textproduct: Grand Forks

KEY MESSAGES

- Next chance for strong thunderstorms are late Monday and Monday night.

UPDATE

Issued at 343 AM CDT Thu Aug 20 2026

Surface low at 08z was in southwest Manitoba east of Brandon. This low will move southeast today into far northwest and north central MN this afternoon. Cluster of t-storms in 850 mb warm advection ahead of this system moving thru NW MN will move out west central MN by 15z. Additional chance for a few showers or t-storms possible in parts of northwest MN this afternoon. Main cold front will be located at 20z from near Bemidji to Fargo but ahead of it is a southwest to west wind shift trough which will serve as the focus for t-storm development late this afternoon and evening. This instability axis with this initial trough will be from near Duluth thru St Cloud/Minneapolis and into southwest MN. Therefore day 1 SPC keeps marginal and slight severe storms risks just to our east and south.

Friday will see a second but weaker short wave move southeast from central Manitoba into southwest sections of NW Ontario and give a chance for a few showers or t-storm in NW MN in the afternoon.

Looking farther ahead based on machine learning severe outlooks some risk of strong storms will exist with cold front moving thru Monday late afternoon and evening.

..Showers and thunderstorms tonight and Thursday

Many of the model solutions have scattered shower and a few thunderstorms entering our northern counties late this afternoon and into the evening as the shortwave currently over southeastern Saskatchewan digs down. Some of the models such as the NAM and the RAP have a narrow band of instability with the system. The surface based CAPE is only in the 500-1000 J/kg range, but some of the CAMs have MU CAPE a bit above 1000 J/kg. Deep layer shear is around 25 to 30 kts, but HREF probabilities of any strong updrafts are minimal, and model soundings this evening are not very impressive. Could see some lightning as HREF has 30 to 50 percent probabilities with this shortwave, along with brief downpours.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 710 AM CDT Thu Aug 20 2026

Quite a bit of altocumulus across the area as the main shower and t-storm area exists our forecast area. Some MVFR cigs are showing up around Roseau and Warroad moving southeast from Manitoba. This is closer to the upper wave and surface low which is tracking southeast toward that area. So MVFR cigs may linger well into the afternoon for those areas. Otherwise broken altocu will scatter out as clearing works in south of the surface low today. Winds will turn west and then northwest over E ND/RRV before 17z today with gusts this afternoon in the 25 kt range. Lighter winds farther east and also wind direction change will take longer.

FGF WATCHES/WARNINGS/ADVISORIES

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