000 AXNT20 KNHC 260534 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT SUN AUG 26 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 27W/28W S OF 19N MOVING W 10-15 KT. THIS WAVE REMAINS POORLY ORGANIZED WITH ISOLATED SHOWERS AND TSTMS CONFINED NEAR THE INTERSECTION OF THE ITCZ FROM 9N-13N WITHIN 120 NM OF THE WAVE AXIS. ALTHOUGH THE SATELLITE PRESENTATION IS UNIMPRESSIVE THE UW-CIMSS TPW ANIMATION DEPICTS A PRONOUNCED AREA OF HIGHER MOISTURE ASSOCIATED WITH THIS FEATURE. THIS ANIMATION ALSO SHOWS THE MOISTURE SURGE FLATTENING IN STRUCTURE OVER TIME POSSIBLY DUE TO A SAHARAN DUST SURGE. TROPICAL WAVE IS ALONG 52W S OF 15N MOVING W 10 KT. THIS SYSTEM HAS GENERALLY CHANGED LITTLE SINCE YESTERDAY WITH LOW LEVEL TURNING CLEARLY APPARENT ON NIGHT CHANNEL VIS IMAGES...THOUGH STILL WELL EMBEDDED IN THE ITCZ. AN EARLIER QSCAT PASS DID INDICATE SLIGHT CYCLONIC TURNING ABOUT THE WAVE AXIS THOUGH NOT AS DEFINED AS IN THE LOW-LEVEL CLOUD DRIFT WINDS...SUGGESTING MUCH OF THE PRESENCE IS JUST ABOVE THE SFC. WHILE LOW-LEVEL TURNING HAS BEEN PERSISTING SHOWER ACTIVITY IS VERY LIMITED NEAR THIS WEAK WAVE. TROPICAL WAVE IS IN THE W CARIBBEAN AND OVER CENTRAL AMERICA ALONG 84W S OF 20N MOVING W 10-15 KT OVER THE PAST 24 HRS. THIS WAVE IS DIFFICULT TO LOCATE WITH THE POSITION BASED ON FORWARD EXTRAPOLATION WHICH MATCHES UP WITH A BIT OF CURVATURE EVIDENT IN SFC OBS AND ISOLATED SHOWER ACTIVITY WITHIN 60 NM OF THE AXIS. THE NRN PORTION OF A HIGH AMPLITUDE TROPICAL WAVE EXTENDS INTO THE BAY OF CAMPECHE FROM 25N93W THRU 19N96W MOVING W 10-15 KT. AN ASSOCIATED AREA OF LOW PRES...ANALYZED 1008 MB NEAR 21N95W...FORMED EARLIER TODAY. THIS LOW HAS GENERALLY BECOME LESS DEFINED WITH ONLY A SMALL CLUSTER OF CONVECTION NEAR IT. NO FURTHER DEVELOPMENT IS EXPECTED. THE WAVE STILL SHOWS UP FAIRLY WELL IN BUOY DATA AND THE INTERACTION WITH AN UPPER LOW IS PRODUCING SCATTERED SHOWERS AND TSTMS ACROSS A PORTION OF THE S GULF...SEE DISCUSSION BELOW FOR MORE DETAILS. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 8N33W 11N49W 9N62W. BESIDES FOR THE CONVECTION DISCUSSED IN THE TROPICAL WAVES SECTION ...SCATTERED MODERATE IS WITHIN 60 NM OF THE AXIS BETWEEN 41W-44W. SIMILAR ACTIVITY IS FROM 11N-14N E OF 18W LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE. DISCUSSION... GULF OF MEXICO... A CONSIDERABLE AMOUNT OF MOISTURE REMAINS IN THE GULF THIS EARLY MORNING. THERE ARE SEVERAL FEATURES CONTRIBUTING TO THIS MOISTENED ENVIRONMENT. STARTING IN THE MID AND UPPER LEVELS...A WELL DEFINED SLOW MOVING UPPER LOW IS CENTERED ACROSS THE MID GULF NEAR 27N90W. UPPER RIDGING LOCATED BOTH E AND W OF THIS UPPER LOW IS PRODUCING AN OVERALL DIFFLUENT PATTERN WHICH HAS GENERALLY PRODUCED WIDESPREAD HIGH LEVEL CLOUDINESS ACROSS THE AREA. DEEP MOISTURE IS CONFINED TO THE S GULF WHERE UPPER DIFFLUENCE IS A BIT MORE CONCENTRATED AND THE AIR IS LIFTED BY A TROPICAL WAVE AND WEAK AREA OF LOW PRES. DISORGANIZED SCATTERED SHOWERS AND TSTMS ARE S OF 25N BETWEEN 86W AND 96W. SCATTERED STRONG CONVECTION IS OVER S MEXICO ASSOCIATED WITH A HIGHLY PERTURBED ITCZ WHICH APPEARS TO BE INLAND ACROSS THAT AREA. THE REMAINDER OF THE SFC PATTERN IS VERY TRANQUIL DUE TO A WEAK AREA OF HIGH PRES CENTERED OVER THE NE GULF. THIS IS KEEPING WINDS VERY LIGHT ACROSS THE E AND CENTRAL GULF. LITTLE CHANGE IN THE WEAK SFC PATTERN IS EXPECTED OVER THE NEXT COUPLE OF DAYS SO WINDS ARE ANTICIPATED TO REMAIN MOSTLY LIGHT. ALSO A DRIER AIRMASS WILL LIKELY PUSH ACROSS THE AREA FROM E TO W AS A MID-LEVEL RIDGE BUILDS OVERHEAD. CARIBBEAN SEA... THERE ARE A FEW SCATTERED PATCHES OF CONVECTION ACROSS THIS BASIN...BUT NONE OF THESE SHOW ANY ORGANIZATION. THE MOST PERSISTENT ACTIVITY IS ASSOCIATED WITH THE ITCZ ACROSS COLOMBIA AND THE SW CARIB S OF 13N W OF 72W. ELSEWHERE MUCH OF THE SENSIBLE WEATHER/MOISTURE APPEARS RELATED TO FEATURES ALOFT. THE MAIN FEATURE IS AN INVERTED MID TO UPPER LEVEL TROUGH WHICH EXTENDS FROM N COLOMBIA TOWARD HISPANIOLA. STRONG NLY FLOW BETWEEN THIS TROUGH AND RIDGING FURTHER W HAS BLOWN OFF LAST EVENING'S TSTM ACTIVITY OVER CUBA AND SPREAD DEBRIS CLOUDINESS ACROSS MUCH OF THE NW CARIB. NEARLY ALL OF THE LEFTOVER SHOWERS ARE DIMINISHING EXCEPT FOR THE AREA OVER HAITI WHICH ACTUALLY LOOKS LIKE IT'S EXPANDING AS IT ROUNDS THE INVERTED TROUGH. MUCH OF THE REMAINDER OF THE AREA IS RELATIVELY QUIET THOUGH ISOLATED TO SCATTERED TRADE WIND SHOWERS CAN OCCUR JUST ABOUT ANYWHERE AS INDICATED BY SAN JUAN'S 88-D. THE TRADE WIND FLOW IS FAIRLY RELAXED...AN EARLIER QSCAT PASS ONLY SHOWED A SMALL AREA NEAR 20 KT. ATLANTIC OCEAN... THE SFC PATTERN ACROSS THE ATLC DISCUSSION AREA REMAINS WEAK THIS MORNING. THIS WEAK PATTERN IS MAINLY DUE TO AN UNUSUAL (FOR AUGUST) FRONT DEEP INTO THE SUBTROPICS ENTERING THE AREA NEAR 32N38W TO A 1012 MB LOW NEAR 27N52W THEN DISSIPATING ALONG 24N57W 29N69W. CURRENT SATELLITE IMAGERY SHOWS THE FRONT AND WEAK LOW BECOMING INCREASING DIFFUSE WITH ONLY ISOLATED SHOWERS WITHIN 60 NM OF THE BOUNDARY. QSCAT STILL DEPICTS A PRONOUNCED WIND SHIFT...THOUGH SPEEDS HAVE DECREASED SINCE YESTERDAY. THE LARGER SCALE EFFECT OF THIS FRONT IS THE DISRUPTION IN THE TYPICAL SUBTROPICAL RIDGING WHICH HAS ALLOWED WINDS TO BE FAIRLY LIGHT ACROSS THE BULK OF THE AREA. IN THE MID AND UPPER LEVELS...A RIDGE IS OVER THE W ATLC COVERING THE AREA W OF 62W. 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 78W. A LARGER SCALE TROUGH...THE SUPPORT FOR THE FRONT DISCUSSED ABOVE...IS OVER THE CENTRAL ATLC EXTENDING FROM A LARGE FALL-TYPE LOW NEAR 42N44W INTO THE AREA ALONG 32N50W TO AN UPPER LOW NEAR 24N57W CONTINUING TOWARD THE NRN LEEWARD ISLANDS. A DOMINATING WELL DEFINED RIDGE TAKES OVER IN THE E ATLC WITH THE MAIN ANTICYCLONE CENTERED NEAR 22N41W. OUTSIDE OF THE SMALL AREAS OUTLINED...DRY AIR ALOFT IS WIDESPREAD ON WATER VAPOR IMAGERY SUPPRESSING SIGNIFICANT SHOWER ACTIVITY. $$ CANGIALOSI