Casselton, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

720
FXUS63 KFGF 231733
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1233 PM CDT Tue Jun 23 2026

.KEY MESSAGES...

- There is a level 2 out of 5 risk for severe thunderstorms this
  afternoon into early evening, mainly along and east of the Red
  River Valley. The main hazards will be hail up to the size of
  golfs balls and tornadoes.

- Growing signal for strong to severe storms late this weekend
  into early next week.

&&

.DISCUSSION...
Issued at 1233 PM CDT Tue Jun 23 2026

...Synopsis...

The system seen on water vapor imagery across southern Manitoba has
become occluded and will very slowly propagate east/southeast.
Large scale pattern will become zonal toward the end of the
week, and then transition to southwest flow aloft by early next
week as western CONUS troughing develops. Ensemble guidance in
good agreement with how the large scale pattern will evolve,
albeit with lower confidence in smaller scale features.

..Severe storm potential today...

Warm sector/theta-e ridge will be near or just east of the valley by
early afternoon, with CI anticipated along the leading edge of this
boundary early-mid afternoon. Given expected storm motion off the
boundary, anticipate discrete mode. Environment will be
supportive of supercell type storms (albeit low topped given
MLCAPE 1000-1500 J/kg) given effective bulk shear near 30 kts
and effective SRH near 200 m2/s2 (environment supportive for
stronger low level mesocyclones). Severe hail up to golf balls
anticipated given straight hodograph structure, lower freezing
level, and favorable mid level lapse rates. Also anticipate
tornadoes given the favorable low level dynamics. AI guidance
(Nadocast and Storm Net) back up this thinking.

The most likely scenario at time has the stronger discrete low
topped supercell storms developing early afternoon (1-3p) along
the eastern edge of the valley affecting much of northwest and
west central Minnesota through 6-7p. There should be 2-5 storms
at any given time. This is the period when low topped
supercells will bring the largest hail and tornado threat. There
is the potential for additional development closer to the sfc
low/upper low later in the afternoon affecting the northern
valley into northwest Minnesota, although more uncertainty
exists with this activity.

...Weekend into early next week severe potential...

The synoptic ingredients typical for producing severe storms in our
region will be in place - and conceptually the large scale pattern
supports severe storm outbreaks. Details are always the tricky part,
especially where individual upper waves track and how far east the
greater instability will be. There does remain some uncertainty with
exactly how amplified the large scale pattern will be and this will
influence those details.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1233 PM CDT Tue Jun 23 2026

Showers/storms currently moving off the east and will be clear
of all TAF sites by 18z. A narrow area of MVFR cigs now just
east of the valley will affect KTVF and KBJI for a brief period
this afternoon, although most likely cigs will eventually become
low VFR. Main aviation threat will be additional thunderstorm
development this afternoon into the evening. Storm coverage
will be limited making thunderstorm forecasting for each
individual TAF site tricky. Went with a Prob30 for the sites
that have the best chance to see a storm or two (KGFK, KTVF, and
KBJI).

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

$$

DISCUSSION...TG
AVIATION...TG