Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 210734
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
235 AM EST FRI NOV 21 2014

.SYNOPSIS...BEHIND A COLD FRONT...HIGH PRESSURE BUILDS OVER THE
REGION FOR TODAY AND SATURDAY. A STRONG LOW PRESSURE SYSTEM MOVING
FROM THE SOUTH PLAINS INTO THE GREAT LAKES SUNDAY SPREADS MOISTURE
OVER THE ENTIRE REGION DURING THE DAY SUNDAY. ANOTHER COLD FRONT
MOVES EAST ACROSS MUCH OF THE MID-ATLANTIC AND CAROLINAS ON MONDAY.

&&

.NEAR TERM /TODAY THROUGH SATURDAY NIGHT/...
AS OF 235 AM FRIDAY...

THE LATEST SURFACE ANALYSIS SHOWED THE COLD FRONT ALMOST THROUGH
CENTRAL NORTH CAROLINA WITH COOLER...DRIER AIR GRADUALLY MOVING
SOUTH. MSAS SHOWED THE SURFACE DEW POINT GRADIENT TIGHTENING OVER
THE NORTHWEST PART OF THE STATE AND SOON THIS DRIER AIR WILL BEGIN
PUSHING SOUTH AND SOUTHEAST WITH SURFACE DEW POINTS OVER MUCH OF
CENTRAL NORTH CAROLINA FALLING FROM AROUND 10 TO THE TEENS DURING
THE DAY. THE 00Z 850MB ANALYSIS NOTED NOTICEABLE COOLING TO THE
NORTHWEST...FROM 2C AT KGSO AND -2C AT KRNK TO -11C AT KILN. 1000-
850MB THICKNESSES WILL RISE LITTLE IF AT ALL TODAY AND THE RESULT IS
AROUND 10F OR SO OF COOLING TODAY...DESPITE THE MANY TEMPERATURES IN
THE 30S AS OF THIS WRITING. SOME CIRRUS IN THE BASE OF THE BROAD
UPPER TROUGH MAY BE NOTICED ESPECIALLY THIS MORNING...BUT THE BUFR
SOUNDINGS AND THE CANADIAN CLOUD COVER MODEL SUGGEST ENOUGH DRYING
ALOFT ALTHOUGH THE 300MB JET AXIS WILL BE OVERHEAD THAT MUCH OF ANY
CIRRUS SHOULD BE ABSENT BY AFTERNOON. THIS COULD BE QUITE POSSIBLY
DUE TO SOME UPSTREAM ENHANCEMENT ON WATER VAPOR IMAGERY MOVING
ACROSS THE OHIO VALLEY MOVING EAST BY THEN. THE SURFACE GRADIENT IS
A LITTLE TIGHTER THIS MORNING AND BUFR SOUNDINGS SUGGEST A FEW GUSTS
IN THE MIDDLE AND UPPER TEENS POSSIBLE WITH MIXING BEFORE HIGH
PRESSURE MOVING OVERHEAD TONIGHT REALLY LIGHTENS THE WINDS.

OVERNIGHT...HIGH-LEVEL RELATIVE HUMIDITY FORECASTS FROM THE NAM AND
GFS SUGGESTS THE POTENTIAL FOR SOME THIN CIRRUS AS THE BROAD RIDGE
AXIS APPROACHES FROM THE WEST. THE CANADIAN CLOUD COVER MODEL
DEPICTS SIMILAR CONDITIONS TO THE MAV AND MET MOS...CLEAR TO FEW
CLOUDS WHICH...UNDER A LIGHT WIND AND DRY SURFACE DEW POINTS...
SHOULD ALLOW TEMPERATURES TO FALL QUICKLY TONIGHT. MAV AND MET
GUIDANCE ARE CLOSE AND TENDED TO STRAY COOLER ESPECIALLY FROM THE
TRIANGLE NORTH AND EAST WHERE ANY CIRRUS SHOULD BE EVEN THINNER AND
LESS NOTICEABLE. THINK SOME TEENS ARE QUITE POSSIBLE ESPECIALLY IN
THE TYPICALLY COOLER LOCATIONS NORTHEAST OF THE TRIANGLE. THE RECORD
LOWS AT KGSO AND KFAY APPEAR SAFE FOR SATURDAY...BUT IT WILL BE
CLOSE AT THE RELATIVELY WARM RECORD LOW AT KRDU. SATURDAY...AGAIN
WITH SOME MOSTLY THIN CIRRUS AROUND...1000-850MB THICKNESSES RISE
ABOUT 30M AND HIGHS SHOULD BE 3 TO 5 DEGREES WARMER THAN THOSE HIGHS
EXPECTED FOR TODAY.

SATURDAY NIGHT...THE 850MB THETA-E GRADIENT IS FORECAST BY THE NAM
AND GFS TO JUST BE MOVING INTO THE FAR SOUTHWEST PIEDMONT BY 12Z
SUNDAY. K INDICES ARE NEAR 0 OR NEGATIVE ON THE GFS THROUGH SATURDAY
NIGHT...AND THE NAM ONLY INCREASES VALUES INTO THE TEENS IN THE FAR
SOUTHWEST CLOSE TO 12Z SUNDAY. BUFR SOUNDINGS ARE DRY AND STABLE FOR
THE NIGHT...SAVE LATE AND MAINLY ON THE NAM WHERE THE MID-LEVEL
MOISTURE IN A SHALLOW VOLUME INCREASES A LITTLE EARLIER SOUTHWEST.
QPF IS ESSENTIALLY ZERO IN CENTRAL NORTH CAROLINA ON BOTH THE NAM
AND GFS...WITH THE 0.01 LINE ON THE NAM EDGING EVER SO CLOSE TO THE
SOUTHWEST PIEDMONT BY 12Z SUNDAY. WILL MAINTAIN A DRY FORECAST
OVERNIGHT SATURDAY ALTHOUGH A SPRINKLE IS POSSIBLE VERY LATE
SATURDAY NIGHT IN THE FAR SOUTHWEST IF ANY CAN WORK THROUGH WHAT
WILL BE A DRY SUB-CLOUD LAYER. OVERNIGHT LOWS WILL PROBABLY BE
REACHED EARLY IN THE OVERNIGHT...WITH TEMPERATURES FALLING QUICKLY
EARLY AND THEN INCREASING HIGH CLOUDS IN PARTICULAR SLOWING ANY FALL
AND WITH POSSIBLY A MINOR RISE IN TEMPERATURES LATE OVER THE WESTERN
PIEDMONT.

&&

.SHORT TERM /SUNDAY AND SUNDAY NIGHT/...
AS OF 235 AM FRIDAY...

SOUTHERN STREAM TROUGH AND ATTENDANT DEEPENING SURFACE LOW OVER THE
SOUTHERN PLAINS/LOWER MS VALLEY SUNDAY MORNING WILL LIFT NORTHWARD
INTO THE UPPER GREAT LAKES SUNDAY NIGHT. WHILE THE BEST TROUGH
DYNAMICS REMAINS WEST OF THE MOUNTAINS...STRONG/DEEP GULF MOISTURE
TRANSPORT WITHIN THE TRANSIENT EASTWARD PROPAGATING WARM CONVEYOR
BELT WILL RESULT IN A WET SUNDAY-SUNDAY EVENING PERIOD ACROSS THE
CAROLINAS. AS PWATS INCREASE TO 1.5-1.75"(2 SD ABOVE NORMAL)...LOOK
FOR POPS TO QUICKLY RAMP UP SW TO NE LATE SUNDAY MORNING THROUGH THE
AFTERNOON VIA SURGE OF ISENTROPIC LIFT/WAA ATTENDANT TO A NORTHWARD
LIFTING WARM FRONT...AND FURTHER AUGMENTED BY DPVA AHEAD OF
SHORTWAVE DISTURBANCES EJECTING NEWD AHEAD OF THE AFOREMENTIONED
PRIMARY TROUGH LIFTING THROUGH THE TN AND OHIO VALLEY. EXPECT
WIDESPREAD RAINFALL AMOUNTS OF A 0.50" TO AN 1.0".  BULK OF PRECIP
LOOKS TO FALL OVER THE AREA BETWEEN 18Z SUNDAY TO 06Z MONDAY WITH
LIGHT RAIN...DRIZZLE AND/OR AREAS OF FOG THROUGH MONDAY MORNING AS
WE LOSE SATURATION ALOFT.

IMPRESSIVE LOW-LEVEL KINEMATIC WIND FIELDS FUELED BY A 60-65KT LOW-
LEVEL JET COUPLED WITH ENHANCED NEAR SURFACE HELICITY/SHEAR ALONG A
NORTHWARD RETREATING WEDGE FRONT LOOKS TO HAVE LIMITED BUOYANCY TO
WORK WITH MODELS KEEPING THE UNSTABLE PORTION OF THE WARM SECTOR
NEAR OR OFF THE SE COAST. WILL CONTINUE TO MONITOR FOR ANY INLAND
INTRUSION OF UNSTABLE AIR INTO INLAND AREAS...BUT BASED ON RECENT
TRENDS WILL KEEP THUNDER OUT OF THE FORECAST.

IN-SITU DAMMING FROM THE OFFSHORE HIGH AND WIDESPREAD RAIN WILL
RESULT IN A SLOW RISE IN TEMPERATURES DURING THE DAY ON
SUNDAY...UNTIL THE WARM FRONT LIFTS NORTH THROUGH THE AREA DURING
THE LATE AFTERNOON/EVENING HOURS. DAYTIME HIGHS WILL OCCUR AFTER
SUNSET IN MANY LOCATIONS WITH TEMPERATURES HOLDING STEADY OR QUITE
POSSIBLY WARM OVERNIGHT. DAYTIME TEMPERATURES HOLDING IN THE 50S
ACROSS THE NW PIEDMONT...WITH 60S ACROSS THE SE.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 235 AM FRIDAY...

MONDAY AND MONDAY NIGHT: IN THE MIDST OF THE UPSTREAM TROUGH OVER
THE CENTRAL US RELOADING...MID-LEVEL DRY AIR INTRUSION FROM THE WEST
AND THE LACK OF APPRECIABLE FORCING WILL RESULT IN MOSTLY DRY
CONDITIONS DURING THE DAY ON MONDAY. MODELS ARE STILL TRYING TO
GENERATE A LITTLE PRECIP UNTIL THE SFC COLD FRONT MOVES THE AREA
MONDAY EVENING/NIGHT...BUT RECENT MODEL TRENDS TO KEEP THE BULK OF
PRECIP EAST OF THE AREA. WILL HANG ON TO SLIGHT TO SMALL CHANCE POPS
WITH HIGHEST CHANCE IN THE EAST. LINGERING LOW-LEVEL MOISTURE
TRAPPED UNDERNEATH A STRONG MID-LEVEL CAP WILL RESULT IN CONTINUED
CLOUDY CONDITIONS ON MONDAY. EVEN WITH THIS OVERCAST/BROKEN CLOUD
DECK...TEMPERATURES IN THE WARM SECTOR WILL WARM INTO THE 60S NW TO
70S SE ON MONDAY.

TUESDAY THROUGH THURSDAY: TUESDAY IS SHAPING UP AS A DRY DAY ACROSS
THE AREA WITH THE STALLED FRONT EAST OF THE AREA WHILE WEAK HIGH
PRESSURE RIDGES IN FROM THE WEST WITH CAA IN THE WAKE OF MONDAY
NIGHT FROPA DROPPING TEMPERATURES BACK TO NEAR NORMAL. THERE IS THEN
A BIT OF UNCERTAINTY REGARDING THE APPROACH OF THE NEXT BATCH OF
SHORTWAVE ENERGY TRAVERSING EASTWARD WITHIN THE BASE OF THE LONGWAVE
TROUGH AND ASSOCIATED SFC CYCLOGENESIS ALONG THE OFFSHORE FRONTAL
ZONE. THE LATEST GFS AND EC HAVE TRENDED WETTER DURING THE TUESDAY
NIGHT-WEDNESDAY PERIOD...WITH PRECIP DEVELOPING INLAND IN THE COOL
SECTOR. FOR NOW...WILL ADD A SLIGHT CHANCE POPS TO COASTAL/EASTERN
PORTIONS OF THE FORECAST AREA...WITH TEMPERATURES RETURNING TO BELOW
NORMAL AS THE UPPER TROUGH MOVES INTO THE EASTERN US.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 1245 AM FRIDAY...

FOR THE 06Z VALID TAF PERIOD...VFR CONDITIONS CONTINUE WITH FEW-TO-
SCATTERED HIGH CLOUDS. THE SURFACE GRADIENT WILL INCREASE DURING THE
LATE NIGHT AND EARLY MORNING HOURS SUCH THAT MODEL SOUNDINGS SUGGEST
A FEW NORTHERLY GUSTS INTO THE TEENS KNOTS WITH MIXING THIS MORNING.
AS THE SURFACE HIGH BUILDS OVERHEAD...WINDS SHOULD BECOME LIGHTER
LATER IN THE DAY WITH MANY CALM SURFACE WINDS TAKING PLACE AFTER
SUNSET.

BEYOND THE 06Z VALID TAF PERIOD...VFR CONDITIONS CONTINUE THROUGH
SATURDAY NIGHT. AS MOISTURE AND PRECIPITATION SPREAD NORTHEAST OVER
CENTRAL NORTH CAROLINA SUNDAY...CONDITIONS SHOULD DETERIORATE
THROUGH MVFR TO IFR IN MOST PLACES AND CONTINUE SUB-VFR AT LEAST
THROUGH SUNDAY NIGHT. AREAS OF MVFR CEILINGS ARE POSSIBLE INTO
MONDAY WITH GUSTY SOUTHWEST WINDS WHICH COULD REACH 40KT BY 2000FT
ALOFT IF THE GFS MODEL VERIFIES. VFR CONDITIONS SHOULD RETURN BY
TUESDAY WITH SOME AREAS OF MID-LEVEL CLOUDS OVER A LIGHTER SURFACE
WIND VEERING NORTHERLY BEHIND A COLD FRONT THAT MOVES THROUGH LATE
MONDAY. THERE IS A CHANCE OF LIGHT RAIN MAINLY TOWARD KFAY AND KRWI
LATE TUESDAY ON THE WEST SIDE OF LOW PRESSURE THAT MOVES ALONG THE
FRONT WHICH WILL LOCATED THEN JUST OFF THE CAROLINA COAST.

&&

.CLIMATE...

RECORD LOW:   GSO  RDUFAY

SAT 11/22 - 13 IN 1914    21 IN 2008    20 IN 2000

&&

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

&&

$$

SYNOPSIS...DJF
NEAR TERM...DJF
SHORT TERM...CBL
LONG TERM...CBL
AVIATION...DJF
CLIMATE...RAH



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