Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 290246
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
946 PM EST SUN DEC 28 2014

.SYNOPSIS...A COLD FRONT WILL MOVE SOUTH THROUGH THE REGION LATER
TONIGHT AND EARLY MONDAY. A WAVE OF LOW PRESSURE WILL DEVELOP ALONG
THE FRONT AND MOVE ACROSS THE REGION MONDAY. THE FRONT WILL MOVE
OFFSHORE MONDAY NIGHT BEFORE HIGH PRESSURE EXTENDS INTO THE REGION
ON TUESDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 730 PM SUNDAY...

THE MAIN COLD FRONT REMAINED TO OUR NW THIS EVENING. RAIN WAS
CONFINED TO JUST BEHIND THE FRONT OVER EASTERN TENNESSEE INTO
SOUTHWEST VIRGINIA MOVING EASTWARD. VERY LITTLE TO NO SHOWERS ARE
NOTED OUT AHEAD OF THE COLD FRONT OVER CENTRAL AND EASTERN NORTH
CAROLINA.

IN THE MEAN TIME... THERE HAVE BEEN ENOUGH BREAKS IN THE CLOUDS OVER
THE WESTERN SANDHILLS AND SOUTHERN/EASTERN PIEDMONT FOR THE
DEVELOPMENT OF PATCHY FOG... SOME DENSE... IN AREAS WHERE SOME LIGHT
RAIN FELL EARLIER. WE WILL ADD SOME PATCHY DENSE FOG IN AREAS FROM
NEAR ALBEMARLE AND TROY NE THROUGH THE SANFORD AND SILER CITY AREAS
TO NEAR AND INCLUDING ROXBORO. AS COLD FRONT DROPS SOUTH INTO
NORTHERN NORTH CAROLINA AFTER MIDNIGHT... CLOUDS WILL THICKEN AND
WINDS WILL SHIFT TO THE NE AT 5-10 MPH. THIS WILL SCOUR OUT THE FOG.

OTHERWISE... CENTRAL NC IS JUST WAITING ON THE FRONT TO DIP INTO THE
REGION AND THE FINAL WAVE TO FORM ON THE FRONT LATER TONIGHT. A GOOD
AREA OF FORCING FOR LIFT WILL DEVELOP BEHIND THE FRONT WITH THE
INCREASE IN WAA AND VERY MOIST FLOW ALOFT AS THE MID/UPPER LEVEL
TROUGH APPROACHES FROM THE WEST. IT APPEARS THAT MUCH OF OUR
RAINFALL WILL BE ANAFRONTAL OR JUST BEHIND THE COLD FRONT LATER
TONIGHT INTO MONDAY MORNING GIVEN THE FAVORABLE CONDITIONS MENTIONED
ABOVE.

THEREFORE... EXPECT THICKENING CLOUDS AND DECREASING FOG OVERNIGHT
WITH RAIN DEVELOPING IN ALL BUT THE SE ZONES. THE SE ZONES SHOULD
SEE THE RAIN DEVELOP AROUND SUNRISE AS THE FRONT SLIPS TO THE SOUTH.
QPF OF 0.50 TO 0.75 IS EXPECTED WITH THIS EVENT... WITH LESSER
AMOUNTS IN THE SE (0.25 TO 0.50 MONDAY). TEMPERATURES SHOULD HOLD IN
THE MID 50S TO AROUND 60 SE... BUT FALL INTO THE 40S NORTH LATER
TONIGHT.

THE RAIN WILL GRADUALLY TAPER TO DRIZZLE MONDAY AFTERNOON AS THE
FAVORABLE UPPER JET AND WARM CONVEYOR BELT RAINS MOVE TO THE NE.
TEMPS WILL FALL INTO 40S AND 50S FROM THE CENTRAL TO THE SOUTHERN
ZONES WITH THE LOW OVERCAST AND NE FLOW.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
AS OF 305 PM SUNDAY...

MONDAY NIGHT INTO TUESDAY... ATMOSPHERE BELOW 700MB TO REMAIN NEARLY
SATURATED AS 925-850MB TROUGH REMAINS WEST OF THE FORECAST AREA
UNTIL TUESDAY AFTERNOON. LIFT TO GENERATE APPRECIABLE PRECIPITATION
LACKING THOUGH 12Z/NAM DOES DEPICT WEAK UPGLIDE AT 290K LEVEL OVER
OUR REGION LATE MONDAY NIGHT-TUESDAY MORNING (GFS DEPICTS NEUTRAL
ADVECTION). MARGINAL UPSLOPE FLOW AT 925 MB MAY GENERATE SPOTS OF
LIGHT RAIN OVER THE NW PIEDMONT OTHERWISE EXPECT AREAS OF DRIZZLE
MONDAY NIGHT THROUGH TUESDAY MORNING. PASSAGE OF 925-850MB TROUGH A
LITTLE SLOWER COMPARED TO MODEL GUIDANCE 24 HOURS AGO. WHILE PARTIAL
CLEARING STILL EXPECTED ACROSS THE FAR WEST-NW PRIOR TO
SUNSET...PARTIAL CLEARING MAY NOT MAKE IT TO THE TRIANGLE AREA OR TO
THE SANDHILLS AND COASTAL PLAIN UNTIL AFTER SUNSET.

MIN TEMPS MONDAY NIGHT MID-UPPER 30S NORTH TO THE LOWER 40S SOUTH.
TEMPS TUESDAY WILL BE HELD DOWN BY EXTENSIVE CLOUDS AND PATCHY LIGHT
RAIN/DRIZZLE. MAX TEMPS TUESDAY LOW-MID 40S NORTH TO THE UPPER
40S/AROUND 50 SOUTH.

TUESDAY NIGHT...PASSAGE OF 925-850MB TROUGH LATE TUESDAY-TUESDAY
NIGHT SHOULD INITIATE SOME PARTIAL CLEARING DUE TO SUBSIDENCE AND
DOWNSLOPE COMPONENT OF LOW LEVEL WINDS. SOME GUIDANCE SUGGEST LOW
CLOUDS HOLDING ON IN THE EAST UNTIL SHORTLY AFTER DAYBREAK
WEDNESDAY. IF PARTIAL CLEARING OCCURS...MAY SEE PATCHY/AREAS OF FOG
DEVELOP AFTER MIDNIGHT. MIN TEMPS UPPER 20S FAR NORTH-NW TO AROUND
30 FAR SOUTH.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 305 PM SUNDAY...

WEDNESDAY AND THURSDAY...S/W IN THE NORTHERN STREAM WILL CROSS THE
GREAT LAKES AND NORTHERN MID ATLANTIC LATE WEDNESDAY AND WEDNESDAY
NIGHT. THIS FEATURE WILL PROPEL A DRY SURFACE COLD FRONT ACROSS
CENTRAL NC WEDNESDAY NIGHT. THIS PASSAGE WILL OCCUR PRETTY
UNEVENTFUL WITH JUST A DECK OF MID-HIGH LEVEL CLOUDS EXPECTED. THUS
PARTIAL CLEARING EARLY WEDNESDAY EXPECTED TO BE SHORT-LIVED AS
APPROACH OF S/W AND ASSOCIATED MID-HIGH LEVEL CLOUDINESS WILL CROSS
CENTRAL NC LATE WEDNESDAY AND WEDNESDAY EVENING. NLY WINDS BEHIND
THIS PASSAGE WILL REINFORCE THE COOL AIR MASS ALREADY IN PLACE BUT
ADVECT A BATCH OF DRIER AIR AS DEWPOINTS WILL LOWER INTO THE
TEENS/LOWER 20S.

LOW LEVEL THICKNESSES BY EARLY THURSDAY ARE IN THE 1290-1295M RANGE.
HISTORICALLY...THIS SUPPORTS MIN TEMPS IN THE MID-UPPER 20S. THE
COOL DRY AIR MASS FOR THURSDAY WILL SUPPORT MOSTLY SUNNY SKIES FOR
THE FIRST DAY OF 2015 WITH AFTERNOON TEMPS WILL AVERAGE 5-6 DEGREES
BELOW NORMAL. HIGH TEMPS THURSDAY MID 40S NORTH TO NEAR 50 SOUTH.

FRIDAY THROUGH SUNDAY... WEATHER PATTERN OVER CENTRAL NC BECOMES
UNSETTLED AS AN UPPER LEVEL LOW WILL SLUGGISHLY LIFT EAST-NE ACROSS
THE MID MS AND OH VALLEYS. MODEL GUIDANCE OFFER DIFFERING SOLUTIONS
WITH TEH GFS MORE PROGRESSIVE THAN THE ECMWF. USUALLY...BETTER TO
LEAN TOWARD THE SLOWER SOLUTION THIS FAR OUT.

EXPECT AIR MASS TO MODIFY FRIDAY AS AS FLOW ASSUMES A RETURN FLOW
OFF THE ATLANTIC. PRECIP CHANCES WILL LIKELY BEGIN TO INCREASE LATE
FRIDAY...AND MORE SO SATURDAY PERSISTING INTO SUNDAY. PRESENCE OF A
MODIFIED ARCTIC AIR MASS IN PLACE OVER CENTRAL NC PRIOR TO PRECIP
ARRIVAL SIGNAL POTENTIAL FOR HYBRID OR INSITU COLD AIR DAMMING
SATURDAY INTO THIS SUNDAY. IF THIS MATERIALIZES...THIS WOULD CREATE
A WIDE VARIANCE IN TEMPS ACROSS CENTRAL NC (CHILLY NW TO RELATIVELY
MILD SE). FOR NOW...WILL KEEP MAX TEMPS CLOSE TO AVERAGE ACROSS THE
PIEDMONT...AND A CATEGORY OR TWO ABOVE NORMAL IN THE SE.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AS OF 946 PM MONDAY...

AVIATION CONDITIONS ARE EXPECTED TO DETERIORATE OVERNIGHT AS A WAVY
SLOW MOVING COLD FRONT MOVES THROUGH THE AREA OVERNIGHT. THERE MAY
BE A BRIEF PERIOD OF SOME DENSE FOG BEFORE THE FRONT FINALLY STARTS
TO MOVE EAST INTO THE AREA...WITH CEILINGS FALLING INTO THE IFR
RANGE AROUND 04-06Z AT KINT/KGSO...AROUND 06-08Z AT KRDU/KRWI AND
AROUND 09-11Z AT KFAY AS A SEVERAL HOUR PERIOD OF LIGHT TO
OCCASIONALLY MODERATE RAIN SPREADS INTO THE REGION. LIGHT SWLY WINDS
IN ADVANCE OF THE FRONT WILL BECOME NORTHERLY AT 5-10KTS BEHIND THE
FRONT AND EVENTUALLY BECOME NORTHEASTERLY ON MONDAY. MEASURABLE
PRECIP CHANCES WILL DIMINISH MONDAY AFTERNOON  BUT A MOIST 1000-
950MB NELY FEED WILL SUPPORT IFR TO LIFR CEILINGS INTO TUESDAY.

LOOKING AHEAD...LINGERING LOW CLOUDS ALONG WITH SOME LIGHT RAIN AND
DRIZZLE WILL CONTINUE INTO TUESDAY AND WILL BEGIN TO IMPROVE LATE
TUESDAY AND WEDNESDAY. FAIR WEATHER AND NO ADVERSE AVIATION
CONDITIONS ARE EXPECTED WEDNESDAY THROUGH EARLY FRIDAY BEFORE THE
NEXT STORM SYSTEM APPROACHES LATE FRIDAY.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...BLAES
NEAR TERM...BADGETT
SHORT TERM....WSS
LONG TERM...WSS
AVIATION...CBL/BLAES



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