textproduct: Bismarck

KEY MESSAGES

- Periodic showers and thunderstorms through Tuesday, beginning in the far southwest tonight before gradually expanding northward on Sunday and eastward Sunday night.

- The threat for severe weather is low this weekend through at least the middle of next week.

- Temperatures will remain below average through the middle of next week, with a slight warm up favored for the end of next week.

UPDATE

Issued at 1007 PM CDT Sat Jun 20 2026

The forecast remains on track. Showers in southwest North Dakota have trended downward for now, but coverage and intensity should increase by early Sunday morning as a mid level low spins northeastward off the Bighorn Mountains.

UPDATE Issued at 718 PM CDT Sat Jun 20 2026

Forecast changes for this update were focused on trending PoPs toward current observations and trends and the latest high- resolution model guidance. Scattered light showers have been falling over far southwest North Dakota since late afternoon with little to no northeastward expansion. The most noticeable trend in recent CAMs has been to keep areas from around Dickinson to the north and east dry through Sunday afternoon as the easterly low level flow rounding Canadian high pressure maintains a drier air mass. This trend has also emerged in global models, and the most recent NBM has decreased PoPs over central North Dakota.

DISCUSSION

Issued at 204 PM CDT Sat Jun 20 2026

Not a whole lot has changed to the ongoing forecast. Upper low over eastern BC/Alberta will ever so gradually meander eastward across southern Canada and eventually down into the Great Lakes Region through the middle of next week. This will lead to daily shower and thunderstorm chances through Tuesday.

Despite daily chances, there are three distinct periods with high probabilities of precipitation. The first starts as surface low pressure develops over central Montana this evening and gradually slides eastwards. Initially this produces low chances in the far southwest this evening that will become medium to high mainly across the western half of the state Sunday. The second is Monday afternoon through Monday night as the surface low begins to propagate quicker to the east and tightens up, which will result in transitory high PoPs from west to east. The third is Tuesday afternoon, especially in the north and east as the aforementioned surface low stalls. The current thinking is that the severe weather threat on any given day is low. However, if a few strong to severe storms were to develop, Sunday afternoon/evening in the northwest and Monday afternoon/early evening in the west and north central would be the most likely times and locations. That said, neither SPC nor CSU machine learning are highlighting the forecast area at this time, and even the most bullish deterministic models generally maintain marginal instability and shear.

Beyond Tuesday, mostly dry conditions are favored across the forecast area through Thursday night with some minor localized exceptions. The NBM then brings the return of additional chances initially Friday, but especially this weekend. Temperatures are currently forecast to remain below average overall through Thursday, before returning to near average towards the end of next week.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 1007 PM CDT Sat Jun 20 2026

VFR conditions are expected at most terminals through the forecast period. Possible exceptions include a low chance of MVFR ceilings developing in southwest North Dakota late tonight into Sunday morning, and reduced visibility with heavier showers across western North Dakota throughout the forecast period. More persistent rain is now forecast to be limited to far southwest North Dakota through Sunday morning, which has prompted the removal of the PROB30 group from KDIK for this TAF issuance. In northwest North Dakota, there is higher confidence in an area of showers with embedded thunderstorms moving in from the west Sunday afternoon. Most of central North Dakota should remain dry through the forecast period, with just a low chance of light rain at KBIS early Sunday morning. Winds will remain easterly to southeasterly around 10-20 kts through the forecast period.

BIS WATCHES/WARNINGS/ADVISORIES

None.