textproduct: Bismarck

KEY MESSAGES

- Critical fire weather conditions in far northwest and parts of south central North Dakota today, with near-critical conditions elsewhere.

- Warmer and windy today with scattered showers and isolated thunderstorms in the afternoon and evening. Then seasonably cool temperatures return for the weekend.

- Sub-freezing low temperatures are possible across northern North Dakota tonight and most of the state Saturday night.

- Warm and windy weather next week could lead to daily critical fire weather conditions, especially in western North Dakota.

DISCUSSION

Issued at 522 AM CDT Fri May 8 2026

Persistent northwest cyclonic flow pattern progged to remain over the Northern Plains today into Sunday. Today will be warmer but windier ahead of a cold front being driven down from Canada by a shortwave digging into the Red River Valley this evening. High temperatures in the mid 60s to to mid 70s yielding afternoon RH around 20 percent combined with northwest winds around 25 to 30 mph and gusting to near 40 mph are expected to result in critical fire weather conditions in far northwest and parts of south central North Dakota, including the James River Valley. Red Flag Warnings have been issued, with more detailed information in the Fire Weather section below. Most CAMs are simulating isolated to scattered high- based showers developing ahead of the front in the mid to late afternoon, becoming scattered to widespread with the frontal passage and stronger DCVA this evening. There may be enough CAPE to support a few thunderstorms this afternoon and evening as well, but the ensemble range of outcomes is from zero CAPE to as much as 500 J/kg, with these differences apparently being driven by surface dewpoint uncertainty. An example of the worst-case scenario, which may be borderline unreasonable, is the 06Z NAMnest that brings a mature bowing segment as part of an MCS through the Turtle Mountains and Devils Lake Basin areas this evening. Up to 500 J/kg of CAPE would support marginally severe convection in the high-shear environment that is forecast, but we are quite skeptical of the mid 40s dewpoints in the NAMnest. HREF mean dewpoints are closer to 40, and the HRRR is in the mid 30s. Meanwhile, the RAP actually has lower 40s dewpoints paired with zero CAPE. Nevertheless, in the absence of the aforementioned worst-case scenario, deep inverted-v thermodynamic profiles could support wind gusts stronger than the background BL momentum transfer gusts with any shower or storm.

The cold front will usher in yet another seasonably cool and dry air mass that is forecast to persist through the first half of the weekend. Temperatures across the northern half of the state could fall to near freezing tonight, followed by near to below freezing temperatures statewide Saturday night as surface high pressure builds over the Canadian prairie provinces. The growing season officially begins today, so frost/freeze headlines may be necessary both tonight and on a much wider basis Saturday night. Despite the cool down to highs in the mid 50s to mid 60s on Saturday, afternoon humidity percentages in the 20s and northwest winds still breezy at around 15 to 20 mph could lead to near-critical fire weather conditions. A shortwave moving down the foothills of the Northern Rockies on Saturday could bring some light rain into the southwest corner of the state, but it more likely to remain dry. Sunday sees a slight warmup with much lighter winds as an amplified transient upper ridge pushes off the Rockies.

Ensemble guidance continues to advertise a potent shortwave/ clipper type system ejecting off the southern Canadian Rockies on Monday and digging into the Upper Mississippi River Valley Monday night. All ensemble clusters show the 850 mb thermal ridge over western North Dakota Monday afternoon, which could allow temperatures to climb above 80. There is also increasing ensemble consistency with this system now bringing medium chances for showers (and thunderstorms) to areas north and east of the Missouri River. Something to keep an eye on is that every cluster contains a narrow ribbon of CAPE on the order of a few hundred J/kg somewhere over central North Dakota Monday afternoon/evening with no lower than 50 kts of deep layer shear. Windy conditions are a given with this system, but there is still higher ensemble uncertainty on the magnitude of 850 mb winds for mixing potential. A brief, slight cool down in the post frontal air mass on Tuesday could be followed by temperatures more persistently above normal for the rest of next week, with ensemble clusters continuing to show near-equal probabilities for either a progressive, high-amplitude wave pattern or stagnant western CONUS ridging. For either synoptic pattern outcome, chances for rain at this forecast time range remain low. The biggest concern for next week is the potential for daily critical fire weather conditions, which is further discussed in the Fire Weather section below.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 522 AM CDT Fri May 8 2026

VFR conditions are expected through the forecast period. A few stray showers or sprinkles are possible early this morning, with higher chances for showers and isolated thunderstorms moving from northwest to southeast across the state this afternoon and evening. Heavier showers and storms could produce strong, erratic wind gusts and brief downpours reducing visibility. Northwest winds will become strong this afternoon at around 15-25 kts, with gusts to around 25-35 kts.

FIRE WEATHER

Issued at 522 AM CDT Fri May 8 2026

Two separate parts of the state are expected to see critical fire weather conditions today, with near-critical conditions elsewhere. The minimum humidity forecast for this afternoon ranges from just under 20 percent in southwest North Dakota to near 35 percent in the Turtle Mountains. Northwest winds with sustained speeds of 20 to 30 mph and gusts to near 40 mph are also expected this afternoon. The strongest surface winds and gusts are forecast to be associated with two separate maxima of 850 mb wind speeds: one over the James River Valley and adjacent areas to the west this afternoon, and another moving over far northwest North Dakota later in the afternoon and evening. Because local research shows our largest wildfires tend to be associated with stronger pockets of 850 mb winds, these two areas were placed in a Red Flag Warning for today, with the James River Valley segment lasting from late morning to early evening and the far northwest segment lasting from early afternoon to late evening. The relatively weaker forecast winds aloft over southwest North Dakota deterred Red Flag Warning issuance there, despite the lower forecast humidity.

A cold front moving down from Canada this evening through tonight could cause a period of shifting gusty winds, from northwest to northeast and back to northwest. But any gusts with the frontal passage are not expected to be as strong as those that occur during the day ahead of the front. Of note though, the wind shift could move through the far northwest segment of the Red Flag Warning prior to RH recovery. Also, as mentioned in the full discussion above, afternoon and evening showers and thunderstorms could produce erratic and strong wind gusts.

Lower dewpoints (than straight NBM) were blended into the forecast on Saturday, resulting in minimum humidity around 20 to 30 percent, lowest in the northwest quadrant of the state. The wind forecast for Saturday afternoon has slightly diminished from previous iterations, but still has northwest winds around 15 to 25 mph, strongest in the James River Valley area. Because the strongest winds and lowest RH are not forecast to greatly overlap, only near-critical fire weather conditions are being messaged for Saturday at this time.

After one day of much lighter winds on Sunday, a long stretch of enhanced fire weather concerns enters the forecast next week as temperatures are favored to be well above normal. Confidence is increasing that much of western North Dakota will experience critical fire weather conditions on Monday, with gusty southerly winds early in the day shifting to the northwest and becoming strong in the afternoon as humidity falls to near 20 percent. The risk for critical fire weather conditions more or less continues in western North Dakota through the work week, with daily gusty winds and minimum RH around 20 percent. Tuesday looks to be the least windy day in the west, but perhaps the windiest day for the eastern half of the state. A secondary area that shows up repeatedly in NBM guidance for critical fire weather next week is a portion of south central North Dakota bounded by Interstate 94, the James River, South Dakota, and Lake Oahe. Daily details for fire weather beyond the Monday/Tuesday time frame remain uncertain, but there is undoubtedly increasing potential for a longer duration of high- impact fire weather, at least until fuels start to green up.

BIS WATCHES/WARNINGS/ADVISORIES

Red Flag Warning from 1 PM this afternoon to 10 PM CDT this evening for NDZ001-009. Red Flag Warning from 11 AM this morning to 8 PM CDT this evening for NDZ023-025-036-037-047-048-050-051.