303
FXUS62 KRAH 210826
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
326 AM EST TUE JAN 21 2025
SYNOPSIS
ARCTIC HIGH PRESSURE WILL REMAIN ENTRENCHED ACROSS THE REGION
THROUGH MID WEEK, BRINGING BITTERLY COLD TEMPERATURES. AN UPPER
LEVEL DISTURBANCE WILL MOVE OVER THE SOUTHEAST STATES LATE TUESDAY
THROUGH TUESDAY NIGHT. LATER IN THE WEEK, A WAVE OF LOW PRESSURE
WILL TRACK NORTHEAST OFF THE COAST OF THE CAROLINAS THURSDAY INTO
FRIDAY.
NEAR TERM /THROUGH TONIGHT/
AS OF 1030 PM MONDAY...
* A COLD WEATHER ADVISORY IS IN EFFECT FOR ALL OF CENTRAL NC FROM
NOW THROUGH 10 AM TUESDAY WITH WIND CHILLS IN THE SINGLE DIGITS
EXPECTED.
NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST THIS EVENING. SKIES
ARE CLEAR ACROSS CENTRAL NC AS HIGH PRESSURE EXTENDS FROM THE TN
VALLEY INTO THE NORTHERN MID-ATLANTIC. THIS ARCTIC HIGH WILL BRING
VERY DRY AND BITTERLY COLD CONDITIONS TO CENTRAL NC TONIGHT, WITH
LOW-LEVEL THICKNESS VALUES IN THE 1245-1265 M RANGE. DEW POINTS
RANGE FROM 0 TO 5 BELOW OVER THE NORTHERN AND WESTERN PIEDMONT TO
SINGLE DIGITS ELSEWHERE. WHILE SOME MID AND HIGH CLOUDS WILL BEGIN
TO SPREAD IN FROM THE SOUTH AND WEST BY EARLY MORNING, IT SHOULD BE
LATE ENOUGH THAT LOW TEMPERATURES WILL ALREADY BE REACHED IN MANY
AREAS, RANGING FROM LOWER-TEENS IN THE FAR NW TO NEAR 20 IN THE FAR
SE. THERE IS ENOUGH OF A PRESSURE GRADIENT THAT LIGHT NORTHERLY
WINDS SHOULD CONTINUE THROUGH THE NIGHT, HELPING WIND CHILLS DROP
INTO THE SINGLE DIGITS TO LOWER TEENS. BE SURE TO DRESS
APPROPRIATELY IF YOU HAVE TO GO OUTSIDE, KEEP PETS INDOORS, AND
CHECK ON THE ELDERLY.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
AS OF 240 PM MONDAY...
* POTENTIAL FOR LIGHT SNOW PERSISTS, MAINLY OVER OUR SOUTHEAST HALF
* ARCTIC OUTBREAK CONTINUES; ANOTHER COLD WEATHER ADVISORY LIKELY
TUE NIGHT INTO WED MORNING
TUE/TUE NIGHT: DEEP FRIGID AIR REMAINS IN PLACE, WITH AN ARCTIC
SURFACE HIGH COVERING MUCH OF THE CENTRAL AND E CONUS, DRIVING OUR
THICKNESSES DOWN TO 55-70 M BELOW NORMAL. THE SURFACE COLD AIR OVER
THE WARM WATERS OF THE GULF AND ATLANTIC WILL SUPPORT MAINTENANCE OF
THE SURFACE FRONTAL ZONE TO OUR SE, AS A LARGE UPPER LEVEL TROUGH
AXIS FROM THE GREAT LAKES DOWN TO N MEXICO EARLY TUE SHIFTS EASTWARD
THROUGH THE SOUTHEAST AND CAROLINAS WITH A POSITIVE TILT THROUGH TUE
NIGHT. WHILE HIGH AND MID LEVEL CLOUDS WILL STEADILY INCREASE FROM
THE WSW TUE AS THE TROUGH APPROACHES, THE DAYTIME HOURS WILL BE DRY
GIVEN THE STUBBORN DRY AIR BELOW 700 MB FOR MUCH OF THE DAY. LATEST
GUIDANCE AND UPSTREAM READINGS STILL SUPPORT HIGH IN THE LOW-MID 30S
OVER MUCH OF THE AREA EXCEPT UPPER 20S/AROUND 30 IN THE TRIAD AND AT
THE VA BORDER. CLOUD BASES WILL DROP GRADUALLY ACROSS THE S AND SE
LATE TUE AND PARTICULARLY INTO TUE EVENING, AS UPPER DIVERGENCE
WITHIN THE RIGHT ENTRANCE REGION OF A NEARLY 200 KT JET WILL PROVIDE
DEEP LAYER FORCING FOR ASCENT AS IT CROSSES THE GULF STATES AND
CAROLINAS THROUGH TUE EVENING AND THE EARLY MORNING HOURS OF TUE
NIGHT. THIS WILL SUPPORT A SWATH OF PRECIPITATION ACROSS AREAS OF
THE DEEP SOUTH AND SOUTHERN/EASTERN CAROLINAS, AREAS UNACCUSTOMED TO
FROZEN PRECIP. CONFIDENCE IS HIGH THAT THE THERMAL AND WET BULB
COLUMN WILL BE BELOW FREEZING IN ITS ENTIRETY ACROSS ALL OF CENTRAL
NC TUE EVENING/NIGHT, STRONGLY FAVORING A PRECIP TYPE OF ALL SNOW
WITH WHATEVER FALLS IN OUR AREA. THE LAST SEVERAL RUNS OF THE LARGE
SCALE MODELS HAVE BEEN BACK AND FORTH WITH HOW FAR INLAND THE PRECIP
GETS INTO CENTRAL NC, WITH THE GFS/GEFS OUTPUT GENERALLY THE DRIEST
(BACK EDGE OF THE PRECIP FARTHER SE) AND THE ECMWF/ENS OUTPUT
GENERALLY THE WETTEST (BACK EDGE WELL NW INTO OUR AREA). THE MORE
RECENT RUNS ARE COMING INTO BETTER AGREEMENT, DEPICTING THE BACK
EDGE OF A DUSTING THREAT NEAR OR JUST SE OF RALEIGH, AND THE HIGHER
PROBABILITIES OF A HALF INCH CONFINED TO AREAS SE OF A CLINTON-TO-
GOLDSBORO LINE. AND NOW WE HAVE THE ADDED VOTES OF SOME HIGH-RES
MODEL OUTPUT, WHICH SUPPORT HOLDING THE NOTEWORTHY ACCUMULATIONS IN
OUR FAR SE, WHILE FURTHER NW TOWARD SOUTHERN PINES, RALEIGH, AND
WARRENTON, FALLING PRECIP WILL BE FIGHTING THE LOW LEVEL DRY AIR AS
THE SURFACE HIGH CORE SHIFTS INTO THE OHIO VALLEY AND CENTRAL
APPALACHIANS; THIS REGION SHOULD SEE LITTLE MORE THAN A DUSTING,
WITH ONLY A FEW INCONSEQUENTIAL FLURRIES IN THE TRIAD REGION.
FOCUSING ON THE HIGHER RES MODELS, THE CHANCES OF ONE-HALF TO NEAR
ONE INCH OF SNOW IS 30-50% OVER THE SOUTHERN TWO-THIRDS OF SAMPSON
COUNTY, AND MUCH OF THAT SEEMS TO FALL IN A SHORT TIME, BETWEEN 8 PM
AND 12 MIDNIGHT TUE EVENING/NIGHT. CONFIDENCE IS STILL NOT HIGH
ENOUGH TO GO WITH A WINTER WEATHER ADVISORY AT THIS TIME, GIVEN HOW
MUCH LOW LEVEL DRY AIR IS IN PLACE THERE AND THE FACT THAT THE
SURFACE FRONT WILL BE HOLDING WELL SE, BUT IF THE CURRENT MODEL
TRENDS HOLD, WE MAY NEED AN ADVISORY FOR A FEW COUNTIES IN OUR SE.
ANY PRECIP WILL TREND DOWN AND OUT OF OUR SE OVERNIGHT TUE NIGHT.
REGARDLESS OF THE SNOWFALL, IT'S GOING TO BE VERY COLD YET AGAIN,
AND ANOTHER COLD WEATHER ADVISORY WILL LIKELY BE NEEDED, WITH LOWS
IN THE TEENS TO AROUND 20 AND WIND CHILLS IN THE SINGLE DIGITS TO
AROUND 10F.
WED/WED NIGHT: FAIR SKIES ARE EXPECTED WED MORNING AS THE MID LEVEL
SHORTWAVE TROUGH PUSHES TO OUR ESE AND THE ARCTIC SURFACE HIGH
SETTLES TO OUR N, NOSING SOUTHWARD THROUGH CENTRAL NC. BUT ANOTHER
SHORTWAVE TROUGH WITHIN THE FAST/LARGE LONGWAVE TROUGH WILL SWING
THROUGH THE CENTRAL PLAINS INTO THE CENTRAL MISS VALLEY, RESULTING
IN CLOUDS RETURNING WED AFTERNOON AND ESP WED NIGHT AS WE GET INTO
THE LEFT EXIT REGION OF ANOTHER JET EXTENDING FROM S OK/N TX INTO
SC. ONCE AGAIN, ANOMALOUSLY LOW THICKNESSES WILL SUPPORT ANOMALOUSLY
COLD TEMPS, WITH HIGHS FROM THE UPPER 20S/AROUND 30 NW TO THE MID
30S SE. LOWS WED NIGHT IN THE TEENS AS PARTLY CLOUDY SKIES TREND TO
MOSTLY CLOUDY LATE. SUFFICE IT TO SAY, WHATEVER SNOW FALLS TUE
EVENING/NIGHT WILL STICK AROUND AT LEAST THROUGH WED NIGHT. -GIH
LONG TERM /THURSDAY THROUGH MONDAY/
AS OF 320 AM TUESDAY...
* HIGH CONFIDENCE BELOW TO WELL BELOW NORMAL TEMPERATURES WILL
CONTINUE THROUGH SAT, WITH GREATEST DEPARTURES FROM NORMAL
EXPECTED THU.
* ANOTHER COASTAL SYSTEM COULD RESULT IN SOME BRIEF WINTRY
PRECIPITATION ACROSS THE SOUTHERN AND CENTRAL COASTAL PLAIN
THU/THU NIGHT, HOWEVER CONFIDENCE IN OCCURRENCE REMAINS LOW AND NO
ACCUMULATION IS EXPECTED AT THIS TIME.
THURSDAY: ALOFT, SWLY FLOW WILL PREVAIL OVER CENTRAL NC. AS A PAIR
OF NRN STREAM SHORTWAVES SWING THROUGH THE UPPER MS VALLEY, OH
VALLEY, AND INTO THE NORTHEAST THU/THU NIGHT, THE PARENT TROUGH AXIS
WILL SHARPEN WEST OF THE APPALACHIANS. AT THE SURFACE, THE RIDGE
SHOULD QUICKLY WEAKEN AND RETREAT OUT OF THE REGION THU AS THE
ARCTIC HIGH MOVES EWD OUT OVER THE NRN ATLANTIC. MEANWHILE, AN
INVERTED TROUGH WILL AMPLIFY OFF THE CAROLINA COAST ON THU, WITH A
LOW DEVELOPING OFF THE CENTRAL FL COAST. MODEL GUIDANCE VARIES WRT
THE TIMING AND STRENGTH OF THIS LOW, CONTRIBUTING TO THE FORECAST
UNCERTAINTY. THE NAM IS QUICKEST TO DEVELOP THE LOW AND BRINGS IT
CLOSEST TO THE NC COAST. IF THE NAM VERIFIES, MOISTURE COULD GET
PULLED INLAND AS FAR AS THE COASTAL PLAIN AND POSSIBLY FAR ERN
PIEDMONT OF CENTRAL NC. THERE IS CONTINUED UNCERTAINTY WRT
TEMPERATURES AS THE HIGH MOVES AWAY FROM THE NORTHEAST AND CLOUD
COVER INCREASES. FOR NOW, EXPECT HIGHS IN THE MID 30S TO LOW 40S AND
LOWS IN THE UPPER TEENS TO MID 20S. WILL MAINTAIN A SLIGHT CHANCE
FOR SOME WINTRY PRECIPITATION, ALBEIT WITH LOW CONFIDENCE AND NO
ACCUMULATION, MAINLY ACROSS THE SRN AND CNTL COASTAL PLAIN.
FRIDAY ONWARD: FORECAST SHOULD REMAIN DRY THROUGH SAT NIGHT, WITH
INCREASING UNCERTAINTY AND CHANCES FOR PRECIPITATION THEREAFTER.
ALOFT, THE PARENT TROUGH WILL GRADUALLY WEAKEN AS IT MOVES EWD
THROUGH THE EASTERN US AND OFF THE EAST COAST FRI/FRI NIGHT, WITH
THE FLOW BECOMING BRIEFLY ZONAL SAT/SAT NIGHT. MEANWHILE OUT WEST, A
NRN STREAM S/W WILL DROP SWD THROUGH THE PACIFIC NORTHWEST FRI/FRI
NIGHT, THEN CLOSE OFF AS IT CONTINUES SWD THROUGH NV/CA SAT AND SUN.
THE PARENT LOW AND ITS EMBEDDED SHORTWAVES WILL MOVE THROUGH CENTRAL
AND EASTERN CANADA SAT AND SUN. A SRN STREAM DISTURBANCE WILL LIFT
NWD INTO AND BLOSSOMS OVER THE SRN PLAINS/LOWER MS VALLEY SAT AND
SUN. THE MEDIUM-RANGE MODEL SOLUTIONS BEGIN TO DIVERGE THEREAFTER.
EVENTUALLY THE SRN STREAM DISTURBANCE SHOULD MIGRATE EWD, BUT
HOW/WHEN IT IMPACTS CENTRAL NC WILL DEPEND ON THE EVOLUTION OF A NRN
STREAM S/W EXPECTED TO MOVE THROUGH THE UPPER MS VALLEY/WRN GREAT
LAKES SUN/MON. AT THE SURFACE, AS THE LOW MOVES AWAY FROM THE
SOUTHEAST US COAST, HIGH PRESSURE WILL MOVE EWD THROUGH THE DEEP
SOUTH AND SOUTHEAST FRI/FRI NIGHT. THE HIGH WILL SIT OVER THE
SOUTHEAST US/CAROLINAS SAT, THEN WEAKEN AND SHIFT EWD ON SUN. THE
GUIDANCE BEYOND SUN DIVERGES SIGNIFICANTLY, ESPECIALLY WRT A
POTENTIAL LOW PRESSURE SYSTEM DEVELOPING OVER THE SOUTHERN
PLAINS/LOWER MS VALLEY. CONFIDENCE IS LOW WRT THIS SYSTEM AND ITS
IMPACTS, BUT FOR NOW EXPECT PRIMARILY LIQUID PRECIPITATION IF/WHERE
IT OCCURS, WITH THE COLD AIR CHASING IT ON THE BACK SIDE.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
AS OF 1242 AM TUESDAY...
THERE IS HIGH CONFIDENCE IN VFR TO START THE TAF PERIOD. WHILE MOST
OF THE PERIOD THROUGH 18-21Z TUE IS EXPECTED TO ALSO BE VFR, THERE
ARE INCREASING SIGNALS IN THE MODEL GUIDANCE THAT LIGHT SNOW WILL
OVERSPREAD THE TERMINALS FROM THE SOUTHWEST TO NORTHEAST. SEVERAL OF
THE 00Z MODEL DATA HAVE COME IN WITH HIGHER PROBABILITIES OF SNOW
ACROSS THE EASTERN TERMINALS (RDU/FAY/RWI), WITH HIGHEST
PROBABILITIES FROM FAY TO RWI. GIVEN A MORE CONSISTENT SIGNAL FOR
SNOW IN BOTH PROBABILISTIC AND DETERMINISTIC GUIDANCE, OUR
CONFIDENCE IS HIGHEST THAT FAY/RWI ARE LIKELY TO SEE IFR OR LOWER
RESTRICTIONS. THE CURRENT TIMING FOR THE SNOW IS ROUGHLY FROM 22-23Z
TUE TO 05-06Z WED. AT RDU, THE BAND OF LIGHT SNOW MAY SKIRT JUST TO
THE EAST BUT CONFIDENCE WAS HIGH ENOUGH TO INCLUDE AT LEAST MVFR VIS
RESTRICTIONS. AT GSO/INT, CONFIDENCE IS TOO LOW TO INTRODUCE SNOW OR
SUB-VFR RESTRICTIONS, BUT DID INCLUDE A PROB30 FOR POTENTIAL LIGHT
SNOW BETWEEN 21 AND 24Z. SOME GUSTS TO 16 KT ARE POSSIBLE LATE IN
THE TAF PERIOD FROM THE N AND NW.
OUTLOOK: LIGHT SNOW SHOULD END AT THE EASTERN TERMINALS EARLY WED,
WITH VFR RETURNING. A SYSTEM IS FORECAST TO CROSS THE REGION FRI
INTO SAT, BUT CONFIDENCE ON ANY SUB-VFR RESTRICTIONS IN WINTRY
PRECIPITATION IS TOO LOW AT THE MOMENT.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
JANUARY 22:
KGSO: 29/2014
KRDU: 27/1970
JANUARY 23:
KGSO: 28/1954
KFAY: 30/1970
RECORD LOW MINIMUM TEMPERATURES:
JANUARY 23:
KRDU: 8/1977
KFAY: 9/1970
RAH WATCHES/WARNINGS/ADVISORIES
COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
COLD WEATHER ADVISORY FROM 3 AM TO 10 AM EST WEDNESDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
WEDNESDAY FOR NCZ028-043-078-088-089.
SYNOPSIS...HARTFIELD
NEAR TERM...DANCO
SHORT TERM...HARTFIELD
LONG TERM...KC
AVIATION...KREN
CLIMATE...RAH
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