textproduct: Bismarck

KEY MESSAGES

- Marginal risk (level 1 of 5) for severe weather this afternoon and evening over far southwest North Dakota.

- Marginal (level 1 out of 5) to Slight Risk (level 2 out of 5) of severe weather on Tuesday.

- Medium to High chances for precipitation continue Wednesday mainly over central North Dakota including the James River Valley where a Slight Risk (level 2 out of 5) exists.

- Low to medium chances of showers and thunderstorms Thursday through the remainder of the week.

DISCUSSION

Issued at 250 PM CDT Mon Jun 1 2026

The passage of a low pressure system across the southern Canadian Prairies will characterize conditions across the region over the next few days. For today, the low is progged to linger over southwestern Saskatchewan. Gusty southwest winds are found across northwestern and portions of north central North Dakota as the pressure gradient tightens between this lingering low and a center of high pressure moving north out of South Dakota. Sustained speeds around 20 to 25 MPH and gusts up to 35 MPH are forecast for the northwest, with speeds more general around 10 to 15 MPH and gusts up to 25 MPH elsewhere. The sky is expected to become partly to mostly cloudy as mid level clouds move in from the northwest. Highs this afternoon are forecast from the upper 60s northwest to upper 70s and lower 80s in the south central.

Late this afternoon into this evening, chances for showers and thunderstorms are expected to increase across the west as the previously mentioned low pressure system begins to move further to the north, lofting a surface trough across the Montana border. Interrogation of CAM soundings during this period reveals fairly strong BULK shear across much of the southwest, model values around 55 to 65 knots this evening. Instability is expected to be comparably limited during this period, with model MUCAPE maxing out around 1000-1250 J/KG in the early evening, and diminish rapidly after sunset. That being said, there is brief period in the late afternoon, early evening where a stronger to marginally severe storm may loft move into far southwestern North Dakota. The main hazards expected would be quarter sized hail and isolated gusts up to 60 MPH. As of this forecast cycle, SPC has a level 1 of 5 risk for isolated severe storms in far southwest for today. After the severe risk diminishes through the evening, chances for showers and thunderstorms are expected to spread from west to east overnight. Otherwise, gusty southwest winds are expected to diminish through the evening and overnight as the low center begins to move to the northeast, turning south southeasterly through Tuesday morning. Lows are forecast in the mid to upper 40s west to the lower 50s central.

With the surface low expected to become stationary in southern Saskatchewan Tuesday morning, with the transition of the inverted surface trough into a weak cold front through the day, showers and thunderstorms are expected to increase in areal coverage through the morning and afternoon. With the position of the low, better moisture influx will drive dewpoints into the lower 60s portions of the west and much of central North Dakota by the early afternoon. CAMs continue to advertise increasing ahead and along the cold front as it moves from west to east across the forecast area Tuesday afternoon and evening, with model MUCAPE values peaking well into the 3000-3500 J/KG range, and BULK Shear around 35 knots up to 55 knots over portions of the far west and north. Orientation of the shear vectors appear to only slightly off parallel from the cold front, which indicates that storm mode would mainly be clustered. Model DCAPE values across portions of the south central also begin to peak into the 1000-1500 J/KG range as we head into the early evening. With this in mind, the main expected hazards with any severe storm that does develop would be hail up to the size of golf balls, as well as wind gusts approaching 70 MPH. An isolated tornado is also possible across portion of the north central, with near surface shear values peaking around 20-25 knots while low level SRH jumps to around 150-200 m2/s2 in the late afternoon, early evening. The window for tornadic development is expected to be somewhat brief, would highly depend on how well the environment recovers from potential convection earlier in the afternoon. The SPC has placed portions of western and much of central North Dakota under a level 2 of 5 risk for scattered severe thunderstorms for Tuesday. Moving into the overnight period, while the overall severe threat is expected to diminish, showers and a few thunderstorms are expected to continue as the cold front moves toward eastern North Dakota. Of note is the potential for heavy rainfall. With high PWATs around 1.3 to 1.4 inches, and with the slow moving nature of this system, much of central North Dakota has medium to high chances for at least 1 inch of rainfall Tuesday through Wednesday morning, with locally heavier amount anticipated where thunderstorms develop. WPC has place much of the central North Dakota in a Slight Risk for excessive rainfall for Tuesday.

Conditions on Wednesday will likely depend on how quickly the aforementioned cold front is able to exit to the east for the forecast area. With the Saskatchewan low progged to slowly move eastward through the day Wednesday, more moisture is expected to stream in from the south southeast across the forecast area, and BULK shear values around 40 to 55 knots are advertised by the CAMs. If the cold front is slow to exit out to the east, any ongoing showers and convection that are ongoing on central North Dakota may perk up in the late morning and afternoon. Thus, SPC has placed much of central North Dakota into a level 2 of 5 risk for severe thunderstorms again on Wednesday.

Behind the exiting low, zonal flow is generally expected over the northern Plains through the remainder of workweek. A decently strong shortwave is progged to move across North Dakota late Thursday into Friday, promoting another round of showers and thunderstorms across the forecast area into this period. Behind this shortwave, there is decent agreement on comparably drier weather on Saturday as a transient shortwave ridge moves across the region. With flow aloft then progged to turn southwesterly Sunday into early next week, another period of active weather can be anticipated.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 250 PM CDT Mon Jun 1 2026

VFR CEILINGS AND VISIBILITY IS FOUND AT ALL TERMINALS TO BEGIN THE 18Z TAF PERIOD. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE ACROSS THE WEST LATE THIS AFTERNOON AND EVENING, SPREADING ACROSS INTO CENTRAL NORTH DAKOTA THROUGH TUESDAY MORNING AND THE END OF THE TAF PERIOD. COVERAGE IN THUNDERSTORMS DURING THIS PERIOD IS FAIRLY UNCERTAIN, THUS HAVE LIMITED PROB30 TO THE WESTERN TERMINALS OF KXWA AND KDIK AT THIS TIME. WHERE THUNDERSTORMS DEVELOP, GUSTY AND ERRATIC WINDS SHOULD BE ANTICIPATED. GUSTY SOUTHWEST WINDS THIS AFTERNOON WILL QUICKLY DIMINISH THROUGH THE EVENING, TURNING SOUTH THEN SOUTHEASTERLY THROUGH THE OVERNIGHT PERIOD.

BIS WATCHES/WARNINGS/ADVISORIES

None.