Area Forecast Discussion
Issued by NWS Rapid City, SD

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000
FXUS63 KUNR 192317
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
517 PM MDT Sun Mar 19 2017

.SHORT TERM...(This Evening Through Monday Night)
Issued at 216 PM MDT Sun Mar 19 2017

20z surface analysis had cold front from eastern ND to the Black
Hills into northwest WY. Front has had less push than previously
thought from high over southern BC. System driven by weak energy
moving across the US/Canadian border.

Tonight, weak surface high slowly builds into the CWA with westerly
flow aloft and weak energy moving across the northern CWA which
may support a few -SHRASN overnight, especially near the ND border
where tightest low level baroclinic zone in place. Cold front
will stall just south of the CWA. Temperatures will be near
guidance.

Monday, large surface high over central Canada pushes into the CWA
sharpening aforementioned frontal boundary as low level flow turns
southeasterly. Better organized shortwave energy moves from the
southern Rockies toward the northern plains under right entrance
region of 130kt jet streak ND/Canadian border. As cold air advection
continues and low level moisture increases per upslope flow,
precipitation will gradually develop, particularly Monday night as
upsidence is maximized. Thermal profiles continue to shows a -RASN
mix, trending toward all -SN late. 1 to locally 2" possible over the
northern two thirds of the CWA. Temperatures will be near guidance.

.LONG TERM...(Tuesday Through Sunday)
Issued at 216 PM MDT Sun Mar 19 2017

Monday night system departs Tuesday with lingering -RASN tapering
off, but another wave will race across the central plains resulting
in an uptick in PoPs again Tuesday night. Upper ridge will bring
warmer weather for Wednesday along with precipitation ending from
southwest to northeast.

Thursday into Saturday, 12z guidance in general agreement taking
bulk of energy well south of the CWA for Thursday/Friday storm
system, but run-to-run continuity low and thus confidence is low.
Given consensus of more southerly track, less cold air is expected.
Temperatures will be highly dependent on track of storm.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 513 PM MDT Sun Mar 19 2017

There is a chance of -SHRA/-SHSN over parts of northeastern
Wyoming and northwestern South Dakota tonight with a chance of
-SHRA over northeastern Wyoming and western South Dakota on
Monday. Local MVFR CIGS may result.


&&

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

$$

SHORT TERM...Helgeson
LONG TERM...Helgeson
AVIATION...10



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