461 
FXUS63 KUNR 252037
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
237 PM MDT Tue Jun 25 2019

.DISCUSSION...(This Evening Through Tuesday)
Issued at 236 PM MDT Tue Jun 25 2019

An active zonal flow pattern has set up across the northern Plains. 
Low level flow has become southerly as a surface high has pushed 
east of the CWA. Visible sat shows an area of convergence stretching 
from southeast MT through the Bear Lodge Mountains and the Black 
Hills. Isolated showers have developed in the last couple hours 
along the eastern Hills. CAPE is decent today while shear is quite 
impressive at over 50kt, so severe storms are expected this 
afternoon and evening, with large hail and damaging winds possible. 
Short range models show additional convection developing over the 
next few hours, especially across northeast WY, then marching 
eastward across the CWA through the evening. Storms are expected to 
clear the CWA by late this evening or not long after midnight. Large 
upper low will drift onshore the Pac NW tomorrow, with upper ridging 
setting up across the northern high plains. Surface low pressure 
will set up across Wyoming to central Montana, with a thermal ridge 
sitting across the northern Plains. Temps tomorrow will reach the 
80s to around 90. With southeast low level flow, dewpoints are 
expected to reach the 60s across much of the western SD plains. Very 
strong instability is expected, but a strong cap will also be in 
place. Shear won't be as strong as today, but decent enough for 
strong storms if the cap can be overcome. Some convection may 
develop on the edge of the cap along a dry line set up across 
northeast WY to the Black Hills area. Models do show convection 
setting up across this boundary tomorrow afternoon, then moving 
eastward through the SD plains in the evening. Ridging aloft will 
continue through the end of the week as the upper low remain 
stationary across the Pac NW. CAPE will be strong each day, but a 
very strong cap will limit convection activity quite a bit through 
the second half of the week into the weekend. Isolated showers are 
expected at best. Temperatures will reach well into the 90s by 
Friday. The warmest day could be Saturday, with some parts of south 
central flirting with triple digit highs.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1121 AM MDT Tue Jun 25 2019

Isolated to scattered thunderstorms will develop across the area 
this afternoon and evening with local MVFR conditions possible. A
few severe storms with large hail and damaging wind gusts also 
are expected. Otherwise, VFR conditions will prevail through the 
period.

&&

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

$$

DISCUSSION...13
AVIATION...10