Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 291053

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
453 AM MDT Thu Jun 29 2017

.DISCUSSION...(Today Through Wednesday)
Issued at 223 AM MDT Thu Jun 29 2017

Upper low is spinning over Saskatchewan/Manitoba, with a trough
stretching across the northwestern states. Within the trough there
are two shortwaves, one currently pushing into the CWA, and
another over northern ID/MT. Radar shows some weak storms across
northeastern WY and northwestern SD, shifting northeastward. At
the surface, winds are variable around 10 kts, and temperatures
are falling into the 50s.

First wave will slide across the ND/SD border today, with
showers/storms expanding across northwestern SD this morning, and
shifting into central/eastern SD in the afternoon. Then the
secondary wave will cross the region, bringing a second round of
showers/storms, mainly to southwestern portions of the CWA.
Instability today will be weak to marginal again. Shear is expected
to decrease throughout the day, although around 40 kts of 0-6 km
shear across southern portions of the area this afternoon may be
enough for an isolated strong to severe storm to develop. Cool air
associated with the trough will keep highs today in the 70s.

Lingering moisture/instability may support a few more showers/storms
on Friday before the trough exits the region. One more day of highs
in the 70s is expected before much warmer weather returns with a
large upper level ridge. Saturday will be dry, but a passing
shortwave will briefly flatten the ridge and produce a few
showers/storms on Sunday. Meanwhile, temperatures will continue to
climb, with highs in the 80s for the weekend. Models are in
agreement about the ridge rebuilding for next week. Highs will be in
the 90s, with mostly dry conditions, other than a few spotty chances
for precip.


.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 451 AM MDT Thu Jun 29 2017

Scattered SHRA/-TSRA with local MVFR conditions across far
northeast WY and northwest SD will move northeast of the area by
18z. Additional TSRA will develop across northeast WY into the
Black Hills this afternoon and push southeast through this evening
with local MVFR conditions and gusty winds/hail. Outside of
precipitation VFR conditions will prevail through the period.


.FIRE WEATHER...With a broad upper ridge covering the western to
central CONUS next week, conditions will become hot and dry. Highs
will be in the upper 80s to lower 90s for several days, with little
to no precipitation expected after Sunday. Minimum relative humidity
values will be 15-25%, but in this pattern, lower RH values are
possible. Will need to continue to monitor next week for fire
weather concerns.




AVIATION...Helgeson is the U.S. government's official web portal to all federal, state and local government web resources and services.