000 AXNT20 KNHC 102333 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI AUG 10 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 27W/28W S OF 17N MOVING W 5-10 KT. SURROUNDING SOUNDING DATA AND MODEL FIELDS INDICATE THAT THIS WEAK FEATURE HAS BEEN EMBEDDED IN VERY LIGHT STEERING OVER THE PAST 24 HOURS. IT IS EXPECTED TO SPEED UP SHORTLY AS AN ELY JET SETS UP IN THIS REGION. CURRENT SATELLITE IMAGES SHOW LITTLE WAVE SIGNATURE...SO THE CURRENT PSN IS BASED ON SLOW FORWARD EXTRAPOLATION WHICH AGREES WELL WITH A NEARLY STATIONARY MOISTURE BUMP SEEN IN THE UW-CIMSS TPW LOOP. TROPICAL WAVE IS ALONG 44W S OF 14N MOVING W 10-15 KT. THIS LOW AMPLITUDE WAVE REMAINS WEAK CAUSING A VERY SLIGHT PERTURBATION IN THE ITCZ. ONLY ISOLATED SHOWERS ARE ASSOCIATED WITH THIS FEATURE. HIGHER AMPLITUDE TROPICAL WAVE IS ALONG 65W S OF 21N MOVING W NEAR 15 KT. THIS WAVE WAS ONE OF THE MORE OBVIOUS SYSTEMS TO TRACK SO FAR THIS SEASON...ALBEIT IT REMAINED DEVOID OF SIGNIFICANT CONVECTION. TODAY IT IS LESS DEFINED AS IT HAS MOVED INTO A REGION WITH CONSIDERABLE MOISTURE PRODUCED BY SEVERAL FEATURES. UPPER AIR TIME SECTION PLOTS INDICATE THAT THE WAVE PASSED BARBADOS ABOUT 18 HOURS AGO. IN ADDITION...THE UW-CIMSS TPW PRODUCT CONTINUES TO A SHOW A NARROW WWD MOVING SURGE OF HIGHER PW. SHOWERS AND TSTMS ARE MOST ORGANIZED TO THE W OF THE WAVE AXIS...WHICH IS LIKELY MORE RELATED TO UPPER DIFFLUENCE. TROPICAL WAVE IS ALONG 75W S OF 19N MOVING W NEAR 15 KT. THIS WAVE HAS BEEN CHALLENGING TO TRACK OVER THE PAST COUPLE OF DAYS. THE UPPER PATTERN ALONG WITH THIS WAVE AND OTHER LOW-LEVEL FEATURES HAVE PRODUCED A LARGE DISORGANIZED AREA OF SHOWERS AND TSTMS ACROSS MUCH OF THE NRN HALF OF THE CARIB SEA...ESPECIALLY BETWEEN 65W-80W. REFER TO THE CARIB SECTION BELOW FOR DETAILS. BASED ON CURRENT IMAGERY...IS IT DIFFICULT TO TELL HOW MUCH OF THIS ACTIVITY IS ASSOCIATED WITH THE WAVE ITSELF. THE UW-CIMSS TPW PRODUCT DOES SHOW AN ENHANCED WWD MOVING MOISTURE SURGE IN AN ALREADY HIGH TPW ENVIRONMENT. THIS IS MAIN SOURCE USED TO TRACK THIS FEATURE. TROPICAL WAVE IS OVER CENTRAL AMERICA ALONG 90W S OF 20N MOVING W 10-15 KT. THIS WAVE LIES UNDERNEATH AN UPPER LOW WHICH IS HELPING TO GENERATE SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 90 NM OF THE AXIS. LITTLE LOW-LEVEL TURNING OR WAVE-TYPE SIGNATURE IS EVIDENT OVER CENTRAL AMERICA...BUT SLIGHT TURNING HAS DEVELOPED NEAR THE SRN EXTENSION OF THE WAVE OVER THE EPAC WATERS. FOR MORE INFO REFER TO THE PACIFIC TWD...MIATWDEP. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 11N15W 11N27W 10N42W 12N61W. SCATTERED MODERATE TO STRONG CONVECTION IS NEAR AND OVER W AFRICA FROM 9N-13N E OF 18W...ASSOCIATED WITH A LARGE TROPICAL WAVE MAKING ITS WAY TO THE COAST. SCATTERED MODERATE IS WITHIN 150 NM S OF THE AXIS BETWEEN 20W-23W AND WITHIN 90 NM EITHER SIDE W OF 49W. DISCUSSION... GULF OF MEXICO... COMBINATION OF A STRONG UPPER HIGH OVER THE SRN U.S. AND AN UPPER LOW ABOVE THE ERN BAY OF CAMPECHE CONTINUES TO PRODUCE STRONG UPPER E TO NE FLOW ACROSS THE GULF. THE ATMOSPHERE HERE IS SLIGHTLY MORE MOIST THAN IT WAS OVER THE PAST FEW DAYS... THOUGH FAIR CONDITIONS STILL COVER THE BULK OF THE AREA. LEFTOVER SHOWERS...FROM EARLIER CONVECTIVE ACTIVITY...IS OVER THE NW GULF N OF 28N BETWEEN 91W-94W. SIMILAR ISOLATED SHOWER ACTIVITY IS OVER THE BAY OF CAMPECHE CAUSED BY INSTABILITY NEAR THE UPPER LOW AND A NEARBY TROPICAL WAVE. ISOLATED TO SCATTERED SHOWERS AND TSTMS ARE ALSO OVER THE SE GULF...S FLORIDA AND CUBA TRIGGERED BY A SFC TROUGH WHICH EXTENDS NWD FROM THE CARIB ACROSS W CUBA INTO SW FLORIDA. THE SFC PATTERN REMAINS WEAK WITH A QUASI-STATIONARY 1016 MB HIGH CENTER NEAR 28N93W. THIS WEAK PRES GRAD IS EXPECTED TO CONTINUE FOR A FEW MORE DAYS ALLOWING WINDS AND SEAS TO REMAIN LIGHT/LOW. THE NEXT MOISTURE SURGE LOOKS TO MOVE INTO THE SE GULF LATE THIS WEEKEND/EARLY NEXT WEEK. CARIBBEAN SEA... A CONSIDERABLE AMOUNT OF MOISTURE REMAINS OVER THE CARIB THIS EVENING. THE DIFFLUENT UPPER PATTERN ENHANCING THIS MOISTURE CONSISTS OF AN UPPER LOW IN THE BAY OF CAMPECHE...TWO UPPER HIGHS NEAR 18N81W AND 14N65W AND ANOTHER UPPER LOW NEAR THE CENTRAL BAHAMAS BAHAMAS. WITHIN THIS MOIST UPPER ENVIRONMENT THERE ARE THREE TROPICAL WAVES AND A SFC TROUGH HELPING TO PROVIDE EVEN MORE LIFT. AS MENTIONED IN THE TROPICAL WAVES SECTION...IT IS DIFFICULT TO DETERMINE WHICH WAVE IS GENERATING WHAT ACTIVITY. CURRENTLY...A LARGE AREA OF DISORGANIZED SCATTERED SHOWERS AND TSTMS ARE AFFECTING THE NRN HALF OF THE CARIB N OF 16N BETWEEN 67W-83W. THE ACTIVITY IS STRONGEST NEAR AND OVER THE ISLANDS OF HISPANIOLA...CUBA AND JAMAICA WHERE SEABREEZE AND TOPOGRAPHIC LIFTS ARE LIKELY PLAYING A ROLE. CONVECTION IS ALSO MAKING ITS WAY TOWARD THE SRN WINDWARDS AS A WEAK IMPULSE ALONG THE ITCZ MOVES INTO THE AREA. ATLANTIC OCEAN... HIGH LEVEL CLOUDINESS AND EMBEDDED POCKETS OF DEEPER MOISTURE LIE ABOVE A PORTION OF THE SW ATLC S OF 25N BETWEEN 60W-75W. THIS IS MOSTLY ASSOCIATED WITH DIFFLUENCE ALOFT BETWEEN AN UPPER LOW NEAR THE CENTRAL BAHAMAS AND AN UPPER HIGH OVER THE E CARIB. A HIGH LEVEL CIRRUS DECK ALSO COVERS THE AREA N OF 27N BETWEEN 55W-67W AS MOISTURE ROUNDS THE WRN EDGE OF AN UPPER HIGH CENTERED OFF THE MID-ATLANTIC COAST. THE UPPER PATTERN THEN FOLDS INTO A LARGE SCALE HIGHLY ELONGATED TROUGH EXTENDING SW ALONG 32N33W 24N52W 17N55W. RIDGING TAKES OVER E OF THERE STRETCHING W FROM AN ANTICYCLONE OVER AFRICA ALONG 23N7W 22N22W 20N45W. THERE IS LITTLE MOISTURE ASSOCIATED WITH EITHER THE RIDGE OR TROUGH. IN FACT...THESE UPPER FEATURES ARE ENHANCING ABUNDANT DRY AIR ALOFT E OF 50W ALLOWING FAIR WEATHER TO DOMINATE. AT THE SFC...THE MAIN FEATURE IS A STATIONARY 1026 MB HIGH CENTERED NEAR 37N34W. THIS HIGH IS PRODUCING LIGHT TO MODERATE TRADES ACROSS THE BULK OF THE ATLC DISCUSSION AREA. A QSCAT PASS NEAR 1930Z SHOWS A SMALL AREA OF SLIGHTLY STRONGER WINDS NEAR THE COAST OF NW AFRICA...BUT THESE WINDS ARE MUCH WEAKER THAN THE PAST FEW DAYS. EARLIER VIS IMAGERY AND THE CIMSS SAL ANALYSIS SHOWS A LARGE MODEST AREA OF SAHARAN DUST BEHIND THE TROPICAL WAVE IN THE E CARIB. THIS STABLE LOW-MID LEVEL AIR IS PROMOTING THE WIDESPREAD FAIR CONDITIONS. $$ CANGIALOSI