828
FXUS63 KUNR 171957
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1257 PM MST MON FEB 17 2025
KEY MESSAGES
- BITTERLY COLD TEMPERATURES PERSIST THROUGH THURSDAY MORNING.
WIND CHILLS WILL RANGE FROM 25 TO 45 BELOW ZERO ACROSS THE
FORECAST AREA.
- LIGHT SNOW WILL CONTINUE THIS AFTERNOON THROUGH TUESDAY MORNING;
ADDITIONAL SNOWFALL AMOUNTS 1 TO 3 INCHES. AREAS OF LIGHT SNOW
WILL LINGER THROUGH WEDNESDAY.
- MUCH WARMER AIR EXPECTED THURSDAY INTO THE WEEKEND AS
TEMPERATURES REBOUND. HIGH LIKELIHOOD (50-60%+) OF WIDESPREAD
50F+ BY SUNDAY INTO EARLY NEXT WEEK.
DISCUSSION
(THIS EVENING THROUGH MONDAY)
ISSUED AT 1252 PM MST MON FEB 17 2025
WATER VAPOR IMAGERY SHOWS WEAK SHORTWAVE PUSHING THROUGH THE CENTRAL
DAKOTAS. FURTHER UPSTREAM, ANOTHER WAVE IS DROPPING INTO MT WITH THE
UPPER TROUGH AXIS EXTENDING FROM ALBERTA WESTWARD INTO WESTERN
OR/WA. AT THE SURFACE, A ~1042 MB HIGH IS CENTERED OVER WESTERN
MANITOBA/EASTERN SASKATCHEWAN WITH A LOW-LEVEL BAROCLINIC ZONE
FROM CENTRAL MT THROUGH NE WY/WESTERN SD INTO NE. WIDESPREAD LIGHT
SNOW CONTINUES ACROSS THE FORECAST AREA THIS AFTERNOON.
LIGHT SNOW IS EXPECTED TO CONTINUE THROUGH TUESDAY MORNING, WITH
SPOTTY LIGHT SNOW LINGERING INTO WEDNESDAY. PROLONGED LOW-LEVEL
FRONTOGENETIC FORCING COUPLED WITH INCREASING ASCENT ALOFT (AS
MANIFEST BY Q-VECTOR CONVERGENCE ASSOCIATED WITH SHORTWAVE TROUGH
AXIS DROPPING THROUGH MT) WILL RESULT IN AN ADDITIONAL 1 TO 3
INCHES OF SNOW ACROSS PORTIONS OF NE WY AND SW SD THROUGH TUESDAY
MORNING. HAVE EXTENDED THE WINTER WEATHER ADVISORY THROUGH 18Z TO
ACCOUNT FOR PROLONGED PERIOD OF LIGHT SNOW.
BITTERLY COLD TEMPERATURES WILL PERSIST THROUGH THURSDAY MORNING,
WITH MANY AREAS (ESPECIALLY NW SD) REMAINING BELOW 0F (AIR
TEMPERATURE) THROUGH AT LEAST MID-MORNING THURSDAY. ARCTIC AIR
WILL REMAIN ENTRENCHED AS THE ARCTIC HIGH PRESSURE SLIDES SLOWLY
SOUTHWARD THROUGH THURSDAY. WHILE WINDS WILL BE RELATIVELY LIGHT,
FRESH SNOW PACK + CLEARING SKIES (ESPECIALLY WEDNESDAY INTO
THURSDAY) WILL RESULT IN WIDESPREAD WIND CHILLS 25 TO 45 BELOW
ZERO THIS AFTERNOON THROUGH THURSDAY MORNING; COLDEST WIND CHILLS
EXPECTED TONIGHT AND AGAIN WEDNESDAY NIGHT. AN EXTREME COLD
WARNING REMAINS IN EFFECT FOR NW SD THROUGH WEDNESDAY MORNING AND
HAVE UPGRADED THE COLD ADVISORY TO A WARNING FOR MUCH OF THE REST
OF WESTERN SD THROUGH 18Z TOMORROW. WILL LIKELY NEED ANOTHER
ADVISORY FOR WESTERN/SW SD INTO NE WY TUESDAY NIGHT/WEDNESDAY
MORNING. WIDESPREAD WARNING CRITERIA WIND CHILLS (< -35F) AGAIN
LIKELY WEDNESDAY NIGHT INTO THURSDAY MORNING ACROSS MOST OF
WESTERN SD.
AS THE SURFACE HIGH PRESSURE SLIDES OFF TO THE SOUTHEAST, UPPER
LEVEL RIDGING WILL BUILD OVER THE WESTERN US WITH WARMER,
SOUTHWESTERLY FLOW DEVELOPING. TEMPERATURES WILL MODERATE THURSDAY
(HIGHS IN THE SINGLE DIGITS TO UPPER TEENS) WITH STEADILY WARMING
TEMPERATURES INTO FRIDAY. MUCH WARMER AIR EXPECTED SATURDAY THROUGH
EARLY NEXT WEEK WITH 13Z NBM MAXT PROBABILITY >50F ~30-60% SATURDAY
(MAINLY FOOTHILLS AND WESTERN SD PLAINS), BECOMING MORE WIDESPREAD
(PROB ~50-75%+) SUNDAY INTO MONDAY; WARMEST ON WESTERN SD PLAINS AND
NORTHEASTERN WY PLAINS.
AVIATION
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY)
ISSUED AT 1026 AM MST MON FEB 17 2025
WIDESPREAD MVFR/AREAS IFR CONDITIONS DUE TO LIGHT SNOW/STRATUS ARE
EXPECTED THROUGH THE PERIOD. PERIODIC LIFR CONDITIONS MAY OCCUR
IN/NEAR THE BLACK HILLS. PERIODIC VFR CONDITIONS MAY OCCUR OVER
FAR NORTHWESTERN SD, ESPECIALLY THIS AFTERNOON/EARLY EVENING.
UNR WATCHES/WARNINGS/ADVISORIES
SD...EXTREME COLD WARNING UNTIL 11 AM MST WEDNESDAY FOR SDZ001-002-
014-078.
EXTREME COLD WARNING UNTIL 11 AM MST /NOON CST/ TUESDAY FOR
SDZ012-013-025-031-032-043-046-047-049-072-073-077.
WINTER WEATHER ADVISORY UNTIL 11 AM MST TUESDAY FOR SDZ026>030-
041-042-044-074>076.
WY...WINTER WEATHER ADVISORY UNTIL 11 AM MST TUESDAY FOR WYZ058-059.
DISCUSSION/KEY MESSAGES...SE
AVIATION...HELGESON
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