040
FXUS63 KUNR 090329
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
829 PM MST THU DEC 8 2022
UPDATE
ISSUED AT 826 PM MST THU DEC 8 2022
LATEST WATER VAPOUR LOOP DEPICTED LOW NEAR KONL WITH TIGHT BAND
OF SNOW WRAPPING AROUND IT INTO SOUTH-CENTRAL SD. BEST LIFT IS
SHIFTING EASTWARD PER IR/RADAR LOOPS. THIS IS INLINE WITH
KRAP/HRRR GUIDANCE AS WELL AS HIGHWAY CAMS. THUS, HAVE LET WINTER
WEATHER ADVISORY EXPIRE ON-TIME FOR PART OF SOUTHERN SD AND
EXPECTED THE REST WILL EXPIRE ON/BEFORE 06Z. REST OF FORECAST IN
GOOD SHAPE.
DISCUSSION
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 228 PM MST THU DEC 8 2022
NEAR ZONAL FLOW IN THE UPPER LEVELS HAS DEVELOPED ACROSS THE
REGION, WHILE A COMPACT UPPER LOW EMBEDDED IN THE FLOW PUSHES
EASTWARD ACROSS CENTRAL NEBRASKA. JUST NORTH OF THE LOW CENTER,
STRONG FORCING IS BRINGING A BAND OF SNOW TO SOUTHWEST SD, AND
BEGINNING TO TRANSITION INTO SOUTH CENTRAL SD. KUDX RADAR SHOWS
MODERATE TO HEAVY SNOW FROM OELRICHS TO MARTIN TO MISSION. SURFACE
OBS AND WEBCAMS ACROSS FALL RIVER COUNTY SHOW SNOWFALL NOT
ACCUMULATING BECAUSE OF TEMPS JUST ABOVE FREEZING. THE EXCEPTION
IS TOWARD THE FAR SE CORNER OF THE COUNTY ALONG THE NEBRASKA
BORDER NEAR HWY 385 WHERE SNOW IS BEGINNING TO ACCUMULATE. GIVEN
THE MAJORITY OF THE COUNTY HAS LITTLE TO NO SNOW ACCUMULATION,
HAVE CANCELLED THE ADVISORY. OTHERWISE ANOTHER TWO TO FOUR INCHES
OF SNOW IS EXPECTED THROUGH THIS EVENING ACROSS THE REST OF THE
ADVISORY AREA. DRY WEATHER WILL RETURN TO THE REGION TOMORROW AND
CONTINUE THROUGH SUNDAY. A SHORTWAVE TROUGH WILL CROSS THE AREA
FRIDAY NIGHT, BUT THE AIR LOOKS TOO DRY IN THE LOW/MID LEVELS FOR
ANY PRECIP TO DEVELOP. WEAK UPPER RIDGING WILL BRING QUIET WEATHER
TO THE AREA SATURDAY AND SUNDAY, WITH TEMPERATURE NEAR OR JUST
ABOVE AVERAGE. THEN THE NEXT SYSTEM APPROACHES, WHICH IS BEGINNING
TO GET A LOT OF ATTENTION. MODELS IN GENERAL ARE SHOWING A STRONG
UPPER LOW ACROSS THE WESTERN CONUS EARLY NEXT WEEK, THEN WILL
BECOME NEGATIVELY TILTED ACROSS THE CENTRAL CONUS, THEN HAVE VERY
LITTLE MOVEMENT THROUGH MUCH OF THE WORK WEEK. THERE IS HIGH
CONFIDENCE THAT THIS STORM WILL BRING SNOW TO WIDE SWATHS OF THE
NORTHERN GREAT PLAINS...AND SOME LOCATIONS MAY GET SIGNFICANT
AMOUNTS OF SNOW. HOWEVER, THERE IS STILL LOW CONFIDENCE ON WHERE
THESE LOCATIONS ARE. IT IS POSSIBLE OUR CWA WILL SEE SOME OF THESE
VERY HIGH ACCUMULATIONS, BUT IT'S STILL EARLY ENOUGH THAT WE
EXPECT TO SEE CHANGES IN MODEL SOLUTIONS OVER THE NEXT SEVERAL
DAYS. THIS IS ESPECIALLY TRUE BEFORE SUNDAY, WHEN THE SYSTEM IS
EXPECTED TO COME ONSHORE. ONLY THEN CAN BETTER DATA SAMPLING BE
OBTAINED FROM RADIOSONDE BALLOON LAUNCHES. IN THE 12Z RUN, THE
ECMWF AND CANADIAN MODELS SHOW THE HEAVIEST SNOW AMOUNTS SLIGHTLY
FARTHER EAST THAN PREVIOUS RUNS, AND WE EXPECT TO SEE MORE
VARIATIONS IN SOLUTIONS THROUGH THE WEEKEND.
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 424 PM MST THU DEC 8 2022
MVFR/IFR CONDITIONS EXPECTED ACROSS FAR SOUTHWEST INTO SOUTH-
CENTRAL SD THROUGH 06Z DUE TO LOW CLOUDS/SNOW. CONDITIONS WILL
IMPROVE FROM WEST TO EAST OVERNIGHT. OTHERWISE (INCLUDING
KRAP/KGCC), VFR CONDITIONS EXPECTED THROUGH THE FORECAST PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...WINTER WEATHER ADVISORY UNTIL 11 PM MST /MIDNIGHT CST/ THIS
EVENING FOR SDZ044-047-049.
WY...NONE.
UPDATE...HELGESON
DISCUSSION...13
AVIATION...HELGESON
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