Colonial Pine Hills, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

647
FXUS63 KUNR 221706
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1106 AM MDT Sun Jun 22 2025

.KEY MESSAGES...

- Slight risk (2 out of 5) of severe thunderstorms later this
  afternoon/evening, especially over southern SD
- Unsettled next week with seasonal temperatures with a slight
  risk (2 out of 5) of severe thunderstorms Tuesday

&&

.UPDATE...
Issued at 1008 AM MDT Sun Jun 22 2025

Low clouds are sticking around longer than originally anticipated,
and so temperatures are cooler. Lowered highs today across parts
of the western SD plains, including southwestern SD, where some
CAMs show storms strengthening. Therefore, confidence is low on
severe weather developing there this evening.

&&

.DISCUSSION...(Today Through Saturday)
Issued at 149 AM MDT Sun Jun 22 2025

07z surface analysis had cool front from central MN to KICR to
northeastern CO with a low pressure over northeastern CO. Water
vapour loop had upper ridge over the eastern CONUS and trough over
the northwest CONUS. CWA had southwest flow aloft with next wave
of interest over eastern ID/UT. Ahead of these features early this
morning, 50kt low-level jet igniting TSRA (2-3KJ/kg MUCAPE, weak
effective shear) over south-central SD with regional radars
showing additional convection developing in/near MT/WY/ND borders
per 700mb theta-e advection (1KJ/kg MUCAPE, 35-45kt effective bulk
shear). Expect best convection to be northeast/north of CWA
overnight, but can`t rule out a stronger storm mainly over
northwestern SD. Effect of ID/UT wave the main short term forecast
concern.

Today/tonight, ID/UT wave lifts northeast with modest QG-
forcing. Northeast CO low will move along cool front into eastern
SD pushing cool front south of CWA tonight. Persistent theta-e
advection ahead of it will promote isolated/scattered shra/TS in
the north this morning and then over the western SD plains later
this afternoon/evening. Buoyancy will average <1KJ/kg in post
frontal environment with rapidly increasing values ahead of the
cool front. 0-6km bulk shear best post-frontal. CAMs show active
storms over southwestern SD (Black Hills downstream convergence
per northerly winds helping convective initiation) later this
afternoon, moving east into south-central SD this evening.
Strongest convection should be associated with front east of CWA.
Thus, marginal risk (1 out of 5) of severe thunderstorms
reasonable over the CWA. High temperatures this afternoon will be
tricky with post-frontal low clouds squashing potential
temperatures in the northwest, so didn`t stray far from guidance.

Next week, upper trough moves east of the area with
west/southwest flow aloft and several perturbations zipping
through the flow. Return flow Tuesday will promote increasing
buoyancy and sufficient shear for the possibility of severe
thunderstorms per SPC Day 3 slight risk. After that, harder to
pinpoint focused areas of precipitation and/or active
thunderstorms, but it`s June so wouldn`t be surprised to see
spritzes of strong/severe TSRA with last nights CSU MLP
portraying that scenario.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1103 AM MDT Sun Jun 22 2025

MVFR ceilings will lift northeast this afternoon leaving mainly
VFR conditions behind. Isolated to scattered showers and
thunderstorms will become more numerous this afternoon and early
evening with local IFR conditions, particularly across southern
SD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

UPDATE...Pojorlie
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Smith