000 AXNT20 KNHC 080002 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT TUE AUG 07 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. ...SPECIAL FEATURE... HURRICANE ERNESTO IS CENTERED NEAR 18.7N 87.1W...AS OF 0000 UTC...OR ABOUT 55 NM E OF CHETUMAL MEXICO. ERNESTO IS MOVING WNW AT 13 KT. MINIMUM CENTRAL PRESSURE IS 980 MB WITH MAXIMUM SUSTAINED WINDS OF 75 KT WITH GUSTS TO 90 KT. PLEASE READ THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT5/WTNT25 KNHC AND THE PUBLIC ADVISORY UNDER AWIPS/WMO MIATCPAT5/WTNT35 KNHC FOR MORE DETAILS. NUMEROUS STRONG CONVECTION IS IMMEDIATELY W OF THE CENTER OF ERNESTO FROM 18N-20N BETWEEN 86W-87W. OUTER RAINBANDS WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION SPAN FROM 15N-23N BETWEEN 81W-91W INCLUDING PORTIONS OF NRN CENTRAL AMERICA AND THE YUCATAN PENINSULA. SCATTERED MODERATE/ISOLATED STRONG CONVECTION ALSO EXTENDS SOUTHWARD INTO NICARAGUA AND COSTA RICA. TROPICAL WAVE IS ALONG 18N30W TO A 1012 MB SURFACE LOW AT 12N31W MOVING W AT 15-20 KT. LOW-LEVEL CYCLONIC FLOW IS AROUND THE LOW CENTER AND SOUTHERN PORTION OF THE WAVE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS MAINLY W OF THE AXIS FROM 10N-15N BETWEEN 31W-35W. WHILE THE LOW IS NOT WELL ORGANIZED AT THIS TIME...UPPER LEVEL CONDITIONS COULD BECOME MORE CONDUCIVE FOR FURTHER DEVELOPMENT OF THE SYSTEM OVER THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 19N48W TO 13N49W MOVING W NEAR 20 KT. A 1011 MB SURFACE LOW IS ALONG THE WAVE AXIS AT 18N49W. THIS LOW IS THE REMNANT LOW OF T.S. FLORENCE THAT WAS DOWNGRADED YESTERDAY. THE WAVE/LOW COINCIDE WITH A LARGE SURGE OF DEEP LAYER MOISTURE THAT IS BETWEEN 44W-56W...EVIDENT IN TOTAL PRECIPITABLE WATER IMAGERY. A SMALL AREA OF SCATTERED MODERATE CONVECTION IS FROM 17N-19N BETWEEN 50W-52W. TROPICAL WAVE IS MOVING THROUGH THE EASTERN CARIBBEAN ALONG 17N64W TO 11N67W MOVING W AT 10 KT. THE WAVE COINCIDES WITH AN AREA OF ENHANCED MOISTURE THAT COVERS THE EASTERN CARIBBEAN E OF 68W. THE WAVE ALSO LIES UNDERNEATH AN AREA OF DIFFLUENCE ALOFT ON THE E SIDE OF AN UPPER TROUGH...WHICH IS ENHANCING CONVECTION. CURRENTLY...SCATTERED MODERATE CONVECTION IS FROM 12N-18N BETWEEN 60W-66W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH IS ACROSS W AFRICA TO THE COAST OF MAURITANIA AT 21N16W WHERE IT CONTINUES OVER WATER ALONG 15N23W 11N38W PASSING THROUGH A SURFACE LOW ASSOCIATED WITH THE EASTERNMOST TROPICAL WAVE. THERE IS CURRENTLY NO DEEP CONVECTION BESIDES THAT ASSOCIATED WITH TROPICAL WAVES. ...DISCUSSION... THE GULF OF MEXICO... CYCLONIC FLOW COVERS THE SOUTHERN GULF OF MEXICO AROUND HURRICANE ERNESTO IN THE NW CARIBBEAN. A FEW SHOWERS AND THUNDERSTORMS ARE EMBEDDED IN THE FLOW FROM OUTER RAINBANDS. A WEAK SURFACE TROUGH IS ACROSS THE NORTHERN GULF FROM 31N86W TO 29N80W...AS OF 2100 UTC. NO SHOWERS ARE NEAR THE TROUGH...HOWEVER...SCATTERED SHOWERS/THUNDERSTORMS ARE ACROSS PORTIONS OF THE FLORIDA PANHANDLE AND THE FLORIDA PENINSULA. THIS IS LIKELY DUE TO DIFFLUENT FLOW ALOFT OVER THE NE GULF BETWEEN AN UPPER LEVEL TROUGH OVER THE EASTERN CONUS AND AN UPPER LEVEL RIDGE OVER THE NW ATLC WATERS. A FEW SHOWERS/THUNDERSTORMS ARE ALSO ALONG THE COAST OF LOUISIANA ASSOCIATED WITH DIFFLUENCE FLOW ALOFT BETWEEN AN INVERTED UPPER TROUGH OVER THE FAR WESTERN GULF AND AN UPPER LEVEL RIDGE...OUTFLOW FROM ERNESTO...THAT COVERS THE MAJORITY OF THE BASIN. EXPECT STRONGER WINDS ACROSS THE SOUTHERN GULF AS ERNESTO TRACKS WESTWARD INTO THE YUCATAN PENINSULA AND EVENTUALLY THE BAY OF CAMPECHE. SHOWERS/THUNDERSTORMS WILL BE VERY LIKELY ACROSS THIS AREA. THE REMAINDER OF THE BASIN WILL BE UNDER WEAK SURFACE RIDGING WITH SHOWERS/THUNDERSTORMS ACROSS THE NORTHERN GULF COAST. THE CARIBBEAN SEA... HURRICANE ERNESTO IS IMPACTING THE NW CARIBBEAN TONIGHT BRINGING STRONG WINDS AND HEAVY SHOWERS/THUNDERSTORMS TO MUCH OF CENTRAL AMERICA AND THE YUCATAN PENINSULA. ERNESTO IS EXPECTED TO MAKE LANDFALL IN THE YUCATAN PENINSULA WITHIN THE NEXT 6-12 HOURS. SEE SPECIAL FEATURES ABOVE FOR MORE DETAILS. THE CENTRAL CARIBBEAN IS MOSTLY CLEAR DUE TO DRY AIR ALOFT AROUND AN UPPER LEVEL RIDGE OVER THE SW CARIBBEAN AND AN UPPER LEVEL LOW CENTERED N OF HISPANIOLA. HOWEVER...DIFFLUENCE ALOFT AROUND THE E SIDE OF THE UPPER LOW IS HELPING HELPING PRODUCE HEAVY SHOWERS/THUNDERSTORMS OVER HISPANIOLA AND ACROSS THE EASTERN CARIBBEAN NEAR A TROPICAL WAVE. SEE TROPICAL WAVE SECTION FOR MORE DETAILS ON THE WAVE. EXPECT THE NW CARIBBEAN TO CONTINUE TO SEE HEAVY WIND AND RAIN AS ERNESTO MOVES WESTWARD INTO THE YUCATAN PENINSULA. MOISTURE ASSOCIATED WITH THE TROPICAL WAVE IN THE EASTERN CARIBBEAN WILL BEGIN TO MOVE INTO THE CENTRAL CARIBBEAN. THE ATLANTIC OCEAN... A WEAK PRESSURE GRADIENT IS ACROSS THE WESTERN ATLC WITH LIGHT MOSTLY ANTI-CYCLONIC FLOW PRESENT. ALOFT...AN UPPER LEVEL RIDGE COVERS THE AREA CENTERED NEAR 33N72W. A WEAK SURFACE TROUGH IS ALONG 24N70W TO 21N70W COINCIDING WITH AN UPPER LEVEL LOW CENTERED NEAR 22N70W. A FEW ISOLATED SHOWERS ARE NEAR THE SURFACE TROUGH. A SECOND SURFACE TROUGH IS TO THE N ALONG 33N60W TO 24N63W SUPPORTED BY AN UPPER LEVEL TROUGH ALONG 37N54W TO 26N64W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 120 NM EITHER SIDE OF THE SURFACE TROUGH AXIS FROM 24N-28N. FARTHER E...SURFACE RIDGING DOMINATES ANCHORED BY A 1024 MB HIGH CENTERED NEAR 33N41W PROVIDING MOSTLY FAIR CONDITIONS. THE RIDGE IS SUPPORTED BY A BROAD UPPER RIDGE COVERING MUCH OF THE TROPICAL ATLC S OF 32N. VISIBLE SATELLITE IMAGERY INDICATES THAT A BROAD AREA OF AFRICAN DUST EXTENDS ACROSS THE ATLC AROUND THE TWO TROPICAL WAVES FURTHER SUPPORTING FAIR CONDITIONS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ WALTON