Winner, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

424
FXUS63 KUNR 021927
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
127 PM MDT Wed Apr 2 2025

.KEY MESSAGES...

-Western CONUS trough will eject east Thur-Fri and support one
 last round of rain/snow before the pattern gradually changes

-Temperatures to remain mainly below seasonal norms through the
 week

-Warming up next week

&&

.DISCUSSION...(This Evening Through Wednesday)
Issued at 126 PM MDT Wed Apr 2 2025

Stubborn mean troughing will finally end this week as the long
wave upper trough is replaced by western CONUS ridging. This will
allow for one more round of cool temps with rain and snow chances
Thur night into Friday. Potent trough now exiting the region with
the cold core upper trough and wrap around moisture supporting
scattered rain and snow showers. Steep lapse rates have allowed a
strong convective component to the activity, with some showers
containing graupel as well. Showers will taper off this evening as
dry air works into the region and the BL cools. Cold cyclonic
flow will persist through Thur as the next trough approaches.
Enough instability will be place for a few rain or snow showers
over the Black Hills and across the far western FA in the
afternoon. Slightly warmer tomorrow as well, but still cool with
highs in the 40s and low 50s outside the BH. The next system will
move into the region Thu night, with pos theta-e adv supporting
increasing chances for rain over scentral SD. Meanwhile the
northern stream counterpart will bring a good chance of rain and
snow to the northwest FA. As the two toughs move east and phase,
the bulk of lift will quickly shift east with the middle of the FA
likely not seeing much precip at all. Hence the highest pops will
be confined to the northwest and southeast FA. Marginal thermal
fields will once again support temps cool enough for snow most
areas, but accums will be difficult given lack of a strong forcing
and timing of rain to snow changeover. Very cool once again
Friday with highs generally in the 30s and low 40s. After this
trough exits, things will then dry out for the weekend with temps
slowly recovering. Warmer weather will return next week as a ridge
builds into the western CONUS and gradually shifts east. Precip
chances look to return by Tue-Wed of next week with the next
impulse or round of impulses.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1135 AM MDT Wed Apr 2 2025

Widespread IFR to LIFR conditions with precipitation will improve
to VFR this afternoon and evening. There is a chance for some
overnight patchy fog to develop in areas, however not enough
confidence to add to the TAF locations.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Dye