Spearfish, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

780
FXUS63 KUNR 231134
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
434 AM MST Sat Nov 23 2024

.KEY MESSAGES...

- Weak cold front this morning with areas of fog on the plains
  north and east of the Black Hills

- Elevated fire weather conditions today across northeast WY

- Cold front Sunday with gusty northwest winds and small chances (40%)
  of light snow/flurries for northeast Wyoming and Black Hills

- Below average temperatures through the Thanksgiving week with
  slight chance (<20%) of snow over the Black Hills Thursday

&&

.DISCUSSION...(Today Through Friday)
Issued at 138 AM MST Sat Nov 23 2024

09Z upper level analysis has broad ridging across the central
CONUS with deep trof entering the Pacific Northwest. Locally,
skies are partly cloudy most areas, with some low stratus and
possible patchy fog across northwestern SD. At the surface, weak
back-door cold front has sagged south across western South
Dakota, with light north to northeast winds behind it.

Ridge axis shifts east of the Northern Plains today as western
trof moves into the Pacific Northwest. Light northeast winds over
western SD shift to the southeast as Canadian high shifts east
and low pressure develops across central WY. Winds become breezy
over northwestern SD by mid day. Persistent easterly boundary
layer flow will keep temperatures cool across the SD plains, with
temps struggling into the 30s for highs. Areas of low stratus and
fog will persist through the morning hours. Just ahead of the
developing low over central WY, breezy south to southwest winds
will bring milder temperatures from northeast WY, to the Black
Hills, into far southwest SD - with highs in the 50s. Winds
eventually taper off this evening and overnight as relatively mild
westerly flow takes over. Lows will mainly be in the upper teens
and 20s under west to southwest upper flow.

On Sunday, an upper trof will cross the forecast area as main
upper low stays in Canada. Surface cold front will slide across
the area, bringing chances for some very light snow fall across
northeast WY, the Black Hills, and southwestern SD. Accumulations
look to be on the light side at this time, with total snowfall
remaining at an inch or less from Sunday afternoon through Sunday
evening. Northwesterly winds are expected to be 20 to 30 mph with
some gusts to 40 mph. Temperatures will be cooler on Sunday,
mainly in the upper 20s to upper 30s. Chilly temperatures are
expected Sunday night, with lows in the single digits and teens.

Persistent northwesterly upper flow is expected for the upcoming
holiday week, setting the stage for below average temperatures
persisting the whole week. A couple of weak weather disturbances
move through the area during the week, bringing very small chances
(<20%) of light snow/flurries. Colder than average temperatures
look to persist through next weekend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Sunday Morning)
Issued At 433 AM MST Sat Nov 23 2024

Areas of fog and low clouds have developed across the western
South Dakota plains this morning, with a period of IFR (and
transient local LIFR) conditions expected on portions of the
western SD plains, mainly in the far west including KRAP.
Conditions will begin to improve after 17-19z Saturday morning
into the afternoon. Breezy southerly winds are expected Sat most
areas, strongest on the northeast WY Plains.

&&

.FIRE WEATHER...
Issued At 138 AM MST Sat Nov 23 2024

Elevated fire weather conditions will develop across northeast WY
late this morning through mid afternoon as southwest winds become
breezy and RH drops to near and below 20 percent. These elevated
conditions could possibly also develop over the higher Black
Hills and far southwest SD.

&&

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

$$

DISCUSSION/KEY MESSAGES...15
AVIATION...SE
FIRE WEATHER...15