000 AXNT20 KNHC 112301 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI AUG 11 2006 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...WEATHER OBSERVATIONS...RADAR... AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2300 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG THE W COAST OF AFRICA ALONG 15W S OF 21N MOVING W NEAR 10 KT. THIS WAVE HAS A FAIR AMOUNT OF SIGNATURE EVIDENT ON SATELLITE IMAGERY AND IS GENERATING SMALL CLUSTERS OF MODERATE CONVECTION FROM 12N-17N BETWEEN 13W-19W. EVEN THOUGH THIS WAVE HAS NOT YET PULLED OFF THE CONTINENT THERE IS GOOD CONFIDENCE IN THIS ANALYZED POSITION BASED UPON THE AVAILABLE SFC DATA AND SATELLITE IMAGERY WHICH SHOWS A CLASSIC WAVE STRUCTURE. IN ADDITION...GLOBAL MODELS HAVE THIS WAVE INITIALIZED WELL AND TRACK IT OFFSHORE TONIGHT EVENTUALLY PICKING UP FORWARD SPEED AS IT MOVES UNDER A LOW-MID LEVEL RIDGE. A TROPICAL WAVE IS ALONG 48W/49W S OF 19N MOVING W NEAR 15 KT. THIS WAVE REMAIN WELL DEFINED AND FAIRLY HIGH AMPLITUDE WITH A LOW-MID LEVEL SWIRL EVIDENT ON THE AXIS NEAR 13N. THIS WAVE HAS BEEN EMBEDDED IN A VERY DRY ENVIRONMENT OVER THE PAST FEW DAYS SUPPRESSING ANY SIGNIFICANT CONVECTION. THERE WAS A LITTLE MORE WEATHER ASSOCIATED WITH IT THIS AFTERNOON BEFORE FALLING APART THIS EVENING. SCATTERED SHOWERS ARE MAINLY AHEAD OF THE WAVE AXIS FROM 11N-14N BETWEEN 49W-55W. A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 72W S OF 21N MOVING W 15-20 KT. THIS WAVE LOOKS A LITTLE MORE ACTIVE TODAY THAN IT WAS YESTERDAY PRODUCING SCATTERED MODERATE CONVECTION FROM 15N-18N BETWEEN 70W-73W. THE STRUCTURE OF THIS WAVE HAS ALSO IMPROVED SLIGHTLY WITH SOME LOW-MID LEVEL CYCLONIC TURNING EVIDENT NEAR THE WAVE AXIS. UPPER LEVEL WINDS DO NOT APPEAR FAVORABLE FOR FURTHER DEVELOPMENT AS AN UPPER LOW IS LOCATED 300 NM TO THE NE OF THE WAVE AND WILL BE MOVING WWARD IN TANDEM. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 13N17W 9N32W 12N47W TO INLAND OVER S AMERICA NEAR 10N62W TO PANAMA NEAR 9N81W. BESIDES FOR THE TROPICAL WAVES...SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 60 NM OF THE AXIS E OF 27W. A PATCH OF SCATTERED SHOWERS AND TSTMS ARE FROM 7N-11N BETWEEN 36W-41W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 240 NM OF THE AXIS W OF 71W EXTENDING ACROSS N COLOMBIA AND PANAMA INTO THE E PACIFIC. ...DISCUSSION... GULF OF MEXICO... QUIET WEATHER PERSISTS ACROSS THE CENTRAL AND EASTERN GULF OF MEXICO UNDER THE INFLUENCE OF BROAD UPPER RIDGING WHICH EXTENDS ACROSS THE SRN U.S. WITH ONE ANTICYCLONE CENTERED OFF THE FL/GA COAST NEAR 31N80W. PLENTY OF DRY/STABLE AIR COVERS THE REGION E OF 90W SUPPRESSING ANY ORGANIZED CLOUDINESS OR SHOWERS. THE ONLY AREA OF SOME ACTIVITY IS IN THE W GULF ASSOCIATED WITH AN UPPER LEVEL LOW WHICH IS CURRENTLY ALONG THE TEXAS/MEXICO BORDER NEAR 26N97W. THIS UPPER LOW HAS BEEN BECOMING INCREASINGLY LESS ACTIVE AS IT TRACKED ACROSS THE GULF NOW WITH ONLY ISOLATED TO SCATTERED SHOWERS SPIRALING AROUND IT W OF 93W FROM 23N-28N. A PATCH OF MODERATE CONVECTION IS MOVING OFF THE YUCATAN PENINSULA INTO THE BAY OF CAMPECHE FROM 18N-20N BETWEEN 89W-92W. AT THE SURFACE...WEAK HIGH PRES RIDGING IS LOCKED INTO THE REGION STRETCHING FROM THE ATLC ACROSS THE GULF. MODELS ANTICIPATE THIS SFC PATTERN TO CHANGE LITTLE THIS WEEKEND KEEPING CONDITIONS FAIRLY TRANQUIL. THE NEXT CHANCE OF ANY ORGANIZED MOISTURE WILL BE LATE THIS WEEKEND INTO EARLY NEXT WEEK AS THE TAIL END OF A FRONTAL BOUNDARY DIPS SWD ACROSS THE NE GULF AND AS THE CENTRAL CARIBBEAN WAVE APPROACHES THE SRN PORTION OF THE AREA. CARIBBEAN SEA... THE MAIN FEATURE IN THE AREA IS A TROPICAL WAVE IN THE CENTRAL CARIBBEAN. THIS WAVE SHOWED SOME SIGNS OF ORGANIZING ON WED BEFORE BECOMING VERY SHEARED AND ILL-DEFINED ON THU. TODAY...THE WAVE IS SLIGHTLY MORE ACTIVE THAN YESTERDAY TRIGGERING SCATTERED MODERATE CONVECTION FROM 15N-20N BETWEEN 70W-74W. SEE TROPICAL WAVES SECTION FOR MORE DETAILS. SCATTERED MODERATE CONVECTION IS OVER PORTIONS OF CENTRAL AMERICA FROM 11N-16N BETWEEN 84W-87W AND OVER THE YUCATAN PENINSULA FROM 18N-20N BETWEEN 89W-92W. SCATTERED MODERATE TO STRONG CONVECTION LIES OVER PORTIONS OF COLOMBIA...PANAMA AND SRN COSTA RICA LIKELY CONTRIBUTED TO THE ITCZ. TRADES ARE GENERALLY IN THE 15-25 KT RANGE ACROSS THE AREA WITH STRONGEST WINDS BETWEEN THE COASTS OF VENEZUELA/COLOMBIA TO HISPANIOLA WHERE THE PRES GRAD IS THE TIGHTEST. IN THE UPPER LEVELS...AN ILL-DEFINED UPPER HIGH IS CENTERED IN THE W CARIBBEAN NEAR 17N87W. AN UPPER LOW IS LOCATED TO THE N OF THE MONA PASSAGE NEAR 21N68W WITH ITS TROF DIPPING TO 14N70W. THE REMAINDER OF THE REGION HAS E-NE UPPER LEVEL FLOW WITH PLENTY OF DRY/STABLE AIR. ATLANTIC OCEAN... A VERY BROAD UPPER RIDGE EXTENDS ACROSS THE SRN U.S. STRETCHING OUT TO 62W. UPPER DIFFLUENCE BETWEEN THIS RIDGE AND A STRONG UPPER TROUGH TO ITS N AND ITS ASSOCIATED SFC FRONT IS PRODUCING SCATTERED SHOWERS AND TSTMS N OF 29N W OF 62W. A NEARLY STATIONARY 1014 MB LOW IS LOCATED NEAR 33N35W WITH A SFC TROUGH DRAPING SWARD FROM THE LOW TO 30N35W THEN SWWARD TO 27N39W. THIS LOW IS EMBEDDED IN A VERY DRY ENVIRONMENT ONLY PRODUCING A FEW SHOWERS WITHIN 150 NM OF THE CENTER. ANOTHER UPPER LOW IS LOCATED TO THE N OF THE MONA PASSAGE NEAR 21N67W. THIS LOW IS ALSO A RATHER DRY FEATURE PRODUCING VERY LITTLE WEATHER. MUCH OF THE E AND CENTRAL ATLC IS COVERED BY AN UPPER RIDGE WITH MODERATE TO STRONG SUBSIDENCE ABOVE THE MAJORITY OF THE AREA LIMITING ANY ORGANIZED CLOUDINESS OR SHOWER ACTIVITY. AT THE SFC...HIGH PRES RIDGING CONTINUES TO BE THE THEME WITH THE SFC RIDGE AXIS EXTENDING FROM A 1020 MB HIGH IN THE E ATLC NEAR 28N30W TO A 1018 MB HIGH IN THE CENTRAL ATLC NEAR 24N54W STRETCHING ACROSS SOUTH/CENTRAL FLORIDA. $$ CANGIALOSI