000 AXNT20 KNHC 222311 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 22 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 ALONG 33W SOUTH OF 20N MOVING WEST 10-15 KT. A 1013 MB LOW IS ALONG THE WAVE NEAR 15N. THIS AREA OF LOW PRES IS CLEARLY DEFINED ON SATELLITE IMAGERY AND IN THE SURROUNDING SHIPS/BUOYS. DESPITE THE WELL DEFINED STRUCTURE OF THE WAVE AND LOW...A WIDESPREAD AREA OF SAHARAN DUST IS SUPPRESSING ANY SIGNIFICANT SHOWER ACTIVITY. ONLY SCATTERED SHOWERS ARE SURROUNDING THESE FEATURES EMBEDDED IN THE ITCZ. THIS WAVE WILL LIKELY INCREASE IN FORWARD SPEED OVER THE NEXT COUPLE OF DAYS AS IT TRACKS UNDER THE STRONG LOW-LEVEL RIDGE. A TROPICAL WAVE IS ALONG 53W S OF 17N MOVING WEST NEAR 15 KT. THIS WAVE HAS LOST MUCH OF ITS IDENTITY OVER THE PAST FEW DAYS...WITH VERY LITTLE SIGNATURE NOTED ON SATELLITE IMAGERY. A TROPICAL WAVE IS IN THE CARIBBEAN ALONG 67W S OF 20N MOVING WEST NEAR 15 KT. SIMILARLY TO THE WAVE TO ITS EAST...THIS WAVE IS ALSO VERY WEAK WITH ONLY A HINT OF SOME WAVE STRUCTURE. LIMITED MOISTURE IS ASSOCIATED WITH THE WAVE...BUT IT MAY BE INFLUENCING...ALONG WITH LOCAL EFFECTS...SCATTERED SHOWERS AND TSTMS ACROSS THE VIRGIN ISLANDS...PUERTO RICO AND HISPANIOLA. A TROPICAL WAVE IS ALONG 95W S OF 21N MOVING W 10-15 KT OVER THE PAST 24 HOURS. THIS WAVE IN PART IS GENERATING A WIDE AREA OF SHOWERS AND THUNDERSTORMS ACROSS S MEXICO AND THE BAY OF CAMPECHE...NAMELY S OF 24N BETWEEN 88W-98W. CURRENTLY THIS AREA APPEARS UNFAVORABLE FOR ANY SIGNIFICANT DEVELOPMENT. THIS WAVE HAS BEGUN TO SLOW IN FORWARD SPEED AS THE STEERING CURRENTS ARE RATHER WEAK. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 13N14W 15N28W 9N41W 8N52W TO INLAND OVER SOUTH AMERICA NEAR 7N58W. SCATTERED SHOWERS AND ISOLATED TSTMS ARE WITHIN 240 NM EITHER SIDE OF THE AXIS E OF OF 39W ENHANCED BY THE TROPICAL WAVE AND SFC LOW ALONG 33W. SMALL CLUSTERS OF SCATTERED SHOWERS AND TSTMS ARE WITHIN 180 NM TO THE SOUTH OF THE AXIS BETWEEN 42W-52W. ...DISCUSSION... GULF OF MEXICO... THERE ARE A FEW AREAS OF UNSETTLED WEATHER IN THE GULF OF MEXICO THIS EVENING. THE MAIN FEATURE IS AN UPPER LEVEL LOW IN THE CENTRAL GULF CENTERED NEAR 26N88W. THIS UPPER LOW HAS AN ILL-DEFINED SFC REFLECTION AS A TROUGH ALONG 26N FROM SOUTH FLORIDA TO 86W. A NARROW UPPER HIGH IS CENTERED TO THE SOUTHEAST OF THE UPPER LOW BETWEEN CUBA AND THE SW BAHAMAS. THIS UPPER LEVEL PATTERN AND WEAK SFC BOUNDARY IS PRODUCING A CONSIDERABLE AMOUNT OF MOISTURE ACROSS THE EASTERN GULF E OF 87W S OF 28N. UPPER DIFFLUENCE APPEARS TO BE THE STRONGEST ACROSS SOUTH FLORIDA AND THE BAHAMAS WHERE THERE ARE NUMEROUS SHOWERS AND TSTMS. HOWEVER THIS ACTIVITY APPEARS TO BE WEAKENING OVER THE PAST FEW HOURS. SIMILAR WEATHER IS OCCURRING IN THE BAY OF CAMPECHE ASSOCIATED WITH A SLOW MOVING TROPICAL WAVE AIDED BY UPPER DIFFLUENCE BETWEEN THE UPPER LOW IN THE CENTRAL GULF AND A UPPER RIDGE OVER S MEXICO. THE THIRD AREA OF UNSETTLED WEATHER IS ALONG THE GULF COAST AND COASTAL WATERS MOSTLY N OF 28N ASSOCIATED WITH A COLD FRONT JUST N OF THE AREA. THE COLD FRONT MAY SAG SLOWLY SOUTHWARD INTO THE N GULF WHILE WEAKENING TONIGHT AND TOMORROW. MODELS KEEP A FAIR AMOUNT OF MOISTURE IN THE REGION OVER THE NEXT COUPLE OF DAYS. CARIBBEAN SEA... SCATTERED MODERATE CONVECTION IS OVER PARTS OF NORTHERN CENTRAL AMERICA AND S MEXICO GENERATED BY A TROPICAL WAVE IN THE BAY OF CAMPECHE AND UPPER DIFFLUENCE. SIMILAR WEATHER IS OCCURRING OVER NORTHERN S AMERICA...PANAMA AND COSTA RICA HIGHLY CONTRIBUTED TO THE ITCZ. SCATTERED SHOWERS AND TSTMS HAVE ALSO BLOSSOMED OVER CUBA ENHANCED BY LOCAL EFFECTS. MUCH OF THE CENTRAL AND EASTERN CARIBBEAN IS QUIET WITH AN UPPER TROUGH COVERING THIS REGION. DRY/STABLE AIR ACCOMPANIES THE TROUGH. THIS STABLE AIR IS SUPPRESSING ANY SIGNIFICANT CONVECTION FROM FORMING WITH ONLY SMALL ISOLATED SHOWERS E OF 75W. A WEAK TROPICAL WAVE IS ALONG 67W INDUCING ONLY A FEW SHOWERS OVER PUERTO RICO...HISPANIOLA AND THE VIRGIN ISLANDS. TRADE WINDS HAVE INCREASED SLIGHTLY TODAY TO NEAR 20-25 KT IN SPOTS. THESE WINDS ARE LIKELY TO INCREASE FURTHER TOMORROW WITH GALE FORCE WINDS EXPECTED SUNDAY NIGHT. LITTLE CHANGES IN MOISTURE ARE EXPECTED TOMORROW. ATLANTIC OCEAN... UPPER DIFFLUENCE BETWEEN AN UPPER RIDGE OVER CUBA AND THE BAHAMAS...AN UPPER LOW OVER THE GULF AND AN UPPER LOW W OF BERMUDA IS PRODUCING AN ABUNDANT AMOUNT OF MOISTURE IN THE W ATLC. A LARGE AREA OF SCATTERED SHOWERS AND TSTMS EXTENDS FROM 24N-32N W OF 67W. A BROAD UPPER RIDGE COVERS THE REMAINDER OF THE ATLC EXTENDING FROM AN UPPER HIGH LOCATED OVER WEST AFRICA. THERE IS A SHARP MOISTURE CONTRAST NEAR 66W-68W WITH MODERATE TO STRONG SUBSIDENCE TO THE EAST OF THIS LINE. A WEAK BENIGN CUT OFF UPPER LOW IS 250 NM N OF PUERTO RICO ENHANCING ISOLATED SHOWERS. AT THE SURFACE...A BROAD RIDGE DOMINATES THE ATLC GIVING THE AREA MODERATE ELY WINDS AND MOSTLY FAIR WEATHER. ACCORDING TO THE 22/2100 UTC SAHARAN AIR LAYER FROM UW-CIMSS...A LARGE AREA OF DENSE AFRICAN DUST EXTENDS TO THE LESSER ANTILLES. THE LEADING EDGE OF THE SAHARAN DUST APPEARS TO BE BEHIND THE CARIBBEAN TROPICAL WAVE LIMITING ANY SIGNIFICANT CONVECTION FROM DEVELOPING. $$ CANGIALOSI