099
FXUS63 KUNR 161718
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1018 AM MST MON DEC 16 2024
KEY MESSAGES
- WIND ADVISORY THROUGH THE MIDDAY HOURS TODAY ACROSS MUCH OF
NORTHWEST INTO CENTRAL SD FOR GUSTY WEST TO NORTHWEST WINDS.
- A WEAK DISTURBANCE WILL BRING CHANCES FOR LIGHT SNOW LATE
TONIGHT INTO TUESDAY. LIGHT SNOW ACCUMULATIONS ARE POSSIBLE
FROM MOSTLY NORTHWEST INTO CENTRAL SD.
- MOSTLY DRY CONDITIONS ARE EXPECTED THROUGH THE REST OF THE WEEK AND
INTO THE WEEKEND, WITH TEMPERATURES NEAR TO ABOVE AVERAGE ON
MOST DAYS.
DISCUSSION
(TODAY THROUGH SUNDAY)
ISSUED AT 306 AM MST MON DEC 16 2024
CURRENT SURFACE ANALYSIS SHOWS LOW PRESSURE NEAR LAKE WINNIPEG,
WITH CANADIAN COLD FRONT EXTENDING SOUTHWEST ACROSS NORTHWESTERN
ND INTO MT. PACIFIC COLD FRONT TO THE SOUTH OF THE LOW IS WELL
EAST OF THE REGION. UPPER LEVEL ANALYSIS SHOWS STACKED LOW OVER
FAR SOUTHERN MB, WITH TROUGH EXTENDING ACROSS THE PLAINS. STRONG
UPPER JET IS IN PLACE FROM THE NORTHERN ROCKIES TO THE CENTRAL
PLAINS. A LOW IS SITUATED OFF THE PACIFIC NW COAST, WITH A
SHORTWAVE RIDGE OVER THE PACIFIC NW. SKIES ARE VARIABLY CLOUDY,
WITH CLEARING SKIES ACROSS EASTERN WY AND FAR WESTERN SD. TEMPS
ARE MOSTLY IN THE MID 20S TO MID 30S. A TIGHT PRESSURE GRADIENT TO
THE WEST AND SOUTHWEST OF THE LOW IS PRODUCING BRISK WINDS ACROSS
MUCH OF WESTERN SD EARLY THIS MORNING, GUSTING TO 30 TO 40 MPH IN
SOME AREAS.
TIGHT PRESSURE GRADIENT REMAINS IN PLACE ACROSS THE AREA THROUGH THE
MIDDAY HOURS, BEFORE LOW MOVES FARTHER AWAY AND WINDS GRADUALLY
DECREASE DURING THE AFTERNOON. THE STRONGEST WINDS LOOK TO BE AFTER
SUNRISE THROUGH MIDDAY, WITH SOME GUSTS OF 40 TO AROUND 50 MPH IN
THE WIND ADVISORY AREA. COLD FRONT TO THE NORTH OF THE REGION WILL
SAG SOUTH ACROSS THE AREA LATER TODAY. SKIES WILL BE MAINLY SUNNY
WITH HIGHS IN THE 30S TO MID 40S, WARMEST SOUTH AND EAST OF THE
BLACK HILLS.
A PIECE OF SHORTWAVE ENERGY EJECTING OUT OF THE SYSTEM OFF THE WEST
COAST WILL QUICKLY PASS OVER THE RIDGE AND ACROSS THE NORTHERN
PLAINS LATE TONIGHT INTO TUESDAY. THIS ENERGY WILL INTERACT WITH THE
COLD FRONT HANGING OVER THE AREA TO BRING CHANCES FOR MOSTLY LIGHT
SNOW TO A GOOD PORTION OF THE AREA LATE TONIGHT AND TUESDAY MORNING.
A BAND OF ACCUMULATING SNOW IS POSSIBLE NEAR STRONGER FRONTOGENESIS
THAT LIKELY DEVELOPS TO THE NORTH OF THE COLD FRONT EARLY TUESDAY.
EXACTLY WHERE THAT OCCURS IS STILL SOMEWHAT UNCERTAIN, BUT IS
FAVORED RIGHT NOW SOMEWHERE ACROSS NORTHWEST AND CENTRAL SD.
ENSEMBLE OUTPUTS MOSTLY SUPPORT THIS AREA, BUT THERE IS SOME
VARIABILITY BETWEEN THE DIFFERENT MODELS AND FROM RUN TO RUN. SOME
OF THE DETERMINISTIC RUNS ARE ALSO SHOWING A BIT MORE SNOW POTENTIAL
THAN THE ENSEMBLE AVERAGES. ANY ACCUMULATIONS ACROSS OUR AREA SHOULD
MOSTLY BE IN THE LIGHT SIDE, WITH PROBS FOR OVER AN INCH OF
ACCUMULATION BEING 20 PERCENT OR LESS EVEN IN THE MOST FAVORED AREA
(NORTHWEST SD), BUT WOULD NOT RULE OUT UP TO A COUPLE OF INCHES IN
SOME AREAS IF A HEAVIER BAND DEVELOPS. THIS DISTURBANCE SHOULD MOVE
QUICKLY OUT OF THE AREA BY EARLY TUESDAY AFTERNOON. HIGHS WILL
MOSTLY BE IN THE UPPER 20S AND 30S WITH RELATIVELY LIGHT NORTH TO
NORTHWEST WINDS.
THE REST OF THE WEEK AND NEXT WEEKEND LOOK TO BE MAINLY DRY ACROSS
MUCH OF THE AREA AT THIS POINT. HOWEVER, WILL HAVE TO WATCH A
CLIPPER SYSTEM THAT WILL CROSS THE REGION WEDNESDAY NIGHT INTO
THURSDAY. MODELS HAVE GENERALLY BEEN TRACKING PCPN WITH THIS SYSTEM
NORTH AND NORTHEAST OF THE CWA, BUT THERE ARE AT LEAST SOME OUTLIERS
THAT BRING SOME SNOWFALL INTO AT LEAST FAR NORTHWEST SD LATER
WEDNESDAY NIGHT. GUSTY WINDS WILL DEVELOP BEHIND THE COLD FRONT THAT
CROSSES WITH THE SYSTEM LATE WEDNESDAY NIGHT AND THURSDAY. CHANCES
FOR ADVISORY CRITERIA WINDS ARE AT LEAST 30 PERCENT IN THE USUAL
FAVORED AREAS ACROSS THE SD PLAINS. SOME VARIABILITY IN TEMPS IS
EXPECTED MID TO LATE WEEK, WITH ABOVE AVERAGE TEMPS GENERALLY FROM
NORTHEAST WY TO SOUTHWEST SD AND NEAR TO BELOW AVERAGE TEMPS TO THE
NORTH AND NORTHEAST OF THE BLACK HILLS. A BROAD RIDGE IS LIKELY TO
BUILD OVER THE ROCKIES INTO THE PLAINS TOWARD THE WEEKEND, WITH MILD
AND DRY CONDITIONS LOOKING MORE LIKELY OVER THE WEEKEND.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1017 AM MST MON DEC 16 2024
GUSTY NORTHWEST WINDS CAN BE EXPECTED ACROSS SOUTH DAKOTA PLAINS
THROUGH THIS MORNING WITH WINDS DECREASING THIS AFTERNOON. SOME
LOW STRATUS/LIGHT SNOW WITH MVFR/IFR CONDITIONS WILL SLIP INTO
NORTHWESTERN SOUTH DAKOTA LATE TONIGHT. OTHERWISE, VFR CONDITIONS
ARE EXPECTED THROUGH THE TAF PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...WIND ADVISORY UNTIL 2 PM MST /3 PM CST/ THIS AFTERNOON FOR
SDZ001-002-012>014-032-043-044-046-047-049-072-073-077-078.
WY...NONE.
DISCUSSION/KEY MESSAGES...26
AVIATION...13
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