093
FXUS62 KRAH 201417
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
915 AM EST MON JAN 20 2025
SYNOPSIS
ARCTIC HIGH PRESSURE WILL REMAIN ENTRENCHED ACROSS THE REGION TODAY
THROUGH MIDWEEK, BRINGING BITTER COLD TEMPERATURES. A WAVE OF LOW
PRESSURE WILL TRACK NORTHEAST OFF THE COAST OF THE CAROLINAS
THURSDAY INTO FRIDAY.
NEAR TERM /TODAY AND TONIGHT/
AS OF 915 AM MONDAY...
* COLD WEATHER ADVISORY IN EFFECT FOR ALL OF CENTRAL NC 10 PM
TONIGHT THROUGH 10 AM TUESDAY WITH WIND CHILLS RANGING FROM 2 TO 9
DEGREES
915AM UPDATE: NO MAJOR CHANGES WITH THIS MORNINGS FORECAST UPDATE.
CLEAR SKIES TODAY WITH COOL HIGH PRESSURE FILTERING THROUGHOUT THE
DAY. HIGHS WILL BE CHILLY WITH TEMPS ON TRACK TO ONLY BE IN THE
UPPER 20S NW TO LOW/MID 30S SE.
PREVIOUS DISCUSSION...
VERY COLD TEMPERATURES ARE EXPECTED TODAY AND ESPECIALLY TONIGHT
INTO TUE MORNING AS 1038 MB ARCTIC HIGH PRESSURE OVER THE MID MS
VALLEY SETTLES INTO THE EASTERN TN VALLEY AND SOUTHERN APPALACHIANS.
ALOFT, WSW FLOW WILL PERSIST MOST OF THE DAY AND NIGHT AHEAD OF A
SHORTWAVE TROUGH OVER THE UPPER MS VALLEY AND NORTHERN PLAINS THAT
WILL REACH THE MID MS VALLEY AND GREAT LAKES BY 12Z TUE.
NORTHWEST WINDS TODAY WILL GUST AT TIMES TO 15 TO 20 MPH. ALONG WITH
SURFACE TEMPERATURES RANGING FROM THE UPPER 20S NW TO MID 30S SE
WILL PRODUCE WIND CHILLS INTO THE AFTERNOON OF UPPER TEENS IN THE NW
TO AROUND 30 IN THE SOUTH AND SOUTHEAST. TONIGHT, THE PRESSURE
GRADIENT RELAXES, ALTHOUGH A 5 MPH OR SO WIND WILL LIKELY PERSIST.
ON TOP OF THAT, THE AIRMASS IS SOME 60 M COLDER THAN AVERAGE UNDER
THE ARCTIC AIR. THIS AIRMASS SUPPORTS LOWS RANGING FROM THE LOW
TEENS IN THE NORTHWEST PIEDMONT TO THE MID TEENS IN THE EASTERN
SANDHILLS AND SOUTHERN COASTAL PLAIN. WIND CHILLS TONIGHT COMBINED
WITH LOW TEMPERATURES WILL RANGE FROM 2 TO 9 DEGREES. WHILE SOME
LOCATIONS IN THE NORTH AND NORTHWEST MAY NOT REACH CRITERIA, GIVEN
THE COLDEST AIRMASS OF THE SEASON, DECIDED TO OPT FOR A COLD
ADVISORY FOR ALL OF CENTRAL NC. IT WOULD BE GOOD PRACTICE TO CHECK
ON NEIGHBORS, WEAR APPROPRIATE CLOTHING, AND KEEP PETS INDOORS.
SHORT TERM /TUESDAY AND TUESDAY NIGHT/
AS OF 240 AM MONDAY...
* LIGHT SNOW POTENTIAL STILL UNCERTAIN, BUT GUIDANCE APPEARS TO
CONTINUE TO TREND SOUTH WITH LIMITED SNOW ACCUMULATION
* ARCTIC AIR REMAINS WELL ENTRENCHED AND A COLD WEATHER ADVISORY MAY
AGAIN BE NEEDED TUE NIGHT INTO WED MORNING
ON THE SYNOPTIC SCALE, MOST GUIDANCE INDICATES TWO SHORTWAVE SYSTEMS
WILL DIRECTLY OR INDIRECTLY IMPACT CENTRAL NC TUE NIGHT INTO EARLY
WED. THE FIRST IS A SHORTWAVE TROUGH OVER THE MID MS VALLEY THAT
LOOKS TO BECOME INCREASINGLY SHEARED ON ITS SOUTHERN FLANK AS IT
TRACKS INTO THE MID-ATLANTIC TUE NIGHT AND INTO NEW ENGLAND
OVERNIGHT. A SECOND SHORTWAVE, PRESENTLY ACROSS CA/NV, TAKES A MORE
SOUTHERN TRACK ACROSS THE NORTHERN GULF AND PORTIONS OF NORTHERN FL
AND THE FAR SOUTHEAST US. THE MAIN FORCING WITH THE SYSTEM WILL
LARGELY BE FROM A 180-200 KT JET STREAK ORIENTED SW TO NE FROM THE
CAROLINAS INTO DELMARVA AND OFFSHORE IN THE ATLANTIC. AS OUR AREA
BECOMES SITUATED IN THE RIGHT-ENTRANCE REGION OF THE JET, MAINLY TUE
NIGHT, THERE LOOKS TO BE A ROUGHLY 6 HR PERIOD WHERE FRONTOGENETICAL
FORCING COULD FAVOR LIGHT SNOW. THIS TIME FRAME APPEARS CENTERED ON
ROUGHLY 5-6 PM TUE UNTIL 12-1 AM WED, STARTING EARLIEST IN THE FAR
SOUTHERN PIEDMONT AND ENDING ACROSS THE FAR SOUTHERN COASTAL PLAIN
AFTER MIDNIGHT.
THE DEVIL IN THE DETAILS REMAINS HOW MUCH, IF ANY, WE WILL GET. THE
00Z SUITE OF DETERMINISTIC MODELS, NAMELY THE NAM/GFS/CMC, INDICATE
LESS FRONTOGENESIS WITH THE JET AND FOCUSING MEASURABLE SNOW
CONFINED MAINLY TO THE COASTAL AREAS OF NC. THE GEFS ENSEMBLE MEAN
ALSO SHOWS THIS. THE 00Z ECMWF REMAINS FURTHER NORTH AND WEST WITH
ITS BAND AND APPEARS RELATED TO STRONGER FRONTOGENETICAL FORCING
ALONG/EAST OF US-1 AND ESPECIALLY ALONG/EAST OF I-95. TRYING TO MAKE
A FORECAST DUE TO THESE DIFFERENCES IS DIFFICULT. THE 12Z LREF
SUGGESTS ABOUT A 30-45 PERCENT CHANCE OF AN INCH OVER THE FAR
EASTERN SANDHILLS TO SOUTHERN COASTAL PLAIN, MAINLY DRIVEN BY THE
EPS AND PARTLY THE GEPS. THE COMPETING FACTOR TO ANY LIFT ALOFT IS
THE VERY DRY AIR SEEN IN FORECAST SOUNDINGS FROM THE NAM/GFS.
SNOWFLAKES MAY SUBLIMATE BEFORE REACHING THE GROUND. OUR LATEST
FORECAST DOES NOT REMOVE SNOW POTENTIAL BUT DOES TREND LOWER GIVEN
THE LATEST MODEL TRENDS, WITH ABOUT A HALF INCH OR LESS ALONG/EAST
OF US-1, WITH HALF INCH POTENTIAL CLOSER TO THE COASTAL PLAIN AND
EASTERN SANDHILLS. HOPEFULLY THE MODELS WILL COME INTO BETTER
AGREEMENT LATER TODAY. HIGH-RES CAMS WILL ALSO BE TELLING, BUT THE
00Z NAM-NEST IS ALSO VERY DRY.
HIGH TEMPERATURES TUE WILL BE VERY COLD IN THE UPPER 20S NW TO LOW
30S SE. LOWS WILL RANGE FROM THE MID/UPPER TEENS TO LOW 20S, WITH
WIND CHILLS IN THE SINGLE DIGITS TO LOWER TEENS. AS A RESULT, A COLD
WEATHER ADVISORY MAY BE NEEDED AGAIN.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
AS OF 300 AM MONDAY...
* HIGH CONFIDENCE BELOW TO WELL BELOW NORMAL TEMPERATURES WILL
CONTINUE THROUGH SAT, WITH GREATEST DEPARTURES FROM NORMAL
EXPECTED WED AND THU.
* ANOTHER COASTAL SYSTEM COULD RESULT IN SOME WINTRY PRECIPITATION
ACROSS THE SOUTHEAST HALF OF CENTRAL NC THU/THU NIGHT, HOWEVER
CONFIDENCE IS LOW AT THIS TIME.
WEDNESDAY AND THURSDAY: ALOFT, THE S/W WILL MOVE ACROSS THE
SOUTHEAST US/MID-ATLANTIC AND OFFSHORE ON WED. MEANWHILE, WITHIN THE
BROAD PARENT TROUGH OVER THE CENTRAL CONUS, A NRN STREAM S/W WILL
DROP SWD THROUGH THE NRN PLAINS. THIS S/W WILL SWING EWD INTO THE MS
VALLEY AS YET ANOTHER S/W DROPS SWD INTO THE PLAINS WED NIGHT. AS
THESE SHORTWAVES SWING THROUGH THE UPPER MS VALLEY, OH VALLEY, AND
INTO THE NORTHEAST THU/THU NIGHT, THE TROUGH AXIS WILL SHARPEN TO
THE WEST AND THE FLOW ALOFT WILL BECOME INCREASINGLY SWLY OVER
CENTRAL NC. AT THE SURFACE, THE ARCTIC HIGH OVER THE NRN
APPALACHIANS WED MORNING WILL GRADUALLY SHIFT EWD THROUGH THE NRN
MID-ATLANTIC WED, THEN WEAKEN AS IT CONTINUES NEWD THROUGH THE
NORTHEAST US. THE HIGH SHOULD CONTINUE TO RIDGE SWWD THROUGH CENTRAL
NC WED NIGHT, BUT RETREAT OUT OF THE REGION THU AS THE PARENT HIGH
MOVES EWD OUT OVER THE NRN ATLANTIC. MEANWHILE, A SURFACE WAVE/LOW
MAY DEVELOP OFF THE SOUTHEAST US COAST ALONG THE OFFSHORE FRONTAL
ZONE WED NIGHT, AMPLIFYING THE COASTAL TROUGH AS IT LIFTS NEWD OFF
THE CAROLINA COAST ON THU. A STRONGER LOW MAY DEVELOP OFF THE
CENTRAL FL COAST AND QUICKLY MOVE ENEWD TOWARD BERMUDA THU NIGHT.
WITH THE RENEWED CYCLOGENESIS THU/THU NIGHT, 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 ON THU. HOWEVER, STILL EXPECT AT LEAST A SLIGHT
CHANCE, ALBEIT WITH LOW CONFIDENCE, FOR SOME WINTRY PRECIPITATION,
MAINLY ACROSS THE COASTAL PLAIN AND SANDHILLS, THU/THU NIGHT.
TEMPERATURES: HIGHS WED IN THE UPPER 20S NORTH TO LOW/MID 30S SOUTH
AND LOWS WED NIGHT IN THE 10-20 DEGF RANGE NORTH TO SOUTH. WITH THE
AFOREMENTIONED UNCERTAINTY IN MIND, CURRENTLY HAVE HIGHS THU IN THE
MID TO UPPER 30S AND LOWS THU NIGHT IN THE UPPER TEENS TO LOW 20S.
FRIDAY ONWARD: ALOFT, THE PARENT TROUGH WILL WEAKEN AS IT AND ITS
EMBEDDED SHORTWAVES MOVE EWD THROUGH THE EASTERN US FRI/FRI NIGHT.
THE FLOW MAY BECOME BRIEFLY ZONAL/BROADLY ANTICYCLONIC SAT/SAT
NIGHT, HOWEVER THE MEDIUM-RANGE GUIDANCE DIVERGES THEREAFTER. AT THE
SURFACE, AS THE LOW MOVES AWAY FROM THE EAST COAST FRI/FRI NIGHT,
HIGH PRESSURE OVER THE SRN PLAINS WILL MOVE EWD THROUGH THE DEEP
SOUTH AND SOUTHEAST. THE HIGH SHOULD LINGER OVER THE SOUTHEAST
US/MID-ATLANTIC SAT/SAT NIGHT. TEMPERATURES SHOULD GRADUALLY
MODERATE TO NEAR NORMAL FROM FRI-SUN. THE WEATHER SHOULD REMAIN DRY
FRI AND SAT, WITH THE NEXT CHANCE FOR PRECIPITATION POSSIBLE SUN/SUN
NIGHT.
AVIATION /12Z MONDAY THROUGH FRIDAY/
AS OF 610 AM MONDAY...
THERE IS HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE 24-HOUR TAF
PERIOD. WINDS HAVE TURNED CALM AT MOST TERMINALS INTO THE EARLY
MORNING HOURS OF MON. AFTER DAYBREAK, HOWEVER, SOME GUSTS OUT OF THE
NW ARE EXPECTED, RANGING IN THE 14-18 KT RANGE. THESE GUSTS ARE
EXPECTED TO DIMINISH EARLIER THAN EXPECTED, WITH MOST GUIDANCE NOW
SUGGESTING BETWEEN 18 AND 20Z. WINDS SHOULD REMAIN CALM THE
REMAINDER OF THE PERIOD, WITH MID AND HIGH CLOUDS BUILDING IN TOWARD
THE END OF THE TAF PERIOD.
OUTLOOK: ALTHOUGH UNCERTAINTY REMAINS HIGH, LIGHT SNOW IS POSSIBLE
TUE NIGHT INTO EARLY WED. AMOUNTS ARE EXPECTED TO BE LIGHT, WITH ANY
ACCUMULATIONS MOST FAVORED AT FAY. OTHERWISE, VFR CONDITIONS ARE
EXPECTED THROUGH THE PERIOD.
CLIMATE
RECORD LOW MAXIMUM TEMPERATURES:
JANUARY 20:
KGSO: 29/1983
KRDU: 28/1970
JANUARY 21:
KFAY: 31/1983
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 FROM 10 PM THIS EVENING TO 10 AM EST TUESDAY
FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089.
SYNOPSIS...KREN
NEAR TERM...CA/KREN
SHORT TERM...KREN
LONG TERM...KC
AVIATION...KREN
CLIMATE...RAH
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