFACE TROUGH REMAINS EMBEDDED WITHIN THE SOUTHERN PERIPHERY OF THE RIDGE MOVING SLOWLY WESTWARD ANALYZED FROM 15N-22N ALONG 44W. THE SURFACE TROUGH ALONG WITH AN UPPER LEVEL TROUGH AXIS FROM 28N41W TO 18N36W IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-28N BETWEEN 30W-39W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN