textproduct: Bismarck

KEY MESSAGES

- Medium to high chances (40 to 80 percent) for showers Monday afternoon through Monday evening along the South Dakota border and into the James River Valley.

- Cold overnight low temperatures near or slightly below freezing tonight (far north), Monday night (west and north central), and Tuesday night (southwest and central).

- Temperatures warming back to above normal by late in the work week and for the weekend, with near daily chances for showers and a few thunderstorms.

UPDATE

Issued at 1245 AM CDT Mon May 18 2026

Limited changes needed so far tonight. Visibility reductions continue across the north and now some eastern portions. Meanwhile, some sites reporting brief light rain. Overall patchy fog, isolated to scattered light rain, and pockets of drizzle will be possible tonight given abundant low level moisture and a nearby upper wave. Expanded slight chances for light rain along with patchy fog mention through the night as a result. Otherwise the forecast remains on track.

UPDATE Issued at 1043 PM CDT Sun May 17 2026

We are starting to see more widespread visibility restrictions in the 1 to 5 mile range across northwest and north central North Dakota, so a mention of patchy fog has been added to the forecast. Dense fog remains unlikely though. There is a chance it becomes more of a drizzle-type scenario, but feel the low chances for light rain paired with patchy fog will suffice for now.

UPDATE Issued at 705 PM CDT Sun May 17 2026

Precipitation continues to diminish from west to east as the inciting surface low lifts out of the area. With this update, have tweaked pops to account for radar trends, with showers lifting slightly more quickly than previously forecast. Did evaluate the potential need for patchy fog across portions of the northwest and south central for Monday morning, though the prevailing thought is the heavy cloudy cover and sufficiently strong winds will keep most areas as low stratus. Will continue to evaluate over the next few hours.

DISCUSSION

Issued at 230 PM CDT Sun May 17 2026

Showers continue to lift northeast through central and northern portions of the State. Another round of showers is also pushing into the south central, extending well into central SD. it looks like this second round will just graze the Bismarck Metro area with most of the activity tracking across the far south central and into the James River Valley.

Farther north, the big winner today for precip was the northwest. Areas around Williston received around a quarter of and inch, but to the north and east, over portions of Burke and Mountrail counties, as well as western McLean and northern Dunn and Mercer counties. NDAWN rain totals were currently between a half inch and an inch. An NDAWN site near Bowbells was reporting nearly an inch and a half of rain as of 3 PM. A nearly stationary inverted trough combined with an area of strong deformation, that also moved very little through the day was responsible for these higher amounts.

Going forward, shower activity has dried up in the far west and adjacent areas of the south central, west of the River. Expect this drying to continue working its way north and east as the wave exits the area.

As the wave exits tonight, our first concern is overnight low temperatures. Although lower clouds have been slow to develop today, we are seeing low stratus now over a good portion of the west. Expect the stratus to also expand behind the precipitation shield. RAP guidance suggests that the 925 to 850 mb layer RH will remain over all but the far southwest tonight, and expanding to include the far southwest towards morning. This expansive cloud cover does not bode well for temperatures dropping below freezing, even with the cold aid aloft dropping south from Canada. We used a blend of the NBM guidance with CONSShort to bump up temperatures a bit. Wouldn't be surprised if the lows were even warmer. We still see lows in the mid 30s over the far north and in our normally cool areas of the southwest. However with the extensive cloud cover, the potential for frost is low and we should remain mostly above freezing, so no Freeze Hazard is anticipated tonight.

On Monday, the next round of precipitation is favored for the far south central into southeast ND, mainly associated with the forcing from the mid-upper level trough. The surface trough remains well off to the southeast. With the upper trough over the area, can not rule out a sprinkle or two elsewhere, or maybe even some drizzle, as low level moisture remains in place. But the best chances (40 to 80 percent) for rain showers will be south and east.

Monday night, and again on Tuesday night we will see the potential for temperatures at or below freezing. It will be interesting to see how temperatures fare tonight. This should help to determine whether or not we need a Freeze Warning for Monday night, as RAP guidance suggests that low level moisture will still be over most of the area. By Tuesday night into Wednesday we may see the low level moisture exit, thus the potential for freezing temperatures looks to be more favorable. Will continue to monitor.

Wednesday through the end of the week we are expecting a gradual warming trend with temperatures possibly returning into the 70s and maybe even the 80s by Sunday. With a broad northwest upper level flow over the area, occasional disturbances will bring near daily chances for showers and a few thunderstorms, but with low confidence in timing and placement.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1245 AM CDT Mon May 18 2026

Low clouds will linger tonight and through much of the day Monday, bringing MVFR to periods of IFR ceilings. Some patchy fog along with isolated to scattered rain/drizzle can also be expected tonight into Monday morning, bringing more IFR to perhaps LIFR conditions. Shower activity is then more confined to the south and east Monday through Monday evening, although most sites will have at least slight chances for rain showers. Any shower has the potential to bring MVFR to IFR conditions. Monday night will see shower activity diminish, although low clouds could linger bringing MVFR to isolated IFR ceilings. A breezy north wind may also be found throughout the forecast period.

BIS WATCHES/WARNINGS/ADVISORIES

None.