Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220205 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1000 PM EDT SUN SEP 21 2014 .SYNOPSIS...A COLD FRONT WILL MOVE EAST INTO THE AREA OVERNIGHT AND WILL TEMPORARY STALL ALONG THE COAST MONDAY AND MONDAY NIGHT. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE NORTH THROUGH MID-WEEK. && .NEAR TERM /THROUGH MONDAY NIGHT/...
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AS OF 1000 PM SUNDAY... THE APPROACHING COLD FRONT IS STILL JUST TO THE WEST OF THE MOUNTAINS...WITH A PREFRONTAL TROUGH NOW EVIDENT OVER THE WESTERN PIEDMONT. A FEW SHOWERS HAVE DEVELOPED ALONG THE TROUGH...MOSTLY FROM THE TRIAD SOUTH TOWARD LEXINGTON...WHERE THERE IS STILL SOME WEAK MLCAPE DESPITE A MID-LEVEL INVERSION JUST ABOVE 600MB. THERE ARE ALSO SOME SHOWERS BACK CLOSER TO THE COLD FRONT TO WATCH..BUT THESE WILL ENCOUNTER A LESS FAVORABLE ENVIRONMENT AS INSTABILITY WEAKENS WITH WESTERLY FLOW AT 850MB AND LIMITED MOISTURE ACCOMPANYING THE FRONT. HAVE ADJUSTED POPS TO REFLECT THE FAIRLY LOCALIZED AREA OF SHOWERS OVER THE WESTERN PIEDMONT AND EXPECT THESE SHOWERS TO ALSO DWINDLE WITH TIME AS THEY PROGRESS EAST NEAR THE HWY 64 CORRIDOR. MOST AREAS THAT SEE A SHOWER WILL GET LESS THAN A TENTH OF AN INCH OF RAIN. BEHIND THE FRONT...DEWPOINTS WILL QUICKLY DROP INTO THE 50S BUT THE CORE OF THE COOLER AIR WILL LIKELY BE SLOW TO CROSS THE MOUNTAINS AND LOWS SHOULD MOSTLY BE IN THE LOW TO MID 60S. THE COLD FRONT AND ATTENDANT NARROW AXIS OF HIGH LEVEL MOISTURE WILL TEMPORARY STALL ALONG THE COAST DURING THE DAY ON MONDAY THROUGH EARLY TUESDAY AS A POTENT VORTMAX EMBEDDED IN THE BASE OF THE UPPER TROUGH ATTEMPTS TO CLOSE AND CUT-OFF OVER THE SOUTHEAST US. THIS WILL DELAY THE ONSET OF STRONG CAA UNTIL LATE MONDAY NIGHT/TUESDAY MORNING...WHICH WILL ALLOW HIGHS MONDAY TO STILL CLIMB INTO THE MID- UPPER 70S NW TO LOWER 80S SE. MUCH COOLER MONDAY NIGHT...ESPECIALLY IN THE NORTHWEST...LOWS RANGING FROM THE UPPER 40S N/NW TO LOWER/MID 50S SE TUE MORNING.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... AS OF 250 PM SUNDAY... STRONG HIGH PRESSURE...BECOMING CENTERED OVER THE NORTHEAST US BY TUESDAY NIGHT...WILL RIDGE DOWN INTO CENTRAL NC...RESULTING IN MUCH COOLER AND DRIER CONDITIONS. CONTINUED CAA WILL RESULT IN HIGHS ONLY REACHING INTO THE LOW TO MID 70S. UNDER MOSTLY CLEAR SKIES TUESDAY NIGHT...OVERNIGHT LOWS ARE EXPECTED TO FALL INTO THE LOW TO MID 50S (WITH SOME UPPER 40S POSSIBLE IN THE NORMAL COOLER LOCALES ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA). && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 250 PM SUNDAY... FORECAST CONFIDENCE REMAINS BELOW NORMAL TOWARDS THE MIDDLE/END OF THE WEEK AS THERE CONTINUES TO BE SOME DISAGREEMENT AMONG THE MODELS. ONE THING IN WHICH THERE IS GENERAL CONSENSUS IS THAT THE LOW LEVEL FLOW AROUND THE HIGH WILL INCREASE AND BEGIN TO GRADUALLY TAKE ON MORE OF AN EAST OF NORTHERLY COMPONENT BEGINNING LATE WEDNESDAY (AS THE HIGH SHIFTS OFF THE NORTHEAST COAST) ALLOWING SOME MOISTURE TO RETURN TO THE AREA. IN ADDITION...MODELS CONTINUE TO HINT AT A WEAKNESS ALOFT AND ASSOCIATED INVERTED TROUGH DEVELOPING NEAR THE SOUTHEAST COAST (ALTHOUGH TO VARYING DEGREES AMONG THE MODELS). THIS WOULD INCREASE CLOUDS AND PRECIP CHANCES (ESPECIALLY ACROSS EASTERN NC). THE MORE CONSISTENT ECMWF SHOWS A CLOSED LOW ALOFT ACROSS THE SOUTHEAST WHICH IN TURN RESULTS IN A STRONGER INVERTED TROUGH AND THEREFORE MORE ENHANCED PRECIP/CLOUD COVER. THE GFS CONTINUES TO INDICATE A BROAD TROUGH ALOFT OVER THE AREA AND THEREFORE IS WEAKER WITH THE COASTAL TROUGH AND ASSOCIATED CLOUD COVER/PRECIP (ALTHOUGH IT IS NOT COMPLETELY DRY). FOR NOW...WILL MAINTAIN MAINLY SLIGHT CHANCE POPS TOWARDS THE END OF THE WEEK GIVEN THE MORE CONSISTENT ECMWF. REGARDLESS...CLOUDY AND COOLER CONDITIONS WILL PERSIST...WITH HIGHS STAYING IN THE LOW TO MID 70S AND OVERNIGHT LOWS MOSTLY IN THE 50S. SOME DRYING MAY COMMENCE BY THE WEEKEND AS RIDGING TRIES TO BUILD EAST. AS A RESULT...TEMPS WILL UNDERGO SOME MODERATION...AND ARE EXPECTED TO RETURN TO NEAR NORMAL VALUES. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... AS OF 825 PM SUNDAY... A MOSTLY DRY COLD FRONT WILL CROSS CENTRAL NC TONIGHT. WHILE VFR CONDITIONS SHOULD PREVAIL...A PERIOD OF 4-7 THOUSAND FT CEILINGS...AND EVEN A FEW SPRINKLES OR SHOWERS MAINLY AT TRIAD TERMINALS WHERE INSTABILITY IS MAXIMIZED THIS EVENING...WILL ACCOMPANY THE FRONT. LIGHT...INITIALLY SW TO W SFC WINDS AHEAD OF THE FRONT WILL GRADUALLY VEER TO NW AS THE FRONT SETTLES THROUGH THE REGION OVERNIGHT...WITH LIGHT NW TO NNW WINDS FORECAST TO CONTINUE THROUGH MON. OUTLOOK: A LOW PRESSURE SYSTEM WILL DEVELOP OFF THE SOUTHEAST COAST AND PROVIDE FOR A GOOD CHANCE OF SUB-VFR CONDITIONS AND RAIN MID- LATE WEEK...WITH RELATIVE HIGHEST PROBABILITY OF OCCURRENCE AND POOREST CONDITIONS AT EASTERN TERMINALS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL/BLS SHORT TERM...KRD LONG TERM...KRD AVIATION...MWS

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