National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KRAH 051942
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
240 PM EST THU DEC 5 2013

.SYNOPSIS...
A WARM AND MOIST SOUTHERLY FLOW WILL PERSIST THROUGH
FRIDAY...RESULTING IN ABOVE NORMAL TEMPERATURES. A COLD FRONT WILL
MOVE IN FROM THE NORTH EARLY SATURDAY BRINGING MUCH COLDER
TEMPERATURES AND OCCASIONAL RAIN THIS WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1038 AM THURSDAY...

LOW PRESSURE SYSTEM LIFTING NORTH ACROSS THE GREAT LAKES... WITH THE
TRAILING COLD FRONT EXTENDING THROUGH THE OHIO VALLEY INTO THE
SOUTHERN PLAINS. UPPER LEVEL TROUGH OVER THE WESTERN US... WITH A
RIDGE AXIS ALONG THE EAST COAST. A WEAK MIDLEVEL PERTURBATION IN THE
SOUTHWEST FLOW CURRENTLY PRODUCING SHOWERS ACROSS WESTERN GA AND SC
WILL BRING A SLIGHT CHANCE OF SHOWERS AS IT CROSSES THE AREA THIS
AFTERNOON. MOSTLY CLOUDY CONDITIONS WILL CONTINUE THROUGH THE REST
OF THE DAY WITH A MOISTURE RICH AIRMASS IN PLACE... AND WITH LOW
LEVEL THICKNESSES 60 M ABOVE AVERAGE... HIGHS SHOULD BE ABLE TO
REACH MID 60S TO LOW 70S NW TO SE. MILD OVERNIGHT LOWS IN THE LOWER
60S.

&&

.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 300 AM THURSDAY...

DOWNSTREAM OF THE LONG WAVE POSITIVE-TILT TROUGH OVER THE
WESTERN/SOUTHWEST US...AFOREMENTIONED ARCTIC COLD FRONT SAGGING
SOUTHWARD ACROSS THE MID-ATLANTIC AND INTO THE SOUTHERN APPALACHIANS
WILL BECOME PARALLEL TO THE DEEPENING SWLY FLOW ALOFT. FRONT WILL BE
VERY SLOW TO CROSS THE MOUNTAINS ON FRIDAY...LEAVING CENTRAL NC IN
THE WARM SECTOR FRIDAY AFTERNOON/EVENING. THE ANA-FRONTAL STRUCTURE
OF THE FRONT WILL ALSO RESULT IN CONTINUED MOSTLY DRY CONDITIONS FOR
CENTRAL THROUGH FRIDAY AFTERNOON WITH INCREASING POPS FROM NW TO SE
FRIDAY EVENING...ESPECIALLY AFTER MIDNIGHT AS FRONT FINALLY PUSHES
SOUTHEAST INTO THE AREA...FORECAST TO BISECT THE AREA BY DAYBREAK
SATURDAY. WEAK INSTABILITY 200-300 J/KG DEVELOPS IN THE EAST FRIDAY
AFTERNOON...BUT IS ERASED BY NOCTURNAL COOLING/STABILIZATION WELL
BEFORE THE FRONT ARRIVES. THUS...WILL KEEP IT ALL SHOWERS WITH NO
MENTION OF THUNDER.

HIGHS FRIDAY IN THE WARM SECTOR WILL APPROACH RECORD
TERRITORY...RANGING FROM LOWER/MID 70S NW TO UPPER 70S/NEAR 80S
SOUTHEAST. MIN TEMPS FRIDAY NIGHT/SATURDAY MORNING WILL DEPEND ON
TIMING/LOCATION OF THE FRONT BISECTING THE AREA. EITHER WAY EXPECT A
LARGE NW-SE SPREAD IN MORNING LOWS RANGING FROM MID 40S NW TO UPPER
50S/NEAR 60 SE.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
AS OF 230 PM THURSDAY...

MODELS REMAIN IN GOOD CONSENSUS AS TO THE TIMING OF THE FRONTAL
PASSAGE LATE FRIDAY NIGHT THROUGH SATURDAY MORNING. WILL BE A LITTLE
PROBLEMATIC FOR FORECASTING MAX TEMPERATURES AS THE HIGH WILL OCCUR
IMMEDIATELY PRIOR TO FROPA...WHICH COULD ALLOW AN HOUR OR SO FOR
TEMPS TO CLIMB A LITTLE IN THE SOUTH AND EAST SATURDAY MORNING.
MORNING LOWS LOOK TO RANGE FROM AROUND 50 NORTHWEST TO LOWER 60S
SOUTHEAST AND WILL SHOW A FALLING TREND THROUGHOUT THE DAY
NORTHWEST...WITH COLD AIR ADVECTION DELAYED TIL PERHAPS LATE MORNING
IN THE FAR SOUTHEAST. WILL CONTINUE CATEGORICAL POP TREND FROM
FRIDAY NIGHT TO AROUND MID DAY AS STRONG LOW LEVEL LIFT WILL
ACCOMPANY THE FRONT AS IT RACES ACROSS AND SOUTH OF THE AREA BY
AFTERNOON.

ISENTROPIC LIFT BECOMES THE MAJOR PLAYER SATURDAY NIGHT INTO SUNDAY
AS SURFACE COLD AIR ADVECTION UNDERCUTS MOIST SOUTHERLY FLOW AT H925
TO H85 AND ESTABLISHES A PRECIP-SUPPORTED COLD AIR DAMMING REGIME IN
THE USUAL LOCATION. THE MOISTURE LADEN FLOW WILL STRENGTHEN LATER
SATURDAY NIGHT AS A MID LEVEL WAVE LIFTS NORTH OF THE AREA AND
CATEGORICAL POPS FOR LIGHT RAIN ARE WARRANTED...ESPECIALLY
NORTHWEST...THROUGH MOST OF THE DAY SUNDAY.

SOMETHING TO BE WATCHED...TEMPERATURE PROFILES ON FORECAST SOUNDINGS
HAVE TRENDED TOWARDS A POTENTIAL FOR LIGHT FREEZING RAIN IN THE
NORTHWEST PIEDMONT AND ALONG THE NORTHERN TIER COUNTIES AFTER
MIDNIGHT SATURDAY NIGHT INTO SUNDAY MORNING. AT THIS POINT...WITH
TEMPS BOTTOMING OUT NEAR FREEZING AFTER A WARM SPELL...WOULD NOT BE
A MAJOR CONCERN AS IT WOULD BE PRIMARILY ON ELEVATED SURFACES...
LIMBS...POWER LINES...THE LIKE. ONLY TAKES A LITTLE...THOUGH...SO IT
WILL BE MONITORED CLOSELY. MINS SATURDAY NIGHT WILL BE IN THE LOWER
30S NORTH TO UPPER 30S SOUTH. WITH CONTINUED DAMMING THROUGHOUT THE
DAY...SUNDAYS HIGHS WILL SHOW LITTLE INCLINATION TO RISE...AND HIGHS
WILL RANGE FROM MID 30S DEEP IN THE DAMMING REGION TO MID 40S IN THE
SOUTHEAST.

CAD EROSION IS UNDERWAY LATE SUNDAY NIGHT INTO MONDAY AS A SURFACE
LOW ASSOCIATED THE SHORT WAVE MENTIONED ABOVE MOVES NORTH INTO THE
GREAT LAKES WITH AN ASSOCIATED COLD FRONT BECOMING BETTER ORGANIZED
WEST OF THE MOUNTAINS. SOUTHERLY FLOW AHEAD OF THIS FRONT WILL NUDGE
A WARM FRONT UP THE EAST COAST AND WILL ALLOW HIGHS TO WARM INTO THE
60S OVER MUCH OF THE REGION EXCEPT FOR SOME MID 50S IN THE NORTHWEST
WHERE THE COLD AIR WILL LINGER THROUGH THE MORNING. THIS COLD FRONT
WILL MOVE EAST ACROSS THE AREA MONDAY NIGHT OR TUESDAY MORNING...
PROLONGING THE CHANCE OF RAIN THROUGH TUESDAY WITH HIGHS RANGING
FROM THE MID 40S NORTHWEST WHERE THE FRONTAL PASSAGE WILL BE
EARLY...TO MID 50S IN THE EAST. UNSEASONABLY COOL HIGH PRESSURE WILL
BE BUILDING IN BY MIDWEEK WITH HIGHS TOPPING OUT IN THE 40S
WEDNESDAY AND THURSDAY.
-- End Changed Discussion --

&&

.AVIATION /18Z THURSDAY THROUGH MONDAY/...
AS OF 101 PM THURSDAY...

LITTLE IMPROVEMENT THIS AFTERNOON AT KGSO AND KFAY WITH IFR
CONDITIONS... SOME BREAKS IN THE CLOUDS LEADING TO VFR OTHERWISE.
GUIDANCE SENDING MIXED SIGNALS FOR TONIGHT... SHOWING 5-10 KT
SURFACE WINDS AND 1/2 MI FOG. BASED ON LIKELY INCREASING SOUTHWEST
WINDS AHEAD OF THE APPROACHING COLD FRONT... BELIEVE THE MOISTURE
WILL MANIFEST AS LIFR CIGS IN THE WEST... AND IFR CIGS AT KFAY AND
KRWI. LATE MORNING WILL START TO SEE CONDITIONS IMPROVE TO
MVFR/VFR... AND SW WINDS WILL GUST FROM 15-25 KTS ACROSS THE AREA.

SUB-VFR CONDITIONS WILL AGAIN BE LIKELY AS A COLD FRONT CROSSES THE
AREA EARLY SATURDAY... AND UNSETTLED WEATHER WITH PERIODS OF RAIN
CONTINUES THROUGH MONDAY.

&&

.CLIMATE...
RECORD HIGH TEMPERATURES FOR DECEMBER 6TH:

GSO... 76 SET IN 1998
RDU... 80 SET IN 1998
FAY... 80 SET IN 1998

&&

$$

SYNOPSIS...BADGETT/NP
NEAR TERM...SEC
SHORT TERM...CBL
LONG TERM...MLM
AVIATION...SEC CLIMATE...