Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 280733 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 333 AM EDT TUE OCT 28 2014 .SYNOPSIS...BERMUDA HIGH PRESSURE WILL RESULT IN WARM SOUTHWEST FLOW UNTIL A COLD FRONT CROSSES OUR REGION WED AFTERNOON AND EVENING. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 330 AM TUESDAY... DEEP LAYER RIDGING ALONG THE EAST COAST WILL DRIFT EAST TODAY...IN ADVANCE OF MIGRATORY TROUGH ALOFT AND ASSOCIATED SURFACE COLD FRONT APPROACHING FROM THE CENTRAL US. WHILE THE DRY AIR RIDGE IN THE LOW LEVELS HAS REMAINS OVER CENTRAL NC...THE LEADING EDGE OF A MODIFIED MARITIME AIR MASS...CHARACTERIZED BY SURFACE DEWPOINTS IN THE 50S TO AROUND 60 DEGREES...HAS RETREATED NORTH TO NEAR SOUTH OF THE BORDER AS OF 07Z. AN AREA OF VERY LOW STRATUS AND FOG HAS DEVELOPED WITHIN THIS MORE MOIST AIR MASS OVER EAST-CENTRAL NC...AND OBSERVATIONAL TRENDS AND FORECAST DATA SUGGEST IT WILL CONTINUE TO DEVELOP NORTH THROUGH ROUGHLY THE US 1 CORRIDOR THROUGH MID-LATE MORNING. IN FACT...AREAS OF FOG...SOME LOCALLY DENSE...AND LOW OVERCAST ARE APT TO BE SLOW TO LIFT/DISPERSE (NOT UNTIL BETWEEN 15-17Z) OWING TO A STRONG SURFACE-BASED INVERSION FROM THE STRONG RADIATIONAL COOLING THAT HAS OCCURRED SINCE SUNSET MON. TEMPERATURES THROUGH NOON OR SO WILL BE SLOW TO RISE THROUGH THE 50S AND 60S IN THOSE AREAS AFFECTED BY THE LOW CLOUDS AND FOG...WHILE THE WESTERN PIEDMONT AND NORTHERN COASTAL PLAIN WARM MORE QUICKLY INTO THE 70S DURING THAT SAME TIME. BY EARLY AFTERNOON...HOWEVER...SUNNY OR MOSTLY SO CONDITIONS AREA- WIDE SHOULD ALLOW THE WARMTH IN A LOW LEVEL THERMAL RIDGE CHARACTERIZED BY LOW PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1400 METERS TO BE REALIZED...WITH HIGHS GENERALLY BETWEEN 80-85 DEGREES. TONIGHT: AREAS OF LOW STRATUS ARE APT TO REDEVELOP AND SPREAD NORTH LATE TONIGHT-EARLY WED...MAINLY OVER THE COASTAL PLAIN...AS LOW LEVEL MOISTURE FURTHER INCREASES IN STRENGTHENING SSW FLOW. MID-HIGH CLOUDS WILL OTHERWISE STEADILY INCREASE FROM THE WEST ESPECIALLY LATE...WITH MILDER LOWS AMIDST SSW STIRRING IN THE 55-60 DEGREE RANGE.
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&& .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
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AS OF 330 AM TUESDAY... A SHEARING SHORT WAVE TROUGH WILL MOVE ACROSS THE GREAT LAKES AND NORTHEAST ON WEDNESDAY INTO WEDNESDAY NIGHT. NWP GUIDANCE IS IN FAIRLY GOOD AGREEMENT IN BRINGING THE ASSOCIATED COLD FRONT SLOWLY EAST ACROSS THE SOUTHERN APPALACHIANS EARLY ON WEDNESDAY THEN MOVE INTO THE PIEDMONT OF NC DURING THE AFTERNOON AND LIKELY REACH THE COAST TOWARD MIDNIGHT. MOISTURE RETURN IS VERY LIMITED AHEAD OF THE SYSTEM BUT GUIDANCE IS SUGGESTING A RATHER NARROW LINE OF SHOWERS WILL TRAIL THE BEHIND THE SURFACE FRONT. GIVEN THE DEEP LAYER FLOW THAT IS LARGELY PARALLEL TO THE FRONT...HAVE OPTED TO SLOW THE ARRIVAL OF THE PRECIPITATION. WE`VE ALSO OPTED TO DEPICT THE NARROW AREA OF SHOWERS IN THE GRIDS VS A BROADER AND LONGER PERIOD OF POSSIBLE RAIN. CONSENSUS SUGGESTS THAT PRECIPITATION AMOUNTS SHOULD BE LESS THAN A TENTH OF AN INCH BUT IT IS WORTH NOTING THAT THE MORE RECENT GFS RUNS HAVE BEEN TRENDING SLIGHTLY WETTER. TEMP FORECAST ON WED WILL BE PROBLEMATIC WITH A REASONABLE BUST POTENTIAL GIVEN THE ARRIVAL OF THE FRONT DURING THE AFTERNOON...BUT WITH THE SLOWER TIMING AND LAGGING RAIN...HAVE OPTED TO RAISE TEMPS UP A DEGREE OR TWO ESPECIALLY IN THE EAST. WEDNESDAYS HIGHS SHOULD RANGE IN THE MID 70S IN THE TRIAD TO LOWER 80S SOUTHEAST. COLD ADVECTION BEGINS FAIRLY QUICKLY BEHIND THE FRONT WITH LOW-LEVEL THICKNESS VALUES DROPPING INTO THE 1330-1350M RANGE BY 12Z THURSDAY. THIS SHOULD SUPPORT LOWS IN THE MID 40S IN THE TRIAD TO THE LOWER 50S IN THE SOUTHEAST.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 252 AM TUESDAY... TROUGH WILL REMAIN OVER THE EAST COAST THURSDAY THROUGH THE WEEKEND. A WEAK AREA OF HIGH PRESSURE WILL BUILD IN TO THE AREA THURSDAY AND FRIDAY... BEFORE ANOTHER COLD FRONT CROSSES THE AREA EARLY ON SATURDAY... BRINGING THE COLDEST AIR SO FAR THIS SEASON. UPPER LEVEL WESTERLY FLOW... AND LIMITED ANTECEDENT MOISTURE... POINT TO A DRY PASSAGE. STRONG PRESSURE GRADIENT DEVELOPS ACROSS THE AREA ON SATURDAY AS A 1032 MB HIGH BUILDS SOUTHEASTWARD FROM THE UPPER MIDWEST ON SATURDAY TO THE CAROLINAS ON SUNDAY... BRINGING GUSTY WINDS AND WELL BELOW NORMAL TEMPERATURES. FROST LOOKS LIKELY ACROSS THE AREA SUNDAY AND MONDAY MORNING... WITH A PROBABLE FREEZE ACROSS TEH PIEDMONT. TEMPERATURES SHOULD BEGIN TO MODERATE ON MONDAY AS HIGH PRESSURE MOVES OFF THE EAST COAST... AND THE UPPER LEVEL RIDGE AXIS MOVES OVER THE AREA. && .CLIMATE... RECORD TEMPERATURES FOR OCTOBER 28TH: MAX HI-MIN RDU 86/1919 69/1984 GSO 86/1919 64/1919 FAY 87/1919 65/2010 && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 230 AM TUESDAY... OBSERVATIONAL AND FORECAST DATA SUGGEST AN AREA OF STRATUS BETWEEN 100-500 FT...AS WELL AS POCKETS OF FOG - INCLUDING SOME LOCALLY DENSE WITH VISIBILITY RESTRICTIONS OF ONE QUARTER MILE OR LESS - WILL DEVELOP NORTH FROM EAST-CENTRAL SC THIS MORNING. THE STRATUS AND FOG ARE MOST LIKELY TO AFFECT KFAY/KRDU/KRWI...AND IF IT INDEED OCCURS...IT WILL LIKELY BE SLOW TO LIFT/DISPERSE (NOT UNTIL BETWEEN 15-17Z) OWING TO A STRONG SURFACE-BASED INVERSION FROM THE STRONG RADIATIONAL COOLING THAT HAS OCCURRED SINCE SUNSET MON. VFR CONDITIONS ARE OTHERWISE EXPECTED THROUGH THE REMAINDER OF THE 06Z TAF PERIOD...WITH SURFACE WINDS INCREASING INTO THE 6-12 KT RANGE...STRONGEST AND OCCASIONALLY GUSTY INTO THE UPPER TEENS KTS AT WESTERN TERMINALS THIS AFTERNOON...BEFORE BECOMING LIGHT ONCE AGAIN THIS EVENING. OUTLOOK: STRENGTHENING SSW FLOW...AND ASSOCIATED MOISTURE ADVECTION AHEAD OF AN APPROACHING COLD FRONT...WILL RESULT IN A CHANCE OF LOW STRATUS LATE TONIGHT THROUGH EARLY WED...PRIMARILY AT EASTERN TERMINALS. THEN THE COLD FRONT...AND ACCOMPANYING CHANCE OF SHOWERS AND EVEN AN ISOLATED THUNDERSTORM AT EASTERN TERMINALS - AND SUB-VFR CONDITIONS - WILL MOVE EAST ACROSS CENTRAL NC WED...INTO WED EVENING AT EASTERN SITES. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...JB LONG TERM...SEC CLIMATE...CBL AVIATION...MWS

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