textproduct: Bismarck

KEY MESSAGES

- Near critical fire weather conditions are expected over far southwest North Dakota through the early evening.

- High chances (70 to 90 percent) for showers late tonight through Sunday, with a few thunderstorms possible far south.

- 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 with overnight low temperatures near or below freezing Sunday night, Monday night and Tuesday night.

UPDATE

Issued at 635 PM CDT Sat May 16 2026

Quiet weather is found over western and central North Dakota at the time of this early evening update. Mid to high level clouds continue to invade from the west, spreading through central North Dakota through the evening. Upstream, weak to moderate radar returns linger over eastern Montana and are slowly beginning to cross into western North Dakota. Cloud bases remain around 6kft, and any precpitation that may be falling has to contend with a very dry near surface layer. As a result, little to no measurable precipitation is expected to reach the ground over the next few hours. Later tonight, lowering cloud bases and better forcing from an upstream low pressure system will promote increasing chances for precpitation across the west, spreading across the forecast area through Sunday morning and afternoon. With this update, have made some minor adjustments to sky cover to better capture satellite trends, though overall the forecast remains in good shape.

DISCUSSION

Issued at 109 PM CDT Sat May 16 2026

Rain chances and much colder temperatures highlight the forecast this afternoon.

Currently skies were partly to mostly sunny across western and central North Dakota with temperatures on the cool side, only in the 40s north to lower and mid 60s south. Winds have shifted southeast over western North Dakota, and will gradually shift east to southeast over central ND late this afternoon and this evening as broad scale low level flow becomes easterly ahead of a digging upper trough currently over eastern Washington and developing surface low pressure in the northern High Plains.

By late tonight surface low pressure is developing over southeast Montana and the upper low pushing into western Montana. One impulse rotating through the upper low lifts through northeast MT into Saskatchewan, with another tracks through eastern Wyoming and into southern ND by Sunday morning. Initially dry atmosphere this evening and during the early overnight hours will moisten quickly with strong synoptic scale forcing. There is strong bulk shear over the forecast area tonight through Sunday, but the initially dry atmosphere tonight and cool easterly flow Sunday will keep instability to a minimum. Currently NBM limits thunder to far southern ND late tonight through Sunday. With a shortwave lifting into south central ND Sunday morning there's a potential for thunder to possibly push up farther north, possibly along the I-94 corridor, but for now will leave the thunder mention to the far south. Once this initial wave moves through late tonight into Sunday morning, the chance for any significant precipitation tapers quickly. There will probably be some lingering shower activity north and east, associated with the mid-upper low circulation, but qpf amounts are quite low over much of western and south central ND Sunday afternoon, and pretty much everywhere by Sunday night.

The next wave moves through the central and northern Plains on Monday. The main forcing with this wave will be over the central Plains. However, there is a bit of forcing that brushes the south central and southeast portion of the state Monday afternoon and evening. We will be remaining quite cool so instability will be at a minimum with highs only in the 40s for most of us. The NBM does bring a mention of thunder to the southern James River Valley Monday afternoon. The threat for severe weather, both tonight into Sunday and on Monday afternoon/evening have been shunted southeast of the forecast area.

Additional impacts with this system will be the cold temperatures on the back side. As far as snowfall is concerned, there could be a little light snow mix in with the rain in the far north and west late Sunday night into Monday morning, and then in the west on Monday night into Tuesday morning. No significant accumulations are expected. Overnight low temperatures are forecast to be near or below freezing Sunday night, and again Monday and Tuesday nights. Sunday night and Monday night there will be enough cloud cover that frost probably won't be an issue, but if temperatures drop to freezing or below, a Freeze Warning will be needed. Tuesday night into Wednesday morning we dry out and widespread frost is possible if we don't cloud up again. Temperatures are also forecast to be at or below freezing so another Freeze Warning may be needed.

As we get into the latter portions of the week we do see a gradual warming trend with near daily chances for showers and possibly a few thunderstorms.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 635 PM CDT Sat May 16 2026

VFR ceilings and visibility is found at all terminals to begin the 00Z TAF 00Z, with increasing mid to high level clouds through this evening. Sunday morning, expect MVFR to IFR ceilings to spread across western and central North Dakota, reaching KJMS by the early afternoon. With the lowered ceilings, scattered rain showers are expected across much of western and central North Dakota through Sunday afternoon. MVFR to IFR visibility is possible where the heaviest rain showers and possible fog develops, mainly over central North Dakota.

Breezy east winds this winds are expected to turn to the southeast overnight, strengthening to around 15 to 30 knots. Winds are then expected to diminish from west to east late Sunday morning through Sunday afternoon.

BIS WATCHES/WARNINGS/ADVISORIES

None.