000 AXNT20 KNHC 291755 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SUN OCT 29 2006 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN SECTIONS OF SOUTH AMERICA...AND THE 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. ...TROPICAL WAVES... A TROPICAL WAVE HAS BEEN ADJUSTED ALONG 54W/55W S OF 13N ESTIMATED TO BE MOVING W NEAR 15 KT. THIS WAVE IS A LOW AMPLITUDE FEATURE AND IS DIFFICULT TO LOCATE. THE ADJUSTMENT IS BASED ON SOME SLIGHT LOW TO MID LEVEL TURNING SEEN IN VISIBLE IMAGES AND A WEAK CLOUD CLUSTER TRACKED IN HOVMOLLER DIAGRAMS. REGARDLESS OF THE PSN OF THE WAVE...ASSOCIATED SHOWER ACTIVITY IS MINIMAL. A STRONG TROPICAL WAVE IS MOVING QUICKLY THROUGH THE CENTRAL CARIBBEAN ALONG 72W MOVING W NEAR 20 KT. THIS WAVE REMAINS WELL DEFINED WITH A LARGE ENVELOPE OF LOW TO MID LEVEL CYCLONIC CURVATURE NOTED IN THE LOW TO MID CLOUD FIELD...BETWEEN HISPANIOLA AND SOUTH AMERICA. SHOWERS AND TSTMS REMAIN ACTIVE WITHIN 240 NM E AND 180 NM W OF THE AXIS. HOWEVER THESE SHOWERS ARE DISORGANIZED AND THERE IS NO EVIDENCE OF A SFC CIRCULATION AT THE MOMENT. UPPER LEVEL WINDS ARE ONLY MARGINALLY CONDUCIVE FOR TROPICAL CYCLONE FORMATION...AND DEVELOPMENT...IF ANY...SHOULD BE SLOW TO OCCUR. A TROPICAL WAVE IS ALONG 80W S OF 17N MOVING W 10 TO 15 KT. THE WAVE AXIS HAS BECOME A LITTLE EASIER TO LOCATE WITH SOME MID LEVEL CLOUD TURNING BECOMING APPARENT ON SATELLITE IMAGES. UPPER DIFFLUENCE ALONG WITH LOW LEVEL CONVERGENCE ASSOCIATED WITH THIS WAVE AND THE ITCZ IS PRODUCING A SCATTERED MODERATE CONVECTION W OF 76W MOSTLY S OF 15N...INCLUDING PARTS OF CENTRAL AMERICA. FOR MORE DETAILS ON THE TROPICAL WAVES REFER TO THE CARIBBEAN SECTION IN THE DISCUSSION BELOW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 8N30W 7N40W 6N48W 7N54W. THE ITCZ IS FAIRLY ACTIVE E OF 40W...WITH CLUSTERS OF SCATTERED MODERATE CONVECTION NOTED WITHIN 240 NM N OF THE AXIS. SCATTERED MODERATE ALSO EXISTS FROM 8N-12N BETWEEN 57W-64W. ...DISCUSSION... THE GULF OF MEXICO... A POST-FRONTAL DRIER AND COOLER AIRMASS IS IN PLACE ACROSS THE GULF OF MEXICO WITH A SFC RIDGE STRETCHED ACROSS THE U.S. GULF COAST WHERE A FEW HIGHS ARE ANALYZED IN THE RIDGE. LIGHT NWLY SFC WINDS ARE COMMON EXCEPT FOR SOME WINDS NEAR 15 KT S OF 24N. THE NRN GULF IS EXPERIENCING CLEAR SKIES WITH OFFSHORE FLOW...WHILE SCATTERED TO BROKEN COOL AIR OVER WARM WATERS STRATOCUMULUS CLOUDS ARE VISIBLE S OF 27N. A W TO SWLY UPPER LEVEL JET OF 70 TO 90 KT ON THE SRN SIDE OF A DEEP TROUGH ORIGINATING IN ERN CANADA CONTINUES TO ADVECT VERY DRY MID TO UPPER LEVEL AIR ACROSS THE GULF...ESPECIALLY ACROSS THE ERN PORTION AND FLORIDA. THE SFC RIDGE WILL SLIDE EASTWARD OVER THE NEXT COUPLE OF DAYS TURNING WINDS TO THE E AND SE ACROSS THE AREA. THIS LOW-LEVEL FLOW WILL MOISTEN UP THE AIR SLIGHTLY BUT FAIR WEATHER IS EXPECTED TO CONTINUE ACROSS MOST OF THE GULF OVER THE NEXT FEW DAYS. THE CARIBBEAN SEA... THERE ARE A FEW AREAS OF ORGANIZED CONVECTION IN THE CARIBBEAN TRIGGERED BY SEVERAL FEATURES. THE MOST IMPRESSIVE AREA IS IN THE CENTRAL CARIBBEAN WHERE SCATTERED MODERATE CONVECTION IS FROM 14N-19N BETWEEN 68W-74W...WHICH INCLUDES THE ISLAND OF HISPANIOLA. THIS ACTIVITY IS BEING TRIGGERED BY A WELL DEFINED TROPICAL WAVE ALONG 72W...WITH SOME ENHANCEMENT FROM UPPER DIFFLUENT FLOW BETWEEN A WEAK UPPER LOW NEAR THE CAYMAN ISLANDS AND LARGE SCALE RIDGING IN THE ATLC. FOR MORE DETAILS REFER TO THE TROPICAL WAVES SECTION. AREAS OF UNSETTLED WEATHER ALSO EXISTS IN THE WRN CARIBBEAN WHERE THE TAIL END OF A WRN ATLC FRONTAL BOUNDARY IS STATIONARY FROM CENTRAL CUBA TO TO THE NRN COAST OF HONDURAS. THIS PART OF THE BOUNDARY IS STARTING TO BECOME STRETCHED OUT AND POSSIBLY BEING PUSHED SLIGHTLY W BY THE EASTERLY TRADES E OF THE BOUNDARY. LOW-LEVEL CONVERGENCE NEAR THE FRONT AND UPPER DIFFLUENT FLOW...BETWEEN UPPER RIDGING ACROSS CENTRAL AMERICA AND THE PRONOUNCED UPPER TROUGHING EXTENDING S FROM THE U.S. EAST COAST...IS PRODUCING CLUSTERS OF SHOWERS AND TSTMS WITHIN 180 NM OF THE SFC FRONT. CLUSTERS OF SCATTERED MODERATE CONVECTION ALSO EXISTS IN THE SW CARIB S OF 14N W OF 74W. THIS ACTIVITY IS ALSO BEING ENHANCED BY UPPER DIFFLUENT FLOW AS DESCRIBED ABOVE...AND LOW-LEVEL LIFT FROM A TROPICAL WAVE ALONG 80W AND THE ITCZ. SOME OF THESE TSTMS ARE AFFECTING PARTS OF COSTA RICA AND PANAMA LIKELY PRODUCING LOCALLY HEAVY RAINS. THE LAST AREA OF ORGANIZED CONVECTION IS IN THE SE CARIB S OF 12N E OF 65W...ASSOCIATED WITH THE ITCZ AND ENHANCED BY UPPER DIFFLUENT AIR JUST SW OF THE STRONG ATLC RIDGE. THE ATLANTIC OCEAN... A RATHER STRONG COLD FRONT IS OVER THE W ATLC EXTENDING ALONG 32N68W 28N72W THROUGH THE BAHAMAS AND CUBA. THE NUMEROUS MODERATE CONVECTION LOCATED E OF THE FRONT EARLIER HAS BEEN DECREASING OVER THE PAST FEW HOURS TO SCATTERED SHOWERS AND TSTMS NOW WITHIN 240 NM E OF THE FRONT. BEHIND THE FRONT ...STRONG W/SWLY UPPER LEVEL WINDS ARE ADVECTING VERY DRY AIR ALOFT INTO THE WRN ATLC. SFC HIGH PRES IS ALSO BUILDING IN TIGHTENING THE PRES GRAD WHICH IS PRODUCING GUSTY SW FLOW E OF THE FRONT. A MUCH STRONGER GRADIENT IS WELL N OF THE AREA OFF THE MID ATLANTIC/NORTHEAST COAST. A LARGE AMPLIFIED MID/UPPER LEVEL RIDGE EXTENDS E OF THE BOUNDARY CENTERED NEAR 26N56W AND COVERS THE REGION BETWEEN 40W AND 65W. A SMALL ANTICYCLONE CENTERED OVER THE SE BAHAMAS IS EXTENDING THE RIDGE WESTWARD IN THE SW ATLC. DRY STABLE AIR ALOFT IS ASSOCIATED WITH THIS RIDGE. E OF THE RIDGE...AN UPPER LOW HAS BECOME CUT OFF FROM THE SHARP TROUGH WITH ITS CYCLONIC CIRCULATION COVERING THE AREA BETWEEN 25W AND 40W MAINLY N OF 25N. AN ASSOCIATED COLD FRONT EXTENDS FROM 32N31W 27N36W 25N44W THEN STATIONARY TO 25N52W. ONLY ISOLATED SHOWERS ARE WITHIN 120 NM S OF THE BOUNDARY E OF 38W. WITH NO SHOWERS NOTED W OF 38W NEAR THE BOUNDARY AS SUBSIDENCE IS LIKELY SUPPRESSING IT. MUCH OF THE E ATLC N OF 15N BETWEEN AFRICA AND 40W IS ALSO IN A DRY/STABLE ENVIRONMENT WITH SCATTERED STRATOCUMULUS CLOUDS. A BROAD UPPER LOW IS SPINNING JUST N OF THE CANARY ISLANDS WITH AN ASSOCIATED WEAK 1011 MB SURFACE LOW NEAR THE WRN CANARIES AT 28N19W. AN ELONGATED UPPER TROUGH WHICH EXTENDS WSW THROUGH THE DEEP TROPICS IS SHEARING THE HIGH CLOUDS FROM THE ITCZ CONVECTION TO THE E/NE. $$ CANGIALOSI