Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 271949
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
149 PM MDT Sat May 27 2017

.DISCUSSION...(This Evening Through Saturday)
Issued at 146 PM MDT Sat May 27 2017

19z surface analysis had low over northern SK with several
troughs rotating around it, one which is pushing through the CWA
right now, another across ND and yet another in southern AB. Water
vapour matinee showed upper low on top of surface low with
shortwave associated with each trough, the strongest of which is
spinning into ND.

Tonight and Sunday, upper low will spin southeast into the western
Great Lakes with several shortwave troughs moving through the
northern Plains, brushing up against the CWA gently. Popcorn
-SHRA/TS have developed per area radar loops/0.5km visible
satellite movie. Activity will be strongly diurnal in nature,
especially for coverage and thus returns will wane this evening
and then return Sunday afternoon and then wane Sunday evening.
Temperatures will be near guidance as gusty northwest winds up to
40 MPH develop for the northwest SD plains Sunday afternoon. Any
convective elements may enhance that a bit.

Monday through Saturday, upper ridge early in the week will be
replaced by weakly split flow. This will prevent large scale storms
from affecting the CWA, but waves during peak heating will bring
a return to afternoon/evening -TSRA starting Wednesday afternoon
as low level moisture creeps north. Temperatures will be near
normal for Monday and Tuesday and then 5-10F above normal for the
end of the week as a thermal ridge becomes more pronounced.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1129 AM MDT Sat May 27 2017

Mainly VFR conditions are expected through the period. Some MVFR
conditions will be possible in isolated showers or thunderstorms.

&&

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

$$

DISCUSSION...Helgeson
AVIATION...MLS


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