textproduct: Bismarck

KEY MESSAGES

- Cooler with widespread rain showers and isolated thunderstorms today. The threat for severe weather is low.

- Medium to high chances (40 to 80 percent) for showers Monday afternoon through Monday evening. A few thunderstorms possible far south central into the southern James River Valley Monday afternoon.

- Cold overnight low temperatures near or below freezing tonight, Monday night and especially Tuesday night.

UPDATE

Issued at 645 AM CDT Sun May 17 2026

A band of rain continues to develop across western North Dakota, with dry air slowing its progress eastward. The low pressure system bringing this rain should still kick this band eastward today. Overall made some minor changes to PoPs based on current radar trends.

DISCUSSION

Issued at 340 AM CDT Sun May 17 2026

Surface low ahead of a broad upper trough is still forecast to move through the state today. The result will be widespread rain chances from west to east, although dry air at the surface may limit coverage initially this morning. Even with dry air this morning NBM still putting a 50 to 90% chance for at least a half inch of QPF within the next 24 hours across much of the state except for southwestern and portions of far western North Dakota. Isolated thunderstorms also remain possible today. Followed SPC's general risk for thunder mention in the HWO which is generally along and east of Highway 83, however, the slightly better instability today is generally from Bismarck to Jamestown and south, which is where the current forecast has thunder mention. Thunderstorms in general today will be isolated, and the threat for severe weather is low. Some breezy easterly winds will also be found today, while cooler high temperatures in the 40s north to the 50s south are found. Tonight, initial push of showers will push eastward out of the CWA this evening, while isolated to scattered shower activity may remain through the night in the northwest and north central associated with the upper level trough. Some snow may mix in at times with these showers, although QPF and snow accumulations looks low. Elsewhere, abundant low level moisture will keep low clouds and perhaps bring slight chances for drizzle or patchy fog. These areas are removed enough from the upper trough or surface low to make confidence too low to include drizzle mention, while a steady north wind should limit fog formation tonight. Lows tonight will generally be in the 30s, with limited frost potential given the steady winds, abundant clouds, and lingering precipitation chances. Upper trough moves through the state on Monday bringing a secondary round of rain showers with perhaps a few isolated thunderstorms. Precipitation with this second wave look to be limited with NBM chances for 0.5 inches around 5 to 20 percent and generally just in the south and east. A breezy north wind may be found for much of the area Monday, while cool high temperatures in the mid 40s to mid 50s are forecast. Showers become isolated Monday night, while low temperatures again remain in the 30s with perhaps some upper 20s. There is some frost potential in the west Monday night, although cloudy skies still look to limit this. Abundant low level moisture will also remain Monday night, perhaps bringing more low clouds, patchy fog, or even pockets of drizzle. Precipitation chances then diminish Tuesday, while cooler temperatures remain with highs forecast in the 50s. Some breezy winds could be found in the east. Tuesday night into Wednesday morning, clearing skies with lows near or below freezing could bring widespread frost or perhaps even freeze conditions.

Active northwest flow could bring a late spring pattern mid to late this upcoming week. Southerly flow at the surface could warm temperatures each day with highs in the 70s by the end of the week, and lows in the 40s. Weak disturbances in this northwest flow pattern will also bring near daily chances for showers and thunderstorms. A slight lowering in afternoon humidity values may also be found during this time period, yet should still remain above 30 percent. This combined with a cool and active start to the week should limit the fire weather concerns this week.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 645 AM CDT Sun May 17 2026

Widespread rain, with isolated thunderstorms, are expected today from west to east. This will bring MVFR to IFR conditions to most sites once rain begins or low clouds move in, with VFR conditions expected beforehand. Confidence was not high enough to include thunderstorm mention at this time in the TAFs, although low to medium chances for thunder generally come from KMOT to KBIS and eastward. Shower activity becomes more isolated this evening and generally confined to the northwest and north central tonight. However, low clouds could persist across most sites through tonight. These low clouds could bring MVFR to perhaps IFR ceilings through the night tonight. Breezy east southeast winds will be found today, becoming a breezy north northeast wind tonight.

BIS WATCHES/WARNINGS/ADVISORIES

None.