000 AXNT20 KNHC 192350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SUN AUG 19 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 2315 UTC. ...SPECIAL FEATURES... HURRICANE GORDON IS CENTERED NEAR 36.4N 26.5W AT 19/1800 OR ABOUT 100 NM SSW OF SAO MIGUEL ISLAND IN THE AZORES MOVING ENE AT 18 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 978 MB. MAXIMUM SUSTAINED WIND SPEED IS 75 KT WITH GUSTS TO 90 KT. SCATTERED MODERATE CONVECTION IS FROM 36N-39N BETWEEN 24W-30W. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT3/WTNT33 AND THE FULL FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS. TROPICAL WAVE EXTENDS FROM 21N38W TO A 1010 MB SURFACE LOW AT 14N39W. THE WAVE/LOW IS MOVING WEST AT ABOUT 20 KT. BROAD CYCLONIC SURFACE FLOW IS AROUND THE WAVE AND CONCENTRATED NEAR THE LOW CENTER. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MAINLY S AND W OF THE SYSTEM FROM 10N-13N BETWEEN 37W-42W...AND FROM 14N-17N BETWEEN 40W-42W. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE FOR A TROPICAL CYCLONE TO FORM DURING THE NEXT DAY OR TWO. ...TROPICAL WAVES... TROPICAL WAVE HAS PUSHED OFF THE AFRICAN COAST ALONG 20N18W TO A 1011 MB SURFACE LOW AT 13N20W MOVING W AT 10-15 KT. UPPER AIR SOUNDINGS FROM DAKAR SENEGAL INDICATE THAT THE WAVE MOVED OFF THE COAST AROUND 19/1200 UTC. SATELLITE IMAGERY SHOWS CLEAR LOW-LEVEL CYCLONIC TURNING AROUND THE LOW CENTER. THE WAVE COINCIDES WITH A SURGE IN DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY...AS WELL AS A CLEARING IN THE SAHARAN AIR LAYER AND DUST PRESENT ACROSS MUCH OF THE TROPICAL ATLC. SCATTERED STRONG CONVECTION IS SW OF THE LOW CENTER FROM 9N-11N BETWEEN 21W-25W. TROPICAL WAVE EXTENDS FROM 18N48W TO A BROAD 1010 MB SURFACE LOW AT 11N48W MOVING W AT 15-20 KT. THE LOW IS EMBEDDED WITHIN THE MONSOON TROUGH AND IS MUCH LESS EVIDENT THAN THE SURFACE LOW TO THE EAST. THE WAVE ALIGNS WITH A NARROW SURGE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED STRONG CONVECTION IS FROM 10N-12N BETWEEN 49W-51W...WITH SCATTERED MODERATE CONVECTION ELSEWHERE FROM 9N-11N BETWEEN 44W-48W...AND FROM 9N-13N BETWEEN 50W-54W. TROPICAL WAVE EXTENDS FROM 22N78W TO 13N77W MOVING W INTO THE WESTERN CARIBBEAN AT 10-15 KT. MODERATE DEEP LAYER MOISTURE COVERS MUCH OF THE CENTRAL CARIBBEAN SEEN IN TOTAL PRECIPITABLE WATER IMAGERY. ISOLATED MODERATE CONVECTION IS MAINLY WEST OF THE WAVE FROM 15N-17N BETWEEN 80W-82W. SCATTERED MODERATE CONVECTION IS ALSO OVER MUCH OF CUBA AND PORTIONS OF HISPANIOLA...BUT THIS ACTIVITY MAY BE MORE ASSOCIATED WITH DAYTIME HEATING AND INSTABILITY PROVIDED BY UPPER LEVEL DIFFLUENCE. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE SURFACE LOW NEAR 13N20W CONTINUING ALONG 15N29W 14N35W TO THE SPECIAL FEATURE SURFACE LOW AT 15N39W TO THE THIRD SURFACE LOW AT 11N49W CONTINUING TO 7N56W. BESIDES CONVECTION ASSOCIATED WITH TROPICAL WAVES AND ASSOCIATED LOWS...SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-9N BETWEEN 29W-33W. ISOLATED MODERATE CONVECTION IS FROM 2N-9N BETWEEN 34W-39W. ...DISCUSSION... GULF OF MEXICO... A LARGE AND BROAD UPPER LEVEL TROUGH COVERS MUCH OF THE CENTRAL AND EASTERN CONUS...AND IS IMPACTING THE NORTHERN GULF SUPPORTING AN ACTIVE SQUALL LINE FROM NORTHERN FLORIDA AT 29N81W ALONG 28N87W 27N95W...AS OF 2100 UTC. SHOWERS/THUNDERSTORMS ARE WITHIN 75 NM S OF THE AXIS. SHOWERS CONTINUE N OF THE AXIS ESPECIALLY OVER THE NE GULF. A WEAK SURFACE RIDGE ACROSS THE SOUTHERN GULF IS PROVIDING MOIST RETURN FLOW TO THE BOUNDARY ACROSS THE NORTHERN GULF. FAIR WEATHER IS ALSO PRESENT WITHIN THE SURFACE RIDGE WITH MOSTLY CLEAR SKIES. HOWEVER...A CLUSTER OF SHOWERS/POSSIBLE THUNDERSTORMS IS ALSO IN THE FAR SW GULF FROM 20N-25N W OF 95W NEAR A WEAK SURFACE LOW JUST INLAND OVER MEXICO. EXPECT WEAK SURFACE RIDGING TO REMAIN ACROSS THE SOUTHERN GULF WHILE A SURFACE TROUGH WILL SWEEP ACROSS THE NORTHERN GULF WITH SHOWERS/THUNDERSTORMS LIKELY. SHOWERS/THUNDERSTORMS WILL ALSO REMAIN OVER THE FAR WESTERN GULF. CARIBBEAN SEA... AN UPPER LEVEL INVERTED TROUGH IS ACROSS THE FAR WESTERN CARIBBEAN WITH AXIS ALONG 87W. THE TROUGH REMAINS MOSTLY DRY AROUND THE NORTHERN EXTENT...BUT DIFFLUENCE ON THE EAST SIDE IS HELPING PRODUCE A CLUSTER OF SHOWERS/THUNDERSTORMS ACROSS EASTERN HONDURAS...AND SIMILAR ACTIVITY OVER CUBA. A TROPICAL WAVE JUST W OF JAMAICA MAY ALSO BE INFLUENCING THE ACTIVITY OVER CUBA. TO THE S...COSTA RICA...PANAMA...AND NORTHERN CUBA ARE BEING HIT WITH SHOWERS/THUNDERSTORMS ASSOCIATED WITH THE MONSOON TROUGH THAT EXTENDS S OF THE COUNTRIES TO A 1009 MB LOW OVER COLOMBIA. DIFFLUENCE AROUND THE INVERTED UPPER TROUGH IS ALSO CONTRIBUTING TO THE ACTIVITY. AN UPPER LEVEL RIDGE COVERS THE REMAINDER OF THE BASIN CENTERED NEAR 15N73W SUPPORTING MOSTLY FAIR WEATHER BESIDES A FEW ISOLATED SHOWERS EMBEDDED WITHIN THE TRADEWIND FLOW. SEVERAL SURFACE OBSERVATIONS ARE INDICATING THE PRESENCE OF DUST ACROSS THE EASTERN CARIBBEAN...WHICH IS HELPING PROVIDE FAIR CONDITIONS. EXPECT THE TROPICAL WAVE TO CONTINUE WESTWARD BRINGING MOISTURE TO THE WESTERN CARIBBEAN. THE NEXT TROPICAL WAVE WILL APPROACH THE LESSER ANTILLES BY TUESDAY. ATLANTIC OCEAN... A BROAD UPPER LEVEL TROUGH COVERING MUCH OF THE CENTRAL AND EASTERN CONUS SUPPORTS A SQUALL LINE THAT COVERS MUCH OF THE NORTHERN GULF OF MEXICO AND EXTENDS ACROSS FLORIDA INTO THE WEST ATLC ALONG 29N81W TO 30N79W. THE REMAINDER OF THE W ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1023 MB HIGH AT 30N59W. THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 33N63W. A FEW ISOLATED SHOWERS ARE EMBEDDED WITHIN THE SW FLOW AROUND THE NW SIDE OF THE SURFACE RIDGE. A WEAK UPPER LOW IS CENTERED NEAR 25N58W...BUT IS NOT CAUSING ANY SIGNIFICANT WEATHER. A BROAD UPPER TROUGH ALSO COVERS THE NE ATLC...BUT AGAIN IS NOT CAUSING ANY ACTIVE WEATHER IN THE DISCUSSION AREA. UPPER LEVEL RIDGING COVERS THE REMAINDER OF THE TROPICAL ATLC WITH A CENTER NEAR 19N42W...AND NEAR 31N20W. THE LAST VISIBLE SATELLITE IMAGES OF THE DAY ALONG WITH SAHARAN AIR LAYER AND DUST ENHANCEMENT IMAGERY INDICATE THAT A WIDESPREAD AREA OF DRY AIR AND DUST EXTENDS FROM THE COAST OF AFRICA AROUND THE SERIES OF TROPICAL WAVES AND INTO THE EASTERN CARIBBEAN. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON