000 AXNT20 KNHC 090605 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0545 UTC. ...SPECIAL FEATURE... A LARGE 1000 MB NON-TROPICAL LOW PRESSURE SYSTEM...CENTERED NEAR 31N78.5W...OR ABOUT 150 NM EAST OF JACKSONVILLE FLORIDA AND ABOUT 140 NM SOUTH-SOUTHEAST OF CHARLESTON SOUTH CAROLINA...HAS BEEN MOVING SLOWLY WESTWARD AT 5 TO 10 MPH. THIS SYSTEM IS PRODUCING GALE FORCE CONDITIONS WITH SHIP AND BUOY OBSERVATIONS AND A RECENT QUIKSCAT PASS SHOWING MAX WINDS IN THE 35-45 KT RANGE. THESE WINDS ARE PRODUCING HIGH SEAS AND HEAVY SURF ALONG THE SOUTHEAST U.S. COAST AND THE BAHAMAS. MODERATE NW SWELL IS ALSO PROPAGATING WELL AWAY FROM THE STORM...WITH THE NEW 41043 BUOY NORTH OF PUERTO RICO SHOWING STEADILY INCREASING LONGER PERIOD SWELL OVER THE LAST SEVERAL HOURS. WAVES WILL SLOWLY SUBSIDE FROM W TO E OVER THE NEXT COUPLE OF DAYS. THE SYSTEM HAS CHANGED LITTLE SINCE THIS EVENING...AND NO SIGNIFICANT STRENGTHENING IS EXPECTED. THE LOW IS BEING MONITORED FOR SIGNS OF TROPICAL OR SUBTROPICAL CYCLONE DEVELOPMENT...AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT IS SCHEDULE TO INVESTIGATE THE SYSTEM TOMORROW MORNING. PLEASE REFER TO THE HIGH SEAS FORECASTS AND STATEMENTS FROM LOCAL WEATHER SERVICE OFFICES FOR MORE DETAILS. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N13W 6N20W 3N30W 2N40W 2N50W. NUMEROUS MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90NM EITHER SIDE OF THE AXIS BETWEEN 21W-36W. SIMILAR CONVECTION...POSSIBLY ASSOCIATED WITH A LOW AMPLITUDE TROPICAL WAVE...IS S OF 4N BETWEEN 36W-43W. ...DISCUSSION... GULF OF MEXICO... THE SPECIAL FEATURE DISCUSSED ABOVE IS PRODUCING ABUNDANT SUBSIDENCE AND ADVECTING DRIER AND COOLER AIR ACROSS THE CENTRAL AND 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 5-15 KT FROM THE N TO NW IN THE ERN GULF AROUND THE SPECIAL FEATURE. THESE WINDS VEER MORE E TO SE THE WRN GULF AROUND A HIGH PRES CENTER FORMING JUST OFF THE LOUISIANA COAST. SEAS ARE MOSTLY IN THE 2-4 FT RANGE...EXCEPT IN THE 5-7 FT RANGE S OF 28N W OF 90W DUE TO A MORE FAVORABLE FETCH S OF HIGH PRES. WINDS AND SEAS EXPECTED TO GRADUALLY 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 5-15 KT RANGE. THE TRADES INCREASE TO 15-20 KT IN THE E CARIB AS RIDGING FROM THE AZORES HIGH HAS TIGTHENED 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. DIFFLUENCE ALOFT/WEAK LOW LEVEL CONFLUENCE IS HELPING TO SUPPORT THE SCATTERED TSTMS NOTED JUST S OF HISPANIOLA. WESTERN ATLANTIC... THE LARGE LOW PRES SYSTEM CONTINUES TO BE THE HIGHLIGHT. THE ASSOCIATED FRONTAL BOUNDARIES CONTINUE TO DISSIPATE...THOUGH NUMEROUS TSTMS ARE NOTED NEAR THE OLD BOUNDARY N OF 27N BETWEEN 67W-73W. SIMILAR ACTIVITY IS OVER THE SE BAHAMAS/N OF HISPANIOLA FROM 20N-25N BETWEEN 68W-76W. 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 61W. CENTRAL AND EASTERN ATLANTIC... A 1029 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-52W ASSOCIATED WITH A PREFRONTAL TROUGH. AN UPPER LOW NEAR MADEIRA ISLAND IS ONLY GENERATING SCATTERED PATCHES OF CIRRUS. $$ WILLIS