598
FXUS63 KUNR 211658
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
958 AM MST SAT DEC 21 2024
KEY MESSAGES
- ABOVE AVERAGE TEMPERATURES AND MOSTLY DRY CONDITIONS ARE
EXPECTED FOR THIS WEEKEND THROUGH NEXT WEEK.
DISCUSSION
(TODAY THROUGH FRIDAY)
ISSUED AT 238 AM MST SAT DEC 21 2024
CURRENT WATER VAPOR IMAGERY DEPICTS UPPER LEVEL RIDGE AXIS
SITUATED OVER THE WESTERN US WITH TROUGHING OVER THE EASTERN US.
SLUG OF MID LEVEL MOISTURE ASSOCIATED WITH A RIDGE RIDING
SHORTWAVE SITS OVER THE CANADIAN ROCKIES WITH SFC ANALYSIS
DEPICTING A DEVELOPING LEE TROUGH. MOST OF WESTERN SD AND
NORTHEASTERN WY ARE EXPERIENCING A PLEASANT IF NOT SLIGHTLY CHILLY
NIGHT. THE CALM CONDITIONS HAVE ALLOWED FOR A FAIRLY STRONG
INVERSION TO DEVELOP. TEMPERATURES ACROSS THE WESTERN SD PLAINS
RANGE FROM THE SINGLE DIGITS TO LOW MID 20S WITH THE HIGHER
ELEVATIONS IN THE BLACK HILLS SLIGHTLY WARMER AT 30 TO 40 DEGREES.
SO TODAY IS TECHNICALLY FIRST DAY OF ASTRONOMICAL WINTER, EVEN
THOUGH IT MOST CERTAINLY WON'T FEEL LIKE IT FOR THE CWA. LOW LEVEL
THERMAL RIDGING FACILITATED BY AFOREMENTIONED LEE TROUGHING WILL
BRING TEMPERATURES THIS AFTERNOON UP INTO THE 50S FOR MUCH OF THE
FORECAST AREA. A FEW SPOTS ALONG THE EASTERN FOOTHILLS MAY EVEN
CLIMB INTO THE LOW 60S THANKS TO DOWNSLOPING. WITH THE WARMER AND
DRIER AIR ADVECTING INTO THE REGION TODAY COMES THE RISK FOR
LOCALLY ELEVATED FIRE WEATHER CONDITIONS, MAINLY ACROSS THE
EASTERN BLACK HILLS AND THE NORTHEASTERN WY PLAINS WHERE RHS WILL
DIP INTO THE 20S.
SHORTWAVE TROUGH WILL FLATTEN OUT THE RIDGE AS IT CROSSES THE
NORTHERN PLAINS SUNDAY. THE BEST MOISTURE AND Q-VECTOR CONVERGENCE
(AND THUS, THE BEST CHANCES FOR MEASURABLE PRECIP) WILL REMAIN TO
THE NORTH OF THE CWA. LREF GRAND ENSEMBLE PAINTS 30-40% PROBS OF
24 HR QPF EXCEEDING 0.01" ACROSS THE ND/SD BORDER WITH LOWER PROBS
FURTHER SOUTH. THERE IS SOME SIGNAL THAT A FEW UPSLOPE SNOW
SHOWERS MAY DEVELOP ACROSS THE NORTHERN BLACK HILLS SUNDAY
AFTERNOON, THOUGH WITH THE LIMITED MOISTURE CHANCES FOR ANY
MEANINGFUL SNOWFALL WILL BE LOW. WINDS WILL PICK UP SUNDAY
AFTERNOON AS THE UPPER WAVE AND ATTENDANT SURFACE FRONT/TROUGH
CROSSES THE REGION. 3 HR PRESSURE RISES OF 1-2 MB BEHIND THE FRONT
WILL FACILITATE A BREEZY AFTERNOON ACROSS THE WESTERN SD PLAINS
WITH THE STRONGEST WINDS (GUSTS OF 35- 40 MPH) BEING IN OUR USUAL
"SQUEEZE" SPOTS AROUND THE BLACK HILLS.
BEYOND SUNDAY, A PROGRESSIVE UPPER LEVEL PATTERN SETS UP ACROSS
THE US. THE NORTHERN PLAINS WILL SIT IN THE MIDDLE OF THE SPLIT
FLOW WITH THE ACTIVE SOUTHERN STREAM STAYING WELL TO OUR SOUTH.
TEMPERATURES WILL REMAIN ABOVE AVERAGE THROUGH NEXT WEEK WITH
EPS/GEFS/GEPS PROBABILITIES STILL PAINTING 70-100% CHANCES FOR 2-M
TEMPERATURE ANOMALIES EXCEEDING 10F FOR MUCH OF THE AREA.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY)
ISSUED AT 956 AM MST SAT DEC 21 2024
VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
DISCUSSION/KEY MESSAGES...WONG
AVIATION...10
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