660
FXUS63 KFSD 170841
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
241 AM CST SUN NOV 17 2024
KEY MESSAGES
- WIDESPREAD RAIN CHANCES (70-100%) ARE EXPECTED FROM LATE
MONDAY MORNING INTO EARLY TUESDAY MORNING. THE PROBABILITY OF
A HALF AN INCH OR MORE IS VERY HIGH (70-90%) EAST OF THE
JAMES RIVER WHILE THE PROBABILITY FOR AN INCH OR MORE IS HIGH
(60-80%) NEAR AND EAST OF I- 29.
- VERY STRONG NORTHWEST WINDS EXPECTED TUESDAY AND WEDNESDAY, POSSIBLY
INTO THURSDAY. WIND GUSTS AROUND 50 MPH POSSIBLE. IF ANY SNOW
CAN DEVELOP, EVEN A COUPLE OF INCHES WITH THESE WINDS WOULD
CAUSE SOME PROBLEMS.
- COLD WIND CHILLS IN THE TEENS AND SINGLE DIGITS LIKELY TUESDAY
NIGHT THROUGH THURSDAY.
DISCUSSION
ISSUED AT 240 AM CST SUN NOV 17 2024
SURFACE LOW PRESSURE WRAPS UP AND SHIFTS EAST TODAY, LEAVING THE
AREA WITH WEST TO SOUTHWEST FLOW AND MILD, ABOVE NORMAL
TEMPERATURES. HIGHS SHOULD MOSTLY BE IN THE 50S.
SURFACE WINDS WILL TURN A BIT MORE SOUTHEASTERLY TONIGHT AS LOW
PRESSURE DEEPENS TO THE SOUTHWEST. PRECIPITATION LOOKS TO HOLD OFF
UNTIL MONDAY. LOWS SHOULD DIP INTO THE LOW TO MID 30S.
LOW PRESSURE RAPIDLY DEEPENS AS IT LIFTS NORTHEAST AND BRINGS A SLUG
OF MOISTURE INTO THE AREA. RAIN CHANCES WILL INCREASE QUICKLY FROM
SOUTH TO NORTH LATE MONDAY MORNING THROUGH MONDAY AFTERNOON.
RAINFALL RATES WILL BE ON THE MODERATE TO BRIEFLY HEAVIER SIDE WITH
SOME WEAK INSTABILITY FROM ABOUT 900MB TO 700MB HELPING TO DELIVER
SOME ADDITIONAL LIFT. RAINFALL AMOUNTS WILL LIKELY EXCEED AN INCH IN
QUITE A FEW LOCATIONS, WITH SOMETHING CLOSER TO A QUARTER TO HALF AN
INCH IN CENTRAL SD. TEMPERATURES WILL REMAIN WARM ENOUGH TO KEEP ALL
PRECIPITATION AS RAIN THROUGH TUESDAY MORNING, BEFORE COMING TO AN
END. LOW PRESSURE THEN STALLS AND FURTHER DEEPENS ACROSS EASTERN ND
INTO NORTHERN MN, BRINGING A STOUT NORTHWEST FLOW TO THE AREA. MODEL
SOUNDINGS INDICATE A GOOD CHANCE TO SEE 40 TO 50 KNOTS IN THE MIXED
LAYER WHICH WILL LEAD TO VERY WINDY CONDITIONS BOTH TUESDAY AND
WEDNESDAY.
STILL A LOT OF QUESTION MARKS AND DISAGREEMENT WEDNESDAY INTO
THURSDAY ON SNOW POTENTIAL. BIG DIFFERENCES BETWEEN GEFS AND EC
ENSEMBLE OUTPUT. THE GEFS HAS THE CHANCE FOR A TENTH OF AN INCH MORE
LIQUID (ROUGHLY 1 INCH OF SNOW) AT LESS THAN 10 PERCENT WHILE THE EC
ENSEMBLE IS RUNNING ABOUT 50-80 PERCENT CHANCE FOR THE SAME WITH A
SMALL CHANCE FOR A HALF AN INCH OF LIQUID NEAR HIGHWAY 14 IN SD
(ROUGHLY 5 INCHES OF SNOW). THE BIG DIFFERENCE APPEARS TO LIE IN
DIFFERENCES IN MOISTURE FROM ABOUT 800MB TO 500 MB, THE EC BEING
MUCH MORE AGGRESSIVE WITH THE MOISTURE THUS GENERATING MORE
PRECIPITATION. THIS WILL BE A TREND TO WATCH AS A TROWAL DOES TRY TO
DEVELOP AROUND WEDNESDAY WHICH COULD HELP FOCUS SNOW DEVELOPMENT,
BUT WITHOUT MOISTURE THAT WILL BE DIFFICULT.
FOR NOW, WILL INCREASE SNOW CHANCES A TOUCH ON WEDNESDAY FROM THE
NBM MAINLY NEAR AND NORTH OF I-90. THE MAIN CONCERNS FOR EVEN AN
INCH OR TWO OF SNOW WILL BE THE POTENTIAL FOR GREATLY REDUCED
VISIBILITY. NOT A LOT OF SNOW, BUT WOULD LIKELY CAUSE SOME ISSUES
WITH 50 MPH WINDS. THE BETTER CHANCE FOR THESE CONDITIONS WILL BE
NORTH OF I-90.
ALONG WITH THE WIND AND SNOW POTENTIAL WILL BE THE COLD
TEMPERATURES, WHICH WILL PROVIDE THE AREA WITH WIND CHILL VALUES IN
THE TEENS AND SINGLE DIGITS. THESE COLDER CONDITIONS REMAIN IN PLACE
INTO NEXT WEEKEND WITH HIGHS GENERALLY IN THE 30S TO LOWER 40S BUT
WINDS WILL BE DOWN QUITE A BIT FROM THE WINDIER MID WEEK DAYS.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1040 PM CST SAT NOV 16 2024
AN AREA OF LOW VFR-LOCALLY MVFR STRATUS WILL SLIDE EAST ACROSS
LOCATIONS NORTH OF I-90 THROUGH THE LATE NIGHT. GUSTY WESTERLY
WINDS ACCOMPANY THE STRATUS WITH GUSTS LARGELY 20-25KT, PERHAPS
BRIEFLY CLOSER TO 30KT.
WINDS TURN BACK TO THE SOUTHWEST AND SOUTH AFTER DAYBREAK SUNDAY,
WITH A FEW HOURS OF GUSTS NEAR 20KT POSSIBLE FROM LATE MORNING TO
MID AFTERNOON. VFR CONDITIONS PREVAIL ON SUNDAY WITH MOSTLY CLEAR
SKIES.
FSD WATCHES/WARNINGS/ADVISORIES
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...08
AVIATION...JH
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