000 AXNT20 KNHC 281749 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU OCT 28 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...SPECIAL FEATURES... A 1010 MB SURFACE LOW IS CENTERED NEAR 27N41W WITH A SURFACE TROUGH EXTENDING NE TO 32N34W AND SW TO NEAR 23N46W...AS DEPICTED ON AN EARLY MORNING 28/1142 UTC ASCAT PASS. LOCATING SOUTH OF AN UPPER LEVEL TROUGH AXIS ALONG 30N...SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS SHEARED EAST OF THE LOW CENTER FROM 25N-28N BETWEEN 36W-40W. A 1009 MB SURFACE LOW IS CENTERED NEAR 24N59W AND EXTENDS A SURFACE TROUGH SOUTHWARD TO 19N61W. THE SURFACE LOW IS COLLOCATED WITH A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH WITH AXIS ALONG 23N THAT IS PART OF A LARGER UPPER LEVEL CYCLONIC CIRCULATION CENTERED NEAR 23N69W. SCATTERED MODERATE AND ISOLATED MODERATE CONVECTION CONTINUES TO BE SHEARED NORTH OF THE UPPER LEVEL TROUGH AXIS AND IS LOCATED OVER A BROAD AREA FROM 25N-29N BETWEEN 56W-67W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 03N50W TO 13N46W MOVING W AT 15-20 KT. A 1006 MB LOW IS CENTERED ALONG THE WAVE AXIS NEAR 07N49W AND CONTINUES TO PROVIDE LOW-LEVEL FOCUS FOR SCATTERED TO NUMEROUS MODERATE AND SCATTERED STRONG CONVECTION FROM 06N-11N BETWEEN 45W-52W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS ELSEWHERE FROM 03N-15N BETWEEN 42W-54W. ENHANCEMENT OF THE STRONGER ONGOING CONVECTION IS DUE TO UPPER LEVEL DIFFLUENCE PROVIDED BY A BROAD UPPER LEVEL ANTICYCLONE CENTERED NEAR 10N50W. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 09N13W 06N20W 08N45W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 04N-12N BETWEEN 08W-19W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 150 NM EITHER SIDE OF THE AXIS BETWEEN 19W-32W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL LONGWAVE TROUGH EXTENDS FROM THE OHIO RIVER VALLEY SOUTHWESTWARD TO A BASE OVER LOUISIANA AND SUPPORTS A COLD FRONT ANALYZED FROM THE FLORIDA PANHANDLE INTO THE GULF NEAR FORT WALTON BEACH ALONG 29N90W TO 26N97W. A PRE-FRONTAL TROUGH EXTENDS FROM THE COLD FRONT NEAR 28N93W SOUTHWARD OVER THE WESTERN GULF TO NEAR COATZACOALCOS MEXICO. SCATTERED SHOWERS AND TSTMS ARE WITHIN 60 NM EAST OF THE COLD FRONT E OF 93W AND WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH N OF 24N. EAST OF THE COLD FRONT AND SURFACE TROUGH...MOSTLY FAIR CONDITIONS PREVAIL UNDER LIGHT EASTERLY SURFACE WINDS AND A DRY AND SUBSIDENT UPPER LEVEL ANTICYCLONE CENTERED OVER THE W ATLC NEAR 30N79W THAT EXTENDS RIDGING ALOFT SW TO 25N87W. WEST OF THE COLD FRONT...STRONG NORTHERLY WINDS AND BUILDING SEAS ARE FORECAST THROUGH SATURDAY WITH NW TO N WINDS REACHING GALE FORCE AS THE FRONT PROGRESSES SOUTHWARD OVER THE SW GULF S OF 21N W OF 95W. CARIBBEAN SEA... BROAD SCALE UPPER LEVEL TROUGHING IS LOCATED ACROSS MUCH OF THE CARIBBEAN BASIN AND IS PROVIDING FOR NW TO W FLOW ALOFT THAT STEMS FROM AN UPPER LEVEL LOW CENTERED NORTH OF HISPANIOLA NEAR 23N69W. WATER VAPOR IMAGERY NOTES THAT THE AIRMASS ASSOCIATED WITH THE UPPER LEVEL LOW IS MOSTLY DRY AND STABLE...HOWEVER...A STREAM OF MID-LEVEL MOISTURE IS NOTED FROM 15N72W TO 20N83W. THIS MOISTURE ALONG WITH MARGINAL LOW-LEVEL SPEED CONVERGENCE IS GENERATING WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 60 NM EITHER SIDE OF A LINE FROM 16N78W TO 20N85W. ANOTHER AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS IS OCCURRING OVER AND IN THE VICINITY OF HISPANIOLA FROM 16N-21N BETWEEN 68W-72W. OTHER ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY ACROSS THE LESSER ANTILLES...INCLUDING TRINIDAD AND TOBAGO...THIS AFTERNOON AS LOW TO MIDDLE LEVEL MOISTURE STREAMS WESTWARD FROM THE TROPICAL ATLC WATERS. ELSEWHERE...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE SW CARIBBEAN S OF 12N BETWEEN 81W-84W DUE TO CONVERGENT LOW-LEVEL FLOW AND CLOSE PROXIMITY OF THE E PACIFIC ITCZ AXIS. ATLANTIC OCEAN... ASIDE FROM THE TWO AREAS OF CONCERN NOTED ABOVE IN THE SPECIAL FEATURES SECTION...A SURFACE RIDGE EXTENDS W-SW FROM A 1027 MB HIGH CENTERED NEAR 36N54W TO THE FLORIDA PENINSULA NEAR CAPE CANAVERAL. THIS SURFACE FEATURE ALONG WITH NORTHEASTERLY FLOW ALOFT OVER THE W ATLC IS PROVIDING FOR OVERALL FAIR CONDITIONS W OF 68W. THE EASTERN ATLC IS UNDER THE INFLUENCE OF ANOTHER SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 33N29W WITH THE RIDGE AXIS EXTENDING FROM THE HIGH SW TO NEAR 17N41W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN