000 AXNT20 KNHC 212313 CCA TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI JUL 21 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... AN EASTERN ATLANTIC TROPICAL WAVE IS RELOCATED APPROXIMATELY 120 NM TO THE EAST OF THE PREVIOUS POSITION BASED UPON LOW LEVEL TURNING ON SHORTWAVE IR IMAGES. THE WAVE IS CURRENTLY ALONG 29W/30W SOUTH OF 19N. A LOW LEVEL SWIRL IS LOCATED ALONG THE WAVE NEAR 15N. THIS POSITION IS ALSO IN A REASONABLE LOCATION BASED UPON A FORWARD MOTION OF 15 KT OVER THE PAST 24 HOURS. THE TROPICAL WAVE HAS FAIR STRUCTURE WITH MUCH OF THE SCATTERED SHOWERS AND TSTMS EMBEDDED WITHIN THE ITCZ...THEREFORE IT WILL BE DISCUSSED IN THAT SECTION. A TROPICAL WAVE IS ALONG 48W S OF 18N MOVING WEST NEAR 15 KT. LOW LEVEL CURVATURE IS RATHER WEAK YET DEFINED ON VIS SATELLITE PICTURES. THIS WAVE CONTINUES TO LACK ANY DEEP CONVECTION OR ORGANIZED SHOWERS AND APPEARS TO BE THE LEADING EDGE OF A LARGE DENSE AREA OF SAHARAN DUST BASED UPON UW-CIMMS SAHARAN AIR LAYER ANALYSIS AND THE HAZY LOOK ON THE LAST FEW VIS IMAGES THIS EVENING. A TROPICAL WAVE IS ALONG 62W S OF 20N MOVING WEST NEAR 15 KT. A VERY FAINT INVERTED V-PATTERN IS EVIDENT ON SATELLITE IMAGERY CONSISTING OF MAINLY LOW-MID LEVEL CLOUDS WITH ISOLATED SHOWERS. NO DEEP CONVECTION IS ASSOCIATED WITH THIS WAVE. A TROPICAL WAVE IS ALONG 90W S OF 21N MOVING WEST NEAR 15 KT. THIS WAVE IS TRIGGERING SCATTERED MODERATE CONVECTION ACROSS S MEXICO AND MANY COUNTRIES IN CENTRAL AMERICA. THE WAVE IS RATHER EASY TO LOCATE WITH THE AXIS ALONG THE LEADING EDGE OF MODERATE CONVECTION ACROSS THE YUCATAN PENINSULA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 15N17W 9N28W 4N40W 3N50W. THE ITCZ IS A LITTLE MORE ACTIVE TODAY THAN THE PAST FEW DAYS WITH SCATTERED MODERATE CONVECTION LOCATED WITHIN 180 NM EITHER SIDE OF THE AXIS BETWEEN 20W-26W. SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM TO THE NORTH OF THE AXIS BETWEEN 29W-42W. ...DISCUSSION... GULF OF MEXICO... A BROAD UPPER RIDGE REMAINS IN PLACE ACROSS THE SOUTH CENTRAL U.S. COVERING THE NW GULF. AN UPPER TROUGH EXTENDS FROM THE EXTRA-TROPICAL CYCLONE BERYL IN THE NW ATLANTIC SOUTHWARD OFF THE EAST COAST OF THE U.S. ACROSS CENTRAL FLORIDA TO THE EASTERN GULF. AN UPPER LEVEL LOW HAS BECOME BETTER DEFINED TODAY AT THE BASE OF THE NARROW TROUGH CENTERED NEAR 26N86W. BUOYS/QUIKSCAT INDICATES SOME SURFACE REFLECTION WITH CYCLONIC TURNING OF WINDS EVIDENT. AS OF 2100 UTC...THE SURFACE TROUGH WAS ANALYZED FROM LAKE OCKEECHOBEE FLORIDA TO 25N86W. THIS UPPER LEVEL PATTERN IS PRODUCING NUMEROUS SHOWERS AND TSTMS E OF 86W ACROSS FLORIDA AND THE BAHAMAS BETWEEN 22N-26N. IN THE CENTRAL/WEST GULF...ISOLATED MODERATE CONVECTION HAS DEVELOPED ON THE WEST SIDE OF THE TROUGH AXIS SOUTH OF THE LOUISIANA COAST THROUGH 25N. SCATTERED MODERATE/ISOLATED STRONG CONVECTION PERSISTS IN THE BAY OF CAMPECHE TRIGGERED BY THE TROPICAL WAVE ACROSS THE YUCATAN AND DUE TO AN UPPER RIDGE EXTENDING WEST THROUGH S MEXICO. WEAK SFC PRES GRADIENT IS PRODUCING LIGHT WINDS ACROSS THE AREA. MODELS KEEP A FAIR AMOUNT OF MOISTURE IN THE GULF THIS WEEKEND...ALTHOUGH IT DOES NOT APPEAR TO BE AS UNSETTLED AS TODAY IN THE E GULF. A COLD FRONT MAY DIG AS FAR SOUTH AS THE N GULF ON SUN. CARIBBEAN SEA... A TROPICAL WAVE ACROSS THE YUCATAN PENINSULA INTERACTING WITH A BROAD UPPER RIDGE EXTENDING FROM S MEXICO INTO THE W CARIBBEAN AND AN UPPER LOW IN THE SE GULF IS PRODUCING SCATTERED MODERATE CONVECTION OVER THE NW CARIBBEAN W OF 83W. AN UPPER TROUGH COVERS THE REMAINDER OF THE CARIBBEAN WITH MODERATE SUBSIDENCE ACCOMPANYING THE TROUGH. FAIR WEATHER COVERS THE REMAINDER OF THE CARIBBEAN E OF 83W EXCEPT FOR SCATTERED SHOWERS AND TSTMS OVER THE LANDMASSES OF PUERTO RICO...HISPANIOLA AND CUBA ENHANCED BY LOCAL SEA-BREEZES AND TOPOGRAPHIC LIFT AND A NARROW BAND OF SHOWERS NORTH OF THE ABC ISLANDS DRIVEN BY SOUTHERLY UPPER LEVEL WINDS. THE TROPICAL WAVE IN THE LESSER ANTILLES IS CAUSING VERY LITTLE SHOWER ACTIVITY AS IT IS EMBEDDED IN A DRY/STABLE ENVIRONMENT. TRADE WINDS ARE MODERATE TODAY AND THEY WILL LIKELY REMAIN THAT WAY TOMORROW. AN INCREASE IN WIND SPEEDS ARE EXPECTED LATE THIS WEEKEND AND MONDAY. ATLANTIC OCEAN... THE MAIN FEATURE IN THE WESTERN ATLANTIC IS AN UPPER TROUGH WHICH EXTENDS FROM THE EXTRA-TROPICAL CYCLONE BERYL TO AN UPPER LOW NEAR 34N70W TO CENTRAL FLORIDA. UPPER DIFFLUENCE ON THE MOIST EAST SIDE OF THE TROUGH AXIS IS GENERATING AN ABUNDANT AMOUNT OF MOISTURE W OF 65W. NUMEROUS SHOWERS AND TSTMS ARE SPREAD OUT ACROSS SOUTH FLORIDA AND THE W BAHAMAS BECOMING MORE SCATTERED FURTHER EAST OUT TO 69W. AN ILL-DEFINED SFC TROUGH IS ALONG 66W FROM 23N-36N. THIS TROUGH MARKS AS A VERY PRONOUNCED MOISTURE BOUNDARY WITH STRONG SUBSIDENCE WIDESPREAD TO IT'S EAST. THE REMAINDER OF THE ATLANTIC...E OF 65W...IS UNDER BROAD UPPER RIDGING. THERE IS AN UPPER LOW EMBEDDED IN THIS AREA NEAR 28N46W GENERATING A FEW SHOWERS TO THE EAST OF THE ITS CENTER BUT FAIR WEATHER IS THE DOMINATE THEME. THE LEADING EDGE OF DENSE SAHARAN DUST HAS PROGRESSED TO NEAR 50W. $$ CANGIALOSI