FXUS63 KUNR 081703
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1103 AM MDT Wed Jul 8 2026

.KEY MESSAGES...

-Unsettled through Thursday as a series of disturbances move 
 through the region 

-Sufficient moisture and shear is in place to support a few 
 strong to severe storms

-Very hot this weekend into early next week with record high 
 temps possible and dangerous heat

&&

.DISCUSSION...(This Afternoon Through Tuesday)
Issued at 1103 AM MDT Wed Jul 8 2026

Impulse filled westerly flow remains in place over the FA. Daily 
chances for thunderstorms can be expected with strong to severe 
storms possible at times, through Thursday. Weak impulse will 
advect through the SW third this afternoon and support TS 
clusters. Ample LL moisture in place combined with sufficient deep
layer shear will support a few strong to severe storms, with 
large hail and damaging wind the main threats, mainly INVOF of the
Black Hills. Given ML CAPE of 1-2 KJ/KG, deep bulk layer shear of
35 to 40 knots expect isolated supercells to be possible, capable
of producing large hail and damaging winds. Storms will carry SE 
across the SW FA through the evening. More storms are expected 
Thur as sufficient LL moisture will be in place with weak 
stability and another impulse. Best chances for storms will be in 
the afternoon/evening. Similar CAPE/shear parameters will be in 
place to again support a few strong to severe storms, esp over the
SW third. Upper ridge builds into the region this weekend, with 
dry and hot conds expected. Hot temps around 35C at h85 with close
to 6000m H5 heights over WY, will offer record to near record 
highs well into the 100s with some areas seeing readings around 
110 on portions of the Plains, esp Sunday and Monday. However, 
given how dry the BL will be with dewpoints falling into the 20s 
in the west to the 50s east, apparent T's will only top out in the
upper 90s to lower 100s, highest on the SD Plains, supporting adv
level numbers. Ridge begins to retrograde the middle of next 
week, with storm chances returning as the active northern 
periphery of the ridge settles back south.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 508 AM MDT Wed Jul 8 2026

Low cigs (IFR) are currently being observed over some of our South
Dakota plains, lurking just to the east of KRAP. Confidence on
this deck creeping into the terminal is low...perhaps 40 percent 
for/60 percent against. Have added SCT012 to the 12z TAF and will
monitor satellite and observational trends for any needed
amendments. Most guidance supports these low clouds through
15-16z/9-10am over the plains before they rapidly burn off with 
diurnal heating. Then, attention turns to our next period of 
thunderstorm potential, generally 19-05z/1pm to 11pm across the 
region today. Only minor tweaks made to ongoing PROB30s for KGCC 
and KRAP based on the latest CAMs. Frequent lightning and 
gusty/erratic winds can be expected with any stronger convective 
cores, along with transient MVFR/IFR conditions. VFR conditions 
are expected tonight into Thursday morning as skies partially 
clear and precip concerns end. A glance at RH/dew point guidance 
suggests the potential for fog or low stratus is perhaps a bit 
less compared to this morning, but we'll continue to evaluate as
that period draws closer in the forecast.

&&

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

$$

DISCUSSION...JC
AVIATION...KSmith