639
FXUS62 KRAH 191628
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1128 AM EST WED FEB 19 2025
SYNOPSIS
LOW PRESSURE WILL TRACK ACROSS AND JUST OFFSHORE THE GULF AND
SOUTH ATLANTIC STATES THROUGH TONIGHT. ARCTIC HIGH PRESSURE
WILL FOLLOW AND MIGRATE FROM THE NORTHERN PLAINS TO THE MIDDLE
ATLANTIC, WHILE WEAKENING AND MODIFYING, THROUGH THE WEEKEND.
NEAR TERM /THROUGH THURSDAY/
AS OF 1125 AM WEDNESDAY...
* NEW THIS MORNING: SAMPSON, WAKE AND JOHNSTON COUNTIES HAVE BEEN
UPGRADED TO THE WINTER STORM WARNING.
* WINTER STORM WARNING AND ADVISORY HAVE BEEN EXTENDED TO 1 PM
THURSDAY TO ACCOUNT SNOW SHOWERS THURSDAY MORNING.
* SNOW/ICE ACCUMULATION CHANGES: INCREASED ICE ACCUMULATION IN THE
SOUTHERN COASTAL PLAIN WITH MINIMAL CHANGES TO THE SNOW AMOUNTS.
REGIONAL RADAR IMAGERY AND SURFACE OBSERVATIONS TELL THE STORY THIS
MORNING. PREDOMINANTLY UPPER-LEVEL DRIVEN RADAR RETURNS OVER
THE TRIAD HAVE THUS FAR STRUGGLED TO REACH THE GROUND WITH 5 TO
8 THOUSAND FEET IN THE WAKE OF THE BACKDOOR COLD FRONT.
CONVERSELY, STRENGTHENING WAA AT 925 AND 850 FROM THE SANDHILLS
INTO THE TRIANGLE AND OVER THE COASTAL PLAIN HAS BLOSSOMED
PRECIPITATION IN THE FORM OF MAINLY SNOW AND SLEET AS THE UPPER
FORCING BEGINS TO SPREAD EASTWARD. OVERALL INTENSITY HAS
REMAINED LIGHT THUS FAR WITH SURFACE OBSERVATIONS MOSTLY +3
MILES AND MAINLY SMALL FLAKES OBSERVED AT THE NWS RALEIGH
OFFICE.
THIS REGIME WILL CONTINUE TO EXPAND ACROSS THE AREA THROUGH THE
EARLY AFTERNOON WITH WARMING TEMPERATURES ALOFT BEGINNING TO BROADEN
A WIDE MIXED P-TYPE ZONE. AT THIS TIME (AFTER 1 PM) WILL LIKELY BE
WHEN THE GREATEST IMPACTS TO TRAVEL WILL OCCUR, SO BE SURE TO BE AT
YOUR DESTINATION BY THIS TIME IF LOCATED IN THE WINTER STORM WARNING
AREAS. THIS DEGRADATION OF CONDITIONS IS DUE TO THE WAA ALOFT
EXPECTED TO FURTHER STRENGTHEN AND PRECIPITATION RATES WILL INCREASE
AND LIFT THE TRANSITION ZONE NORTHWARD. HOW FAR NORTH THIS LIFTS IS
STILL UNCERTAIN BUT WILL BE INCREDIBLY IMPORTANT AS HI-RES GUIDANCE
SUGGESTS A BANDING OF PRECIPITATION TO DEVELOP. THIS WILL BE AN AREA
OF MAXIMIZED RATES AND LIKELY A NARROW SWATH OF HIGHER TOTALS. WPC
SNOW BAND GUIDANCE SUGGESTS THIS BAND MAY STRETCH WESTWARD TO
AS FAR AS WAKE AND JOHNSTON COUNTY AND A CONTRIBUTING FACTOR TO
THEIR UPGRADE TO A WINTER STORM WARNING. INCREASED RATES AND
GREATEST ACCUMULATIONS WILL CONTINUE UNTIL AROUND 8 PM TO
MIDNIGHT BEFORE DRYING AIR ALOFT WILL SUBSTANTIALLY DECREASE
PRECIPITATION RATES, BUT CONTINUING COOLING SURFACE TEMPERATURES
MAY RESULT IN SLICK ELEVATED SURFACES AND UNTREATED ROADWAYS
THROUGH THE REMAINDER OF THE NIGHT IN ADDITION TO LIGHT FREEZING
DRIZZLE.
THE APPROACHING STRONG UPPER TROUGH AND STEEPENING LAPSE RATES
WILL RESULT IN THE REDEVELOPMENT OF SNOW SHOWERS THURS MORNING
WITH GREATEST CHANCES TOWARDS THE NC/VA BORDER. OVERALL SNOW
ACCUMULATIONS WILL BE LIGHT, BUT A VERY COLD GROUND, DEEP
SATURATION IN THE DGZ, AND HIGH SNOW RATIOS CAN RESULT IN
EFFICIENT AND QUICK ACCUMULATIONS UP TO AN INCH IN SPOTS, BUT
MOSTLY A DUSTING IS EXPECTED. AS THIS AREA MOVES EAST AND
DOWNSLOPING DRYING TAKES OVER BEHIND A COLD FRONT, STRONG WIND
GUSTS OF 20 TO 30 MPH WITH INFREQUENT GUSTS UP TO 35 MPH
POSSIBLE. SOME GUSTINESS MAY CONTINUE OVERNIGHT DUE TO CONTINUED
CAA, BUT MAY BE MORE INFREQUENT AND LOWER THAN DURING THE
AFTERNOON/EVENING. LOWS TONIGHT WILL SETTLE IN THE 20S WITH
HIGHS ON THURS IN THE 30S. INCREASING SUNSHINE THROUGH THE
AFTERNOON WILL HELP TO MELT SOME SNOW/ICE BEFORE SUNSET.
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/
AS OF 220 AM WEDNESDAY...
* VERY COLD CONDITIONS THURSDAY AND FRIDAY NIGHTS WITH LOWS 14 TO 20
DEGREES BELOW AVERAGE.
* WIND CHILL VALUES ON FRIDAY MORNING WILL RANGE BETWEEN 10 AND 15
DEGREES AND THEY COULD BRIEFLY DROP INTO THE SINGLE DIGITS.
COLD ARCTIC HIGH PRESSURE ACROSS THE CENTRAL PLAINS ON THURSDAY
EVENING WILL EXTEND INTO THE MIDDLE ATLANTIC THROUGH EARLY SATURDAY
MORNING. THE COMBINED CIRCULATION AROUND THE HIGH AND THE DEPARTING
WINTER STORM WITH RESULT IN A PERIOD OF COLD ADVECTION AND VERY
COLD CONDITIONS. LOW LEVEL THICKNESS VALUES ARE FORECAST TO
DROP INTO THE 1260'S ON FRIDAY MORNING SUPPORTING LOWS IN THE
MID TEENS TO AROUND 20 DEGREES. THESE TEMPERATURES COMBINED A
NORTHWEST WIND OF 5 TO 10 MPH WILL RESULT IN WIND CHILLS VALUES
OF 10 TO 15 DEGREES WHICH MAY BRIEFLY DROP INTO THE SINGLE
DIGITS FRIDAY MORNING.
EXPECT COLD AND FAIR WEATHER ON FRIDAY WITH BRIGHT SUNSHINE AND
CHILLY TEMPERATURES. HIGHS IN THE IN THE NORTHERN COASTAL PLAIN AND
VA BORDER COUNTIES WILL LIKELY BE CHILLED BY SNOW/ICE COVER AND
MELTING WITH HIGHS IN THE UPPER 30S. MOST OTHER LOCATIONS WILL HAVE
HIGHS IN THE LOWER 40S. THESE HIGHS ARE 12 TO 20 DEGREES BELOW
AVERAGE.
ANOTHER CHILLY NIGHT IS EXPECTED ON FRIDAY NIGHT. A NORTHERN STREAM
WAVE WILL APPROACH FROM THE MO/OH VALLEYS AND COULD RESULT IN SOME
INCREASED HIGH CLOUDS. LOW LEVEL THICKNESS VALUES WILL WARM 20 TO
25M FROM THE PREVIOUS 24 HOURS. THIS SHOULD RESULT IN A NIGHT THAT
WONT BE AS COLD AS THURSDAY NIGHT BUT WITH A SHALLOW COLD AIRMASS IN
PLACE LOWS SHOULD RANGE IN THE UPPER TEENS TO LOWER 20S. -BLAES
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 250 AM WEDNESDAY...
NWP GUIDANCE NOTES THAT A MID AND UPPER LEVEL SHORT WAVE TROUGH WILL
MOVE FROM THE TN VALLEY ON SATURDAY MORNING AND OFF THE CAROLINA
COAST ON SATURDAY NIGHT. THIS FEATURE HAS LIMITED MOISTURE BUT SOME
GUIDANCE NOTES THAT A SURFACE REFLECTION MAY DEVELOP NEAR AND JUST
OFF THE SOUTHEAST COAST ON SUNDAY MORNING BEFORE MOVING NORTHEAST
AWAY FROM AREA ON SUNDAY NIGHT. OUR FORECAST INCREASED CLOUD
COVER ACROSS THE AREA FOR SATURDAY INTO EARLY MONDAY BUT GIVEN
MOST OF THE FORCING FOR ASCENT IS OFF THE COAST AND JUST ABOUT
EVERY MEMBER OF THE LATEST GFE AND EC ENSEMBLES NOTE NO
PRECIPITATION, WILL KEEP THE FORECAST DRY. A GENERALLY FAIR AND
DRY NORTHWEST FLOW IS EXPECTED FOR LATE SUNDAY INTO LATE
MONDAY. THERE IS A SIGNAL FOR PERTURBATIONS IN THE NORTHWEST AND
WESTERLY FLOW TO APPROACH OR MOVE INTO THE AREA FOR LATE
TUESDAY AND INTO WEDNESDAY. GUIDANCE IS ALL OF THE PLACE WITH
HOW THIS WILL SHAKE OUT BUT A HANDFUL OF GFS/EC ENSEMBLE MEMBERS
PRODUCING LIGHT PRECIPITATION FOR LATE TUESDAY AND WEDNESDAY.
GIVEN THE UNCERTAINTY WILL KEEP THE FORECAST DRY. TEMPERATURES
SHOULD GENERALLY MODERATE THROUGH THE PERIOD WITH HIGHS IN THE
40S TO NEAR 50 ON SATURDAY MODERATING INTO THE LOWER TO MID 50S
ON SUNDAY AND THE LOWER TO MID 60S ON TUESDAY. -BLAES
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
AS OF 700 AM WEDNESDAY...
LOW PRESSURE WILL STRENGTHEN AND TRACK ALONG AND JUST OFFSHORE THE
COAST OF THE CAROLINAS THROUGH TONIGHT; AND AS IT DOES SO,
PRECIPITATION AND FLIGHT RESTRICTIONS WILL EXPAND ACROSS CNTL NC.
ASSOCIATED VFR CONDITIONS AT THE START OF THE FORECAST PERIOD WILL
DETERIORATE TO MVFR, AND POTENTIALLY IFR ESPECIALLY AT ERN SITES,
FROM LATE THIS MORNING THROUGH AFTERNOON, THEN REMAIN SO THROUGH THE
END OF THE TAF PERIOD. THE PRECIPITATION TYPE AT INT/GSO SHOULD BE
ALL SNOW, WHILE A SNOW AND SLEET MIX WILL BE MORE LIKELY AT RDU AND
ESPECIALLY RWI. AFTER A SHORT PERIOD OF RAIN AT ONSET AT FAY, THE
PREDOMINANT P-TYPE THERE WILL BE FREEZING RAIN. ALTHOUGH FLIGHT
RESTRICTIONS WILL LIKELY BE RELATIVELY STEADY OVERNIGHT, THERE
REMAINS A CHANCE THAT PRECIPITATION MAY TAPER TO LIGHT FREEZING
RAIN/FREEZING DRIZZLE, WHEN LIFT WILL DIMINISH AND THE CLOUD LAYER
MAY BECOME DOMINATED BY SUPERCOOLED WATER VERSUS ICE.
OUTLOOK: LIGHT SNOW WILL PROBABLY REDEVELOP AND MAINTAIN FLIGHT
RESTRICTIONS WITH THE PASSAGE OF A VIGOROUS MID/UPR-LEVEL TROUGH
EARLY THU, BEFORE SKIES CLEAR TO VFR AND NWLY SURFACE WINDS
STRENGTHEN AND BECOME GUSTY DURING THE AFTERNOON.
RAH WATCHES/WARNINGS/ADVISORIES
WINTER STORM WARNING UNTIL 1 PM EST THURSDAY FOR NCZ007>011-
026>028-041>043-078-089.
WINTER WEATHER ADVISORY UNTIL 1 PM EST THURSDAY FOR NCZ021>025-
038>040-073>077-083>086-088.
SYNOPSIS...MWS
NEAR TERM...SWIGGETT
SHORT TERM...BLAES
LONG TERM...BLAES
AVIATION...MWS/HELOCK
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