000 AXNT20 KNHC 202353 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT FRI AUG 20 2010 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...METEOROLOGICAL ANALYSIS...WEATHER OBSERVATIONS...AND RADAR. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...SPECIAL FEATURES... A 1009 MB LOW IS CENTERED OVER THE TROPICAL EASTERN ATLC NEAR 11N27W THAT REMAINS THE FOCAL POINT OF A BROAD MONSOONAL TROUGH S OF 14N BETWEEN 18W-36W. WHILE CONVECTION REMAINS GENERALLY UNORGANIZED...THE UPPER LEVEL ENVIRONMENT FOR TROPICAL CYCLONE DEVELOPMENT IS FAVORABLE GIVEN BETTER UPPER LEVEL DIFFLUENCE AND MINIMAL WIND SHEAR LOCATED TO THE WEST OF THE LOW. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION COVERS A BROAD AREA FROM 06N-14N BETWEEN 23W-35W. ...TROPICAL WAVES... TROPICAL WAVE EXTENDS FROM 11N41W TO 26N44W MOVING W AT 15-20 KT. SATELLITE PRESENTATION INDICATES LOW-LEVEL CYCLONIC FLOW ALONG THE WAVE AXIS AND THIS WAS ALSO NOTED ON AN EARLIER MORNING ASCAT PASS AROUND 20/1214 UTC OVER THE NORTHERN PORTION OF THE WAVE. AN AREA OF MAXIMUM DEEP LAYER MOISTURE IS OBSERVED ON THE TPW IMAGERY FROM 12N-24N BETWEEN 39W-46W...HOWEVER MUCH OF THIS MOISTURE IS POSITIONED BENEATH A STABLE SAHARAN AIR LAYER THAT COVERS MUCH OF THE ATLC EAST OF THE WAVE AXIS TO 25W. NO SIGNIFICANT DEEP ORGANIZED CONVECTION ACCOMPANIES THE WAVE... HOWEVER ISOLATED SHOWERS ARE FROM 20N-23N BETWEEN 40W-44W. A TROPICAL WAVE EXTENDS FROM 12N64W TO 24N66W MOVING W AT 15-20 KT. THE WAVE COINCIDES WITH A MID-LEVEL...700 MB...LOW CENTERED ALONG THE WAVE AXIS NEAR 18N65W. MAXIMUM TOTAL PRECIPITABLE WATER VALUES ARE HIGHEST N OF 17N BETWEEN 62W-69W AS THIS MOISTURE CONTINUES TO ADVECT NORTHWARD DUE TO A WEAKNESS IN THE SUBTROPICAL RIDGE BETWEEN 60W-70W. ISOLATED MODERATE CONVECTION AND WIDELY SCATTERED SHOWERS ARE OCCURRING FROM 17N-24N BETWEEN 62W-70W. TROPICAL WAVE EXTENDS FROM 13N92W TO 22N94W MOVING W AT 10-15 KT. LOW-LEVEL CYCLONIC FLOW IS NOTED ON SATELLITE IMAGERY ACROSS THE SW GULF OF MEXICO AND CENTRAL AMERICA THIS EVENING. LOW- LEVEL SURFACE CONVERGENCE ALONG WITH PEAK DAYTIME HEATING...AND PLENTY OF LOW-LEVEL MOISTURE IS GENERATING A LARGE AREA OF SCATTERED MODERATE AND ISOLATED STRONG CONVECTION OVER MUCH OF THE WESTERN CARIBBEAN AND CENTRAL AMERICA. THIS ACTIVITY IS LOCATED W OF A LINE FROM 11N75W OVER NORTHERN COLOMBIA TO 22N86W IN THE YUCATAN CHANNEL TO 24N98W NEAR LA PESCA MEXICO. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 11N30W 11N41W 12N63W. EMBEDDED WITHIN THE MONSOONAL TROUGH MENTIONED IN THE SPECIAL FEATURES SECTION...A 1010 MB LOW IS CENTERED NEAR 13N20W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS FROM 10N-16N BETWEEN 17W-23W. ELSEWHERE...ISOLATED MODERATE CONVECTION AND WIDELY SCATTERED SHOWERS ARE FROM 05N-12N BETWEEN 35W-58W. ...DISCUSSION... GULF OF MEXICO... ONE UPPER LEVEL ANTICYCLONIC CIRCULATION IS CENTERED OVER WEST TEXAS NEAR 31N105W AND ANOTHER IS CENTERED OVER GEORGIA NEAR 33N84W THAT IS PROVIDING MUCH OF THE GULF WITH E-NE UPPER LEVEL FLOW FROM THE FLORIDA PENINSULA TO THE COAST OF MEXICO. THIS UPPER LEVEL RIDGE SUPPORTS A 1016 MB HIGH CENTERED OVER THE W ATLC NEAR 26N77W THAT EXTENDS A SURFACE RIDGE AXIS ALONG 25N TO 98W. NORTH OF THE RIDGE AXIS...LOW-LEVEL WARM AIR ADVECTION... AND PEAK DAYTIME INSTABILITY ARE SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE NE GULF N OF 28N E OF 87W... INCLUDING MUCH OF THE INTERIOR GULF COAST AND NORTHERN FLORIDA BETWEEN 81W-96W. THE SW GULF IS UNDER THE INFLUENCE OF A TROPICAL WAVE ALONG 94W IMPACTING THE YUCATAN PENINSULA AND AREAS SW OF A LINE FROM 21N88W TO 24N98W WITH SCATTERED SHOWERS AND TSTMS. A FEW ISOLATED SHOWERS AND TSTMS ARE ALSO OCCURRING FROM 24N-26N BETWEEN 94W-97W. ELSEWHERE...SCATTERED SHOWERS AND TSTMS ARE OCCURRING OVER THE SOUTHERN FLORIDA PENINSULA THIS EVENING FROM 25N-28N BETWEEN 80W-82W. THE REMAINDER OF THE GULF IS UNDER GENERALLY CLEAR SKIES AND FAIR CONDITIONS THIS EVENING. CARIBBEAN SEA... WITH THE PASSAGE OF A TROPICAL WAVE ALONG 94W...CONVERGENT LOW-LEVEL SOUTHEASTERLY FLOW DOMINATES ACROSS THE WESTERN CARIBBEAN W OF 80W AND CENTRAL AMERICA. ABUNDANT MOISTURE AND INSTABILITY ASSOCIATED WITH THE TROPICAL WAVE ARE GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS W OF A LINE FROM 11N75W OVER NORTHERN COLOMBIA TO 22N86W IN THE YUCATAN CHANNEL. SATELLITE IMAGERY DENOTES THE STRONGEST ACTIVITY LIES WITHIN 90 NM OF A LINE FROM WESTERN PANAMA NEAR 09N83W TO THE SW YUCATAN PENINSULA NEAR 19N91W...MOSTLY OVER INTERIOR CENTRAL AMERICA THIS EVENING. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED OVER EASTERN CUBA NEAR 20N76W AND ALONG WITH A TROPICAL WAVE ALONG 66W IN THE EASTERN CARIBBEAN IS PROVIDING SCATTERED SHOWERS AND ISOLATED TSTMS OVER THE NORTH-CENTRAL CARIBBEAN FROM 17N-20N BETWEEN 66W-73W. A LACK OF LOW-LEVEL MOISTURE ACCOMPANIES THE REMAINDER OF THE TROPICAL WAVE OVER THE EASTERN CARIBBEAN AS DRY AIR IS NOTED ON WATER VAPOR IMAGERY S OF 17N E OF 73W. ATLANTIC OCEAN... A WEAK 1016 MB HIGH IS CENTERED OVER THE NW BAHAMAS NEAR 26N77W THAT RESIDES ON THE SE PERIPHERY OF AN ANTICYCLONIC CIRCULATION CENTERED OVER THE SE CONUS NEAR 33N84W. MOSTLY NE UPPER LEVEL FLOW COVERS THE W ATLC N OF 23N W OF 70W. WITH A FRONTAL BOUNDARY DRAPED TO THE NORTH OF THE DISCUSSION AREA ALONG 33N... WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING OVER THE W ATLC W OF 68W. SE OF THE UPPER LEVEL ANTICYCLONE...AN UPPER LEVEL LOW IS CENTERED NEAR 24N66W AND EXTENDS UPPER LEVEL TROUGHING TO 30N BETWEEN 60W-70W AND SOUTHWARD INTO THE NE CARIBBEAN SEA. THIS TROUGHING EXTENDS W-SW INTO AN UPPER LEVEL LOW CENTERED OVER EASTERN CUBA NEAR 20N76W. A SURFACE TROUGH IS ANALYZED FROM 25N66W TO 30N63W WITH POSSIBLE ISOLATED SHOWERS WITHIN 180 NM EAST OF THE TROUGH AXIS. SOUTH OF THE SURFACE TROUGH...A TROPICAL WAVE IS ALONG 66W AND IS PROVIDING FOR WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS FROM 17N-24N BETWEEN 62W-70W. ELSEWHERE ACROSS THE REMAINDER OF THE CENTRAL AND EASTERN ATLC...SURFACE RIDGING DOMINATES N OF 26N ANCHORED BY A 1021 MB HIGH CENTERED NEAR 32N26W MAINTAINING GENERALLY FAIR WEATHER. THE RIDGE AXIS EXTENDS FROM THE HIGH CENTER ALONG 30N TO 48W THEN SW TO 24N58W. ALOFT...AN UPPER LEVEL ANTICYCLONE COVERS THE CENTRAL ATLC CENTERED NEAR 31N47W. 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