textproduct: Bismarck

KEY MESSAGES

- Critical fire weather conditions continue northwest and north central North Dakota with near-critical conditions elsewhere.

- Frigid low temperatures tonight, thus Freeze Warnings and Frost Advisories are in effect through early Sunday morning.

- Daily windy conditions and low humidity values through the upcoming work week may lead to daily critical fire weather conditions for parts of the area.

DISCUSSION

Issued at 156 PM CDT Sat May 9 2026

Current surface analysis places low over southeast Ontario with high settling through Saskatchewan into eastern Montana. Upper level analysis places low over northern Ontario, with ridge over the western CONUS. Slightly cyclonic north-northwesterly flow remains over our area resulting in some cloud development over our eastern areas. Otherwise, dry conditions continue with temperatures about 5 to 10 degrees below average.

For the rest of today into tonight, dry conditions remain resulting in humidity values dipping into the mid teens to mid 20s over most of the area, with the overlap of the higher winds with the lowest humidity values remaining over parts of northwest/north central North Dakota where a Red Flag Warning remains in place. See fire weather discussion below for more details. As we get into tonight winds will diminish as aforementioned surface high pushes over. With the dry atmosphere in places, mainly clear skies, and light winds, expect temperatures to drop below NBM guidance. Most locations should dip into the mid 20s to lower 30s, but some clouds loitering over the southwest may keep that area a bit warmer. Therefore, have issued a Freeze Warning for all areas except parts of the southwest where a Frost Advisory is in place.

On Sunday, high pressure meanders to the east keeping winds generally light over the area. Temperatures warm a bit behind the high as upper ridge nudges into the northern plains. Therefore, highs will push above average over the west, but still may stay a bit on the cooler side over our eastern locations. Surface trough deepens to the lee of the Canadian/Northern Rockies overnight as surface high pushes east. This will allow southerly winds to start increasing overnight.

Monday will see aforementioned lee side trough close off and move easterly through the southern prairie provinces, as a potent short wave trough busts through the ridge into the northern plains. Southerly winds will be on the increase bringing a very warm day to parts of the area, with highs in the 80s over our west. Surface trough followed by a cold front slide through with the passing low, with winds shifting west then northwest and remaining gusty. This will combine with a dry lower atmosphere to cause another day of fire weather problems, especially over the west (again see fire discussion below). To the east, humidity may be a bit higher depending on timing of the aforementioned system. Guidance is suggesting an area of instability developing. Although this may only be CAPE values of 200-500 J/kg, quite high forecast deep layer shear (50-60 kts effective bulk) is noted, thus the potential for a damaging wind threat. Therefore have painted in low thunderstorm chances in the afternoon/evening hours over parts of our east.

On Tuesday highlight will be the potential for higher winds over eastern portions of our area in the wake of the aforementioned cold front. With that said, the airmass behind the cold front will actually be quite mild, so expect highs to push into the upper 60s to mid 70s.

Warm and dry conditions continue through at least mid-week. Towards the end of the week a few disturbances might move through, but guidance remains lean with producing precipitation with this. Temperatures remain mild, with even the NBM 25th percentile of temperature spreads remain notably above average through Saturday.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 1150 AM CDT Sat May 9 2026

VFR conditions will prevail through the forecast period.

FIRE WEATHER

Issued at 525 AM CDT Sat May 9 2026

Critical fire weather conditions will continue this afternoon into this evening, mainly along and north of Highway 2 and along and west of Highway 83. Winds will be northwest around 20 mph with gusts near 30 mph, while minimum relative humidity values drop as low as 15 percent. Near critical fire weather conditions will continue elsewhere with minimum humidity values in the mid teens to mid 20s.

Fire weather concerns are relatively lowest on Sunday, with forecast minimum RH around 20 to 30 percent and afternoon winds ranging from northerly around 10 mph in the James River Valley to variable around 5 mph or less across the rest of western and central North Dakota.

The most concerning period for fire weather this coming week is Monday through Tuesday. By midday Monday, southerly winds are forecast to increase to around 20 to 30 mph, strongest between the Missouri and James River Valleys where gusts could approach 45 mph. Even though southerly winds will be relatively lighter in western North Dakota to start the day, a cold front is scheduled to arrive from the west by mid afternoon. This cold front will shift winds to the northwest and could increase speeds as high as 30 mph, with gusts to 45 mph. This wind shift could occur close to the timing of lowest diurnal humidity, which could be under 20 percent in some areas. There is high confidence in minimum RH around 20 percent west to 30 percent central on Monday. But even with the slightly higher RH in central North Dakota, the southerly winds could still be strong enough to approach critical fire weather conditions.

The cold front will continue to progress eastward across the state Monday evening, shifting winds to the northwest. The strength of gusts trailing the front becomes less certain with the loss of diurnal heating, but deterministic guidance does show modest values of cold air advection and pressure rises paired with an increasing low level wrap-around jet. Ensembles continue to trend windier for Tuesday, with broad medium chances for northwest winds gusting in excess of 50 mph across the eastern half of the state. The sustained winds of 35 to 40 mph projected by the latest iteration of the NBM may be too high, but still resemble a reasonable worst-case scenario. The minimum humidity forecast for Tuesday is around 20 percent for the western half of the state, with even lower pockets in the far west. From the Turtle Mountains through the northern James River Valley, minimum RH is closer to 30 percent. Even though the strongest winds may not overlap with the lowest RH on Tuesday, there is still potential for critical fire weather conditions across all of western and central North Dakota. Areas of greatest concern on Tuesday include northwest parts of the state along and north of the Missouri River, all of central North Dakota, and especially areas from east of Lake Oahe to the southern James River Valley where a stronger wind outcome could place the entire afternoon and early evening in non-stop critical conditions.

On Wednesday, latest forecast guidance places the highest fire weather concerns back over western North Dakota, with southerly winds projected to increase to around 25 mph and minimum RH around 20 percent. Forecast details become less certain to end the week, but every day through at least Saturday has a potential for warm temperatures, low RH, and gusty winds.

BIS WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 9 PM CDT this evening for NDZ001>003- 009>011. Freeze Warning from 1 AM CDT /midnight MDT/ to 9 AM CDT /8 AM MDT/ Sunday for NDZ001>005-009-010-012-013-017>020-022-023-025- 033-035>037-046>048-050-051-055>060. Frost Advisory from 1 AM CDT /midnight MDT/ to 9 AM CDT /8 AM MDT/ Sunday for NDZ031-032-040>044-061-062.