Area Forecast Discussion
Issued by NWS Rapid City, SD

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FXUS63 KUNR 222024

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
224 PM MDT SUN MAY 22 2016

.SHORT TERM...(This Evening Through Monday Night)
Issued at 223 PM MDT Sun May 22 2016

Upper low spins over southern Alberta, with a 100+ kt
jet pushing into the Northern Plains. Cold front has stalled over
western SD and isn`t progged to leave the CWA until around 06Z.
Skies are mostly sunny, and cumulus are developing over the Black

Shortwave associated with upper low will push into the region this
afternoon and evening. Latest runs of hi-res convective models show
showers and thunderstorms initiating across northeastern WY and far
western SD, under best upper divergence with excellent 0-6 km shear
of 60-70 kts. However, strength of these storms will be limited by
lack of CAPE there. As upper energy shifts northeastward,
thunderstorms are expected to develop and strengthen along the
frontal boundary this evening. Severe thunderstorms are expected,
with 2000-3000 J/kg MLCAPE and 0-6km shear of 30-50 kts. Large hail
and strong winds are possible, likely becoming more of a wind event
later as the system forms a line and possibly bows out. Heavy rain
is possible as well, but with storm motion at 30-40 kts, storms
should be moving pretty quickly and not lingering over an area for a
while. There is a potential for tornadoes, as 0-1 km shear is 30-40
kts, 0-1 km helicity is near 300 m2/s2, and LCL heights dip well
below 1200 m across south central SD. Storms will transition
eastward tonight and move out of the CWA by morning.

Some lingering moisture and instability, along with weak upper
energy, may result in a few showers/storms over the Hills and
northwestern SD Monday into Monday evening. Otherwise mainy dry
conditions are expected for Monday, with highs generally in the 70s.

.LONG TERM...(Tuesday Through Sunday)
Issued at 223 PM MDT Sun May 22 2016

Slow-moving upper trough with periodic shortwaves will
continue to affect the region through much of this week. Weather
will be unsettled with daily chances for showers and thunderstorms
into next weekend. Temperatures will be near seasonal averages.


.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 223 PM MDT Sun May 22 2016

Scattered to numerous thunderstorms will develop over
much of northeast Wyoming and western South Dakota later this
afternoon and last into the evening hours before pushing east.
Outside of the storms VFR conditions are expected. In and near
storms, IFR ceilings and visibilities are expected along with the
potential for strong gusty winds and hail.


.UNR Watches/Warnings/Advisories...


SHORT TERM...Pojorlie
LONG TERM...Pojorlie
AVIATION...Helgeson is the U.S. government's official web portal to all federal, state and local government web resources and services.