textproduct: Bismarck

KEY MESSAGES

- Isolated to scattered severe thunderstorms are possible late this afternoon and this evening in western and parts of central North Dakota. The main hazards are hail up to around golf ball size and wind gusts up to 60 mph.

- Hot temperatures are expected today with highs in the 90s in most areas, and in the mid to upper 90s in southwest North Dakota.

- Periodic chances of showers and thunderstorms will continue this week, with the highest odds of them on Tuesday.

- A cooling trend will begin Monday and continue through midweek. A warming trend will resume by late this week.

UPDATE

Issued at 637 AM CDT Sun Jul 5 2026

A few showers -- and most recently, some non-severe storms with a few cloud to ground lightning strikes -- have indeed emerged in northeast MT and northwestern ND early this morning. This activity is high-based in an environment of steepening midlevel lapse rates, but meager bouyancy. The forecast was nonetheless updated to include a mention of this activity spreading east across northwest and north central ND this morning.

DISCUSSION

Issued at 327 AM CDT Sun Jul 5 2026

Today's forecast will be highlighted by hot temperatures, in the 90s in most locations, and isolated to scattered late afternoon and evening strong to severe storms in western and parts of central ND.

Early this morning, light south-southeast flow is developing in response to broad lee-side surface troughing from south central Saskatchewan into central MT and WY. Surface dewpoints are in the lower 60s F in central ND along and east of the Highway 83 corridor. Thus far, there has been little to signal fog despite small temperature-dewpoint spreads and the light surface winds. The potential for shallow ground fog will nonetheless be one minor thing to watch through sunrise. Otherwise, the leading portion of height falls aloft and modest midlevel warm air advection is leading to development of midlevel clouds in north central and northeastern MT as of 08z. A subset of recent CAMs suggest an isolated shower could accompany this progression into northwest ND this morning, but confidence was too low to include that in the forecast at this time.

By this afternoon, a significant low- and midlevel thermal ridge is expected to develop in western ND as the upstream height falls become more prominent and the surface trough concurrently shifts into western ND. Guidance strongly agrees the thermal ridge axis will be characterized by 850 mb temperatures on the order of 25 to 29 C along the ND/MT border, supporting highs in the middle to upper 90s in southwest and west central ND. Even further east, the air mass will warm sufficiently for highs to be in the lower to middle 90s F across most all of western and central ND. The surface pressure gradient will result in a breezy south-southeast wind along and ahead of the surface trough this afternoon and evening, as well.

Where severe thunderstorm potential is concerned, isolated to scattered thunderstorms are expected to form in western and north central ND in the late afternoon and evening. Very steep low- and midlevel lapse rates will be present, particularly in the vicinity of the low-level thermal ridge axis in western ND by afternoon. Early morning surface observations suggest that low-level moisture is relatively shallow in southwestern ND, so it seems reasonable that surface dewpoints there will only be around 50 F during peak heating. Further north and east, where the boundary layer will be a bit more capped and where surface flow will have a more southeast trajectory, surface dewpoints are expected to remain in the lower if not middle 60s F from northwest into central ND. The result will be MLCAPE ranging from around 1000 J/kg in southwest ND, to 1500-2500 J/kg in northwest and central ND by late afternoon and evening. We expect supercell-favorable wind profiles to be in place with veering winds with height and 30-40 kt of effective-layer bulk shear, highest in northwest and north central ND.

Overall forcing for ascent is modest, but hot temperatures in the 90s F are expected to be sufficient to erode inhibition, with initiation favored along the surface wind shift/trough in western ND initially by late afternoon. CAMs are understandably dispersive in the exact location of their simulated thunderstorm development given the stronger large-scale ascent will still be upstream during the peak of the diurnal heating cycle. This is supportive of broad, low to medium thunderstorm chances across western and north central ND beginning around 21z and spreading eastward close to the Highway 83 corridor by evening. Having said that, it's plausible that initial high-based storms could form near the low-level thermal ridge axis and surface trough overlap in west central ND, and become more intense as they move northeast into richer low-level moisture. Given the expected CAPE-shear setting, any sustained supercells will be capable of producing large hail up to around golf ball size and damaging wind gusts to around 60 mph. The most favorable parameter space is expected to be in northwest and north central ND. Note that as the low-level jet increases during the evening, low-level SRH will quickly increase in the 01-03z timeframe, but the tornado threat is forecast to be minimized due to 1) the high- based nature of the storms (with ML LCL heights around 2000 m AGL) and 2) an expected decrease in storm intensity around the same time as the boundary layer cools and MLCIN increases.

We do need to stress that the coverage of severe storms this afternoon and evening is expected to be only isolated to scattered in nature, including the aforementioned hazard potential. There is even a potential low-probability scenario where storms largely fail to develop or become sustained due to the weak forcing and residual capping aloft.

Overnight tonight a stronger shortwave trough and surface cold front will cross the area with medium chances of showers and thunderstorms. A strong or severe storm remains possible overnight, but capping is expected to minimize that potential after sunset compared to this afternoon and evening. Forecast soundings do suggest sufficient elevated bouyancy, and relatively dry and warm low levels, supporting high-based convection amid a low- level jet. This setting could enable gusty or even strong winds from these overnight showers and storms as they move from eastern MT and across western and central ND, though again, the overall risk of severe storms will be lower overnight.

On Monday, the surface front will continue moving slowly east and southeast. Depending on when it moves through the James River Valley, scattered thunderstorms with an attendant risk of large hail and damaging winds could impact that area in the afternoon or early evening, but uncertainty is high regarding the timing of that front through that area. Passage of the cold front will begin a cooling trend in most areas Monday, and by Tuesday and Wednesday highs will only be in the mid 70s to lower 80s F. Easterly surface winds and passage of a shortwave trough and its associated high precipitation chances late Monday night and Tuesday could result in highs on Tuesday being even cooler than forecast. Our location north of the surface front that is forecast to be in SD during this period suggests the overall risk of severe storms Monday night and Tuesday will be limited by a lack of greater bouyancy. The probability of 0.50" inches or more of rainfall in this period is 50 to 70 percent in parts of southern ND, though.

Thereafter, by the end of the week and into next weekend, we expect a warming trend to resume, with low shower and storm chances in the forecast due to low-predicability, mainly low- amplitude shortwave troughs cresting the broad upper-level ridge to our south.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 637 AM CDT Sun Jul 5 2026

VFR conditions will generally prevail through the 12Z TAF cycle. South-southeast winds gusting to 20-25 kt are expected this afternoon and evening in southwest and central North Dakota. A front and related wind shift will move into northwestern North Dakota this afternoon, passing through KXWA around 21Z. This front is expected to produce isolated to scattered thunderstorms along and ahead of it in western and north central North Dakota beginning around 21Z and continuing into the evening. KMOT and KDIK have the highest likelihood of being impacted by a storm and a Prob30 group has been included at those terminals. Local MVFR to IFR conditions are possible with any storms. Overnight the front will gradually move across the area, with scattered showers and a few storms possible behind it after 06Z.

BIS WATCHES/WARNINGS/ADVISORIES

None.