325 
FXUS63 KUNR 152318
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
518 PM MDT Wed May 15 2019

.DISCUSSION...(This Evening Through Wednesday)
Issued at 138 PM MDT Wed May 15 2019

Upper level analysis shows a broad ridge over the central CONUS, 
and a trough pushing into the west coast. A shortwave is crossing 
the ridge over MT/ND. Satellite shows clouds spreading into the 
northern plains and cumulus developing over the Black Hills and 
northeastern WY. A few showers have popped up on radar. A surface 
trough is crossing the western Dakotas, with breezy southerly 
winds ahead of the trough, and a cold front trailing behind. 
Temperatures early this afternoon are warming into the 70s and 
80s. 

A few showers and thunderstorms will be possible this afternoon and 
early evening. CAMs are keeping the strongest storms to the north 
with the stronger forcing, showing nothing significant in our CWA. 
MLCAPE is progged to be 1000-2000 J/kg across central SD, and the 
trough moving through could help spark a few storms, but it might be 
too capped for anything to occur. If anything were to break the cap, 
shear is decent enough for a stronger storm or two.

The west coast upper trough will come onshore Thursday, pushing the 
ridge eastward. Temperatures will begin to cool, with highs ranging 
from the upper 60s in northwestern SD to near 80 across southern SD. 
Around 1000 J/kg MLCAPE will develop along the area of warmer air 
stretching across northeastern WY and the southern half of SD. 
Energy will eject ahead of the trough into eastern WY/western SD in 
the afternoon, sparking thunderstorms; with 0-6 km shear of 40-50 
kts, some of these could be severe. 

Thursday night into Friday, the upper trough will begin crossing the 
Rockies. Strong forcing in southwest flow will push into the 
central/northern plains Friday afternoon, creating showers and 
thunderstorms across much of the CWA. However, with cool easterly 
low-level flow, temperatures will be only in the 50s to lower 60s, 
and CAPE will be minimal. Although shear will be 50-60 kts, do not 
expect much for severe weather besides possibly across far south 
central SD.

This upper trough will slowly swing through the central states this 
weekend, resulting in cool and showery weather. Highs will be in the 
40s and 50s, with lows in the 30s and 40s. At these temps, some snow 
will be possible in the Black Hills. There could be a brief break in 
showers on Sunday night/Monday but another trough will bring more 
cool/wet weather next week. 

&&

.AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening)
Issued At 516 PM MDT Wed May 15 2019

Isolated SHRA/TS with local MVFR conditions across northeast WY 
into southwest SD will dissipate as they move east this evening.
Additional storms may develop later Thursday as a more significant
disturbance approaches the region. Outside of storms, VFR
conditions expected.

&&

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

$$

DISCUSSION...Pojorlie
AVIATION...Helgeson