textproduct: Grand Forks

KEY MESSAGES

- Low chance for isolated showers and thunderstorms Thursday afternoon and evening within Minnesota. Main hazard is lightning, although couldn't rule out small hail and gusty winds to 50 mph.

UPDATE

Issued at 924 PM CDT Wed Aug 5 2026

Updated the Key Message to note on Thursday's conditional chance for isolated thunderstorms within Minnesota.

Two forcing mechanisms may spark attempts at deep convection - the first is relatively higher low level moisture / theta-e advecting into the southern Red River Valley and Minnesota during the day.

Later in the evening, a second area of forcing intrudes in the form of a fairly progressive cold frontal passage. Most guidance pinpoints far northwest MN as the favored zone for potential storms from this forcing, likely due to this area being closer to the mid/upper wave responsible for driving the cold front. However, combating these forcing mechanisms will also be at least weak to moderate convective inhibition. Given the meager strength of forcing in addition to the relatively lower overall moisture and instability parameter spacing. This is the reason why the chance for storms remains low (but not zero). In the scenario where storms do develop, the relatively increase in low level instability will supply the instability needed for convection, albeit nearly all guidance has instability on the low end, on the order of 500 J/kg to 1000 J/kg. This is in tandem with veering winds with height through the cloud bearing layer, and mean wind speed within the layer of around 40 kt.

Despite increasing low level moisture, overall moisture in the low levels still looks to be on the lower side. This may be another failure mode, with deep convection perhaps struggling to survive, juxtaposed with meager forcing and some form of convective inhibition in this regime.

However, should a storm develop and sustain itself, there may be enough wind shear to help organize the likely spatially miniature storm, offering opportunity for small hail to be generated. Couldn't rule out sub-severe gusty winds due to well mixed boundary layer and the general momentum of wind aloft that could be transferred toward the surface.

For the conditional chance to see low end severe, or near severe hazards, a Key Message was introduced to raise awareness of this potential.

..Synopsis

Fairly vigorous shortwave seen on water vapor loop rounding the back side of the upper trough and moving into ND. Regional radar shows some showers with the shortwave, with most of the significant returns up in Canada. NDAWN network has yet to show and precipitation in ND reaching the ground, and that fits the QPF forecasts for the most of the high resolution models. Very little instability across the area, so if any precipitation does reach the ground it will be little more than some light sprinkles. A stronger shortwave approaches tonight and moves into Manitoba and Ontario tomorrow, helping to push a cold front Thursday night into the forecast area. Many of the models try to develop some showers and thunderstorms out ahead of that boundary Thursday afternoon and evening, but CAPE values are expected to be in the 500-1000 J/kg and low level moisture not that great. Currently the HREF has some 20 to 30 percent probability for thunder, but updraft helicities indicating severe are pretty minimal. There does look to be some low level and elevated smoke moving into the area ahead of the front, so increased high cloud cover a bit along with some patchy smoke.

Friday looks fairly quiet with high pressure building in behind the front. Northwesterly flow aloft sets up for the weekend into the first part of the work week. Various weak embedded shortwaves could bring some precipitation chances, but all solutions look pretty light and timing and strength of such minor features is hard to tell at this point anyway. Temps look near seasonal values.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 924 PM CDT Wed Aug 5 2026

Low level wind shear is forecast for most TAF sites between 06Z and 13Z. There is also a low chance for isolated thunderstorms within Minnesota Thursday afternoon and evening. However, the chance for this potential is currently low enough to keep any mention of -TSRA/VCTS omitted from TAFs. This may change as confidence increases, although, this may not occur until very near in time when storms would be developing - as early as 19Z Thursday early afternoon, lasting as late as 04Z Thursday night.

Otherwise, winds will generally remain out of the southwest before 00Z, After 00Z, a cold front will sweep through the region shifting and increasing winds out of the north and northwest. This wind shift is currently outside of the 00Z TAF window.

FGF WATCHES/WARNINGS/ADVISORIES

ND...None. MN...None.