Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 260603 CCA AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 203 AM EDT WED AUG 26 2015 .SYNOPSIS...A STALLED FRONT WILL PERSIST IN VICINITY OF THE CAROLINA COAST THROUGH THE DURATION OF THE WEEK. && .NEAR TERM /OVERNIGHT/... AS OF 935 PM TUESDAY... 00Z MESO-ANALYSIS DEPICTS A TONGUE OF MOISTURE AND INSTABILITY ACROSS THE COASTAL PLAIN...AND INTO THE EASTERN SECTIONS OF THE SANDHILLS. PRECIP WATER VALUES WERE AVERAGING 1.6-1.7 INCHES IN THIS REGION. FARTHER WEST...PRECIP WATER VALUES AVERAGED 1.1 INCHES. WATER VAPOR IMAGERY SUGGESTED A SHEAR AXIS EDGING SLOWLY EAST ACROSS EASTERN NC. THIS FEATURE INTERACTING WITH AVAILABLE MOISTURE AND MODEST INSTABILITY WAS TRIGGERING A FEW SHOWERS ALONG AND EAST OF HIGHWAY 1...MAINLY IN VICINITY OF WILSON...AND OVER SECTIONS OF THE WESTERN SANDHILLS. LATEST RUC MODEL SUGGEST A VORT MAX AND ATTENDANT SHEAR AXIS DRIFTING EAST ALONG THE SC-NC BORDER THROUGH THE PRE-DAWN HOURS. BASED ON HOW WELL ISOLATED-SCATTERED CONVECTION HAS MAINTAINED ITSELF THROUGH MID EVENING AND NEAR TERN MODELS SUGGESTING A THREAT LASTING WELL INTO THE NIGHT...WILL MAINTAIN A SLIGHT-SMALL CHANCE POP...GENERALLY ALONG AND EAST OF I-95 THROUGH THE PRE-DAWN HOURS. ANOTHER SHEAR AXIS NOTED CROSSING THE TN-LOWER OH VALLEY THIS EVENING...APPROACHING THE SOUTHERN-CENTRAL APPALACHIANS. WHILE MOISTURE IS MORE LIMITED OVER WESTERN NC...THIS FEATURE MAY ENHANCE CLOUDINESS A BIT AND POSSIBLY TRIGGER A SPRINKLE OR TWO OVERNIGHT IN VICINITY OF THE TRIAD. IN ANTICIPATION OF MORE CLOUDINESS...HAVE RAISED MIN TEMPS ABOUT TWO DEGREES IN SOME SPOTS...ESPECIALLY IN THE NW PIEDMONT. MIN TEMPS SHOULD VARY FROM THE MID 60S NW TO AROUND 70 SE. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 100 PM TUESDAY... LITTLE CHANGE IN THE OVERALL PATTERN IS EXPECTED ON WED...WITH THE UNSEASONABLY STRONG UPPER LEVEL LOW STALLED NORTH OF THE GREAT LAKES...CYCLONIC FLOW ALOFT ALONG THE EASTERN SEABOARD...AND A STALLED FRONTAL ZONE IN VICINITY OF THE CAROLINA/SOUTHEAST COAST. AS A RESULT...EXPECT CONDITIONS ON WED TO BE SIMILAR TO TODAY...WITH THE BEST POTENTIAL FOR CONVECTION IN COASTAL/FAR-EASTERN NORTH CAROLINA. WILL KEEP PRECIP CHANCES GENERALLY CONFINED TO THE FAR SE COASTAL PLAIN COUNTIES (I.E. CUMBERLAND/SAMPSON/WAYNE). ADDITIONAL SHORTWAVE ENERGY DIGGING SOUTHEAST ALONG THE WESTERN PERIPHERY OF THE STALLED UPPER LOW IS PROGGED TO PROGRESS INTO THE CENTRAL APPALACHIANS LATE WED NIGHT...AND IT IS POSSIBLE THAT THE FRONTAL ZONE SHIFTS FURTHER INLAND (ALONG WITH A POTENTIAL FOR PRECIP) AFTER MIDNIGHT AS LOW-LEVEL WIND/HEIGHT FIELDS RESPOND TO THE APPROACHING SHORTWAVE. FORECAST CONFIDENCE REMAINS LOW WITH REGARD TO THE EVOLUTION/TIMING OF THE APPROACHING WAVE...THE STALLED FRONTAL ZONE...AND WHETHER AN INLAND SHIFT IN PRECIPITATION WILL OCCUR (AS THE GFS SUGGESTS) OR PRECIPITATION REMAINS ALONG THE COAST (AS THE NAM SUGGESTS). -VINCENT && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 115 PM TUESDAY... FRONTAL ZONE REMAINS PINNED ALONG THE NC COAST AS MILD HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES AND SOUTH DOWN THE EASTERN SPINE OF THE APPALACHIANS INTO THE WEEKEND. MEANWHILE...ALOFT...THE FRONTAL ZONE LIES BETWEEN A WEAK UPPER TROF OVER THE ATLANTIC COAST AND STRONGER OFFSHORE RIDGE WHICH WILL BEGIN TO RETROGRADE INTO THE SOUTHEAST ATLANTIC COAST...PROVIDING ADDITIONAL MOISTURE AS WELL AS NUDGING THE FRONT SLOWLY INLAND. WILL KEEP THE CHANCE OF RAIN ONLY MARGINALLY ABOVE CLIMATOLOGICAL...~30%...AND FOCUSED PRIMARILY ON THE SOUTHEAST THROUGH SATURDAY. CLOUDINESS WILL BECOME MORE PREVALENT ON SATURDAY AS OVERRUNNING EASTERLY FLOW SETS UP...WHICH COULD LEAD TO INCREASING POPS AS THE WEEKEND APPROACHES. HIGHS EACH DAY WILL BE PRETTY NEAR CLIMATOLOGICAL...POTENTIALLY COOLER ON SATURDAY...POSSIBLY SUNDAY AS WELL...IF THE DAMMING AND PRECIP SCENARIO MATERIALIZES. UNCERTAINTY INCREASES BY EARLY NEXT WEEK AS WE WILL POTENTIALLY BE SUBJECT TO THE INFLUENCE OF TS ERIKA. WE WILL BE IN THE WEAK TROF AREA BETWEEN AN AMPLIFYING RIDGE IN THE MIDWEST AND THE STRONGER AND STILL RETROGRADING SUBTROPICAL RIDGE OVER THE SOUTHWEST ATLANTIC...WHICH SHOULD BE THE DETERMINING STEERING MECHANISM FOR ERIKA OR HER REMAINS. REGARDLESS...HEIGHTS WILL INCREASE EARLY NEXT WEEK AND SHOULD SEE AN UPTICK IN TEMPS...UPPER 80S TO LOWER 90S MONDAY AND TUESDAY...WITH AT LEAST WIDELY SCATTERED DIURNAL CONVECTION IN THE MOIST AIRMASS. STAY TUNED. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 200 AM WEDNESDAY... 24 HOUR TAF PERIOD: ALL THE SENSIBLE WEATHER IN THE TAF PERIOD WILL MOST LIKELY OCCUR IN THE EASTERN HALF OF THE AREA WITH KFAY AND KRWI BEING THE PRIMARY TERMINALS AFFECTED. AS FAR AS CONVECTION IS CONCERNED...THERE ARE CURRENTLY SHOWERS AND THUNDERSTORMS IN THE VICINITY OF KFAY AND THESE ARE EXPECTED TO CONTINUE FOR THE NEXT SEVERAL HOURS BUT WEAKEN OVER TIME. OF SECONDARY CONCERN WILL BE AREAS OF FOG THIS EVENING...PARTICULARLY AT KRWI AND KFAY. TO THIS POINT...ANY OBSERVATIONS OF VISIBILITY RESTRICTIONS HAVE BEEN IN THE MVFR RANGE AND THIS IS EXPECTED TO BE THE PRIMARY CATEGORY FOR THE EVENING WITH AN OUTSIDE CHANCE OF SOME IFR CONDITIONS...ESPECIALLY AFTER THE RAIN AT KFAY. LATER IN THE DAY EXPECT ANOTHER ROUND OF CONVECTION IN THE EAST...WITH KRWI AND KFAY ONCE AGAIN THE MOST LIKELY AFFECTED HOWEVER IT IS POSSIBLE THAT SHORTWAVE ENERGY WILL HELP SOME ISOLATED SHOWER ACTIVITY FURTHER WEST IN THE VICINITY OF KRDU NEAR THE END OF THE TAF PERIOD. LONG TERM: WITH THE FRONTAL ZONE STALLING OUT OVER THE EASTERN HALF OF THE STATE...TERMINALS ALONG AND EAST OF ROUTE 1 WILL BE UNDER CONTINUED THREAT FOR DAILY SHOWERS AND THUNDERSTORMS...PARTICULARLY DURING AFTERNOON PEAK HEATING. TRIAD TERMINALS SHOULD REMAIN LARGELY VFR FOR MUCH OF THE WEEK BUT UNCERTAINTY INCREASES TOWARDS THE WEEKEND WHEN THE FRONTAL ZONE COULD RETROGRADE A LITTLE AS A WEAK LOW FORMS SOUTH OF THE AREA. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...WSS SHORT TERM...VINCENT LONG TERM...MLM AVIATION...ELLIS

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