000 AXNT20 KNHC 091044 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 AM EDT WED MAY 09 2007 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1030 UTC. ...SPECIAL FEATURE... A LARGE 1000 MB NON-TROPICAL LOW PRESSURE SYSTEM...CENTERED NEAR 31N79W...OR ABOUT 125 NM EAST OF JACKSONVILLE FLORIDA...HAS BEEN MOVING SLOWLY WESTWARD OVERNIGHT. THIS SYSTEM IS PRODUCING MOSTLY GALE FORCE CONDITIONS ALTHOUGH STORM FORCE WINDS TO 50 KT ARE POSSIBLE UNDER THE DEEPEST CONVECTION. THESE WINDS ARE PRODUCING HIGH SEAS AND HEAVY SURF ALONG THE SOUTHEAST U.S. COAST AND THE BAHAMAS...BUT OVERALL WAVE ACTION HAS SUBSIDED QUITE A BIT OVER THE LAST 24 HOURS. MODERATE NW SWELL IS ALSO PROPAGATING WELL AWAY FROM THE STORM...WITH THE NEW 41043 BUOY NORTH OF PUERTO RICO REGISTERING 5-6 FT LONGER PERIOD SWELL OVER THE LAST SEVERAL HOURS. THUNDERSTORM ACTIVITY HAS BECOME A LITTLE MORE CONSOLIDATED ESPECIALLY NORTH AND EAST OF THE CENTER OVER THE LAST FEW HOURS. THE LOW IS BEING MONITORED FOR SIGNS OF TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT...AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS CURRENTLY INVESTIGATING THE SYSTEM. PLEASE REFER TO THE HIGH SEAS FORECASTS AND STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES FOR MORE DETAILS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 6N20W 3N30W 2N40W 1N50W. SCATTERED MODERATE CONVECTION IS OFF THE COAST OF LIBERIA FROM 5N-7N BETWEEN 12W-15W. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 150NM N AND 210NM S OF THE AXIS BETWEEN 20W-45W. ...DISCUSSION... GULF OF MEXICO... THE SPECIAL FEATURE DISCUSSED ABOVE IS PRODUCING ABUNDANT SUBSIDENCE AND ADVECTING VERY DRY AIR THROUGH THE ERN GULF. SMOKE PLUMES ORIGINATING FROM FIRES IN FLORIDA AND S GEORGIA CONTINUE TO AFFECT THE E/SE GULF AND FLORIDA. THIS HAS BEEN PRODUCING VISIBILITIES OF 3-5 SM AT TIMES IN SOUTH FLORIDA AND THE KEYS. SFC WINDS ARE 5-10 KT FROM THE N TO NW IN THE ERN GULF AROUND THE SPECIAL FEATURE. THESE WINDS VEER MORE E TO SE UP TO 15 KT IN THE WRN GULF AROUND A HIGH PRES CENTER JUST OFF THE LOUISIANA COAST. SEAS ARE MOSTLY IN THE 2-4 FT RANGE...EXCEPT IN THE 5-7 FT RANGE S OF 27N W OF 90W DUE TO A MORE FAVORABLE FETCH S OF HIGH PRES. WINDS AND SEAS EXPECTED TO RELAX FURTHER THROUGH THE SECOND HALF OF THE WORKWEEK AS WEAK HIGH PRES MEANDERS OVER THE NW GULF. AN UPPER HIGH IN THE EPAC S OF MEXICO IS TRANSPORTING UPPER MOISTURE INTO THE WRN GULF. CARIBBEAN SEA... WEAK PRES PATTERN IN THE WRN CARIB CONTINUES TO PRODUCE LIGHT NE WINDS GENERALLY IN THE 5-10 KT RANGE. THE TRADES INCREASE TO 15 KT IN THE E CARIB AS RIDGING FROM THE AZORES HIGH HAS TIGHTENED THE GRADIENT. SIMILAR CONDITIONS EXPECTED AT THE SFC OVER THE NEXT COUPLE OF DAYS. IN THE UPPER LEVELS...A TROUGH/RIDGE PATTERN REMAINS IN PLACE. STRONG SWLY UPPER FLOW BETWEEN THESE FEATURES IS TRANSPORTING A SWATH OF DEBRIS MID TO HIGH LEVEL CLOUDS AND EMBEDDED SHOWERS FROM CONVECTIVE BLOW-UPS ALONG THE ITCZ...WHICH RUNS ACROSS PANAMA AND COLOMBIA...THROUGH THE LEEWARD ISLANDS. MODERATE CONVECTION S OF HISPANIOLA HAS PERSISTED OVER THE LAST FEW HOURS...AIDED BY DIFFLUENCE ALOFT AND WEAK LOW LEVEL CONFLUENCE. WESTERN ATLANTIC... THE LARGE LOW PRES SYSTEM CONTINUES TO BE THE HIGHLIGHT. THE ASSOCIATED FRONTAL BOUNDARIES HAVE BEEN REMOVED FROM THE MAP THOUGH A SFC TROUGH IS ANALYZED ALONG 31N72W 25N71W 18N73W. NUMEROUS TSTMS ARE OVER THE DISCUSSION AREA BETWEEN 66W-75W. IN ADDITION TO THE SFC SUPPORT THIS CONVECTION IS ALSO BEING SUPPORTED BY DISTINCT UPPER DIFFLUENCE BETWEEN THE VERTICALLY STACKED LOW OFF THE SOUTHEAST U.S. AND RIDGING EXTENDING N ALONG 60W. CENTRAL AND EASTERN ATLANTIC... A 1026 MB HIGH JUST W OF PORTUGAL IS IN CONTROL OF THE PATTERN PROVIDING WIDESPREAD FAIR WEATHER AND MODERATE TRADES ACROSS THIS PORTION OF THE ATLC. SAHARAN DUST APPEARS TO HAVE SPREAD TO ABOUT 40W...ALTHOUGH THICKEST E OF 30W. THIS DUST IS ERODING THE TYPICAL STRATOCUMULUS DECK ASSOCIATED WITH THE SUBTROPICAL RIDGE. SCATTERED SHOWERS ARE POSSIBLE N OF 26N BETWEEN 40W-50W ASSOCIATED WITH THE TAIL END OF A FRONTAL TROUGH. AN UPPER LOW NEAR MADEIRA ISLAND IS ONLY GENERATING SCATTERED PATCHES OF CIRRUS. $$ WILLIS