530
FXUS62 KRAH 212033
AFDRAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
330 PM EST TUE JAN 21 2025
SYNOPSIS
ARCTIC HIGH PRESSURE WILL REMAIN ENTRENCHED ACROSS THE REGION
THROUGH EARLY THURSDAY. AN UPPER LEVEL DISTURBANCE WILL MOVE OVER
THE SOUTHEAST STATES TONIGHT INTO WEDNESDAY MORNING, BRINGING
SNOW TO THE REGION. 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 330 PM TUESDAY...
* WINTER STORM WARNING HAS BEEN ISSUED FOR A PORTION OF THE COASTAL
PLAIN AND EASTERN SANDHILLS FROM 5 PM UNTIL 7 AM WEDNESDAY.
* WINTER WEATHER ADVISORY IS IN EFFECT FOR A ROW OR TWO OF COUNTIES
WEST OF THE WINTER STORM WARNING. A TIGHT GRADIENT IN SNOWFALL
AMOUNTS IS EXPECTED SOMEWHERE OVER THE ADVISORY AREA.
* COLD WEATHER ADVISORY REMAINS IN EFFECT FOR TONIGHT INTO EARLY
WEDNESDAY MORNING.
NO MAJOR CHANGES WERE MADE TO THE FORECAST FOR THE AFTERNOON UPDATE.
OVER THE PAST HOUR, SEVERAL EM AND MPING REPORTS INDICATE SOME VERY
LIGHT SNOW IS BEGINNING TO REACH THE GROUND FROM THE SOUTHERN
PIEDMONT INTO THE SANDHILLS.
PREVIOUS DISCUSSION AS OF 1240 PM...
THE WINTER STORM THAT IS EXPECTED TO IMPACT OUR AREA LATER THIS
EVENING INTO THE OVERNIGHT HOURS IS WELL UNDERWAY OVER LA, SOUTHERN
MS, AND AL. A POTENT 180 KT 250MB JET WILL CONTINUE TO STRENGTHEN TO
AROUND 200 KTS AS THE RIGHT-ENTRANCE REGION SAGS OVER THE SOUTHERN
MID-ATLANTIC AND SOUTHEAST. THIS WILL BE THE MAIN PLAYER IN BRINGING
IN VERY LIGHT SNOW LATER THIS AFTERNOON AND EVENING. SNOW RATES ARE
EXPECTED TO INCREASE AS THE COLUMN BEGINS TO FURTHER SATURATE AND
STRONG LOW/MID-LEVEL FORCING BEGINS TO SPREAD INTO OUR AREA AFTER
00Z.
TRENDS IN THE LATEST MODEL GUIDANCE SHOWS A STEADY INCREASE THE
LIQUID EQUIVALENT AMOUNTS OVER OUR AREA. NOW, WE ARE ONLY TALKING
ABOUT ON THE ORDER OF A HUNDREDTHS TO A TENTH, BUT ANOMALOUSLY HIGH
SNOW-LIQUID RATIOS FOR THE CAROLINAS RESULTS IN DRASTIC DIFFERENCES
IN THE EVENTUAL SNOWFALL AMOUNTS. A COMBINATION OF MORE LIQUID
EQUIVALENT AND HIGHER SNOWFALL RATIO HAS RESULTED IN 2 TO 4 INCHES
OF SNOW POSSIBLE IN THE WINTER STORM WARNING AREA WITH A DUSTING TO
2 INCHES IN THE ADVISORY AREA. GREATEST ACCUMULATIONS WILL LIKELY BE
FROM 9 PM TO 3 AM.
A COUPLE VERY IMPORTANT POINTS TO REMEMBER FOR THIS EVENT. THE VERY
COLD ANTECEDENT CONDITIONS AHEAD OF THIS SYSTEM WILL RESULT IN
HIGHLY EFFICIENT ACCUMULATIONS AS SOON AS SNOW BEGINS TO FALL. FIRST
FLURRIES WILL LIKELY BEGIN VERY LIGHT AND NOT RESULT IN MUCH IMPACT
UNTIL THIS EVENING WHEN RATES ARE EXPECTED TO INCREASE. HOWEVER,
ONCE SNOW BEGINS TO FALL ON ANY UNTREATED SURFACE, EXPECT SURFACES
TO BECOME IMMEDIATELY SLIPPERY. ALSO, WITH HIGH SNOW-LIQUID RATIOS
RESULTING IN DRY AND POWDERY SNOW, WE ARE NOT EXPECTING MUCH IMPACT
FROM SNOW LOAD, OR STRESS ON TREES TO RESULT IN MANY POWER OUTAGES
WITH THE MAIN IMPACT FROM HAZARDOUS DRIVING CONDITIONS.
OVERNIGHT LOWS WILL BE WELL BELOW NORMAL WITH APPARENT TEMPERATURES
IN THE SINGLE DIGITS FOR MOST LOCATIONS GIVEN THE CONTINUED MIXED
BOUNDARY LAYER. AS SUCH, THE COLD WEATHER ADVISORY REMAINS IN EFFECT
FOR TONIGHT.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 130 PM TUESDAY...
WEDNESDAY AND THURSDAY COLD HIGH PRESSURE WILL BE PASSING TO OUR
NORTH. ON WEDNESDAY, HIGH TEMPERATURES SHOULD BE SIMILAR TO THIS
AFTERNOON OR SLIGHTLY COOLER WITH SNOWFALL KEEPING TEMPERATURES
COOLER. THUS, HIGHS ON WEDNESDAY SHOULD BE IN THE UPPER 20S TO LOW
30S. ALTHOUGH TEMPERATURES MAY STAY BELOW FREEZING, SNOW SHOULD
START TO MELT IN THE SUNLIGHT TOMORROW, WHICH WILL REFREEZE ONCE THE
SUN GOES DOWN AND TEMPERATURES ARE BELOW FREEZING. LOWS ON WEDNESDAY
NIGHT ARE EXPECTED TO BE IN THE LOW TO MID TEENS, HOWEVER A COLD
WEATHER ADVISORY IS NOT EXPECTED AS WINDS ARE EXPECTED TO BE LIGHT
AND THEREFORE APPARENT TEMPERATURES ARE NOT EXPECTED TO FALL TO
ADVISORY CRITERIA.
THE CHANCE FOR PRECIPITATION ON THURSDAY HAS DECREASED, AS MODELS
HAVE KEPT MOISTURE FURTHER TO THE EAST. EACH MODEL RUN HAS DECREASED
THE CHANCES FOR PRECIPITATION IN OUR FAR EASTERN COUNTIES, SO POPS
WERE CAPPED BELOW SLIGHT CHANCE, MEANING ANY PRECIPITATION IS NOT
LIKELY AT THIS TIME. AS THE HIGH MOVES OFF THE ATLANTIC COAST AND
CLOUD COVER IS EXPECTED TO INCREASE, TEMPERATURES ON THURSDAY SHOULD
BE WARMER THAN WEDNESDAY BUT STILL BELOW NORMAL, WITH HIGHS IN THE
UPPER 30S TO LOW 40S AND LOWS IN THE UPPER TEENS TO LOW 20S.
LONG TERM /FRIDAY THROUGH TUESDAY/
AS OF 1240 PM TUESDAY...
NO MAJOR CHANGES IN THE EXTENDED AT THIS TIME. THE MEAN, POSITIVELY
TILTED LONG WAVE TROUGH BRIEFLY GIVES WAY TO FLATTER ZONAL FLOW
ACROSS THE SOUTHERN USA AND HIGH MIGRATING ACROSS THE SOUTHEAST.
THIS WILL PROVIDE A WELCOME OPPORTUNITY FOR MODERATING TEMPERATURES
WITH NEAR NORMAL CONDITIONS BY SUN/MON. MEANWHILE AN UPPER LOW IS
EXPECTED TO DEVELOP OVER THE SOUTHWESTERN US WITH SPLIT FLOW
EVOLVING DOWNSTREAM ACROSS THE CENTRAL US. THE NEXT CHANCE OF
PRECIPITATION LOOKS TO COME EARLY NEXT WEEK AS A NORTHERN STREAM
WAVE IS FORECAST DIVE INTO THE MIDWEST, WHICH RESULTS IN A WAVE OF
LOW PRESSURE AND PRECIPITATION BREAKING ACROSS THE DEEP SOUTH.
LATEST MODEL RUNS SUGGEST THE BEST TIMING FOR PRECIP ACROSS NC WILL
BE SUNDAY NIGHT INTO MONDAY, WITH A RELATIVELY LIGHT EVENT THAT
SHOULD BE ALL LIQUID GIVEN THE LACK OF A PARENT HIGH AND COLD
ADVECTION FROM THE NORTH. THAT SAID THE ARCTIC AIRMASS WILL STILL
BE JUST TO THE NORTH AND CRITICAL THICKNESSES ARE CLOSE ENOUGH THAT
THIS SYSTEM WILL BE MONITORED FOR PTYPES. THERE'S STILL ENOUGH MODEL
DISCREPANCY TO WARRANT JUST CHANCE POPS AT THIS TIME.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AS OF 1240 PM TUESDAY...
VFR CONDITIONS TO START THE TAF PERIOD BUT AN AREA OF LIGHT SNOW IS
EXPECTED TO OVERSPREAD CENTRAL NC LATER THIS AFTERNOON. ALL 5 TAF
SITES SHOULD SEE SOME DEGREE OF AVIATION IMPACTS, PRIMARILY IN THE
FORM OF REDUCED VSBYS. DETAILS AS FOLLOWS:
INT AND GSO: LIKELY TO BE ON THE FAR WESTERN EDGE OF THE SNOW. SNOW
ARRIVING BETWEEN 20-22Z, AND WHILE RESTRICTIONS TO MVFR ARE POSSIBLE
THIS EVENING, THEY SHOULD BE SHORT LIVED. RECOVERING TO VFR BEFORE
MIDNIGHT WITH SKIES CLEARING OUT ENTIRELY BEFORE DAYBREAK.
RDU: EXPECT LIGHT SNOWFALL ONSET JUST BEFORE 00Z, WITH A FEW
HOURS OF IFR SNOW BETWEEN 00Z AND 04Z. THIS SHOULD ALSO WRAP UP
QUICKLY WITH DRY WEATHER AND VFR CONDITIONS RETURNING SHORTLY
AFTER MIDNIGHT, WITH CLEAR SKIES BY DAYBREAK.
FAY/RWI: LIKELY TO SEE THE LONGEST DURATION OF SNOW WITH THE LOWEST
VSBYS AND CEILINGS. SNOW ARRIVING AROUND 21-22Z, HEAVIEST FROM 00Z
TO 06Z, TAPERING OFF AROUND 08Z, CLEARING OUT ENTIRELY AFTER 14Z.
GUSTY NORTH WINDS AROUND 15-18KTS POSSIBLE AT ALL SITES THROUGH
WEDNESDAY MORNING.
OUTLOOK: VFR IS EXPECTED TO RETURN WED MORNING. A SYSTEM IS FORECAST
TO CROSS THE REGION THU 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 FROM 3 AM TO 10 AM EST WEDNESDAY FOR
NCZ007>011-021>028-038>043-073>078-083>086-088-089.
WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR NCZ011-026-027-
040>042-073>077-083-084.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR NCZ028-043-078-085-
086-088-089.
SYNOPSIS...KREN/HARTFIELD
NEAR TERM...SWIGGETT
SHORT TERM...HELOCK
LONG TERM...SMITH
AVIATION...LEINS
CLIMATE...RAH
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