337
FXUS63 KUNR 051121
AFDUNR
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
521 AM MDT TUE MAY 5 2026
KEY MESSAGES
- ACTIVE NORTHWEST FLOW WILL PERSIST THROUGH THE WEEK WITH
UNSETTLED WEATHER.
- COOLER TEMPERATURES PERSIST THROUGH WEDNESDAY BEFORE WARMING
TREND INTO THE WEEKEND.
UPDATE
ISSUED AT 954 PM MDT MON MAY 4 2026
NO SIGNIFICANT FORECAST CHANGES NEEDED WITH THIS EVENING'S UPDATE.
THINGS STILL LOOKS QUITE COOL AND UNSETTLED THROUGH TUESDAY
EVENING WITH CAMS CONTINUING TO ADVERTISE AT LEAST ISOLATED SHOWER
POTENTIAL, BUT QPF PROBABILITIES ARE QUITE LOW SO NOT MUCH OF ANY
RAINFALL IS EXPECTED. SOME SHOWERS WILL FALL AS SNOW OVER THE
BLACK HILLS AND PERHAPS NORTHEASTERN WYOMING, BUT EVEN AT THE
HIGHER ELEVATIONS OF THE BLACK HILLS WHERE TEMPERATURES WILL BE
COLDEST, LESS THAN 2 INCHES ARE EXPECTED WHERE IT DOES SNOW.
WEDNESDAY WILL STILL LEAN COOL (HIGHS IN THE 50S), BEFORE
TEMPERATURES NOTICEABLY WARM FROM THURSDAY INTO THE WEEKEND (60S
AND LOW 70S).
DISCUSSION
(THIS EVENING THROUGH MONDAY)
ISSUED AT 113 PM MDT MON MAY 4 2026
WATER VAPOR IMAGERY SHOWS ACTIVE NORTHWESTERN FLOW ACROSS THE
NORTHERN PLAINS. CLOSED UPPER LOW IS CENTERED OVER WESTERN ONTARIO
WITH ANOTHER CLOSED LOW OVER CENTRAL CA COAST. THE SURFACE COLD
FRONT PUSHED THROUGH THE AREA AROUND 11Z THIS MORNING AND NOW
STRETCHES FROM THE SURFACE LOW IN CENTRAL ONTARIO SOUTHWESTWARD
THROUGH SOUTHERN NE.
WEAK MID-LEVEL FRONTOGENESIS COUPLED WITH STEEP LOW-LEVEL LAPSE
RATES HAVE RESULTED IN SCATTERED SHOWERS THIS AFTERNOON, MAINLY
SOUTH OF I-90. GIVEN DRY BOUNDARY LAYER AND WEAK FORCING, EXPECT
MINIMAL PRECIPITATION AMOUNTS.
WELL-MIXED BOUNDARY LAYER WITH 35-40 KNOT WINDS ATOP THE BOUNDARY
LAYER WILL SUPPORT GUSTS UP TO 45-50 MPH THIS AFTERNOON ACROSS
NORTHWESTERN SD. A WIND ADVISORY REMAINS IN EFFECT FOR PORTIONS OF
THE NORTHWESTERN SD PLAINS THROUGH 6 PM MDT.
ACTIVE NORTHWEST FLOW PERSISTS THROUGH MID-WEEK WITH COOLER THAN
AVERAGE TEMPERATURES (5-10F BELOW NORMAL) BEFORE WARMER AIR FILTERS
BACK INTO THE REGION WITH SEASONABLE TO ABOVE AVERAGE (~5-10F)
TEMPERATURES FOR THE LATTER HALF OF THE WEEK INTO THE WEEKEND.
SHOWERS AND THUNDERSTORMS POSSIBLE SATURDAY AS UPPER SHORTWAVE
TROUGH DROPS INTO THE NORTHERN PLAINS.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 520 AM MDT TUE MAY 5 2026
LOW CLOUDS (CIGS 4-6KFT) WILL PERSIST TODAY AND TONIGHT ACROSS
THE PLAINS...AND SOME AREAS OF MVFR CIGS WILL BE POSSIBLE ACROSS
THE BLACK HILLS. ISOLATED RAIN SHOWERS WILL BE POSSIBLE TODAY,
WITH SOME SNOW SHOWERS ACROSS THE BLACK HILLS AND PORTIONS OF NE
WY.
UNR WATCHES/WARNINGS/ADVISORIES
SD...NONE.
WY...NONE.
UPDATE...KSMITH
DISCUSSION/KEY MESSAGES...SE
AVIATION...13
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