Area Forecast Discussion

KEY MESSAGES

- Very windy conditions behind a cold front for Thursday

- Unsettled weather through the weekend per a series of fronts with up/down temperatures trending coolish for the weekend.

- Near critical fire weather conditions Friday.

UPDATE

Issued at 1013 PM MDT Wed Jun 10 2026

Clouds are increasing as a strong vort lobe moves in from the west. Surface obs show temps in the 60s across the western SD plains...and 40s/50s over NE WY through NW SD where a cold front has pushed through. The front will continue through the CWA overnight, bringing cooler max temps on Thursday. Radar shows light post-frontal showers across NW SD, and more extensive shower development is expected late tonight through Thursday morning as the next strong wave moves in. Increasing winds are also expected late tonight through Thursday. Latest guidance shows the strongest gusts early in the morning when boundary layer winds peak at 45kt before gradually decreasing through the early/mid afternoon. Downsloping across the southern Black Hills (primarily Fall River County) may allow these gusts to reach foothills locations earlier in the morning before the rest of the western SD plains mix out enough. Will keep the Wind Advisory going with no changes needed.

DISCUSSION

(This Evening Through Wednesday) Issued at 1228 PM MDT Wed Jun 10 2026

18z surface analysis had weak high over the CWA. 0.5km visible satellite loop had CU field starting to increase in size per daytime heating/weak buoyancy. Might see a few shra/TS during peak heating this afternoon/early evening. Water vapour loop had mean upper trough over central Canada, extending into the northern Plains. Distinct shortwave trough rotating southeast into MT per water vapour, which is the main forecast concern.

Shortwave trough whips through the northern plains overnight into Thursday morning pushing a cold front through the CWA. Decent QG- forcing should assist shra/isolated TS moving across the area. Isallobaric forcing modest, but it will be accompanied by steep low-level lapse rates and good subsidence for Thursday which should tap into 25-40kt mixed boundary layer. Showers could enhance. NBM looks rather strong for peak wind gusts (~60mph) given forecast Bufkit momentum transfer. Have shaved some speed from prescribed forecast wind elements. Still, very good chances (50-90% chance >45mph gusts) for Wind Advisory gusts behind the cold front for the usual areas from K2WX-KRAP and far southwestern SD. ECMWF EFI guidance paints 80th percentile wind gusts with a shift of tails contour. Temperatures will be near guidance.

Rest of the forecast looks unsettled as a series of disturbances traverse the northern plains per northwest flow aloft. Deeper trough brings PoPs/cooler temperatures for the weekend. Each front/disturbance will bring gusty winds. There are hints that an upper ridge may develop for the middle of next week, but increasing ensemble spreads portend lower confidence.

AVIATION

(For the 18Z TAFS Through 18Z Friday) Issued At 1115 AM MDT Thu Jun 11 2026

Cloud cover is slowly thinning this morning, although lingering broken cloud deck around 4-6k feet AGL remains. Any lingering MVFR conditions in the Black Hills will erode by 19-20z. Isolated showers will linger through the afternoon, although coverage will be limited. Transient MVFR conditions possible with heavier showers. Otherwise, VFR conditions will prevail.

Gusty northwest winds will continue through the afternoon hours with gusts 25 to 40 knots, strongest across the western SD plains. Winds will diminish quickly after 00z this evening.

FIRE WEATHER

Issued At 921 PM MDT Wed Jun 10 2026

Elevated to near-critical fire weather conditions are expected Friday due to very dry air. Minimum relative humidities in the teens are expected over northeast Wyoming and much of western South Dakota south of I-90. At this time where the humidity will be most critical, winds are not expected to be strong enough to reach critical fire weather thresholds.

UNR WATCHES / WARNINGS / ADVISORIES

SD...Wind Advisory until 5 PM MDT this afternoon for SDZ001-002-012- 013-027-031-041-072-073-075-078. WY...None.