464
FXUS63 KUNR 151125
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
425 AM MST Sun Feb 15 2026

.KEY MESSAGES...

- Critical fire weather conditions for portions of northeastern
  Wyoming through south-central South Dakota Sunday afternoon
- Mild and dry through Monday with highs 15-25F above normal
- Couple of disturbances will bring increasing chances for
  precipitation Tuesday through Thursday along with cooler
  temperatures

&&

.UPDATE...
Issued at 840 PM MST Sat Feb 14 2026

Minor changes to the previous forecast. Bumped up winds the next
few days as deep mixing can be expected per warm temps and lack of
snow cover. Mild weather will persist through Tuesday as downstream
ridging is ongoing per the deep western CONUS trough. Expect
highs the next 3 days to be 15 to 25 degrees above seasonal
norms. Cold front will move through Tues, with strong gusty winds
expected and adv level winds likely on the SD Plains. Delayed
precip chances until Tues night when better forcing arrives.
However, ensemble spreads per QPF amounts remain quite high later
in the week, with a higher potential for lower amounts given
split flow tendencies.

&&

.DISCUSSION...(This Evening Through Saturday)
Issued at 1244 PM MST Sat Feb 14 2026

19z surface analysis had weak flow over the CWA with a couple of
weak troughs. Some high clouds floating by. Water vapour matinee
had zonal split flow over the CONUS with a developing upper trough
off the west coast. Effect of the upper trough and fire weather
are the main concerns this afternoon.

Tonight/Sunday, weak shortwave moving across the US/Canadian
border will push a warm front through the CWA late tonight into
Sunday. Behind it, deep boundary layer mixing is expected as
3-5mb/3hr pressure falls ramp up over eastern SD. Gusty westerly
downslope winds are foreseen, especially across the southern
third of the CWA with the chance of wind gusts >25mph 60-90%.
Temperatures will be 15-25F above normal per lower tropospheric
thermal ridge/dry air in place.

Monday, upper trough moves onshore into the western CONUS turning
upper flow southwesterly over the northern Plains. This will
sustain the unseasonably warm temperatures with gusty southerly
winds at times.

Tuesday, western CONUS upper trough slings a compact shortwave
into the northern plains with nice QG-forcing bubble. Surface low
winds up over northwest SD, pushing a cold front through the area
later in the day. Much of the initial synoptic lift will be wasted
on saturation. As the low propels a cold front through the area,
low level frontogenesis should be sufficient for a band of QPF
over the northwest half of the CWA. Chance of >0.25" QPF for the
plains <20%, but ~50% for the northern Black Hills, which may lead
to some light snow accumulations. Looks pretty windy behind the
cold front with magnitude still uncertain but headlines certainly
possible.

Wednesday, shortwave ridging expected, but still quite windy per
gradient. Thursday, second shortwave moves through with much lower
condensation pressure deficits, so QG-forcing/frontogenesis will
translate to better chances for (mostly) snow for the CWA with the
best chance for a few inches over the Black Hills (~50% chance
>0.25" QPF). Rest of the week looks unsettled as the upper
trough/cyclonic flow move through the northern Plains.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Monday Morning)
Issued At 424 AM MST Sun Feb 15 2026

VFR conditions through the forecast period.

&&

.FIRE WEATHER...
Issued At 1244 PM MST Sat Feb 14 2026

Critical fire weather conditions are expected Sunday afternoon
with elevated to near critical fire weather conditions for parts
of the area Monday and Tuesday. Deep mixing Sunday will drop
minimum relative humidities into the teens from southern Campbell
County Wyoming through south-central South Dakota. Gusty west
winds will develop, reaching 12 to 25 mph with gusts from 25 to 35
mph at times. Minimum relative humidities Monday and Tuesday will
be in the upper teens to 20s over parts of northeastern Wyoming
and southwestern South Dakota. Gusty southwest to southeast winds
are expected Monday and Tuesday, but quickly switch to the
northwest (and quite gusty) behind a cold front later Tuesday.
Temperatures will be 15 to 25 degrees above normal Sunday and
Monday. A disturbance will bring increasing chances for
precipitation Tuesday through Thursday, which will quell elevated
fire weather conditions as temperatures cool. Best chance for
wetting precipitation will be over the northern Black Hills, and
then maybe getting close on the plains for Thursday.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from 11 AM MST /noon CST/ this morning to 5 PM
     MST /6 PM CST/ this afternoon for SDZ321-322-325-326-
     332>335.
WY...Red Flag Warning from 11 AM this morning to 5 PM MST this
     afternoon for WYZ315-317.
&&

$$

UPDATE...JC
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Dye
FIRE WEATHER...Helgeson