000 AXNT20 KNHC 210506 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT MON AUG 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0415 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 35W/36W S OF 18N MOVING W 15-20 KT. BROAD MID LEVEL ROTATION IS OBSERVED ON INFRARED SATELLITE IMAGERY ALONG THE ITCZ. CONVECTION IS CONFINED TO WITHIN THE ITCZ AREA. TROPICAL WAVE IS ALONG 50W/51W S OF 18N MOVING W NEAR 15-20 KT. WELL DEFINED INVERTED-V CURVATURE IS OBSERVED ON INFRARED SATELLITE IMAGERY. CONVECTION IS WITHIN THE ITCZ AREA. TROPICAL WAVE IN THE E CARIBBEAN IS ALONG 68W/69W S OF 18N MOVING W 10-15 KT. WAVE IS BENEATH AN UPPER RIDGE WHICH IS ENHANCING SCATTERED MODERATE/ISOLATED STRONG CONVECTION OVER THE MONA PASSAGE. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 14N-18N BETWEEN 63W-69W. TROPICAL WAVE IN THE W CARIBBEAN IS ALONG 83W/84W S OF 18N MOVING W 15 KT. WAVE IS BENEATH AN UPPER LOW OVER THE NW CARIBBEAN AND AN UPPER RIDGE OVER THE SW CARIBBEAN MASKING THE CLASSIC SATELLITE SIGNATURE. WAVE IS ALSO EMBEDDED WITHIN A BROAD AREA OF SHOWERS AND THUNDERSTORMS THAT ENCOMPASSES THE ENTIRE W CARIBBEAN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 12N15W 9N31W 9N48W 8N61W ACROSS THE N PORTION OF SOUTH AMERICA AND THE SW CARIBBEAN OVER COSTA RICA INTO THE E PACIFIC REGION. A TROPICAL WAVE IS EMERGING OFF THE COAST OF AFRICA WITH A BROAD MID LEVEL ROTATION OBSERVED ON INFRARED SATELLITE IMAGERY WITH SCATTERED MODERATE TO STRONG CONVECTION COVERING THE AREA FROM 9N-16N E OF 21W TO JUST INLAND OVER AFRICA. CLUSTERS OF SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 200 NM N OF THE ITCZ AXIS FROM 31W-42W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM OF LINE 10N16W-6N24W...FROM 4N-9N BETWEEN 34W-41W...WITHIN 120 NM OF THE ITCZ AXIS FROM 41W-50W...AND FROM 8N-13N BETWEEN 50W-56W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE ANCHORED OVER E TEXAS EXTENDS OVER THE N GULF N OF 27N. AN UPPER TROUGH EXTENDS ACROSS THE S GULF FROM THE SW COAST OF FLORIDA NEAR NAPLES TO AN UPPER LOW NEAR 23N89W TO A SECOND UPPER LOW ALONG THE COAST OF MEXICO JUST S OF TAMPICO AND IS PROVIDING ENOUGH DIFFLUENCE OVER THE S GULF TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE AREA S OF 27N WITH THE STRONGEST THUNDERSTORMS S OF 27W E OF 85W ACROSS FLORIDA AND THROUGH THE FLORIDA STRAITS INTO THE W ATLC. CARIBBEAN SEA... THE UPPER TROUGH IN THE S GULF OF MEXICO EXTENDS INTO THE NW CARIBBEAN N OF 18N W OF 80W. BROAD UPPER RIDGE EXTENDS ACROSS THE S CARIBBEAN FROM N NICARAGUA ALONG 16N75W ACROSS HISPANIOLA INTO THE W ATLC. THIS IS PROVIDING ENOUGH DIFFLUENCE OVER W CARIBBEAN TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF A LINE FROM THE PANAMA/COSTA RICA BORDER NW TO TO THE MONA PASSAGE WITH THE LARGEST CONCENTRATION OF THUNDERSTORMS N OF 16N ACROSS CUBA FROM 75W-80W. SCATTERED STRONG CONVECTION IS INLAND OVER COLOMBIA AND E PANAMA MOVING INTO THE FAR S CARIBBEAN ASSOCIATED WITH THE ITCZ AXIS THAT EXTENDS ALONG 9N ACROSS THAT AREA. MODERATE/STRONG TRADEWINDS ARE ACROSS THE AREA. ATLANTIC OCEAN... SMALL UPPER LOW IS IN THE W ATLC CENTERED NEAR 29N79W AND IS GENERATING THE SCATTERED SHOWERS/THUNDERSTORMS S OF 28N W OF 74W ACROSS FLORIDA INTO THE E GULF OF MEXICO. AN UPPER LOW REMAINS SE OF BERMUDA NEAR 30N60W WITH AN ASSOCIATED SURFACE TROUGH EXTENDING FROM 23N66W-30N63W. HOWEVER...WITH DRY AIR IN PLACE THIS FEATURE IS ONLY ABLE TO GENERATE ISOLATED SHOWERS FROM 20N-26N BETWEEN 60W-66W. THE UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS HISPANIOLA TO NEAR 25N66W IN THE W ATLC. THE REMAINDER OF THE ATLC IS DOMINATED BY MOSTLY BENIGN FEATURES WHICH INCLUDE AN UPPER LOW NEAR 23N42W AND AN UPPER HIGH NEAR 22N28W BUT WITH DRY AIR IN PLACE OVER THE E ATLC NO SIGNIFICANT CLOUDS OR SHOWERS ARE ASSOCIATED WITH THESE FEATURES. A SURFACE RIDGE DOMINATES THE MUCH ATLC WITH THE SURFACE HIGHS N OF THE REGION. SIGNIFICANT AMOUNTS OF AFRICA DUST CONTINUE TO MOVE OFF THE COAST OF W AFRICA TO NEAR 50W. $$ WALLACE