376
FXUS62 KCAE 181825
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
125 PM EST SAT JAN 18 2025
SYNOPSIS
AFTER A QUIET PERIOD THIS AFTERNOON, ANOTHER ROUND OF SHOWERS IS
EXPECTED TO MOVE THROUGH THE AREA TONIGHT AS A COMPLEX LOW PRESSURE
SYSTEM MOVES INTO THE EASTERN U.S. A STRONG COLD FRONT WILL MOVE
THROUGH THE AREA BY MIDDAY SUNDAY WITH STRONG GUSTY WINDS IN ITS
WAKE THROUGH THE AFTERNOON. BEHIND THE FRONT, VERY COLD AIR WILL
BEGIN TO SPREAD ACROSS THE REGION. WELL BELOW NORMAL TEMPERATURES
ARE EXPECTED NEXT WEEK AS AN ANOMALOUSLY DEEP TROUGH AND SURFACE
HIGH PUSHES AN ARCTIC AIR MASS INTO THE CENTRAL AND EASTERN US. ON
TUESDAY, A COASTAL LOW WILL LIKELY INCREASE PRECIPITATION CHANCES
WITH WINTRY POTENTIAL INCREASING, BUT THE DETAILS REMAIN UNCERTAIN.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- OVERCAST CONDITIONS EXPECTED THROUGHOUT THE DAY TODAY.
- ANOTHER ROUND OF RAIN EXPECTED TONIGHT TONIGHT.
WE MAY SEE A FEW GLIMPSES OF SUN ACROSS THE FORECAST AREA THIS
AFTERNOON AS A SHORTWAVE TROUGH PUSHES THROUGH THE AREA. A LULL IN
THE RAIN IS EXPECTED THROUGH THIS EVENING, BUT DURING THIS TIME VERY
LOW CLOUDS ARE LIKELY TO REDEVELOP. SOME WEAK WARM ADVECTION IS
SLOWLY PUSHING TEMPS INTO THE LOW 50S BUT ALSO INCREASING DEWPOINTS
INTO THE UPPER 40S TO AROUND 50.
ANOTHER SHORTWAVE IS CURRENTLY DIGGING ACROSS THE CENTRAL ROCKIES
AND IS EXPECTED TO INFLUENCE OUR WEATHER TONIGHT, AS WELL. THIS IS
FORECAST TO PHASE WITH THE INITIAL SHORTWAVE AS THE OVERALL LONGWAVE
TROUGH THAT CONTAINS BOTH AMPLIFIES AND DIGS THROUGH THE EASTERN
HALF OF THE CONUS. AS A RESULT, LIFT IS EXPECTED TO QUICKLY INCREASE
AGAIN TONIGHT, WITH A SURFACE LOW DEVELOPING NEAR THE FORECAST AREA.
PWS ARE FORECAST TO RAPIDLY INCREASE TO THE 1.0"-1.25" RANGE AS THIS
OCCURS AND WIDESPREAD SHOWERS ARE LIKELY TO DEVELOP AGAIN AFTER 00Z
AS A RESULT. OVERALL, PRECIP TOTALS SHOULD REMAIN UNDER AN INCH
BETWEEN BOTH EVENTS. CLOUDS ARE EXPECTED TO HANG AROUND ALL NIGHT,
WITH LOWS FALLING ONLY INTO THE UPPER 40S.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
KEY MESSAGE(S):
- A STRONG COLD FRONT PUSHES THROUGH SUNDAY, BRINGING BREEZY
CONDITIONS AND MUCH COLDER TEMPS OVERNIGHT.
- THE COLDEST AIRMASS SO FAR THIS SEASON WILL MOVE IN MONDAY WITH
TEMPERATURES NEAR 20 DEGREES BELOW NORMAL.
- A COLD WEATHER ADVISORY MAY BE NEEDED MONDAY NIGHT.
SUNDAY AND SUNDAY NIGHT...THE HIGHLY AMPLIFIED UPPER TROUGH FROM
THE UPPER MIDWEST SOUTH THROUGH THE MISSISSIPPI VALLEY WILL BE
BE SHIFTING INTO THE EASTERN CONUS. A LOW PRESSURE AREA WILL BE
NEAR THE REGION IN THE MORNING BUT WILL BE LIFTING TO THE
NORTHEAST. A FEW LINGERING SHOWERS POSSIBLE IN THE MORNING BUT
ONCE THE STRONG COLD FRONT MOVES THROUGH AROUND NOON, EXPECT
DRIER AIR TO BEGIN ADVECTING INTO THE AREA. STRONG COLD
ADVECTION WILL DEVELOP IN THE AFTERNOON WITH STRONG MIXING.
WESTERLY WINDS 15 TO 25 MPH WITH GUSTS TO 30-35 MPH ARE EXPECTED
AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THE LOW OFF THE MID
ATLANTIC COAST AND A VERY STRONG RIDGE IN THE MIDWEST. TEMPS
MAXING OUT NEAR 60 DEGREES BUT COLDER AIR WILL BE SPREADING IN
DURING THE LATE AFTERNOON HOURS. COLD ADVECTION CONTINUES
THROUGH THE OVERNIGHT WITH TEMPERATURES FALLING INTO THE 20S AS
THE ARCTIC AIR MASS OVER THE MIDWEST BUILDS EAST.
MONDAY AND MONDAY NIGHT...THE ARCTIC AIR MASS (1040 MB HIGH
PRESSURE SITUATED TO THE NORTH) WILL BE BUILDING OVER THE AREA.
THIS IS INDICATED BY THE VERY LOW DEW POINTS, IN THE SINGLE
DIGITS. EC EFI AND NAEFS CONTINUES TO SHOW THIS AIRMASS WITH A
CHARACTERISTIC "HIGHLY ANOMALOUS BUT LIKELY NOT HISTORIC"
SIGNAL. TEMPERATURES WILL STRUGGLE STAYING IN THE 30S ACROSS
MUCH OF THE REGION WITH FULL INSOLATION DUE TO CONTINUED STRONG
COLD ADVECTION. NOTE 850MB TEMPERATURES AROUND -10C IN THE
AFTERNOON. WIND CHILL TEMPERATURES ARE EXPECTED TO FALL INTO THE
TEENS MONDAY NIGHT NEAR THE COLD WEATHER ADVISORY CRITERION.
LONG TERM /TUESDAY THROUGH FRIDAY/
KEY MESSAGE(S):
-CONFIDENCE IS INCREASING FOR IMPACTS FROM A WINTER STORM LATE
TUESDAY INTO WEDNESDAY.
THE LATEST 00Z MODEL GUIDANCE HAS TRENDED FURTHER INLAND WITH
THE WINTRY PRECIPITATION, MAINLY SNOW LATE TUESDAY INTO
WEDNESDAY. THE CANADIAN MODEL CONTINUES TO BE THE MOST
AGGRESSIVE WITH THIS STORM BUT THE LATEST GFS AND ECMWF ARE
SUGGESTING A STRONGER AND MORE PHASED SYSTEM (EARLIER IN TIME)
BETWEEN THE NORTHERN STREAM TROUGH MOVING OUT OF THE NORTHERN
PLAINS AND THE TROUGH MOVING OUT OF THE DESERT SOUTHWEST. THE
BASE OF THE UPPER TROUGH MOVES INTO THE GULF OF MEXICO. THIS
LEADS TO SURFACE LOW DEVELOPMENT IN THE GULF OF MEXICO WHICH
TRACKS EAST ACROSS FLORIDA TO OFF THE GA/SC COAST TUESDAY NIGHT.
THE ECMWF LOW CENTER IS CLOSER TO THE COAST THAN THE GFS. THE
ECMWF ENSEMBLES HAVE TRENDED MORE TOWARD THE CANADIAN ENSEMBLES
WITH A GREATER THREAT OF WINTRY PRECIPITATION. THE MODELS
CONTINUE TO POINT TO HIGHER PROBABILITIES OF ACCUMULATING SNOW
SOUTH AND EAST OF I-20, BUT NOTE PROBABILITIES APPEAR TO BE
INCREASING TO THE NORTHWEST.
BASED ON THE CLIMATOLOGY AND TYPICAL MODEL BIASES, THERE IS A
NORTHWARD CAP ON HOW FAR THE PRECIP SHIELD SHOULD BE ABLE TO
LIFT INTO SC BASED ON THE POSITIONING AND STRENGTH OF THE
SURFACE HIGH IN THE TN VALLEY. SO A SUPPRESSED LOW WITH HIGHER
CHANCES FOR SNOW- WINTRY PRECIP ALONG I-20 AND I-95, AS COMPARED
TO I-85, REMAINS FAVORED. BUT THE TYPICAL NORTHWESTWARD DRIFT
IN CYCLOGENESIS ACROSS GUIDANCE REMAINS POSSIBLE AS MODELS COME
INTO BETTER DEPICTIONS OF THE SURFACE HIGH POSITION AND
STRENGTH. ADDITIONALLY, LIKE WE SAW IN THE LAST WINTRY PRECIP
EVENT, GUIDANCE WILL UNIFORMLY STRUGGLE IN DEPICTING THE
STRENGTH AND TIMING OF THE WARM ADVECTION ALONG THE DEVELOPING
WARM FRONT ALOFT AND THIS ADDS SOME UNCERTAINTY IN PRECIP TYPE,
ESPECIALLY CLOSER TO THE COAST. ITS TOO FAR OUT FOR ANY
SPECIFICS ON IMPACTS, BUT ITS WORTH NOTING THE POTENTIAL FOR AN
IMPACTFUL WINTER STORM.
SO CONFIDENCE IS INCREASING IN IMPACTS INTO THE CENTRAL MIDLANDS
(POPS HAVE BEEN RAISED ALL AREAS) AND ESPECIALLY SOUTH OF I-20,
BUT UNTIL THE SYNOPTIC SCALE FLOW IS RESOLVED BETTER ALOFT
(HOPEFULLY LATER TODAY OR SUNDAY), SPECIFICS ON THE EXTENT WILL
REMAIN UNCLEAR. REGARDLESS OF ANY WINTRY PRECIP IMPACTS, AN
IMPACTFUL COLD AIRMASS WILL SETTLE INTO THE AREA THROUGH
THURSDAY. HIGH TEMPS WILL REMAIN IN THE 30'S FOR MULTIPLE DAYS
IN A ROW ALONG WITH OVERNIGHT LOWS IN THE TEENS. SO FROZEN PIPES
AND RELATED IMPACTS ARE EXPECTED FROM MONDAY ONWARD.
AVIATION /18Z SATURDAY THROUGH WEDNESDAY/
WIDESPREAD RESTRICTIONS EXPECTED FOR MUCH OF THE PERIOD.
THE FIRST ROUND OF RAIN IS EXITING TO THE EAST OF THE AREA AND
SHOULD KEEP THE TAF SITES CLEAR FOR MUCH OF THE AFTERNOON.
RESTRICTIONS MAY EASE FOR A FEW HOURS AS A RESULT, BUT GUIDANCE
REMAINS IN GOOD AGREEMENT THAT DETERIORATING CONDITIONS WILL RETURN
THIS EVENING THROUGH TONIGHT. SCATTERED TO NUMEROUS SHOWERS ARE
EXPECTED TO RETURN TO THE AREA FROM SOUTHWEST TO NORTHEAST AFTER
19/00Z, WITH BOTH CIGS AND VSBYS DROPPING AS MOISTURE INCREASES
PARTICULARLY IN THE LOWER LEVELS. -SHRA THEN EXPECTED TO CONTINUE
THROUGH DAYBREAK SUNDAY, AND PERHAPS FOR A FEW HOURS MORE, BEFORE
CLEARING OUT TO THE EAST. HAVE CONTINUED CIG RESTRICTIONS UNTIL THE
END OF THE VALID TAF PERIOD, BUT THEY MAY START TO EAST AN HOUR OR
TWO PRIOR.
WINDS WILL GENERALLY BE LIGHT AND VARIABLE OR SLY TODAY, GENERALLY
LESS THAN 12 KTS. WE SHOULD SEE A PERIOD OF LIGHT AND VARIABLE WINDS
AROUND 19/00Z, THEN A BIT OF STRENGTHENING FROM THE S/SW AFTER
19/06Z AS A SURFACE LOW TRACKS ACROSS THE AREA. SPEEDS INCREASE
SUNDAY MORNING AFTER SUNRISE TO 10-15 KTS AND CONTINUE VEERING W AND
EVENTUALLY NW BY SUNDAY AFTERNOON, BECOMING QUITE BREEZY WITH GUSTS
OF 25-30 KTS.
EXTENDED AVIATION OUTLOOK
EXPECTING CEILING RESTRICTIONS TO
CONTINUE INTO SUNDAY MORNING. COLD FRONT IS FORECAST TO PASS
THROUGH THE AREA BY SUNDAY AFTERNOON, WHICH SHOULD IMPROVE
CONDITIONS. GUSTY WINDS ARE EXPECTED WITH THIS COLD FRONT. NO
RESTRICTIONS ARE EXPECTED MONDAY, BUT COULD RETURN ON TUESDAY WITH
THE NEXT WEATHER SYSTEM.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page