000 AXNT20 KNHC 180500 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 AM EDT WED JUL 18 2007 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 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...METEOROLOGICAL ANALYSIS... WEATHER OBSERVATIONS...AND RADAR. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0415 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS TITLED ALONG 20N26W THROUGH A 1012 MB LOW NEAR 15N28W 6N29W MOVING W NEAR 20 KT. WELL DEFINED CIRCULATION ASSOCIATED WITH THE SURFACE LOW COVERING A BROAD AREA FROM 11N-22N BETWEEN 25W-25W. NO ASSOCIATED DEEP CONVECTION. TROPICAL WAVE IS TILTED ALONG 18N50W 10N54W 3N55W MOVING W 15-20 KT. WAVE IS LESS TILTED THAN 24 HOURS AGO. BROAD WAVE WITH LOW/MID LEVEL INVERTED-V CURVATURE COVERING THE AREA FROM 49W-65W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 8N-15N BETWEEN 49W-59W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS COVER A BROADER AREA S OF 15N FROM 50W-65W INCLUDING THE WINDWARD ISLANDS. TROPICAL WAVE IS ALONG 81W/82W S OF 18N MOVING W NEAR 20 KT. WAVE IS JUST TO THE E OF AN UPPER RIDGE ENHANCING ANY SHOWER/THUNDERSTORMS IN THE AREA. ...THE ITCZ... ITCZ AXIS IS CENTERED ALONG 15N15W 14N26W THEN ALONG 9N30W 6N41W 11N52W 9N62W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF LINE FROM 10N24W TO 7N36W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 5N-10N BETWEEN 39W-50W AND AND WITHIN 90/120 NM ALONG THE COAST OF AFRICA S OF 10N W OF 12W. ...DISCUSSION... GULF OF MEXICO... BROAD UPPER LEVEL LOW IS CENTERED OVER N/CENTRAL MEXICO COVERING TEXAS AND MEXICO N OF 21N. AN UPPER LEVEL RIDGE EXTENDS FROM S MEXICO ACROSS THE BAY OF CAMPECHE AND THE W GULF TO THE N GULF COAST NEAR 31N94W ENHANCING SCATTERED SHOWERS/THUNDERSTORMS S OF 27N W OF 88W AND INDUCING A SURFACE TROUGH THAT EXTENDS ROUGHLY E/W FROM 26N87W TO 24N97W. ANOTHER UPPER RIDGE EXTENDS FROM AN UPPER HIGH OFF THE E COAST OF THE FLORIDA PENINSULA TO OVER THE E GULF ENHANCING SCATTERED SHOWERS/ ISOLATED THUNDERSTORMS OVER S OF 29N E OF 88W. A SURFACE RIDGE CONTINUES TO MAINTAIN ITS HOLD OVER THE GULF EXTENDING ALONG 30N FROM THE W ATLC TO TEXAS. CARIBBEAN SEA... THE UPPER RIDGE OVER THE W GULF OF MEXICO EXTENDS OVER THE FAR W CARIBBEAN W OF 85W. A CUT-OFF UPPER LOW IS CENTERED OVER THE CAYMAN ISLANDS NEAR 19N79W COVERING THE AREA N OF 16N FROM 71W-85W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 21N FROM 80W-86W. AN UPPER RIDGE EXTENDS FROM THE E PACIFIC S OF PANAMA NW OVER CENTRAL AMERICA TO NEAR 16N83W GENERATING SCATTERED SHOWERS/THUNDERSTORMS S OF 20N FROM 81W-85W. WEAK UPPER HIGH IS IN THE W TROPICAL ATLC E OF THE LEEWARD ISLANDS EXTENDING A RIDGE AXIS E ACROSS THE LEEWARD ISLANDS TO 16N70W. DRY STABLE AIR COVERS THE E CARIBBEAN E OF 75W WITH ONLY SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE WINDWARD ISLANDS ASSOCIATED WITH THE APPROACHING TROPICAL WAVE. ATLANTIC OCEAN... AN UPPER HIGH OFF THE E COAST OF THE FLORIDA PENINSULA NEAR DAYTONA BEACH COVERS THE W ATLC N OF 24N W OF 71W. THE CUT-OFF UPPER LOW OVER THE CAYMAN ISLANDS COVERS THE W ATLC S OF 24N W OF 73W GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS S OF 27N W OF 77W ACROSS S FLORIDA INTO THE E GULF OF MEXICO. AN UPPER LOW IS NEAR 28N65W COVERING THE AREA N OF 22N FROM 60W-68W WITH A WEAK SURFACE TROUGH EXTENDING FROM 29N59W TO N OF PUERTO RICO NEAR 20N65W. SCATTERED SHOWERS/THUNDERSTORMS ARE WITHIN 90/120 NM OF LINE FROM 24N60W TO 32N61W. WEAK UPPER HIGH IS IN THE W TROPICAL ATLC E OF THE LEEWARD ISLANDS NEAR 18N61W EXTENDING A RIDGE AXIS E INTO THE CARIBBEAN AND NE TO 30N56W ENHANCING THE ABOVE SHOWER/THUNDERSTORM ACTIVITY. WEAK UPPER TROUGH IS OVER THE N/CENTRAL ATLC N OF 26N BUT THE ASSOCIATED LOW/FRONTAL BOUNDARY IS N OF THE REGION. ANOTHER UPPER RIDGE EXTENDS OFF THE COAST OF AFRICA OVER THE E ATLC E OF 30W. THE LAST VISIBLE IMAGES SHOW A LARGE SURGE OF AFRICAN DUST COVERS THE E ATLC S OF A LINE FROM MOROCCO NEAR 34N7W 30N22W 23N43W. THE TROPICAL WAVE/LOW IS EMBEDDED WITHIN THIS DUST. THE REMAINDER OF THE ATLC CONTINUES TO BE DOMINATED BY A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED N OF THE REGION NEAR 37N48W AND EXTENDS TO OVER THE GULF OF MEXICO. $$ WALLACE