895
FXUS63 KFSD 182125
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
325 PM CST WED DEC 18 2024
KEY MESSAGES
- A FAST MOVING CLIPPER LIKE SYSTEM WILL MOVE THROUGH TONIGHT
AND THURSDAY. PRECIPITATION, MAINLY SNOW BUT POSSIBLY MIXED
WEST EARLY, WILL BE POSSIBLE LATE TONIGHT INTO THURSDAY
MORNING. STRONG WINDS WILL DEVELOP IN THE WAVE OF THIS SNOW
WITH GUSTS OF 40 TO 60 MPH POSSIBLE ALONG WITH SCATTERED SNOW
SHOWERS IN THE AFTERNOON. THIS COULD CAUSE REDUCED VISIBILITY.
- DRY CONDITIONS RETURN FOR THE END OF THE WEEK AND WEEKEND WITH
TEMPERATURES MODERATING BACK TO NEAR TO ABOVE AVERAGE.
- CHANCES FOR ANY WIDESPREAD TRAVEL TROUBLES REMAINS VERY LOW FOR
NEXT WEEK.
5
DISCUSSION
ISSUED AT 322 PM CST WED DEC 18 2024
SURFACE HIGH PRESSURE CURRENTLY SITUATED ACROSS THE REGION WILL
SLIDE TO THE EAST OVERNIGHT, THIS AS SURFACE TROUGH/UPPER LEVEL
SHORTWAVE TRACKS ACROSS THE DAKOTAS INTO THURSDAY MORNING. OUT AHEAD
OF THOSE FEATURES, MIDLEVEL WARM AIR ADVECTION WILL OVERSPREAD THE
REGION, WITH INCREASING LIFT PROVIDED BY AN UPPER LEVEL JET DIVING
FROM WESTERN SD INTO IA DURING THE NIGHT TIME HOURS. IN RESPONSE TO
THAT, LOOK FOR LIGHT PRECIPITATION TO DEVELOP IN AREAS GENERALLY
FROM THE INTERSTATE 90 CORRIDOR AND NORTHWARD AFTER 06Z TONIGHT AND
CONTINUE INTO EARLY MORNING ON THURSDAY - THIS COLLOCATED WITH THE
BETTER LIFT AND DEEPER MOISTURE. MOST MODEL SOUNDINGS INDICATE THE
POSSIBILITY OF A WINTRY MIX OF PRECIPITATION POSSIBLE THROUGH THE
NORTHERN JAMES RIVER VALLEY WITH THE ONSET OF THE PRECIPITATION -
WITH A RATHER DEEP ELEVATED WARM LAYER PRESENT OVER THE AREA. EVEN
SO, THERE IS ALSO DRY AIR IN THE LOW LEVELS WHICH WILL KEEP ANY
PRECIPITATION LIGHT, THOUGH WE CANNOT RULE OUT A BRIEF PERIOD WITH
THE POTENTIAL FOR A LIGHT GLAZE OF ICE THROUGH THAT AREA. FARTHER TO
THE EAST, SNOW LOOKS TO BE THE MORE LIKELY PRECIPITATION TYPE, WITH
MODELS AND ENSEMBLES SUPPORTING AMOUNTS AROUND AN INCH FROM EAST
CENTRAL SD THROUGH SOUTHWESTERN MN INTO EARLY THURSDAY MORNING.
TEMPERATURES EARLY TONIGHT WILL BE IN THE TEENS AND 20S, THEN WITH
WARM AIR ADVECTION OUT AHEAD OF THE SYSTEM TEMPERATURES WILL RISE
INTO THE 20S AND 30S BY THURSDAY MORNING.
STRONG COLD AIR ADVECTION SWEEPS INTO THE AREA ON THURSDAY BEHIND
THE SYSTEM, AND WITH STEEPENING LOW LEVEL LAPSE RATES, MIXING WILL
TAP INTO STRONG WINDS ALOFT. SOUNDINGS ARE INDICATING WINDS RUNNING
AROUND 55 TO 60 KTS AT THE TOP OF THE MIXED LAYER THROUGH SOUTH
CENTRAL SD, WITH 40 TO 45 KTS JUST TO THE EAST OF THAT AREA. IN
LIGHT OF THAT, ISSUED A HIGH WIND WARNING FOR SOUTH CENTRAL SD, AND
A WIND ADVISORY BORDERING THIS AREA TO THE EAST FOR 15Z TO 00Z ON
THURSDAY. A SECONDARY SHORTWAVE WILL DIVE ACROSS THE REGION ON
THURSDAY AFTERNOON, AND MOST HI-RES MODELS ARE SHOWING THE
POSSIBILITY OF SCATTERED SNOW SHOWERS - MAINLY OVER EAST CENTRAL SD
AND SOUTHWESTERN MN. ALTHOUGH ANY ADDITIONAL ACCUMULATION WILL
REMAIN A FEW TENTHS, ANY SNOW THAT FALLS TONIGHT OR IS ALREADY
LAYING ON THE GROUND WILL BLOW AROUND WITH THE WINDS AS MENTIONED
ABOVE. FORTUNATELY, THE STRONGEST WINDS ARE OFFSET FROM AREAS
EXPECTING TO OR ALREADY HAVING RECEIVED SNOW - THOUGH REDUCED
VISIBILITIES (POSSIBLY AS LOW AS ONE MILE) ARE LIKELY IN SNOW COVERED
LOCATIONS/OR WHERE SNOW IS FALLING AND TRAVEL MAY BECOME DIFFICULT.
RELATED TO THE STRONG COLD AIR ADVECTION AS MENTIONED ABOVE, WHILE
TEMPERATURES WILL RISE INTO THE 20S AND 30S EARLY IN THE DAY,
READINGS WILL FALL DURING THE AFTERNOON.
AFTER THE DEPARTURE OF MAINLY LIGHT SNOW OR FLURRIES ON THURSDAY
EVENING, THE MUCH COLDER AIR SETTLES SOUTHWARD FOR THURSDAY NIGHT
THROUGH FRIDAY NIGHT. LOWS ON THURSDAY NIGHT WILL BE IN THE SINGLE
DIGITS, THEN IN THE SINGLE DIGITS AND LOWER TEENS FOR FRIDAY NIGHT.
HIGHS ON FRIDAY WILL REMAIN IN THE TEENS TO LOWER 20S.
AFTER THAT, A LESS AMPLIFIED UPPER LEVEL PATTERN WILL LEAD TO
WARMING TEMPERATURES INTO CHRISTMAS WEEK - TRENDING TO ABOVE NORMAL
FOR SUNDAY THROUGH CHRISTMAS. NO SIGNIFICANT WEATHER IS EXPECTED
THROUGH THE PERIOD, WITH ONLY SMALL LIGHT PRECIPITATION CHANCES
(20% OR LESS) SOME TIME AROUND THE CHRISTMAS EVE TIME FRAME.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1120 AM CST WED DEC 18 2024
MODELS ARE NOT HANDLING THE CURRENT STRATUS ACROSS THE AREA, BUT
THINKING THAT BROKEN MVFR STRATUS WILL LINGER INTO THE LATE
AFTERNOON. LIGHT SNOW WILL DEVELOP ALONG AND NORTH OF THE
INTERSTATE 90 CORRIDOR LATE TONIGHT AND CONTINUE INTO THURSDAY
MORNING. WINDS WILL ALSO INCREASE LATER TONIGHT INTO THURSDAY,
AND ANY SNOW THAT ACCUMULATES DURING THAT PERIOD (OR IS ALREADY
ON THE GROUND) WILL MAY BLOW AROUND - ESPECIALLY BY LATER ON
THURSDAY MORNING AND AFTERNOON - CAUSING DECREASED VISIBILITY.
WINDS WILL GUST 30 TO 40 KTS OR HIGHER DURING THIS TIME FRAME,
WITH STRONGEST WINDS THROUGH THE MO RIVER CORRIDOR. THERE WILL
ALSO BE A PERIOD OF LLWS AT TAF SITES ON THURSDAY MORNING AS
WINDS ALOFT INCREASE AND SURFACE WINDS SLOWLY RAMP UP.
FSD WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY FROM 9 AM TO 6 PM CST THURSDAY FOR SDZ038-
052>054-059>062-065>067-069>071.
HIGH WIND WARNING FROM 9 AM TO 6 PM CST THURSDAY FOR SDZ050-
057-058-063-064-068.
MN...NONE.
IA...WIND ADVISORY FROM 9 AM TO 6 PM CST THURSDAY FOR IAZ012-020-
031.
NE...WIND ADVISORY FROM 9 AM TO 6 PM CST THURSDAY FOR NEZ013-014.
DISCUSSION...JM
AVIATION...JM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page