000
FXUS63 KUNR 041939
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
139 PM MDT Wed Oct 4 2023

.DISCUSSION...(This Evening Through Wednesday)
Issued at 139 PM MDT Wed Oct 4 2023

Unsettled NW flow will continue over the region through the end 
of the work week. Steep low level lapse rates ahead of the 
approaching shortwave will support isold showers this afternoon, 
with most places not seeing much more than sprinkles where showers
do materialize. Fast moving shortwave trough will push through 
the region tonight supporting chances for sct rain showers. Breezy
NW winds will also develop as this system moves through. Showers 
will end most places by sunrise, with perhaps a few lingering 
showers over NW WY. Main impact from this wave will be gusty NW 
winds Thur afternoon. Wind speeds may reach low end adv levels for
a period of time. However, given the downtrend in spreads from 
recent model runs and late arrival of faster winds, will let the 
night shift decide if an adv is needed for NW SD. In addition, 
steep ll lapse rates may support isold showers in the afternoon 
over much of the area, but given very dry profiles, will hold off 
on adding pops. Another fast moving clipper type system will push 
through the region Thu night, supporting another round of showers,
possibly mixed with snow in the higher elevations of the Black 
Hills. This wave looks pretty dry attm, however, if a wetter 
solution, materializes, some light accums cannot be ruled out, esp
above 6 kft. Temps will drop into the low to mid 30s most places 
Thur night with a few places dropping below freezing where skies 
clear and winds drop off. However, with the gusty winds and 
clouds, many locations may dodge a hard freeze or frost. Breezy 
and cool conds expected Friday. Sfc ridge will shift SE of the 
region Friday night with light winds, clear skies, and dry air 
allowing for strong radiational cooling. This will allow most 
locations to see a frost/freeze with temps falling around or below
freezing. Upper ridge will then shift east into the Plains with 
dry weather and a warming trend expected through mid next week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1127 AM MDT Wed Oct 4 2023

A weak disturbance crossing the area tonight will bring isolated
showers and a period of breezy to windy northwest winds. LCL MVFR
CIGS may occur with any showers, and also over and near the 
northern Black Hills. Otherwise, VFR conditions will prevail 
through the TAF period.

&&

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

$$

DISCUSSION...JC
AVIATION...10