AXNT20 KNHC 272350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 805 PM EDT SAT JUL 27 2013 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 EXTENDS FROM 10N27W TO 19N29W MOVING W AT 10-15 KT. EMBEDDED WITHIN THE INFLUENCE OF THE MONSOON TROUGH AXIS... SATELLITE IMAGERY INDICATES A LOW-LEVEL CYCLONIC CIRCULATION OR MONSOONAL GYRE HAS SET UP IN THE VICINITY OF 10N27W AND IS FORECAST TO REMAIN NEARLY STATIONARY THROUGH LATE SUNDAY. OTHERWISE...THE WAVE EXHIBITS A LACK OF CONVECTION DUE TO THE SAHARAN AIR LAYER AND SUSPENDED DUST COVERING A LARGE PORTION OF THE EASTERN ATLC WITH NO SIGNIFICANT DEEP CONVECTION OCCURRING AT THIS TIME. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 15N17W TO 10N27W TO 06N36W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N36W TO 05N41W TO 07N49W TO 06N54W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 06N-12N BETWEEN 17W-23W... AND FROM 06N-09N BETWEEN 23W-31W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF NORTHERN MEXICO AND THE SOUTHWESTERN CONUS CENTERED NEAR 29N105W THAT IS PROVIDING MUCH OF THE GULF WITH NORTHWESTERLY TO NORTHEASTERLY FLOW ALOFT. WATER VAPOR IMAGERY ALSO INDICATES THAT THE UPPER LEVEL RIDGE WEAKENS OVER THE EXTREME NE GULF WATERS AND OVER INLAND PORTIONS OF THE SE CONUS AS MIDDLE TO UPPER LEVEL TROUGHING IMPACTS THE GULF COASTAL PLAINS THIS EVENING. THE TROUGHING SUPPORTS A FRONTAL BOUNDARY EXTENDING FROM WESTERN SOUTH CAROLINA TO CENTRAL MISSISSIPPI THEN SW ACROSS SE TEXAS. LOW-LEVEL CONVERGENCE AND MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING SCATTERED SHOWERS AND TSTMS 26N BETWEEN 84W-93W...INCLUDING INLAND PORTIONS OF THE COASTAL SE CONUS. OTHERWISE...AT THE SURFACE...A 1017 MB HIGH CENTERED NEAR 25N88W CONTINUES TO PROVIDING MOSTLY FAIR CONDITIONS FOR A LARGE PORTION OF THE SOUTHERN GULF WITHIN LIGHT AND BROAD ANTICYCLONIC WINDS. THE RIDGING IS FORECAST TO SLOWLY DRIFT EASTWARD THROUGH EARLY MONDAY AS E-SE WINDS RE-ESTABLISH ACORSS THE WESTERN GULF IN THE RANGE OF 10-20 KT ON MONDAY. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONIC CIRCULATION INFLUENCES MUCH OF THE WESTERN CARIBBEAN AND CENTRAL AMERICA THIS EVENING CENTERED OVER NORTHERN NICARAGUA NEAR 13N85W. THIS UPPER LEVEL FEATURE IS PROVIDING THE WESTERN CARIBBEAN WITH NORTHWESTERLY FLOW ALOFT...AND AN OVERALL DRY AND STABLE ATMOSPHERE AS NOTED IN WATER VAPOR IMAGERY. AS A RESULT...SKIES ARE FAIR WITH A GENERAL LACK OF ANY SIGNIFICANT DEEP CONVECTION. A FEW ISOLATED SHOWERS AND TSTMS ARE HOWEVER OCCURRING OVER EASTERN HONDURAS AND NORTHERN NICARAGUA. FARTHER SOUTH...SCATTERED SHOWERS AND TSTMS ARE OCCURRING S OF 11N BETWEEN 76W-86W...INCLUDING PANAMA AND COSTA RICA. THIS CONVECTION IS LIKELY ENHANCED DUE TO THE CLOSE PROXIMITY TO THE MONSOON TROUGH AXIS ANALYZED ALONG 09N FROM NORTHERN COLOMBIA TO SOUTHERN COSTA RICA. OVER THE EASTERN CARIBBEAN...AN UPPER LEVEL LOW IS CENTERED NORTH OF THE BASIN NEAR 22N69W AND EXTENDS A TROUGH AXIS SOUTHWARD ALONG 68W TO A BASE NEAR 15N. LOW TO MIDDLE LEVEL MOISTURE CONTINUES TO ADVECT NORTHWARD ACROSS PUERTO RICO...THE US/UK VIRGIN ISLANDS...AND THE MONA PASSAGE THIS EVENING GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS N OF 16N BETWEEN 64W-69W. LOOKING AHEAD...THE REMNANTS OF DORIAN...CURRENTLY LOCATED E-NE FROM THE LEEWARD ISLANDS...WILL SKIRT NORTH OF THE EXTREME NE CARIBBEAN LATE SUNDAY INTO MONDAY AS A SURFACE TROUGH BRINGING THE CHANCE FOR INCREASED CLOUDINESS AND PRECIPITATION THROUGH EARLY TUESDAY. LITTLE CHANCE FOR RE-DEVELOPMENT IS ANTICIPATED AT THIS TIME. HISPANIOLA... CURRENTLY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING ACROSS THE ISLAND AND THIS ACTIVITY IS EXPECTED TO WANE DUE TO THE LOSS OF PEAK DAYTIME HEATING AND INSTABLITY. ON THE SYNOPTIC SCALE...AN UPPER LEVEL LOW IS CENTERED N-NE OF HISPANIOLA NEAR 22N68W THAT IS FORECAST TO SLOWLY DRIFT NORTHWESTWARD DURING THE NEXT FEW DAYS. AS THIS OCCURS...THE ISLAND WILL GRADUALLY FALL WITHIN AN AREA OF SOUTHWESTERLY FLOW ALOFT BY EARLY MONDAY THAT WILL PRESENT A HIGHER CHANCE FOR AFTERNOON AND EARLY EVENING SHOWERS AND TSTMS FOR EARLY NEXT WEEK. IN ADDITION...THE REMNANTS OF DORIAN ARE FORECAST TO TRACK NORTH OF THE ISLAND MONDAY INTO TUESDAY...WITH SURFACE TROUGHING EXTENDING SOUTHWARD PROVIDING ANOTHER MECHANISM TO INITIATE SHOWERS AND TSTMS. ATLANTIC OCEAN... BROAD UPPER LEVEL TROUGHING IS NOTED ON WATER VAPOR IMAGERY ACROSS THE EASTERN CONUS N OF 28N BETWEEN 75W-88W THAT CONTINUES TO PROVIDE AN AREA ACROSS FLORIDA AND THE SW NORTH ATLC W OF 70W FAVORABLE FOR LIFT AND PRECIPITATION. AT THE SURFACE...A WEAK 1015 MB LOW IS CENTERED NEAR 29N78W WITH A SURFACE TROUGH EXTENDING FROM 31N78W TO THE LOWER FLORIDA KEYS NEAR 25N82W. THIS BOUNDARY...ALONG WITH SEABREEZE INTERACTIONS ALONG THE EASTERN FLORIDA PENINSULA IS GENERATING SCATTERED SHOWERS AND TSTMS N OF 24N BETWEEN 74W-82W. FARTHER SE...AN UPPER LEVEL LOW IS CENTERED N-NE OF HISPANIOLA NEAR 22N69W THAT CONTINUES TO ADVECT MOISTURE NORTHWARD AND GENERATE SCATTERED SHOWERS AND ISOLATED TSTMS FROM 17N-28N BETWEEN 60W-70W. OTHERWISE THE REMAINDER OF THE SW NORTH ATLC AND CENTRAL ATLC ARE UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1030 MB HIGH CENTERED NEAR 36N49W. THE ONLY COMPROMISE OF THE SURFACE RIDGE IS THE REMNANTS OF DORIAN LOCATED NEAR 19N54W. HAVING WEAKENED INTO A TROPICAL WAVE DURING THE PAST 6 HOURS...GALE FORCE WINDS IN THE NORTHERN SEMICIRCLE PERSIST DUE TO THE STRONG PRESSURE GRADIENT WITH THE SURFACE RIDGE TO THE NORTH. FURTHER WEAKENING OF THE REMNANTS IS ANTICIPATED DUE TO THE PREVIOUSLY MENTIONED UPPER LEVEL LOW WHICH WILL PROVIDE AN INCREASED WIND SHEAR ENVIRONMENT. FINALLY...OVER THE EASTERN ATLC...A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 35N16W TO 20N34W THAT SUPPORTS A 1015 MB LOW CENTERED NEAR 33N20W AND AN ASSOCIATED SURFACE TROUGH EXTENDING FROM THE LOW SW TO 27N34W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN
Posted on: Sun, 28 Jul 2013 01:34:34 +0000
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