Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 300418
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1018 PM MDT Mon May 29 2017

.DISCUSSION...(This Evening Through Monday)
Issued at 134 PM MDT Mon May 29 2017

19z surface analysis had low over central ON with upper low
spinning just north of Lake Superior. Cyclonic flow assisting
cellular CU field over eastern half of CWA. Quiet weather.

Tonight, upper low moves northeast as upper ridge builds over the
Rockies. 1024mb surface high centered over southern SK with ridge
axis through the CWA. Clearing skies and light winds will allow
upstream Td/s in the 30s to be realized for overnight lows over much
of the CWA. Frost looks like a good bet on the northwestern SD
plains, so will hoist headlines. Few low-lying spots might even
drop 0C, but not widespread or low enough for freeze warning.
These minimums are lower than guidance.

Tuesday, upper ridge and subsidence bring a pleasant day to the area
with temperatures near guidance.

Wednesday, upper ridge moves toward the plains and weakens, with
a weak shortwave forecast to move through during peak heating.
Decent return flow is expected as surface high moves into the OH
valley. 1-2KJ/kg MLCAPE forecast in a narrow tongue from the Black
Hills southward into Nebraska with 15-20m/s 0-6km bulk shear. If
a shortwave actually moves through, 25-50 MLCIN combined with
terrain should pop TS. Supercells would be possible with very slow
movement, possibly bring a few severe reports. Temperatures will
be noticeably warmer.

Thursday, upper ridge overhead with convection likely limited to the
Black Hills if any. Temperatures will be summer-like.

Friday through Monday, mostly progressive split flow will bring a
series of disturbances through the CWA with convection possible each
day. Friday will be warmer than average.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1016 PM MDT Mon May 29 2017

VFR conditions will continue through the period with mostly clear
skies.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Frost Advisory from 2 AM to 8 AM MDT Tuesday for SDZ001-002-
     012>014-031-073.

WY...None.
&&

$$

DISCUSSION...Helgeson
AVIATION...10


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