Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 252251
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
451 PM MDT Mon Mar 25 2019

.DISCUSSION...(This Evening Through Monday)
Issued at 237 PM MDT Mon Mar 25 2019

Departing shortwave continues to support light rain and light
snow over the eastern FA this afternoon, with isolated showers
over the southern Hills. Drier/warmer weather on track for the
middle of this week as ridging ensues. Much drier air continues to
work into the region from the west and will advect in aloft over
the moist BL tonight. Ensuing inversion will support fog
development tonight, esp on the SD Plains. Fog may be thick enough
to support another dense fog adv on the SD Plains. However as
drainage flow develops over the Black Hills tonight, clearing is
expected into the Foothills. Fog may linger over parts of NW SD
into late Tues morning and early afternoon before dry air mixes
down. Much warmer air is then expected into the region through Wed
as shortwave ridging develops per the advancing western CONUS
trough. This will support temps in the 50s and 60s with even a few
70s possible across the southern third, esp Wed. NW SD may see
temps struggle at first Tues due to low clouds and fog. Upper low
will push into the Rockies by Thurs and support cyclogenesis over
the Central Plains as a northern stream Canadian trough traverses
northern NOAM. The northern stream system will force a cold front
south into the Northern Plains, supporting dry air into the FA
ahead of the southern stream system. The overall effect will be to
keep the best precip chances and higher QPF south of the FA, with
NE WY into far SW SD expected to see some rain/snow. At this time
1-3 inches of snow looks likely in the aforementioned portion of
the FA. Active, cold NW flow looks likely this weekend into next
week. Temps look to be at or below normal with passing drier
impulses likely supporting more sct showery precip.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening)
Issued At 451 PM MDT Mon Mar 25 2019

IFR/LIFR cigs will persist through the night across much of the SD
plains and foothills, with LIFR vsbys in FG overspreading these
locations through 06z. Farther west over nern WY, including at
KGCC, VFR conditions will likely continue through the TAF period.

With winds aloft becoming increasingly westerly overnight, FG
should be shorter-lived tonight east of the Black Hills due to
some downsloping and drying. As a result, expect gradual
improvement here beginning around 09z. Conditions should improve
to VFR area-wide on Tuesday morning.

&&

.HYDROLOGY...
Issued at 237 PM MDT Mon Mar 25 2019

Snowmelt and ice jam flooding is ongoing across parts of the
forecast area. See current Flood Warning/Advisory products for
details. After cool conditions and light precipitation today, dry
weather and much warmer temperatures are expected for Tuesday and
Wednesday.

Another storm system will cross the central plains late Thursday
through Friday, and bring some rain/snow to our area. Based on
current model solutions, NE WY-Black Hills into southwest SD
could receive one-quarter to one-half inch liquid equivalent
precipitation with this storm.

&&

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

$$

DISCUSSION...JC
AVIATION...Sherburn
HYDROLOGY...JC


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