000 AXNT20 KNHC 282358 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 28 2012 TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF SOUTH AMERICA...AND 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 2245 UTC. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 19N46W TO 10N51W MOVING W NEAR 20 KT. TOTAL PRECIPITABLE WATER IMAGERY INDICATES THAT THE WAVE LIES WITHIN A SURGE OF DEEP LAYER MOISTURE WITH MAXIMUM VALUES NEAR THE AXIS. THERE IS ALSO A CLEARING IN THE WIDESPREAD SAHARAN AIR LAYER THAT IS PRESENT ACROSS MUCH OF THE TROPICAL ATLC. AN ASCAT SCATTEROMETER PASS FROM EARLIER TODAY ALSO INDICATES LOW LEVEL CYCLONIC FLOW IS AROUND THE WAVE AXIS. DUE TO THE LARGE AREA OF DUST NEAR THE WAVE...NO DEEP CONVECTION IS NEAR THE AXIS BESIDES A SMALL CLUSTER NEAR THE NRN EXTENT OF THE WAVE. TROPICAL WAVE IS MOVING W THROUGH THE E CARIBBEAN ALONG 18N64W TO 11N67W AT 20 KT. THE WAVE IS MOVING THROUGH A VERY DRY ENVIRONMENT DUE TO THE SURROUNDING DUST. HOWEVER...THE WAVE DOES ALIGN WITH A LOW-AMPLITUDE SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY THAT EXTENDS TO ABOUT 15N. A SMALL AREA OF MODERATE CONVECTION IS W OF THE WAVE AXIS FROM 14N-15N BETWEEN 67W-69W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ALSO OVER INLAND VENEZUELA E OF THE AXIS. TROPICAL WAVE PREVIOUSLY IN THE BAY OF CAMPECHE HAS NOW DISSIPATED OVER INLAND MEXICO. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF SENEGAL AT 14N17W CONTINUING ACROSS ATLC WATERS THROUGH A 1011 MB SURFACE LOW AT 9N26W TO 11N39W 12N47W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS AROUND THE CIRCULATION OF THE SURFACE LOW FROM 7N-10N BETWEEN 18W-27W...AND FROM 7N-12N BETWEEN 27W-35W. ...DISCUSSION... GULF OF MEXICO... SHOWERS AND THUNDERSTORMS DOT MUCH OF THE NORTHERN GULF OF MEXICO COAST FROM LOUISIANA TO FLORIDA ASSOCIATED WITH AN UPPER LEVEL TROUGH THAT EXTENDS ACROSS THE EASTERN CONUS TO THE N CENTRAL GULF. THE UPPER TROUGH IS ALSO SUPPORTING A WEAK SURFACE TROUGH THAT EXTENDS FROM 31N84W TO 28N87W. AN UPPER LEVEL LOW IS ALSO OVER THE SW GULF CENTERED NEAR 23N94W SUPPORTING A FEW WIDELY ISOLATED SHOWERS/THUNDERSTORMS ACROSS THE SW GULF AND THE YUCATAN PENINSULA. THE REMAINDER OF THE BASIN IS DOMINATED BY A SURFACE RIDGE AROUND A WEAK 1021 MB HIGH CENTERED NEAR 28N93W. LIGHT ANTI-CYCLONIC FLOW IS AROUND THE HIGH. DRY AIR ALOFT IS COVERING MOST OF THE CENTRAL PORTIONS OF THE GULF...WHICH IS CONTRIBUTING TO THE FAIR CONDITIONS PRESENT. EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS. CARIBBEAN SEA... THE ENTIRE CARIBBEAN REMAINS MOSTLY DRY AS IT IS IMPACTED WITH SAHARAN DUST AND DRY AIR ALOFT...DESPITE THE PRESENCE OF A TROPICAL WAVE OVER THE ERN CARIBBEAN. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. AN UPPER LEVEL LOW CENTERED N OF CENTRAL CUBA IS FLARING UP A FEW SHOWERS/THUNDERSTORMS OVER THE ISLAND...AS WELL AS HISPANIOLA. STRONG SHOWERS/THUNDERSTORMS COVER MUCH OF COSTA RICA AND PANAMA ASSOCIATED WITH DIFFLUENT FLOW ALOFT AND SURFACE CONVERGENCE AROUND THE E PACIFIC MONSOON TROUGH. TRADEWIND FLOW OF 15-20 KT IS ACROSS MUCH OF THE BASIN WITH SOME STRONGER WINDS AROUND THE COAST OF COLOMBIA. EXPECT THE TROPICAL WAVE TO CONTINUE W OVER THE NEXT COUPLE OF DAYS. SHOWERS/THUNDERSTORMS ARE POSSIBLE...ESPECIALLY AS IT APPROACHES THE UPPER LOW OVER CUBA. ATLANTIC OCEAN... A LARGE UPPER LEVEL RIDGE COVERS THE NW ATLC CENTERED NEAR 34N65W SUPPORTING A SERIES OF SURFACE HIGH CENTERS FROM N OF THE AZORES ISLANDS TO THE CENTRAL ATLC NEAR 31N50W TO A WEAK HIGH CENTER NEAR 27N73W. A SURFACE TROUGH IS IMMEDIATELY E OF THE WESTERNMOST HIGH CENTER WITH AXIS ALONG 28N68W TO 26N71W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE FROM 26N-29N BETWEEN 69W-74W. A PAIR OF UPPER LEVEL LOWS ARE S OF THIS AREA CENTERED NEAR 23N78W AND 24N62W. NEITHER LOW IS CAUSING MUCH ACTIVE WEATHER. HOWEVER...THE SECOND IS ABOVE A SURFACE TROUGH EXTENDING FROM 26N59W TO 21N63W. THE TROUGH ORIGINATED FROM A TROPICAL WAVE IN THE EASTERN CARIBBEAN. THE WAVE SPLIT AROUND 24 HOURS AGO AS THE ENERGY TO THE N BEGAN WRAPPING AROUND THE RIDGE TO THE N. THE TROUGH SHOULD CONTINUE TO MOVE AROUND THE RIDGE. THE REMAINDER OF THE BASIN IS DOMINATED BY THE 1027 MB HIGH CENTERED N OF THE AZORES ISLANDS. ALOFT...A BROAD UPPER TROUGH COVERS THE ERN ATLC. HOWEVER...UPPER LEVEL RIDGING COVERS THE TROPICAL ATLC. SATELLITE IMAGERY CONTINUES TO SHOW A LARGE AREA OF SAHARAN DUST ACROSS MUCH OF THE TROPICAL ATLC...WHICH IS SUPPORTING MOSTLY FAIR CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON