534
FXUS63 KFSD 182339
AFDFSD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
539 PM CST MON NOV 18 2024
KEY MESSAGES
- WIDESPREAD RAIN HAS ARRIVED, MOVING OUT TUESDAY MORNING.
RAINFALL TOTALS REMAIN IN THE 1-1.5" RANGE EAST OF THE JAMES
RIVER VALLEY, WITH A SHARP GRADIENT DOWN TO 0.25" WEST OF THE
JAMES IN SOUTH-CENTRAL SD.
- STRONG NORTHWESTERLY WINDS ARE EXPECTED ON TUESDAY AND
WEDNESDAY WITH WIND GUSTS BETWEEN 45 TO 55 MPH POSSIBLE. THE
STRONGEST WINDS ARE MOST LIKELY ON WEDNESDAY.
- COLD WIND CHILLS IN THE SINGLE DIGITS TO TEENS ARE LIKELY
TUESDAY NIGHT INTO THURSDAY MORNING.
- LIGHT SNOW REMAINS EXPECTED NEAR AND NORTH OF I-90 FROM
OVERNIGHT INTO TO WEDNESDAY. WHILE AMOUNTS LOOK TO REMAIN
BELOW AN INCH, REGARDLESS OF AMOUNTS THE STRONG WINDS COMBINED
WITH FALLING/BLOWING SNOW WILL LEAD TO DIFFICULT TRAVEL
CONDITIONS.
DISCUSSION
ISSUED AT 301 PM CST MON NOV 18 2024
WIDESPREAD RAINFALL IS OVERSPREADING THE AREA FROM THE SOUTH AS A
SURFACE AND UPPER LEVEL LOW ARE MOVING TOWARDS THE AREA, WITH
AFTERNOON TEMPERATURES CURRENTLY IN THE UPPER 40S TO LOWER 50S. AS
OF 2 PM, THE CENTER OF THE SURFACE LOW IS MOVING INTO SOUTHEASTERN
NEBRASKA, WITH RADAR COVERAGE BEGINNING TO SCATTER OUT AS THE DRY
SLOT GETS MIXED INTO THE SYSTEM ACROSS EASTERN NEBRASKA. HOWEVER,
THIS IS ALSO WHEN THE SYSTEM INCREASES ITS INSTABILITY, WHICH WILL
BRING SOME ISOLATED THUNDERSTORMS ALONG WITH LOCALLY HEAVIER
RAINFALL. SO, WHILE THERE WILL BE SOME BREAKS IN THE RAINFALL THIS
AFTERNOON, RAINFALL CHANCES (80-100%) CONTINUE INTO THE EVENING
HOURS. MOST WILL BE DRY BY TUESDAY MORNING, WITH THE FEW
REMAINING RAIN CHANCES MOVING OFF INTO CENTRAL MINNESOTA.
AS THE LOW PRESSURE SYSTEM MOVES TO OUR NORTHEAST THROUGHOUT THE
OVERNIGHT AND MORNING HOURS, THE SURFACE PRESSURE GRADIENT (SPG)
TIGHTENS AND REMAINS STRONG ACROSS THE AREA FURTHER AIDED BY COLD
AIR ADVECTION (CAA) RESULTING IN STRONG WESTERLY WIND GUSTS. WIND
GUSTS OF 40 TO 50 MPH ARE EXPECTED ALONG AND WEST OF I-29, A TOUCH
WEAKER EAST OF I-29 WITH GUSTS IN THE 30 TO 40 MPH RANGE, EITHER WAY
BE SURE TO BRING IN ANY LOOSE AND UNSECURED OUTDOOR OBJECTS. HAVE
ISSUED A WIND ADVISORY FOR AREAS ALONG AND WEST OF THE JAMES RIVER
VALLEY WHERE GUSTS OF 45 TO 50 MPH ARE EXPECTED. WHILE AFTERNOON
TEMPERATURES PEAK IN THE MID 40S TO LOWER 50S, THE STRONG WINDS WILL
BRING WIND CHILL VALUES DOWN INTO THE 30S, EVEN COOLER OVERNIGHT
WHERE WIND CHILL VALUES FALL DOWN IN THE TEENS.
OVERNIGHT INTO WEDNESDAY, MODELS CONTINUE TO SHOW OUR PREVIOUS
SURFACE LOW MOVING OFF INTO SOUTHERN MANITOBA WHERE IT INTERACTS
WITH ANOTHER STRONG UPPER LEVEL LOW. MODEL AGREEMENT IS FAIRLY
DECENT IN THE PROGRESSION OF WRAPPING MOISTURE AROUND THE LOW AND
BACK DOWN INTO THE REGION, THOUGH THE SOUTHWARD EXTENT OF THIS
MOISTURE IS NOT WELL AGREED UPON. FOR NOW, HAVE INCLUDED CHANCES (20-
40%) FOR LIGHT SNOW WHERE THE ENSEMBLE MEANS FROM THE VARIOUS
ENSEMBLES SHOW QPF IS GREATER THAN ZERO. SNOWFALL AMOUNTS REMAIN
UNCERTAIN, ESPECIALLY GIVEN THE STRONG WINDS GUSTING 40-50 MPH THAT
WILL BE ACCOMPANYING THE FALLING SNOW WHICH WILL ACT TO SHRED
SNOWFLAKES AS THEY FALL. CHANCES FOR A TRACE OF SNOW ARE HIGHEST
NORTH OF I-90 IN THE 30-50% RANGE, DROPPING INTO THE 10-20% RANGE
FOR AREAS ALONG THE I-90 CORRIDOR. JUST TO REITERATE, SNOWFALL
AMOUNTS WILL NOT BE THE WHOLE STORY, AS THE STRONG WINDS COMBINED
WITH ANY FALLING SNOW WILL LEAD TO LOWERED VISIBILITIES RESULTING IN
DIFFICULT TRAVEL CONDITIONS. WHILE BLIZZARD CONDITIONS ARE NOT
EXPECTED GIVEN THE LACK OF SNOWPACK AND LIGHT SNOW, EXERCISE CAUTION
IF YOU'LL BE OUT TRAVELING THROUGHOUT THE DAY ON WEDNESDAY.
SURFACE HIGH PRESSURE COMES SLIDING DOWN THURSDAY INTO FRIDAY,
KEEPING THE COOLER TEMPERATURES AROUND A BIT LONGER WITH AFTERNOON
HIGHS IN THE 30S AND LOWER 40S INTO THE WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 531 PM CST MON NOV 18 2024
IFR AND LIFR CONDITIONS CONTINUE THROUGH THE FIRST HALF OF THE
PERIOD AS RAINFALL PIVOTS OVER THE AREA. IMPROVEMENT TO
CONDITIONS IS EXPECTED FROM WEST TO EAST TUESDAY MORNING AND
AFTERNOON AS LOW PRESSURE MOVES OFF TO THE NORTHEAST. VISIBILITY
MAY IMPROVE TO MVFR OR VFR BEFORE CEILINGS LIFT, AS IT MAY TAKE
A BIT LONGER FOR STRATUS TO CLEAR OUT THAN THE RAINFALL.
WINDS VARY IN DIRECTION THROUGH TUESDAY EVENING DUE TO THE
AFOREMENTIONED LOW PRESSURE, SHIFTING IN DIRECTION A COUPLE OF
TIMES BEFORE BECOMING MORE WESTERLY TUESDAY AFTERNOON. WINDS
INCREASE OVERNIGHT AND INTO THE MORNING HOURS. GUSTS BY LATE
MORNING AND EARLY AFTERNOON AROUND 30 TO 40 KNOTS EXPECTED,
STRONGEST WEST OF US HWY 281 TUESDAY AFTERNOON AND EVENING.
GIVEN THE STRONG WIND GUSTS, LLWS IS NOT EXPECTED OUTSIDE OF A
COUPLE HOURS OF DIRECTIONAL SHEAR AT THE BEGINNING OF THE PERIOD
FOR KSUX AND SURROUNDING AREAS.
FSD WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY FROM 7 AM TO 6 PM CST TUESDAY FOR SDZ038-050-052-
053-057>060-063>065-068-069.
MN...NONE.
IA...NONE.
NE...NONE.
DISCUSSION...APT
AVIATION...SG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page