000 AXNT20 KNHC 172342 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE JUL 17 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. ...TROPICAL WAVES... TROPICAL WAVE IS APPROACHING THE CAPE VERDE ISLANDS ALONG 21N22W TO 15N21W MOVING W AT 5-10 KT. A LARGE AREA OF DUST SURROUNDING THE WAVE HAS DAMPENED MOST OF THE MOISTURE SIGNAL NEAR THE AXIS AS SEEN IN TOTAL PRECIPITABLE WATER IMAGERY. THERE IS A MOISTURE SURGE WELL W OF THE WAVE...BUT MODEL GUIDANCE AGREES WITH THE CURRENT POSITION AND NOT A POSITION FARTHER W. THE DUST IS CURRENTLY LIMITING CONVECTION NEAR THE WAVE AXIS. TROPICAL WAVE IS ALONG 19N50W TO 11N49W MOVING W AT 15 KT. THE WAVE LIES ON THE W SIDE OF A SURFACE OF DEEP LAYER MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. A SMALL AREA OF MODERATE CONVECTION IS FROM 13N-14N BETWEEN 49W-50W. TROPICAL WAVE MOVES ACROSS CENTRAL CUBA ALONG 24N80W TO 16N80W MOVING W NEAR 10 KT. THE WAVE IS EMBEDDED WITHIN AN AREA OF ENHANCED MOISTURE PRESENT ACROSS MUCH OF THE WRN CARIBBEAN. AN UPPER LEVEL LOW CENTERED OVER THE YUCATAN PENINSULA IS HELPING FLARE UP CONVECTION OVER THE WRN CARIBBEAN AND NEAR THE WAVE. IT IS HARD TO SAY WHETHER IT IS RELATED MOST TO THE WAVE OR DAYTIME HEATING AND UPPER LEVEL DIFFLUENCE. REGARDLESS...A CLUSTER OF STRONG CONVECTION IS ACROSS CUBA W OF THE WAVE AXIS FROM 22N-24N BETWEEN 80W-82W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 16N-19N BETWEEN 80W-86W. THE REMAINDER OF THE CONVECTION IN THE W ATLC IS FARTHER REMOVED FROM THE WAVE AND WILL BE DISCUSSED IN THE CARIBBEAN SECTION. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS ACROSS W AFRICA TO THE COAST OF SENEGAL AT 14N17W CONTINUING S OF THE TROPICAL WAVE TO NEAR 12N27W 9N38W 10N48W. THE ITCZ BEGINS AT 10N48W CONTINUING TO 7N58W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS S OF THE MONSOON TROUGH FROM 10N-13N BETWEEN 19W-24W. SCATTERED MODERATE CONVECTION IS FROM 5N-10N BETWEEN 32W-44W...AND FROM 7N-10N BETWEEN 48W-53W. ...DISCUSSION... GULF OF MEXICO... A PAIR OF UPPER LEVEL LOWS CONTINUE TO IMPACT THE GULF OF MEXICO TONIGHT SUPPORTING LARGE AREAS OF SHOWERS/THUNDERSTORMS. THE FIRST UPPER LOW IS CENTERED OVER SE GEORGIA NEAR 31N82W SUPPORTING A SURFACE TROUGH FROM 31N83W TO 27N85W. RADAR IMAGERY INDICATES NUMEROUS SHOWERS/SCATTERED THUNDERSTORMS ARE ACROSS MUCH OF THE FLORIDA PANHANDLE N OF 29N BETWEEN 82W-88W. ISOLATED SHOWERS/THUNDERSTORMS COVER THE REMAINDER OF THE STATE AND THE ERN GULF E OF 88W. SOME OF THE ACTIVITY NEAR S FLORIDA AND THE SE GULF ARE TIED TO THE SECOND UPPER LEVEL LOW CENTERED OVER THE NRN YUCATAN PENINSULA NEAR 21N88W. IT IS HELPING SUPPORT STRONG SHOWERS/THUNDERSTORMS ACROSS THE YUCATAN PENINSULA AND PORTIONS OF CENTRAL AMERICA. SOME ISOLATED SHOWERS ARE ALSO OVER THE FAR WRN GULF W OF 95W. THE REMAINING PORTION OF THE CENTRAL GULF IS EXPERIENCING FAIR WEATHER INFLUENCED BY DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE OVER THE MIDWEST CONUS SUPPORTING A SURFACE 1018 MB HIGH OVER SE LOUISIANA. THE UPPER LOWS ARE EXPECTED TO REMAIN SOMEWHAT STATIONARY AND WILL LIKELY KEEP THE ERN GULF UNDER MOIST CONDITIONS FOR AT LEAST THE NEXT 24 HOURS. CARIBBEAN SEA... THE UPPER LEVEL LOW OVER THE NRN YUCATAN PENINSULA IS SUPPORTING STRONG SHOWERS/THUNDERSTORMS ACROSS MUCH OF NRN CENTRAL AMERICA INCLUDING BELIZE...GUATEMALA...HONDURAS...AND NRN NICARAGUA. A STRONG CLUSTER OF SHOWERS/THUNDERSTORMS IS ALSO OVER WRN CUBA WITH SOME ISOLATED ACTIVITY OVER THE NW CARIBBEAN WATERS POSSIBLY TIED TO A TROPICAL WAVE ALONG 80W. SEE TROPICAL WAVE SECTION ABOVE FOR MORE DETAILS. STRONG SHOWERS/THUNDERSTORMS ARE ALSO ACROSS COSTA RICA AND PANAMA ASSOCIATED WITH THE E PACIFIC MONSOON TROUGH THAT EXTENDS S OF BOTH COUNTRIES TO A 1008 MB LOW OVER NRN COLOMBIA. THE REMAINDER OF THE CARIBBEAN IS EXPERIENCING FAIR WEATHER DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL TROUGH OVER THE ERN CARIBBEAN...AND AN UPPER LEVEL RIDGE OVER THE S CENTRAL CARIBBEAN. A LARGE AREA OF SAHARAN DUST IS ALSO PRESENT ACROSS THE CENTRAL AND ERN CARIBBEAN EVIDENT IN SATELLITE IMAGERY AND SURFACE OBSERVATIONS. TRADEWIND FLOW OF 20-25 KTS IS PRESENT OVER THE CENTRAL CARIBBEAN WITH LIGHTER WINDS TO EITHER SIDE. EXPECT THE TROPICAL WAVE TO CONTINUE MOVING WWD FURTHER INTO THE NW CARIBBEAN. MOIST CONDITIONS WILL BE LIKELY ACROSS THIS AREA. ATLANTIC OCEAN... AN UPPER LEVEL LOW CENTERED OVER SE GEORGIA IS SUPPORTING SCATTERED SHOWERS/THUNDERSTORMS JUST E OF THE FLORIDA COAST ALONG WITH SOME ISOLATED SHOWERS/THUNDERSTORMS N OF 27N W OF 73W. THE REMAINDER OF THE W ATLC IS DOMINATED BY SURFACE RIDGING AROUND A 1021 MB HIGH NEAR 27N66W PROVIDING FAIR CONDITIONS. THE HIGH IS SUPPORTED BY AN UPPER LEVEL RIDGE CENTERED NEAR 31N67W. AN UPPER LEVEL TROUGH IS TO THE E ALONG 31N57W TO 18N63W WHERE IT CONTINUES INTO THE ERN CARIBBEAN. THE UPPER TROUGH SUPPORTS A WEAK SURFACE TROUGH ALONG 32N52W TO 28N53W WITH ISOLATED SHOWERS WITHIN 75 NM EITHER SIDE. THE ERN ATLC IS COVERED BY SURFACE RIDGING ANCHORED BY A PAIR OF 1030 MB AZORES HIGHS...WHICH ARE PROVIDING FAIR WEATHER ACROSS THE REMAINDER OF THE BASIN. THE SURFACE RIDGE IS SUPPORTED BY AN UPPER LEVEL RIDGE COVERING THE ERN TRPCL ATLC. VISIBLE SATELLITE IMAGERY INDICATES A LARGE AREA OF SAHARAN DUST COVERS MUCH OF THE TROPICAL ATLC AROUND THE TROPICAL WAVES...WHICH IS HELPING SUPPORT FAIR SURFACE CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON