Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 250811

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
211 AM MDT Thu May 25 2017

.DISCUSSION...(Today Through Wednesday)
Issued at 209 AM MDT Thu May 25 2017

Closed low will linger over the Northern Plains through the
weekend, supporting a long period of unsettled cyclonic flow
aloft. Sfc cold front is in the process of pushing through the fa,
with a prefrontal trough supporting convection east of the fa.
Southern periphery impulse supported a weak MCS over WY earlier,
with the remnants of this feature continuing to support showers
over central WY. This feature will continue to progress east this
morning, possibly clipping the far southern FA with showers.
Otherwise, dry conds expected today most areas with windy conds NW
SD where near adv winds are forecast. There is a very small
chance for a shower over the far NW third as lower heights spread
into the region and support some week instability. Did not include
a pop mention for this given very dry profiles, with sprinkles
expected at best.

Closed low will slowly shift east with several weak impulses
rotating around the low, advecting through the region. This will
support cool and unsettled conds through the weekend, with near
daily chances for shra/ts. Southern stream impulse will phase with
the northern CONUS trough Fri night/Sat, resulting in a decent
FGEN response coupled with pos theta-e adv. Forecast models
continue to favor the SD/NE border area attm for a decent rain
event (save for the outlier 00Z Nam which is biased well north).
However, further track adjustment is likely per this feature as
convective feedback and closed flow aloft introduce model
limitations. Upper low will finally shift east by Mon-Tue of next
week as the western CONUS ridge trends east. This will support a
warming and drying trend by mid next week, although warmer temps
and fair conds looks short-lived as the next deep upper trough
approaches in ECMWF and GFS solutions.


.AVIATION...(For the 00Z/06Z TAFS Through 00Z/06Z Thursday Evening)
Issued At 829 PM MDT Wed May 24 2017

Mainly VFR conditions expected next 24 hours. Isold high based
-tsra will cross the SD plains tonight along/ahead of a cold
front. Some LLWS will also be found ahead of this cold front on
the SD plains.




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