000 AXNT20 KNHC 271808 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT THU JUL 27 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1730 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 20W/21W S OF 20N MOVING W 15 TO 20 KT. VISIBLE IMAGERY REVEALS SOME MOSTLY MID LEVEL CYCLONIC TURNING ASSOCIATED WITH THIS WAVE. SCATTERED MODERATE CONVECTION LIES FROM 7 TO 13N BETWEEN 18 AND 25W WHICH IS MOSTLY ASSOCIATED WITH THE NEAR EQUATORIAL TROF ALONG THE ITCZ. A HIGH AMPLITUDE TROPICAL WAVE IS ALONG 47W S OF 22N MOVING WEST NEAR 15 KT. THIS LARGE WAVE REMAINS WELL DEFINED WITH CLEAR LOW-MID LEVEL TURNING EVIDENT WITH AN INVERTED V PATTERN ON SATELLITE IMAGERY. THE WAVE IS STILL ENHANCING CONVECTION EMBEDDED WITHIN THE ITCZ FROM 7N TO 15N BETWEEN 43W-53W...BUT HAS DIMINISHED IN BOTH COVERAGE AND INTENSITY SINCE THE OVERNIGHT HOURS TO JUST ISOLATED MODERATE. CONVECTIVE ACTIVITY MAY PULSE AGAIN THIS EVENING...ESP THE SOUTHERN PORTION...AS CLOUD TOPS COOL WITH ENHANCED OUTGOING RADIATION. THE NORTHERN EXTENSION OF THE WAVE HAS LIMITED SHOWER ACTIVITY AS IT REMAINS EMBEDDED IN A DRY/STABLE ENVIRONMENT LIKELY DUE TO SAHARAN DUST. A HIGH AMPLITUDE TROPICAL WAVE IS IN THE EASTERN CARIBBEAN ALONG 68W SOUTH OF 23N MOVING WEST NEAR 15 KT. THIS WAVE HAS BEEN WELL-DEFINED OVER THE PAST SEVERAL DAYS. SHOWER AND TSTM ACTIVITY HAS PERSISTED ALONG THE NORTHERN PORTION OF THIS WAVE TODAY...WITH IR IMAGERY SHOWING SCATTERED MODERATE CONVECTION FROM 18N TO 24N AND BETWEEN 63W AND 72W. THIS WILL CONTINUE PUSHING WEST THROUGH NORTHERN HISPANIOLA...THE TURKS AND CAICOS ISLANDS...BAHAMAS...AND POSSIBLY PARTS OF FLORIDA AS WE MOVE INTO THE WEEKEND. HOWEVER...THIS SYSTEM IS NOT EXPECTED TO DEVELOP INTO A TROPICAL CYCLONE AS IT ENCOUNTERS UNFAVORABLE UPPER LEVEL WINDS AS IT INTERACTS WITH AN UPPER TROF TO ITS NW. A TROPICAL WAVE IN THE WESTERN CARIBBEAN IS ALONG 84W/85W SOUTH OF 19N MOVING WEST NEAR 15 KT. LOW CLOUD MOTIONS IN VISIBLE SATELLITE IMAGERY THIS AFTERNOON SHOWS SOME BROAD/WEAK CURVATURE ASSOCIATED WITH THIS WAVE...BUT OVERALL THE WAVE REMAINS DIFFICULT TO DISCERN. A SMALL PATCH OF MODERATE CONVECTION LIES EAST OF THIS WAVE OFF THE CARIBBEAN COAST OF NICARAGUA. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 11N14W 9N40W 10N63W THROUGH NORTHERN VENEZUELA AND COLOMBIA TO NEAR 9N82W NEAR PANAMA. SCATTERED MODERATE CONVECTION LIES FROM 7N TO 13N BETWEEN 18W AND 25W THROUGH THE TROPICAL WAVE ALONG 21W. SCATTERED MODERATE CONVECTION ALSO LIES WEST OF THIS WAVE FROM 5N TO 11N BETWEEN 26W AND 33W. A SMALL PATCH OF MODERATE CONVECTION NORTH OF THE AXIS IS JUST EAST OF TRINIDAD AND TOBAGO. ...DISCUSSION... GULF OF MEXICO... THE GULF OF MEXICO IS NOW VOID OF SIGNIFICANT CONVECTION...WITH THE SURFACE LOW THAT AFFECTED THE WESTERN GULF EARLIER IN THE WEEK WELL NORTH/INLAND OF THE AREA AND DISSIPATING. THE WESTERN EXTENSION OF AN ATLANTIC 500MB ANTICYCLONE COVERS MUCH OF THE GULF THIS AFTERNOON. MOISTURE/WEAK LOW LEVEL CONVERGENCE BETWEEN THE WESTERN PORTION OF THE ATLANTIC SFC HIGH WITH A WEAK SFC HIGH NEAR ATLANTA GA IS PRODUCING A SMALL PATCH OF MODERATE CONVECTION NEAR LAKE OKEECHOBEE AT 27/17Z. THE ANTICYCLONIC TRACK OF THESE CLOUDS WILL PUSH WHATEVER IS LEFT INTO THE SW GULF THIS EVENING. SFC WINDS AND SEAS IN THE EASTERN GULF REMAIN LIGHT/LOW RESPECTIVELY WITH A LITTLE STRONGER SFC PRESSURE GRADIENT...S/SE FLOW AND WIND WAVES IN THE WESTERN GULF. SIMILAR CONDITIONS EXPECTED THROUGH FRI. CARIBBEAN SEA... TWO TROPICAL WAVES REMAIN IN THE CARIBBEAN SEA WITH THE WAVE ALONG 68W THE MOST DEFINED AND CONVECTIVELY ACTIVE...AS IT INTERACTS WITH AN UPPER LOW IN THE ATLC WATERS TO ITS NW. THIS IS DISCUSSED IN DETAIL ABOVE IN THE TROPICAL WAVES SECTION. A WEAK UPPER LOW IS NOTED IN WATER VAPOR IMAGERY THIS AFTERNOON IN THE NW CARIBBEAN CENTERED NEAR 18N87W...WITH WEAK UPPER RIDGING NOTED IN THE CENTRAL AND WESTERN CARIBBEAN SEA. THE SOUTHERN PORTION OF THE BERMUDA HIGH CONTINUES TO EXTEND INTO THE CARIBBEAN...WITH TRADE FLOW GENERALLY BETWEEN 10 AND 20 KT. ATLANTIC OCEAN... LARGE SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE NORTH/CENTRAL ATLANTIC...WITH A COL REGION FOUND BETWEEN THIS HIGH AND THE UPPER HIGH EXTENDING WEST FROM AFRICA NEAR 26N20W. AN UPPER TROF JUST OFF THE SE/MIDATLANTIC EAST COAST ALONG WITH SOME WEAK SFC CONVERGENCE IS GENERATING A BAND OF SCATTERED MODERATE CONVECTION EXTENDING NE FROM PALM BEACH COUNTY INTO THE ADJACENT ATLANTIC WATERS. ANOTHER UPPER LOW IS LOCATED JUST EAST OF THE BAHAMAS NEAR 26N67W...AIDING THE TROPICAL WAVE ALONG 67W IN ITS CONVECTION DEVELOPMENT. ANOTHER WEAK LOW/MID LEVEL CYCLONIC SWIRL OF LOW/MID CLOUDS IS NOTED NEAR 29N36W. AT THE SURFACE...A 1030MB SURFACE HIGH IS CENTERED NEAR 34N52W WITH TRADE FLOW ROTATING LOW CLOUDS ANTICYCLONICALLY AROUND THE TROPICAL ATLANTIC WATERS TO ITS SOUTH. A WIDESPREAD AREA OF DENSE SAHARAN DUST EXTENDS OUT TO ABOUT 65W...BEHIND THE E CARIBBEAN TROPICAL WAVE. $$ WILLIS