Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 251104
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
504 AM MDT Fri May 25 2018

.DISCUSSION...(Today Through Thursday)
Issued at 104 AM MDT Fri May 25 2018

Water vapor shows upper low over southern Manitoba, with dirty
ridge extending northward through the Northern Rockies. At the
surface, trof extends across the eastern Dakotas. Some isolated
-tsra tracking eastward across northwest SD early this morning
 along weak short wave south of the main upper low.

Upper level heights will increase slightly as ridge builds
eastward from the Northern Rockies, which will result in warmer
temps than Thursday. Short wave moving through the upper ridge
may result in a few -tsra over the Black Hills/eastern foothills,
given modest CAPE and high-res CAM solutions. Conditions should
remain dry elsewhere.

Saturday looks to be the warmest day of the season thus far as
upper ridge peaks overhead. Temps should reach into the 90s at
many plains locations, especially south/east of the Black Hills.
While large scale subsidence will keep things dry during the day,
ridge axis shifts east overnight with increasing theta-e advection
and the possibility of a few overnight storms.

Sunday and Monday look to be quite active as upper low shifts
slowly eastward from the Great Basin into the Central Rockies,
with multiple waves in southwest flow aloft ejecting northeast
through the Northern Plains. CAPE/Shear values will likely be
ample for some periods of severe weather. Temps should be above
average both days.

Even though shra/tsra should continue on Tuesday, the best threat
for severe storms should be pushing to our east, with upper
trof/low moving into the plains and surface front mostly east of
our zones.

Wednesday could be drier behind departing upper trof, but
southwest flow aloft returns for the end of the week for more
unsettled weather. Above average temps likely for the last half of
the week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 501 AM MDT Fri May 25 2018

Other than some brief MVFR conditions possible in any
thunderstorms that develop around the Black Hills area today, VFR
conditions are expected through Saturday morning.

&&

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

$$

DISCUSSION...Johnson
AVIATION...Pojorlie


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