textproduct: Grand Forks

KEY MESSAGES

- There is a level 1 out of 5 risk for severe thunderstorms Monday afternoon and evening. Hail to the size of golf balls and wind gusting to 70 mph will be the main threats.

UPDATE

Issued at 321 AM CDT Sun Aug 23 2026

Patchy fog has developed over parts of northwest MN, but impacts have been very brief/localized in the KTVF area. I can't rule out other fog impacts during the morning period due to broad surface ridging and near calm winds along/east of the RRV, however the saturated layer is very shallow and tendency will be for highly localized pockets of ground fog.

Looking ahead to Monday's severe chances: There has continued to be a trend over the last 24hr on guidance favoring the frontal zone pushing into our CWA during the afternoon. While larger scale forcing is primarily in Canada or mainly during the late evening/overnight, there should be enough lift associated with the front to support a few thunderstorms potentially initiating during the favorable afternoon/evening period when SBCAPE/DCAPE could be maximized near the frontal zone. Due to increasing mid/upper level flow effective shear values greater than 35kt+ are advertised with generally straight hodographs supportive of splitting supercells. Discrete cells could support sig hail potential, though with shear profiles orientation in relation to the cold front mergers may be more likely if coverage increases. Higher DCAPE and mix layers higher gusts could accompany RFD's, though weaker 0-3km shear lowers confidence in a larger sig wind threat.

The best chance for thunderstorms is actually later as the main wave passes to the north in Canada and better forcing moves through our region. If thunderstorms fail to initiate early on, the tendency would be for lower impacts from thunderstorm activity that would be much more elevated in nature later in the evening/overnight.

..Isolated Severe Thunderstorms Late Monday

There is a chance for strong to severe thunderstorms late Monday afternoon into the evening as a moderately strong shortwave pushes across the area. Steep low and mid level lapse rates will be in place during peak heating, with a cold front approaching from the northwest. Modeled surface CAPE ranges from 1500 to 2500 J/Kg across various ensembles and deterministic NAM/NAM Nest. Low to mid level shear is marginal, especially further ahead of the cold front. Hodographs, however, are relatively straight and have a degree of consistency in model soundings. If storms are able to form, there should be just enough shear to allow a mention of supercells, with a chance for splitting supercells or hybrid clusters. In a higher impact scenario, supercells form, bringing potential hazards including wind gusts upwards of 75 mph and large hail to the size of golf balls. If atmospheric support shifts more towards clusters, the potential hazards could include wind gusts upwards of 70 mph and hail up to the size of ping pong balls. Alternatively, in a lower end scenario, storms form later in the evening and severe storms become less likely, but could still support elevated hail producing storms during the late evening and overnight.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 621 AM CDT Sun Aug 23 2026

Patchy ground fog has developed over parts of eastern ND and northwest MN, with highly localized/brief visibility reductions under 1sm. Fog impacts at TAF sites are highly uncertain due to the isolated nature of this fog. If impacts were to occur they would be before 14Z. Otherwise, VFR conditions should prevail through the TAF period with light winds becoming southeast 5-10kt in eastern ND (around 12kt at KDVL). A few showers may move into northeast ND after 09Z with the best chance during this TAF period (30%) at KDVL.

FGF WATCHES/WARNINGS/ADVISORIES

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