FXUS63 KUNR 191957
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
157 PM MDT Tue May 19 2026

.KEY MESSAGES...

- Cold again Wednesday morning, but gradually warming up towards
  the weekend.

- Isolated chances for precipitation mid-week, better chances late
  Thursday into Friday. 

- Much warmer temperatures settle in over the weekend into next
  week.


&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 125 PM MDT Tue May 19 2026

Current upper air models show the upper trough axis east of the
forecast area this afternoon, with west northwest flow over the
region. 19Z surface analysis depicts high pressure over Wyoming,
weak surface trough over central MT. Satellite shows widespread CU
across the forecast area, with little vertical extent.
Temperatures currently sit in the 40s to mid 50s with light winds
predominantly out of the northwest. 

Brief shortwave ridge settles in Wednesday into Thursday,
prompting a slow warming trend with mostly dry conditions. Weak
surface trough in MT passes through Wednesday. This forcing may 
spark some isolated to showers/storms but no significant QPF is 
expected through the first half of Thursday. As ridge shifts
eastward, troughing once again slides across the Rockies and into
the northern and central plains. Synoptic forcing will prompt
widespread precipitation the latter half of Thursday into Friday.
Current NBM probabilities for precip >= 0.25" has a wide swath of
60 to 80 percent over most of western SD, excluding far
northwestern SD. Based off the current track of this system,
highest QPF amounts are expected in the Black Hills and
southwestern SD

Precipitation is expected to taper off from west to east later
Friday, and upper ridge slowly builds over the weekend. Expect
highs to jump into the 70s and 80s by Saturday, and stick around
through the forecast period. 





&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1051 AM MDT Tue May 19 2026

VFR conditions expected through the forecast period. Low & mid-
level clouds over western South Dakota will gradually dissipate 
this afternoon from west to east. 

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Frost Advisory from midnight MDT /1 AM CDT/ tonight to 8 AM MDT 
     /9 AM CDT/ Wednesday for SDZ002-012>014-027-030>032-041>044-
     046-047-049-073-075>078.
WY...Freeze Warning from 2 AM to 8 AM MDT Wednesday for WYZ055-056-
     058>060.
&&

$$

DISCUSSION/KEY MESSAGES...Dye
AVIATION...13