Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 140913
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
313 AM MDT Sat Jul 14 2018

.DISCUSSION...(Today Through Friday)
Issued at 244 AM MDT Sat Jul 14 2018

Latest analysis shows an upper ridge over the forecast area with
an upper low/trough over ALberta. At the surface, high pressure is
centered over Nebraska, eastern South Dakota and Minnesota with a
deepening low pressure trough over Saskatchewan, eastern Montana
and central Wyoming. A cold front has recently moved southward
into northern Montana.

For today, high temperatures will be mainly in the mid-90s as the
thermal ridge builds over the region. Synoptic scale subsidence
and a strong capping inversion are expected to hold off convection
during most of the afternoon possibly developing first over the
Black Hills. Expect scattered thunderstorms to develop early this
evening with enhanced forcing due to the upper trough and the
surface cold front moving into the region.

Sufficient CAPE and increasing shear will support support a few
strong to perhaps isolated severe storms this evening, with the
better chances for severe storms over northwestern SD. The cold
front will cross the forecast area tonight, providing the focus
for shra/ts chances, especially behind the front tonight through
Sunday morning when a secondary upper disturbance affects the
region. CAA/clouds/and precip will hold temps down Sunday, with
highs struggling to get out of the 60s in some locations around
the Black Hills. Upper flow will then turn more NW early next
week as the western CONUS ridge rebuilds, with enough lingering
moisture in place to support shra/ts with any weak impulse. Most
activity in this pattern will be widely scattered to isolated,
with the best chances around and SE of the Black Hills. The upper
ridge looks to shift east by mid week, with warmer/drier weather
expected after. Look for seasonable temps in the period, with the
coolest day on Sunday.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Saturday Night)
Issued At 1124 PM MDT Fri Jul 13 2018

Isolated TSRA will develop over northeast WY/far western SD late
Saturday, but a cold front overnight Saturday will bring the best
chances for storms and local IFR conditions. Otherwise, expect
VFR conditions through the period.

&&

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

$$

DISCUSSION...10
AVIATION...Helgeson



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