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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KUNR 042326
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
426 PM MST Thu Mar 4 2021

.DISCUSSION...(This Evening Through Thursday)
Issued at 153 PM MST Thu Mar 4 2021

20z surface analysis had lee trough from central MT into eastern
WY. Stationary front from western ND into central NE.
East/southeast flow over the CWA as thin cirrus pushes through in
response to upper low spinning over eastern CO.

Tonight, upper low spins east well south of the CWA. Nearly
stationary front may slip eastward overnight. Low/mid 30s Td/s
along boundary slip westward into the eastern reaches of the CWA.
Forecast lows east of the Black Hills in the mid 20s to lower 30s
so some fog/stratus may develop. NAM most aggressive with
fog/stratus. If this happens, it may have an effect on
temperatures Friday from KD07 to KPHP to KICR.

Friday/Saturday, upper ridge dominates with spring-like
temperatures. Morning fog/stratus may affect temperatures over
eastern reaches of CWA each morning, but northeast WY into far
northwest/southwest SD should reach guidance forecast. Some warmer
than guidance readings possible Saturday afternoon given thermal
ridge/downslope southwest boundary layer flow. A few records may
be in jeopardy. Upper trough moves through Saturday night pushing
a dry cold front through the CWA.

Sunday through Tuesday, southwest flow aloft and less of a
cooldown compared to previous ensemble guidance. Temperatures
will remain 10-15F above normal.

Tuesday night through the end of the week, mean upper trough
develops over the Rockies, extending into the plains states. This
trend is warmer than previous probabilistic guidance along with
less moisture. Still looks like "typical" March weather with some
snow at times, particularly at night.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 421 PM MST Thu Mar 4 2021

VFR conditions will continue through the evening and overnight
hours for much of the area. Light, easterly flow across portions
of the central/western SD plains may result in the development of
fog and low clouds. MVFR/IFR conditions will be possible with any fog
that develops. However, do not expect that fog will reach KRAP or
KGCC. Fog will diminish Friday morning with VFR conditions across
the region.

&&

.FIRE WEATHER...
Issued At 153 PM MST Thu Mar 4 2021

Unseasonably warm weather will occur Saturday with highs in the
60s to lower 70s and minimum RHes dropping into the 20s - some
upper teens over the Black Hills. Gusty south/southwest winds will
occur. Elevated fire weather conditions expected. If it looks a
little drier/warmer, a Fire Weather Watch/Red Flag Warning may be
needed.

&&

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

$$

DISCUSSION...Helgeson
AVIATION...Eagan
FIRE WEATHER...Helgeson