000 AXNT20 KNHC 220518 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT TUE AUG 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0415 UTC. ...SPECIAL FEATURE... TROPICAL DEPRESSION FOUR IS CENTERED NEAR 12.2N 23.2W 0R ABOUT 170 NM SOUTH-SOUTHEAST OF THE SOUTHERN MOST CAPE VERDE ISLANDS AT 22/0300 UTC MOVING WNW AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1007 MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. SEE LATEST NHC FORECAST/ADVISORY UNDER HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. LARGE WELL-ORGANIZED SYSTEM IN SPITE OF THE LOSE OF CONVECTION SURROUNDING THE CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM OF THE CENTER IN THE NW QUADRANT. LARGER AREA OF SIMILAR CONVECTION IS FROM 7N-11N BETWEEN 21W-27W. ANOTHER WAVE OF AFRICAN DUST IS N OF THE T.D WHICH USUALLY HAMPERS CONVECTION. SLOW DEVELOPMENT IS FORECASTED AS THE SYSTEM MOVES INTO A MORE FAVORABLE ENVIRONMENT. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 42W/43W S OF 19N MOVING W 15-20 KT. BROAD MID LEVEL ROTATION REMAINS ON INFRARED SATELLITE IMAGERY ALONG THE ITCZ. CONVECTION IS CONFINED TO WITHIN THE ITCZ AREA. TROPICAL WAVE IS ALONG 58W S OF 19N MOVING W NEAR 15-20 KT. INVERTED-V CURVATURE PREVIOUSLY OBSERVED ON INFRARED SATELLITE IMAGERY IS BECOMING LESS WELL-DEFINED AS THE WAVE APPROACHES THE LESSER ANTILLES. CONVECTION IS CONFINED TO WITHIN THE ITCZ AREA. TROPICAL WAVE IN THE CARIBBEAN IS ALONG 75W S OF 19N MOVING W 15 KT. DESPITE THE WAVE BEING BENEATH AN UPPER RIDGE LOW LEVEL INVERTED-V CURVATURE IS OBSERVED ON INFRARED SATELLITE IMAGERY. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 17N-19N BETWEEN 72W-77W. TROPICAL WAVE OVER CENTRAL AMERICA IS NO LONGER EFFECTING THE ATLC BASIN. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N16W 10N29W 8N48W 10N55W 9N62W ACROSS THE N PORTION OF SOUTH AMERICA AND PANAMA INTO THE E PACIFIC REGION. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 6N-14N BETWEEN 40W-60W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER RIDGE ANCHORED OVER THE CENTRAL MISSISSIPPI VALLEY EXTENDS OVER THE N GULF N OF 28N. AN UPPER TROUGH EXTENDS FROM AN UPPER LOW INLAND OVER CENTRAL MEXICO INTO THE GULF NEAR TAMPICO TO THE COAST OF FLORIDA NEAR NAPLES PROVIDING ENOUGH DIFFLUENCE OVER THE S GULF TO GENERATE CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER MOST OF THE GULF EXCEPT THE N GULF COAST FROM THE FLORIDA PENINSULA THROUGH TEXAS CLEAR MOSTLY CLEAR SKIES PREVAIL. A WEAK SURFACE TROUGH EXTENDS FROM NEAR 24N95W INTO THE E BAY OF CAMPECHE AND S MEXICO NEAR CARMEN ISLAND. CARIBBEAN SEA... BROAD UPPER RIDGE EXTENDS OVER THE W CARIBBEAN FROM AN UPPER HIGH IN THE GULF OF HONDURAS NEAR 17N87W ENE ACROSS E CUBA TO THE CENTRAL BAHAMAS IN THE W ATLC. THIS IS PROVIDING ENOUGH DIFFLUENCE OVER W CARIBBEAN TO GENERATE A LARGE AREA OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 17N W OF 76W AND N OF 10N W OF 81W WITH AN AREA OF SCATTERED STRONG CONVECTION WITHIN 90 NM OF LINE FROM NICARAGUA/HONDURAS TIP NEAR 15N83W TO 20N86W AND SCATTERED MODERATE/STRONG CONVECTION WITHIN 60 NM OF 19N FROM 78W-82W. MODERATE/STRONG TRADEWINDS ARE ACROSS THE AREA. ATLANTIC OCEAN... BROAD UPPER LOW REMAINS SE OF BERMUDA NEAR 30N62W COVERING AN AREA N OF 23N FROM 50W-79W. ASSOCIATED SURFACE TROUGH EXTENDS FROM 24N71W-29N66W. HOWEVER...WITH DRY AIR IN PLACE THIS FEATURE IS ONLY ABLE TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS IS SMALL AREAS FROM 24N-27N BETWEEN 73W-78W....24N-27N BETWEEN 63W-70W...AND FROM 26N-28N BETWEEN 55W-58W. THE UPPER RIDGE EXTENDS FROM THE CARIBBEAN ACROSS E CUBA TO THE CENTRAL BAHAMAS NEAR 23N75W IN THE W ATLC. THE REMAINDER OF THE ATLC IS DOMINATED BY MOSTLY BENIGN FEATURES WHICH INCLUDE AN UPPER TROUGH EXTENDING FROM THE E ATLC NEAR 32N19W THROUGH AN UPPER LOW NEAR 29N27W THROUGH A SECOND UPPER LOW NEAR 20N43W TO THE TROPICAL ATLC NEAR 15N59W. DRY AIR REMAINS IN PLACE OVER THE ATLC NO SIGNIFICANT CLOUDS OR SHOWERS ARE ASSOCIATED WITH THESE FEATURES. BROAD SURFACE RIDGE DOMINATES THE ATLC THUS KEEPING THE ITCZ AND ANY DEVELOPING SYSTEMS FAR TO THE SOUTH. SIGNIFICANT AMOUNTS OF AFRICA DUST COVER THE E TROPICAL ATLC FROM THE ITCZ TO 24N FROM 30-60W WITH A SECOND SURGE COVERING THE FAR E ATLC BETWEEN THE CAPE VERDE ISLANDS AND THE AFRICAN COAST. $$ WALLACE