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Area forecast discussion for western South Dakota and northeastern Wyoming 
National Weather Service Rapid City South Dakota
255 am MDT Sat may 23 2015

Short through Sunday night
issued at 254 am MDT Sat may 23 2015

A large upper low was nearing the 4-corners region this morning
as a 90-knots jet was moving across the eastern rockies. A lead short-
wave trough was moving over the County Warning Area but was getting damped by an
upper-level ridge. The result was virtually no precipitation over the
County Warning Area...except for a few rain showers over far southern sections. For today the
upper low will slowly approach the County Warning Area as low-level moisture
slowly increases. Given considerable midlevel cloud cover the
atmosphere will not destabilize very much...and thus lapse rates
and cape will be rather modest this afternoon. As a result...precipitation will
continue to be limited today. By tonight into Sunday...however...
the models continue to advertise much better lift moving across
the County Warning Area as the upper low moves to eastern Wyoming. There should be a decent
band of showers and isolated thunderstorms and rain moving northward late tonight and across the
area Sunday morning. By late Sunday the upper low will be over eastern Wyoming
with some clearing across western South Dakota. This will allow for midlevel
lapse rates to steepen to 6-7.5 c/km with SBCAPE reaching 1000
j/kg over southern South Dakota. Although deep layer shear will be sufficient for
super- cells...the cape profile is rather skinny...and thus do not
except much severe weather (consistent with the marginal outlook
from spc). On Sunday night the upper low will move east across the
County Warning Area... bringing additional shra/tsra. High temperatures will continue to
be below average given the considerable cloud cover and
precipitation...but overnight lows will be near average.

Long term...Monday through Friday
issued at 254 am MDT Sat may 23 2015

Medium range models in pretty good agreement on features through
early next week. Upper-level low will lift north and east into
Canada on Monday. Lingering showers and isolated thunderstorms
will be possible on Monday. Highs on Memorial Day will be in the
50s and lower 60s.

Behind the system...flow aloft will be from the west-southwest next
week. This will keep active weather pattern in place...with daily
chances for showers and thunderstorms expected through the week. The
better chances at this point look to be Wednesday through Friday.
Temperatures will return to near average levels in most areas for
Tuesday and the rest of the week.


Aviation...for the 06z tafs through 06z Saturday night
issued at 254 am MDT Sat may 23 2015

MVFR/IFR ceilings will expand early this morning...with
local LIFR ceilings/visibility for the higher terrain of the Black Hills.
MVFR/IFR conditions with scattered showers will persist through the
day. More steady rain and continued IFR/LIFR conditions are expected
later tonight.


Unr watches/warnings/advisories...
South Dakota...none.


Short term...bunkers
long term...15

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