876 
FXUS63 KUNR 120831
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
231 AM MDT Tue Sep 12 2023

.DISCUSSION...(Today Through Monday)
Issued at 226 AM MDT Tue Sep 12 2023

08z surface analysis had weak trough from central MT into south-
central SD. A few AC along it within weak mid-level warm air
advection pattern. Water vapour loop had upper level ridge 
building into the northern Plains. Cool temperatures across the 
area with 33F at Deerfield (2am).

Key Messages
- Quiet weather through Wednesday mid-afternoon
- Upper trough brings PoPs back to CWA late Wednesday afternoon 
  through Thursday

Today through Wednesday mid-afternoon, upper level ridge 
dominates the the northern Plains. Amplifying thermal ridge will 
bring warm temperatures (about 5F above normal) by Wednesday.
Expect breezy return flow (south-southeast winds) on the plains.

Late Wednesday afternoon through Thursday, upper trough passes 
through dragging a cold front across the CWA Wednesday night. 
Limited buoyancy along front combines with modest QG-forcing to 
bring chance PoPs to the area. QPF amounts generally on the 
lighter side (<0.25") with latest ensemble guidance showing drier
air working into the region faster than previous guidance. 
Temperatures will be about 5F below normal.

Friday into early next weeks looked seasonal and mostly dry with 
a slow warming trend. There might be a system by the middle of 
next week as west-northwest progressive flow potentially develops.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1118 PM MDT Mon Sep 11 2023

VFR conditions are expected through the forecast period. Breezy 
southeasterly winds will develop across northwest SD Tuesday 
afternoon.

&&

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

$$

DISCUSSION...Helgeson
AVIATION...26