239
FXUS63 KFGF 210351
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1051 PM CDT Wed Aug 20 2025

.KEY MESSAGES...

- There is a 1 of 5 chance for severe thunderstorms after
  midnight. Hazards include damaging wind gusts to 60 mph and
  hail up to 1 inch in diameter. Highest chances will be the
  Devils Lake Basin eastward into the northern Red River Valley.

- There will be a 1 of 5 risk for severe thunderstorms Thursday
  afternoon and evening across much of eastern North Dakota,
  northwest Minnesota, and west central Minnesota. Hazards could
  include damaging wind gusts to 70 mph and large hail up to
  the size of golf balls. An isolated tornado cannot be ruled
  out.

&&

.UPDATE...
Issued at 1051 PM CDT Wed Aug 20 2025

Storms have begun to form across southern Canada, closer to the
nose of the low level jet. Storms across southern Canada should
become more widespread over the next several hours, tracking to
the east. Precipitation in this FA should hold off for several
more hours until better forcing arrives from the west.
Environmentally, instability and shear are both more on the
limited side, and storms will be elevated. This means if any
storm would manage to become stronger, hail up to at most the
size of a quarter would be the main threat. Upped POPs a bit for
the overnight showers/storms, otherwise just blended in latest
observations.

UPDATE
Issued at 700 PM CDT Wed Aug 20 2025

Quiet in this FA right now. Watching upstream trends to see what
exactly develops this evening thunderstorm wise. Initial area of
thunderstorm development is north of the Canadian border near
the SK/MB provincial line. Other currently severe thunderstorms
are still way out west near Havre MT. Latest CAMs show
thunderstorm activity holding off until after midnight. That
seems reasonable considering the current placement of the
strongest and most established convection. Otherwise, the
forecast remains on track with minimal updates.

&&

.DISCUSSION...
Issued at 350 PM CDT Wed Aug 20 2025

...Synopsis...

H5 ridge continues to flatten this afternoon, with an upper low
approaching from the northwest. A pre-frontal trough is expected to
move into northeastern North Dakota late this afternoon and evening,
bringing a chance for strong to severe thunderstorms to portions of
northeastern North Dakota. Shower and thunderstorm chances persist
through the overnight and into Thursday morning. As the cold front
moves into the area later on Thursday, this line of showers and
storms could strengthen and produce another round of strong to
severe storms during the afternoon and evening. Heading into Friday
and the weekend, much cooler temperatures prevail, with high temps
on Friday reaching into the 70s and highs this weekend only reaching
the 60s both Saturday and Sunday. Cool weather continues on Monday
before temperatures start to rebound on Tuesday.

...Severe Thunderstorms Possible late this Evening...

A prefrontal trough is slowly working eastward into central and
eastern North Dakota this evening. Elevated instability increases
during the evening and overnight along and ahead of this trough.
CAMs still show a wide range of scenarios, especially regarding
timing. Progressive models develop storms along and north of the
International Border this evening, with slower models showing
development much later during the overnight. In both cases, the
primary hazards will be hail up to 1 inch and damaging wind gusts to
60 mph. At this time, capping is rather strong across the area;
however, with the lift along the prefrontal trough, initiation could
still occur.

...Severe Thunderstorms Thursday Afternoon and Evening...

Ongoing showers and thunderstorms are expected Thursday morning into
the midday hours along a prefrontal trough. A cold front moves into
eastern North Dakota early Thursday afternoon, then into northwest
and west central Minnesota late in the afternoon. Instability will
be high along the prefrontal trough as well as the cold front, but
will be a somewhat narrow corridor. MLCAPE values could reach up to
4000 J/Kg along the primary theta-e gradient boundary, with 0-6 km
shear of around 30-40 knots within the corridor of high instability.
Supercell parameters are minimal; however, hybrid clusters remain
possible and upscale potential is favored. DCAPE values range from
1000 J/Kg to 1300 J/Kg, with PW of around 1.4-1.6 inches, thus
justifying a mention of wind gust potential upwards of 70 mph. Hail
potential will be up to the size of golf balls, especially during
the early to mid afternoon where we see the stronger clusters or
hybrid clusters.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1051 PM CDT Wed Aug 20 2025

Timing of any rain/storms is the main challenge during this TAF
period. A cold front sagging from northwest to southeast will
provide lift throughout the period to spark showers/storms.
Added VCSH during the period of highest confidence, in addition
to PROB30`s for when rain is most likely to impact the terminal
sites within the next 9 hours. Rain should wane from northwest
to southeast Thursday afternoon, but a second round of
thunderstorms may develop along the front. There remains
significant uncertainty in the placement/coverage during this
potential second round of thunderstorms, so left them out of
this round of TAFs.

&&

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

&&

$$

UPDATE...Rafferty
DISCUSSION...Lynch
AVIATION...Rafferty