000 AXNT20 KNHC 250537 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SAT AUG 25 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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 0515 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 23W S OF 16N MOVING W 10 KT. WHILE SATELLITE IMAGERY DOES NOT SHOW MUCH ORGANIZATION OR STRUCTURE TO THIS FEATURE THE UW-CIMSS TPW PRODUCT DEPICTS A PRONOUNCED AREA OF MOIST AIR...COMPARED TO THE SURROUNDINGS...ASSOCIATED WITH THIS WAVE. AN EARLIER QSCAT PASS AND OBS FROM THE CAPE VERDE ISLANDS INDICATE LITTLE ASSOCIATION AT THE SFC BUT...THE LOW TO MID LEVEL SATELLITE WINDS SHOW AN ELONGATED GYRE TYPE FEATURE. SHOWER ACTIVITY IS ISOLATED IN NATURE FROM 9N-13N E OF 25W. TROPICAL WAVE IS ALONG 49W/50W S OF 15N MOVING W 10 KT. THIS WAVE APPEARS TO HAVE BECOME A LITTLE BETTER ORGANIZED WITH LOW LEVEL TURNING APPARENT ON NIGHT CHANNEL VIS IMAGES...THOUGH STILL WELL EMBEDDED IN THE ITCZ. SCATTERED SHOWERS AND TSTMS ARE CONFINED TO THE INTERSECTION OF THE ITCZ FROM 8N-11N WITHIN 180 NM EITHER SIDE OF THE WAVE AXIS. TROPICAL WAVE IS IN THE W CARIBBEAN ALONG 80W S OF 18N MOVING W 20 KT OVER THE PAST 24 HRS. IR IMAGES SHOWS A BIT OF CURVATURE TO THE TSTM ACTIVITY NEAR THE BASE OF THE WAVE EMBEDDED WITHIN THE ITCZ S OF 11N BETWEEN 77W-83W. OTHERWISE...LITTLE SIGNATURE OR SHOWER ACTIVITY IS APPARENT IN THE AVAILABLE DATA ACROSS THE REMAINDER OF THE AXIS. THE NRN PORTION OF A HIGH AMPLITUDE TROPICAL WAVE EXTENDS INTO THE S GULF ALONG 88W/89W S OF 24N MOVING W 15 KT. LOW-LEVEL LIFT ASSOCIATED WITH THIS WAVE AND DIFFLUENCE ALOFT IS GENERATING SCATTERED TSTM ACTIVITY OVER THE YUCATAN PENINSULA AND WEAKENING SHOWERS ACROSS THE SE GULF. SHIP/BUOY DATA INDICATE SOME SFC TURNING AND SLIGHTLY LOWER PRESSURES NEAR THIS WAVE. FOR MORE DETAILS REFER TO THE GULF OF MEXICO SECTION BELOW. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 8N28W 9N46W 10N62W. BESIDES FOR THE ACTIVITY DISCUSSED ABOVE...THE ITCZ IS RATHER LINEAR WITH NO SIGNIFICANT CONVECTION. DISCUSSION... GULF OF MEXICO... A WELL DEFINED UPPER LOW IS CENTERED ACROSS THE MID GULF NEAR 26N88W. INSTABILITY ASSOCIATED WITH THIS UPPER CIRCULATION AND S-SWLY FLOW ALOFT E OF THE CENTER IS ADVECTING MOISTURE ACROSS THE E GULF AND FLORIDA. CURRENTLY...LIGHTNING DATA SHOWS MOST OF THE TSTM ACTIVITY OVER THE E GULF WATERS FROM 26N-30N BETWEEN 84W-86W. SHOWERS/TSTMS ARE MORE ISOLATED IN NATURE IN THE S CENTRAL GULF LIKELY ENHANCED SOME BY A TROPICAL WAVE IN THE REGION. CONVECTION HAS REALLY FIRED UP OVER THE WRN HALF OF THE YUCATAN AND IN THE S BAY OF CAMPECHE. DIFFLUENCE ALOFT APPEARS TO BE THE PRIMARY TRIGGER THOUGH NO DOUBT THERE IS INFLUENCE FROM THE NEARBY TROPICAL WAVE AND SMALLER SCALE FLOWS. THE SFC PATTERN IS VERY TRANQUIL WITH WEAK RIDGING FROM THE ATLC STRETCHING JUST N OF THE AREA. THIS IS KEEPING E TO SELY SFC FLOW ON THE LIGHT SIDE. CARIBBEAN SEA... MOST OF THE CARIB IS FAIRLY QUIET THIS EARLY MORNING THOUGH THERE ARE A FEW AREAS EXPERIENCING SOME UNSETTLED WEATHER. THE MOST ACTIVE IS IN THE SW CARIB WHERE A TROPICAL WAVE IS ENHANING ITCZ RELATED CONVECTION...SEE ABOVE FOR DETAILS. ELSEWHERE MUCH OF THE SENSIBLE WEATHER/MOISTURE APPEARS RELATED TO FEATURES ALOFT. THE MID AND UPPER PATTERN CONSISTS OF A N-S STRETCHED HIGH PRES RIDGE CENTERED OVER CENTRAL CUBA AND ELONGATED TROUGH EXTENDING FROM THE ATLC ACROSS THE NRN LEEWARDS TOWARD THE COAST OF COLOMBIA. STRONG N TO NELY FLOW BETWEEN THESE FEATURES HAS BLOWN OFF EVENING TSTM ACTIVITY OVER E CUBA AND HISPANIOLA INTO THE COASTAL WATERS TO NEAR JAMAICA. LIGHTNING DATA IS DETECTING SOME FLASHES ESPECIALLY IN THE CLUSTER S OF HISPANIOLA. MUCH OF THE REMAINDER OF THE CENTRAL CARIB LIES IN AN UPPER CONFLUENT ZONE HELPING TO SINK AND SUPPRESS DEEP CLOUD COVER. HIGH LEVEL CLOUDINESS LIES OVER THE E CARIB ON THE RETURN SIDE OF THE TROUGH AND OVER THE W CARIB LOCKED WITHIN THE RIDGE. ATLANTIC OCEAN... THE SFC PATTERN ACROSS THE ATLC DISCUSSION AREA REMAINS WEAK THIS EVENING. THIS WEAK PATTERN IS MAINLY DUE TO AN UNUSUAL (FOR AUGUST) COLD FRONT DEEP INTO THE SUBTROPICS ENTERING THE AREA NEAR 32N41W TO A 1012 MB LOW NEAR 28N52W CONTINUING ALONG 25N58W 32N66W. A RECENT QSCAT PASS DEPICTED THIS BOUNDARY WELL...MARKING IT AS A PRONOUNCED NLY WIND SHIFT AND INCREASE TO 20 KT N OF IT NEAR THE LOW. SATELLITE IMAGERY ALSO SHOWS SCATTERED SHOWERS WITHIN 60 NM AHEAD OF THE BOUNDARY AND A SCATTERED STABLE STRATOCUMULUS DECK BEHIND IT. THIS LOW-LATITUDE FRONT HAS GREATLY BROKEN UP THE TYPICAL SUBTROPICAL RIDGING ALLOWING TRADES TO BE FAIRLY LIGHT ACROSS THE BULK OF THE AREA. IN THE MID AND UPPER LEVELS...A RIDGE IS OVER THE W ATLC CENTERED VERY NEAR BERMUDA. A DIFFLUENT PATTERN LIES AT THE W EDGE OF THE RIDGE ASSOCIATED WITH SOME TROUGHING OVER THE BAHAMAS AND IN THE GULF OF MEX. THIS DIFFLUENCE IS PRODUCING A FAIR AMOUNT OF CLOUDINESS ACROSS THE AREA W OF 76W. A LARGER SCALE TROUGH...THE SUPPORT FOR THE FRONT DISCUSSED ABOVE...IS OVER THE CENTRAL ATLC EXTENDING FROM 32N46W TO AN UPPER LOW NEAR 22N57W CONTINUING INTO THE E CARIB. A DOMINATING WELL DEFINED RIDGE TAKES OVER IN THE E ATLC WITH THE MAIN ANTICYCLONE CENTERED NEAR 18N35W. OUTSIDE OF THE AREAS OUTLINED IN THE ABOVE PARAGRAPH...DRY AIR ALOFT IS WIDESPREAD ON WATER VAPOR IMAGERY. $$ CANGIALOSI