textproduct: Bismarck

KEY MESSAGES

- Dense fog across much of northern North Dakota into the northern James River Valley this morning.

- Hot and smoky conditions continue through at least the middle of the week, with highs around 90 to 100.

- Medium to high chances (30 to 70 percent) for showers and thunderstorms Wednesday afternoon through Thursday. A few storms could be severe.

UPDATE

Issued at 311 AM CDT Tue Jul 28 2026

A Dense Fog Advisory has been issued for for areas along and east of Highway 52 from the Canadian border to the Highway 200 corridor.

UPDATE Issued at 135 AM CDT Tue Jul 28 2026

Fog is beginning to settle in across north central North Dakota from the Turtle Mountains to the northern James River Valley. A Special Weather Statement has been issued for these areas, but this could quickly escalate to a Dense Fog Advisory as sub- quarter mile visibility is becoming more prevalent.

UPDATE Issued at 1003 PM CDT Mon Jul 27 2026

Earlier elevated showers and weak thunderstorms have largely exited the area, though we will maintain low, ~20 percent chances of additional activity overnight in parts of central ND in respect to modest midlevel warm air advection that is still forecast to redevelop, especially after 05Z. Otherwise, the main change with this update was to add patchy to areas of fog into the forecast in northern and north central ND into parts of the James River valley. As of mid evening, temperature-dewpoint spreads in those areas are 5 F or less, with surface dewpoints around 70 F. Recent HRRR/RAP guidance also has begun simulating fog development in those areas. We will need to monitor in case it becomes more widespread and/or dense, especially in north central ND, given the weak surface winds and high dewpoints. Lastly, significant amounts of high-level clouds are spreading eastward out of MT around the periphery of the upper-level ridge as of mid evening too, which will likely lead to considerable cloud cover overnight. This may act to keep low temperatures a bit warmer than forecast, too.

UPDATE Issued at 638 PM CDT Mon Jul 27 2026

Weak convection continues moving eastward across central ND as of early evening, driven by broad midlevel warm air advection, and the influence of a modest jet streak aloft. Bouyancy has been meager over most of western and central ND, and lightning has dwindled in the last 60 minutes. We believe the risk of a strong storm is diminishing, though at least broad/weak warm air advection is forecast to persist over central ND through the night, constituting a low chance of elevated showers or a thunderstorm continuing.

DISCUSSION

Issued at 115 PM CDT Mon Jul 27 2026

Currently, scattered thunderstorms remain just north of the International Border, in northwest and north central ND, but do extend south as you get to the Turtle Mountains area. Elsewhere, Isolated showers and thunderstorms were located over eastern Montana.

For this afternoon and tonight, there is some elevated instability across northern and western portions of the forecast area. There is a marginal risk (level 1 out of 5) of severe storms over the far southwest (mainly Bowman and Adams Counties). Surface low pressure over southeast Montana is forecast to move into southwest ND later this afternoon. Southwest ND will be in an area of surface convergence ahead of the low. There is on the order of 500-1000 J/kg of elevated CAPE above an area of good CIN. The far southwest looks to be the one area in the west which could see most of the CIN erode later this afternoon into early evening. Every so often one of the CAMs will show a few stronger cells over the far southwest. A combination of the decreased CIN and surface convergence could support a strong to severe storms with the main threat being wind gusts to 60 mph. In the north convection continues along the International Border. Instability does increase with good shear as you move east across the north central. The SPC mesoanalysis page indicated increasing CIN over both western and northern ND later this afternoon into this evening. Therefore, the overall threat for severe storms looks to remain low.

Tonight CAMs do show scattered shower/thunderstorm activity spreading west to east over the southwest and south central, along with scattered convection along the north spreading south and east. Really uncertain about overall coverage of any activity tonight given the general strong capping, so stuck more to a broadbrush of slight chance pops through tonight.

Elevated smoke looks to remain over the area for the next few days, so kept a mention of smoke in the forecast and put a lower limit on the sky cover through Tuesday.

Temperatures climb higher Tuesday and Wednesday. Tuesday looks to be mostly dry with upper level ridging building over the area. The lack of low level moisture should also keep heat index values below critical values, even as surface temperatures climb into the upper 90s south and west of the Missouri River. On Wednesday, temperatures are about the same as or a little higher than Tuesday. A southerly return flow should also bump up dew point temperatures a little. This could bump apparent temperatures high enough for a Heat Advisory. However, the uncertainty is high enough at this time to give it another day. Currently it appears that it would probably be a limited area and for a limited duration so would most likely pass if we were needing to make a decision today.

Wednesday night and Thursday we see a series of waves propagating through the mean upper ridge, bringing us better chances for showers and thunderstorms than we have seen in a while. Right now things look a bit messy with perhaps a southern stream and a northern stream wave traversing the forecast area with a lot of uncertainty in timing and placement of said waves and resulting convection. NBM continues with it's broadbrush area of medium to high pops Wednesday night and Thursday. As was mentioned yesterday, not overly excited about the areal extent of high pops but this far out. a broadbrush approach seems justified.

Temperatures do drop a little after Wednesday, with highs mainly in the mid 80s to mid 90s Thursday and Friday, followed by a warm-up as we head into the weekend.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 135 AM CDT Tue Jul 28 2026

Fog was developing across north central and eastern North Dakota to start the 06Z forecast period. Confidence is low on whether dense fog will reach KMOT or KJMS. Included TEMPO groups for MVFR/IFR visibility at each of these terminals from 09-13Z. VFR conditions are otherwise expected through the forecast period, with winds remaining light. Smoke from distant wildfires will remain present, but categorical visibility restrictions due to smoke alone are unlikely. An isolated shower or thunderstorm could develop from time to time throughout the forecast period, mainly across southern North Dakota.

BIS WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 10 AM CDT this morning for NDZ002>005- 012-013-022-023-025-055-056.