445
FXUS62 KCAE 210928
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
428 AM EST SAT DEC 21 2024
SYNOPSIS
STRONG HIGH PRESSURE TO OUR NORTH WILL BRING US A CHILLY
SATURDAY FOLLOWING FRIDAY'S COLD FRONT. THIS COLD PATTERN WILL
CONTINUE FOR SEVERAL DAYS INTO EARLY NEXT WEEK WITH WELL BELOW
AVERAGE DAYTIME AND OVERNIGHT TEMPS. A WARMING TREND IS
EXPECTED TOWARDS CHRISTMAS ALONG WITH THE NEXT CHANCE OF RAIN.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- HIGH PRESSURE SLOWLY PUSHING INTO THE EASTERN US WITH STRONG COLD,
DRY ADVECTION ACROSS OUR AREA.
STRONG COLD AND DRY ADVECTION CONTINUES ACROSS THE AREA FOLLOWING
FRIDAY'S COLD FRONT PASSAGE WITH DEEP NORTHWESTERLY FLOW IN PLACE
FROM THE SURFACE THROUGH 250MB. THE PARENT SURFACE HIGH PRESSURE
PRESSURE AND THE CENTER OF THIS ARCTIC AIRMASS IS STILL BASICALLY
OVER LAKE SUPERIOR, SO THE PRESSURE GRADIENT WILL REMAIN RELATIVELY
STRONG THROUGHOUT SATURDAY. WITH THE HIGH SHIFTING EAST, LOW LEVEL
FLOW BELOW 850MB WILL TURN MORE NORTHERLY TODAY BUT THE STRONG
ADVECTION WILL REMAIN AND KEEP TEMPS WELL BELOW AVERAGE. HIGH TEMPS
WILL ONLY REACH THE LOW 50'S ACROSS THE AREA, DESPITE CLEAR SKIES,
AND DEW POINTS WILL FALL INTO THE LOW 20'S.
THERE IS NOT MUCH CHANGE IN THE SYNOPTIC SETUP AS WE MOVE INTO
SUNDAY MORNING. STRONG HIGH PRESSURE WILL SLOWLY SHIFT ACROSS
THE GREAT LAKES, DRIVING NORTH-NORTHEASTERLY LOW LEVEL FLOW,
COLD AND DRY ADVECTION INTO THE AREA. MORNING LOW TEMPS SUNDAY
WILL AGAIN RUN WELL BELOW AVERAGE, DOWN INTO THE MID-20'S. IT'S
A PRETTY CLASSIC SETUP FOR US WITH THE ADVECTION OFFSETTING THE
RADIATIONAL COOLING COMPONENT ENOUGH TO PREVENT ANY SORT OF
RECORD (OR EVEN NEAR RECORD) SETTING COLD.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
KEY MESSAGE(S):
- NOTICEABLY COLDER AND DRIER WITH SUBFREEZING OVERNIGHT
TEMPERATURES.
COLD AND DRY AIR WILL BE WELL ESTABLISHED OVER THE REGION SUNDAY AND
MONDAY WITH SURFACE HIGH PRESSURE EXTENDING FROM THE GREAT LAKES AND
NEW ENGLAND INTO THE SOUTHEAST. DAYTIME TEMPERATURES WILL BE 8-12
DEGREES BELOW NORMAL ON SUNDAY (HIGHS IN THE 40S) UNDER CLEAR SKIES.
THE PRIMARY NIGHT OF CONCERN IS SUNDAY INTO MONDAY, WHEN OVERNIGHT
LOWS ARE LIKELY TO FALL INTO THE UPPER TEENS ALONG THE SC/NC BORDER
WITH LOW 20S ELSEWHERE THROUGH THE MIDLANDS AND CSRA. THE LATEST
LREF PROBABILITIES FOR APPARENT TEMPERATURES 15 DEGREES OR LESS
MONDAY MORNING HAS TRENDED DOWNWARD FROM 24 HOURS AGO, WITH ONLY
ABOUT 15%-25% CHANCES. THEREFORE, UNLESS THERE IS A NOTICEABLE
UPTICK IN THESE VALUES OVER THE NEXT 12 OR SO HOURS, THINK THAT COLD
WEATHER ADVISORY CRITERIA IS UNLIKELY TO BE MET. THAT SAID, THERE
WILL STILL BE IMPACTS TO SUSCEPTIBLE PLANTS, PIPES, PETS AND PEOPLE
GIVEN THESE VERY COLD TEMPERATURES.
AS ALLUDED TO, MONDAY STARTS OFF DOWNRIGHT COLD, BUT WEAK UPPER
RIDGING WILL START TO PHASE ACROSS THE REGION. DAYTIME TEMPERATURES
RISE A FEW DEGREES FROM SUNDAY, KICKING OFF A SLOW WARMING TREND
THAT WILL CONTINUE MUCH OF THE WEEK. WHILE THE ATMOSPHERE WILL BE
MOISTURE-STARVED WITH PWATS AROUND 0.25" THROUGH MONDAY AFTERNOON, A
WEAK SHORTWAVE AND INVERTED SURFACE TROUGH OFF THE COAST WILL START
TO REINTRODUCE MOISTURE TO THE REGION FROM THE SOUTH MONDAY NIGHT.
OVERNIGHT LOWS WILL DIP INTO THE MID 25S TO MID 30S, AND PWAT VALUES
MAY APPROACH 0.75" BY DAYBREAK TUESDAY MORNING.
LONG TERM /TUESDAY THROUGH FRIDAY/
KEY MESSAGE(S):
- SLOW WARMING TREND TUESDAY INTO NEXT WEEKEND.
- RAIN CHANCES INCREASE MIDWEEK, BUT SOME UNCERTAINTY REMAINS.
ADDITIONAL TEMPERATURE AND MOISTURE ADVECTION OCCURS TUESDAY AS A
WEAK SURFACE LOW TRACKS OFF THE COAST AND A NEW AREA OF HIGH
PRESSURE ESTABLISHES OVER THE GREAT LAKES. THIS MAY BRING A SLIGHT
CHANCE FOR SHOWERS PARTICULARLY FOR THE COASTAL PLAIN. THE PATTERN
SEEMS TO BECOME MORE ACTIVE WITH A SERIES OF DISTURBANCES MOVING
THROUGH THE MEAN FLOW, BUT RUN TO RUN MODEL DISCREPANCIES EXIST AND
OVERALL CONFIDENCE IN THE PRECIPITATION FORECAST WEDNESDAY ONWARD
REMAINS LOW. STILL, A GRADUAL INCREASE IN HEIGHTS SHOULD BRING A
SLOW WARMING TREND, AND ENSEMBLE MEAN PWAT VALUES LOOK TO BE BETWEEN
0.75" AND 1" AT THE END OF THE WEEK.
TEMPERATURES WILL RISE INTO THE MID 50S ON TUESDAY TO THE UPPER
50S/LOW 60S BY WEDNESDAY AND THURSDAY AND A FEW DEGREES WARMER ON
FRIDAY. LOWS WILL FOLLOW SUIT, STARTING OUT IN THE MID TO UPPER 30S
TUESDAY NIGHT AND THE 40S BY WEDNESDAY, THURSDAY AND FRIDAY NIGHTS.
AVIATION /10Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD.
EXTREMELY DRY AIR CONTINUES TO PUSH INTO THE AREA THROUGHOUT
SATURDAY AND INTO SUNDAY MORNING. CLEAR SKIES ARE EXPECTED
THROUGH THE PERIOD, SO WINDS ARE THE ONLY FEATURE OF NOTE.
SURFACE WINDS WILL START THIS MORNING OUT OF THE NORTHWEST,
SUSTAINED 8-10 KNOTS BEFORE TURNING NORTHERLY THIS AFTERNOON
WITH SUSTAINED 6-8 KNOTS AND GUSTS UP TO 16 KNOTS. WINDS WILL
REMAIN SLIGHTLY OVERNIGHT INTO SUNDAY MORNING.
EXTENDED AVIATION OUTLOOK...NO SIGNIFICANT IMPACTS TO AVIATION.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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