Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 191443
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
943 AM EST FRI DEC 19 2014

.SYNOPSIS...HIGH PRESSURE CENTERED OVER THE MID MISSISSIPPI RIVER
VALLEY WILL GRADUALLY EXTEND INTO THE CAROLINAS TODAY. A WEAK STORM
SYSTEM WILL DEVELOP OVER THE TEXAS GULF COAST TODAY... THEN TRACK
EASTWARD ACROSS THE SOUTHEAST STATES ON SATURDAY. WEAK HIGH PRESSURE
WILL BRIEFLY EXTEND ACROSS CENTRAL NC ON SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 943 AM FRIDAY...

TODAY...AS EXPECTED...EARLIER CLOUDINESS HAS DISSIPATED AND SKIES
HAVE CLEARED OUT NICELY OVER CENTRAL NC. EXPECT THIS TO CONTINUE FOR
THE NEXT SEVERAL HOURS BEFORE SOME HIGHER CLOUDS COULD BEGIN TO
CREEP IN LATER THIS AFTERNOON. PLUS OR MINUS 5 KT WINDS THIS MORNING
GENERALLY OUT OF THE NORTH NORTHWEST. THESE COULD VEER AROUND TO
NORTH OR NORTH NORTHEASTERLY AS THE MORNING PROGRESSES. OTHERWISE
COOL AIRMASS IN PLACE WILL KEEP TEMPERATURES DOWN A BIT BELOW
NORMAL WITH MAX TEMPS IN THE LOWER 50S NORTH TO MID 50S SOUTH. -ELLIS

TONIGHT...A S/W LIFTING E-NE FROM THE SOUTHERN PLAINS WILL ADVANCE
EAST ACROSS THE LOWER MS VALLEY TONIGHT. WARM AIR ADVECTION AHEAD OF
THIS SYSTEM WILL INCREASE MOISTURE ACROSS OUR REGION...RESULTING IN
THICKENING CLOUD COVERAGE FROM THE WEST-SW. MODEST ISENTROPIC
UPGLIDE MAY CAUSE PATCHES OF LIGHT RAIN TO DEVELOP OVER THE FAR
WESTERN-SOUTHERN PIEDMONT PRIOR TO DAYBREAK. MIN TEMPS GENERALLY IN
THE LOW-MID 30S THOUGH SOME PLACES IN THE WEST AND SOUTHWEST WILL
SEE MIN TEMPS OCCUR SHORTLY AFTER MIDNIGHT...WITH TEMPS HOLDING
STEADY THEREAFTER DUE TO THE THICKENING CLOUDS. -WSS

&&

.SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
AS OF 315 AM FRIDAY...

S/W CROSSING THE DEEP SOUTH EARLY
SATURDAY WILL SPREAD MOISTURE INTO CENTRAL NC. BEST LIFT THROUGH THE
COLUMN ASSOCIATED WITH SPEED CONVERGENCE AT 700MB AND MODEST
HEIGHT FALLS IN THE MID LEVELS. THE MODEL GUIDANCE HAS BEEN
TRENDING DRIER COMPARED TO 48-72 HOURS AGO WITH SOME NEAR TERM MODELS
NOW SUGGESTING LITTLE IF ANY MEASURABLE PRECIP OVER THE NORTHERN
PIEDMONT. WILL NEED TO MONITOR THE DEVELOPING RAIN SHIELD OVER THE
LOWER MS VALLEY TODAY...AND THE TN VALLEY/DEEP SOUTH TONIGHT. PER
LATEST MOISTURE PROFILES AND LIFT...FELL THAT A FEW HUNDREDTHS
PROBABLE ACROSS THE PIEDMONT SATURDAY MORNING. THUS HAVE ADJUSTED
POPS BACK INTO THE LIKELY CATEGORY OVER THE NW PIEDMONT AND
MAINTAINED A LIKELY POPS IN THE SOUTH. FOR AREAS NORTH AND EAST OF
RDU..CONTINUED CHANCE POPS. AGAIN...WHAT PRECIP THAT OCCURS WILL BE
LIGHT WITH AMOUNTS VARYING BETWEEN A TRACE TO LESS THAN A TENTH OF
AN INCH.

NAM AND GFS BUFKIT SOUNDINGS SUGGEST A BRIEF OPPORTUNITY FOR MIXED
PRECIP IN THE NW PIEDMONT AROUND DAYBREAK...COINCIDING WITH THE BEST
LIFT. THE GFS AND NAM HAVE TRENDED SLIGHTLY COOLER WITH PARTIAL
THICKNESSES SUGGESTING A RAIN/SNOW MIX POSSIBLE IN THE TRIAD AND
POSSIBLY THE ROXBORO AREAS...MAINLY WHEN HEAVIER PRECIP INTENSITY IS
OCCURRING. WHILE BULK OF PRECIP WILL BE LIQUID...CANNOT RULE OUT THE
POSSIBILITY OF SOME SNOW MIXED IN AT TIMES NORTH OF TEH I-85/40
CORRIDOR IN THE TRIAD.

HIGH TEMPS SATURDAY DEPENDENT UPON EXTENT OF PRECIP SATURDAY AND
WHETHER PRECIP DOES DIMINISH SATURDAY AFTERNOON. HAVE ADJUSTED MAX
TEMPS UP A DEGREE OR TWO.

HAVE LEANED TOWARD A DRIER FORECAST FOR SATURDAY NIGHT AS SUBSIDENCE
IN THE WAKE OF THE DEPARTING S/W SHOULD END THE THREAT OF PRECIP
ACROSS THE REGION BY LATE SATURDAY...AND MORE SO SATURDAY EVENING
WITH SOME DECREASE IN CLOUDS POSSIBLE AFTER SUNSET. IF ENOUGH
CLEARING OCCURS...MAY SEE POCKETS OF FOG DEVELOP AFTER MIDNIGHT. IN
ANTICIPATION OF SOME PARTIAL CLEARING...HAVE LOWERED MIN TEMPS A FEW
DEGREES FROM THE PREVIOUS FORECAST (LOW-MID 30S).

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 320 AM FRIDAY...

SUNDAY: SURFACE HIGH PRESSURE WILL CONTINUE TO EXTEND SOUTHWARD INTO
THE AREA FROM NEW ENGLAND ON SUNDAY... WHILE BRIEF MID LEVEL S/W
RIDGING BUILDS ACROSS CENTRAL NC. HOWEVER... THE NEXT SOUTHERN
STREAM S/W DISTURBANCE WILL BEGIN TO SPREAD CLOUD COVER
NORTHEASTWARD FROM THE GULF OF MEXICO AND INTO OUR REGION. THIS WILL
YIELD PARTLY SUNNY SKIES DURING THE MID MORNING BECOMING MOSTLY
CLOUDY BY LATE DAY INTO THE EVENING. AFTERNOON LOW LEVEL THICKNESS
VALUES ARE EXPECTED TO BE NEAR NORMAL. THUS... GIVEN WE SHOULD SEE
SOME SUN ON SUNDAY EXPECT HIGH TEMPS WILL BE NEAR NORMAL... FROM
AROUND 50 N TO LOWER 50S SOUTH.

SUNDAY NIGHT THROUGH WEDNESDAY: THE AFOREMENTIONED SOUTHERN STREAM
S/W DISTURBANCE WILL LIFT NORTHEASTWARD OUT FROM THE GULF COAST
STATES ON SUNDAY NIGHT INTO MONDAY MORNING... SPREADING WIDESPREAD
RAIN ACROSS ALL OF CENTRAL NC AS ISENTROPIC LIFT RAMPS UP. WITH A
1030 MB SURFACE HIGH STILL EXTENDING SOUTHWARD INTO OUR AREA AS IT
EVER SO SLOWLY SHIFTS EASTWARD EXPECT WE WILL SEE A PRONOUNCED
DAMMING EVENT DEVELOP.... WITH TEMPS FALLING INTO THE UPPER 30S
MONDAY MORNING ACROSS THE NORTHWEST PIEDMONT AND HARDLY MOVING FOR
THE NEXT DAY OR SO. HOWEVER... BOTH THE GFS AND ECMWF CONTINUE TO
DEPICT AN ALL RAIN EVENT ACROSS THE AREA. WITH THE SURFACE LOW
EXPECTED TO LIFT NORTH-NORTHEASTWARD ALONG THE COAST ON MONDAY...
THINK WE COULD SEE OUR COASTAL PLAIN COUNTIES WARM UP A LITTLE BIT
MONDAY... BEFORE THE COLD AIR PUSHES FURTHER EAST AGAIN AS THE
SURFACE LOW MOVES TO THE NORTH AND EAST OF NC ON MONDAY NIGHT. AS
THIS HAPPENS THE MORE SUBSTANTIAL PRECIP WILL COME TO AN END... WITH
ONLY LINGERING AREAS OF LIGHT RAIN AND DRIZZLE REMAINING. LOWS
MONDAY MORNING ARE EXPECTED TO BE IN THE UPPER 30S NW TO LOWER 40S
SE. HIGHS MONDAY WILL BE TRICKY... FOR NOW WILL GO WITH HIGHS
RANGING FROM THE UPPER 30S/NEAR 40 NW TO THE MID 50S FAR E/SE.

A NORTHERN STREAM DISTURBANCE WILL HAVE FORMED A DEEP TROUGH BY
TUESDAY MORNING WITH STACKED LOW PRESSURE OVER THE UPPER MIDWEST.
BOTH THE GFS AND ECMWF ARE IN GOOD AGREEMENT IN SHOWING THE DEEP
ASSOCIATED TROUGH AXIS SHIFTING EASTWARD ON TUESDAY INTO WEDNESDAY
WHILE TAKING ON MORE OF A NEGATIVE TILT... WITH THE ASSOCIATED
SURFACE FRONT AND POSSIBLE TRIPLE POINT LOW MOVING ACROSS CENTRAL NC
ON WEDNESDAY MORNING INTO THE EARLY AFTERNOON (AS IT STANDS NOW...
STILL SEVERAL DAYS OUT THOUGH). QUESTIONS REMAIN AS TO WHERE A
POSSIBLE TRIPLE POINT LOW MAY FORM THOUGH... AS FINER DETAILS LIKE
THIS ARE HARD TO NAIL DOWN THIS FAR OUT IN THE FORECAST. HOWEVER...
WITH THE POTENTIAL FOR A RETREATING CAD BOUNDARY AND STRENGTHENING
LOW LEVEL WIND FIELD... WE WILL NEED TO KEEP AN EYE ON HOW THIS
SYSTEM DEVELOPS. THIS WOULD BE A HSLC TYPE OF SYSTEM. GIVEN THE TIME
OF YEAR IT IS QUITE HARD TO GET THE NEEDED INSTABILITY FOR POSSIBLE
SEVERE STORMS THOUGH. AS THE FRONT APPROACHES AND MOVES THROUGH THE
AREA ON WEDNESDAY MORNING INTO THE AFTERNOON WE SHOULD SEE A BAND OF
RAIN/SHOWERS ALONG AND IN ADVANCE OF IT... WITH THINGS DRYING OUT
QUICKLY BEHIND THE EFFECTIVE FRONT ON WEDNESDAY AFTERNOON.

HIGHS ON TUESDAY WILL BE TRICKY AND DEPEND ON HOW MUCH THE CAD
BOUNDARY RETREATS. FOR NOW WILL GO WITH HIGHS IN THE MID 40S NW TO
AROUND 60S SE. TEMPS BY WEDNESDAY MORNING WILL NOT FALL MUCH... WITH
LOWS WEDNESDAY MORNING IN THE MID 40S NW TO MID 50S SE/E. HIGHS
WEDNESDAY IN THE 50S TO AROUND 60.

WEDNESDAY NIGHT THROUGH THURSDAY: WE SHOULD SEE RAPID CLEARING ON
WEDNESDAY NIGHT AND CONTINUING INTO THURSDAY... WITH A RETURN TO
QUITE WEATHER. LOWS THURSDAY MORNING ARE EXPECTED TO BE IN THE
30S... WITH HIGHS THURSDAY AFTERNOON NEAR NORMAL IN THE UPPER 40S TO
LOWER 50S.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 635 AM FRIDAY...

HIGH PRESSURE CENTERED OVER THE LOWER OH VALLEY WILL GRADUALLY
EXTEND INTO CENTRAL NC THROUGH EARLY THIS EVENING. PATCHES OF MID
LEVEL CLOUDS WITH BASES 6000-8000FT WILL CROSS THE REGION THROUGH
MID MORNING. OTHERWISE VFR CONDITIONS WILL PERSIST. FEWER CLOUDS
ANTICIPATED LATER THIS MORNING THROUGH THE AFTERNOON WITH LIGHT AND
VARIABLE SURFACE WINDS.

A LOW PRESSURE SYSTEM WILL ADVANCE TOWARD CENTRAL NC LATER TONIGHT
AND CROSS THE REGION SATURDAY. AREAS OF LIGHT RAIN WILL DEVELOP
TOWARD DAYBREAK SATURDAY AND CROSS CENTRAL NC SATURDAY MORNING
THROUGH EARLY AFTERNOON. THE LIGHT RAIN FALLING THROUGH THE LOWER
LEVELS OF THE ATMOSPHERE WILL AID TO MOISTEN THIS LEVEL...LEADING TO
THE POTENTIAL FOR PATCHES OF MVFR CEILINGS...MAINLY IN THE 14Z-20Z
SATURDAY TIME FRAME. WINDS EXPECTED TO REMAIN LIGHT AND VARIABLE.

VFR CONDITIONS EXPECTED SATURDAY NIGHT INTO SUNDAY AS WEAK HIGH
PRESSURE EXTENDS ACROSS THE AREA. ANOTHER LOW PRESSURE SYSTEM...THIS
ONE STRONGER THAN THE SATURDAY SYSTEM...WILL BEGIN TO AFFECT CENTRAL
NC SUNDAY NIGHT INTO SUNDAY...LEADING TO A PERIOD OF WIDESPREAD
MVFR/IFR CEILINGS AND AREAS OF RAIN. THE RAIN WILL DIMINISH ACROSS
THE REGION BY MONDAY NIGHT THOUGH MVFR/IFR CEILINGS WILL PERSIST
MONDAY NIGHT INTO TUESDAY.

&&

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

&&

$$

SYNOPSIS...WSS
NEAR TERM...ELLIS/WSS
SHORT TERM...WSS
LONG TERM...BSD
AVIATION...WSS



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