177
FXUS63 KFSD 181724
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1124 AM CST WED DEC 18 2024
KEY MESSAGES
- A FAST MOVING CLIPPER LIKE SYSTEM WILL MOVE THROUGH THURSDAY.
PRECIPITATION, MAINLY SNOW BUT POSSIBLY MIXED EARLY, WILL BE
POSSIBLE LATE TONIGHT INTO THURSDAY MORNING. STRONG WINDS WILL
DEVELOP IN THE WAVE OF THIS SNOW WITH GUSTS OF 40 TO 50 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.
DISCUSSION
ISSUED AT 245 AM CST WED DEC 18 2024
A RIDGE OF SURFACE HIGH PRESSURE WILL DRIFT EAST TODAY TURNING WINDS
FROM THE NORTHWEST TO THE SOUTHEAST. OVERALL WINDS WILL BE ON THE
LIGHTER SIDE, MAYBE A FEW GUSTS AROUND 20 MPH IN CENTRAL SD LATER
THIS AFTERNOON. WITH THE FRESH SNOWPACK IN MANY AREAS, ESPECIALLY
NORTH OF I-90, TEMPERATURES WILL REMAIN ON THE COLDER SIDE, BUT
STILL ONLY A FEW DEGREES BELOW NORMAL.
OF MUCH MORE INTEREST WILL BE A FAST MOVING CLIPPER LIKE SYSTEM
MOVING INTO THE NORTHERN PLAINS LATER TONIGHT, THEN QUICKLY MOVING
INTO NORTHERN IL BY THURSDAY NIGHT. MOISTURE ALOFT QUICKLY INCREASES
THIS EVENING, ESPECIALLY EAST OF THE JAMES RIVER. WITH THE DENDRITIC
LAYER POSITIONED FAIRLY HIGH WITHIN THIS INCREASING MID LEVEL
MOISTURE PRECIPITATION WILL LIKELY TRY TO DEVELOP AROUND MIDNIGHT,
BUT WILL BE FIGHTING A MODERATE TO WEAK DRY LAYER FROM 700 MB TO
NEAR THE SURFACE. FORCING APPEARS TO BE PRETTY STRONG FROM ABOUT 6-
12Z THURSDAY FROM ABOUT A DE SMET TO SPENCER IA LINE. THIS LIFT,
LIKE THE SYSTEM, WILL MOVE THROUGH QUICKLY. THE FARTHER SOUTH AND
WEST YOU GO FROM THIS LINE, THE MORE DIFFICULTY THE SYSTEM HAS
SATURATING AND ALLOWING SNOWFALL TO DEVELOP. THIS SHOULD LEAVE A
FAIRLY SHARP CUT OFF TO THE POTENTIAL MEASURABLE SNOWFALL. FOR NOW,
PARTS OF SOUTHWEST MN MAY SEE THE BEST CHANCE FOR SOME SNOW TO FALL
DURING THE MORNING COMMUTE. BY AFTERNOON THE STRONGER LIFT WILL BE
OUT OF THE AREA, BUT MODEL SOUNDINGS INDICATE THAT TEMPERATURES WILL
CRASH WITH THE LOW LEVELS FALLING INTO THE DENDRITIC LAYER AND WHAT
APPEARS TO BE ENOUGH MOISTURE TO SUPPORT SCATTERED SNOW SHOWERS IN
MANY LOCATIONS. WHILE SNOW AMOUNTS FROM THESE SNOW SHOWERS WILL BE
MINIMAL, THE MAIN CONCERN WILL BE THE POTENTIAL FOR REDUCED
VISIBILITY WITH NORTHWEST WINDS LIKELY GUSTING 40 TO 50 MPH. THIS
WILL BE SOMETHING TO WATCH FOR AS THE POTENTIAL FOR BLOWING SNOW AND
VISIBILITIES BELOW A MILE WILL EXIST.
ONCE THIS SYSTEM PASSES ON THURSDAY NIGHT, COLDER CONDITIONS WILL BE
IN PLACE FRIDAY AND SATURDAY, ESPECIALLY FRIDAY. DRY NORTHWEST FLOW
WILL BE IN PLACE KEEPING PRECIPITATION CHANCES AT BAY. BY SUNDAY A
WAVE WILL MOVE ONTO THE PLAINS BUT ALL INDICATIONS ARE THAT THIS
SYSTEM WILL STRUGGLE TO PRODUCE PRECIPITATION AS IT QUICKLY MOVES
BY. THE DENDRITIC LAYER WILL BE WELL ABOVE 600 MB AND MOISTURE WILL
BE MINIMAL BELOW THIS.
MONDAY AND TUESDAY LOOK DRY WITH ABOVE NORMAL TEMPERATURES AS WEAK
TROUGHING ALOFT ALLOWS FOR WEAK WESTERLY FLOW AND MILDER
TEMPERATURES.
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...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...08
AVIATION...JM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page