Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 270511
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1111 PM MDT Sun Mar 26 2017

.SHORT TERM...(This Evening Through Monday Night)
Issued at 116 PM MDT Sun Mar 26 2017

Water vapor shows upper trof crossing the plains, weak upper ridge
building into the nrn Rockies, and next upper trof moving onshore
the west coast. At the sfc, weak inverted trof extends from nern
CO through wrn SD. Light rain, and higher elevation snow, continues
across much of wcntrl SD but is showing signs of weakening.

Pcpn will end rather quickly this evening as upper trof shifts
east, and weak upper ridge builds into the nrn plains. Dry weather
then expected through Monday, with warmer and drier conditions
for tomorrow.

Monday night, upper trof will work into the Rockies with upper
low forming at the base of the trof near the Four Corners. A
significant piece of upper energy expected to move from sern WY
into swrn SD, with lift possibly enhanced through jet coupling,
bringing widespread pcpn to our swrn portion of the cwfa along a
developing inverted sfc trof.

.LONG TERM...(Tuesday Through Sunday)
Issued at 116 PM MDT Sun Mar 26 2017

Aformentioned piece of upper energy slows down and potential
closes off around the Blkhls on Tuesday before finally shifting
ewd Tuesday night. Majority of models continue to show rather
significant qpf totals of 1-2 inches especially around the Blkhls
into swrn SD, aided in part by strong and moist sely bl flow to
the east of a strong inverted trof extending nwd through ern CO
and along the WY/NE-SD borders. Thermal profiles also suggest
enough dynamic cooling for snow at higher elevations of the
Blkhls, and some models even hint these accumulations could be
significant. Confidence not high enough to warrant a winter storm
watch for the Black Hills at this time, but it certainly bears
watching closely with the next few models runs. Pcpn at lower
elevations on the plains looks to be mainly rain.

Pcpn should taper off Wednesday with dry and warmer conditions by
Thursday. Next splitting upper trof then quickly moves in for
Thursday night into Friday for our next chance of pcpn, with drier
wx over at least the early part of the weekend. Temps not expected
to be exceptionally cold or warm through the extended period.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Monday Night)
Issued At 1108 PM MDT Sun Mar 26 2017

Light winds and lingering low level moisture will support
patchy/areas of fog tonight with IFR/LIFR conds possible. This
includes KRAP. KGCC may see IFR conds later tonight with SE flow
possibly advecting stratus NW. Conds will trend VFR Monday
afternoon all places. The next low pressure system will move into
the region Monday night, with showers possibly developing late in
the period over NE WY.

&&

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

$$

SHORT TERM...Johnson
LONG TERM...Johnson
AVIATION...JC


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