Severe Thunderstorm Warning 172, NWS Grand Forks, ND

Area Forecast Discussion
National Weather Service Grand Forks ND
235 PM CDT Thu Aug 21 2025

.KEY MESSAGES...

- There is a 2 of 5 risk for severe thunderstorms this afternoon
  and evening across portions of the area. Hazards could include
  damaging wind gusts to 75 mph, large hail up to the size of
  golf balls, and perhaps an isolated tornado.

&&

.DISCUSSION...
Issued at 235 PM CDT Thu Aug 21 2025

...Synopsis...

Ridging continues to retreat southwest this afternoon, with H5
troughing extending southward from an upper low, situated over
Saskatchewan and Manitoba. Scattered showers and thunderstorms are
expected to continue through the afternoon and early evening, with
severe thunderstorms possible. A cold front traverses the area
tonight into Friday morning, with much cooler and drier weather
expected as we head into Friday afternoon and into the weekend. Look
for highs in the 70s on Friday, with breezy west winds, then in the
60s for Saturday and Sunday with breezy northwest to north winds.
Lows could fall into the low 40s Sunday night, with cooler spots
possibly seeing upper 30s. Slightly warmer temperatures return on
Tuesday as highs climb into the lower to middle 70s.

...Severe Thunderstorms this Afternoon and Evening...

There is a conditional chance for scattered severe thunderstorms
this afternoon and evening. Dew points have climbed into the upper
60s to near 70 degrees following a prefrontal trough. West of this
feature, instability is expected to climb upwards of 3500 J/Kg,
along with deep layer shear ranging from 30-40 knots. Low level flow
remains weak; however, near storm influences could allow low level
shear to be locally supportive of hybrid supercells and clusters.
Forcing is somewhat weak due to the lack of H5/H7 shortwave support
and most of the initiation is likely to occur just ahead of the cold
front, where the steepest theta-e gradients exist. Soundings
continue to support upscale growth, with line segments potentially
leading to damaging wind gusts as the afternoon progresses. DCAPE
values are in the range of 1100 to 1300 J/Kg, along with PW values
ranging from 1.3 to 1.7 inches. This should allow for moderate
precip loading into any updraft that is able to initiate. Wind gusts
of 75 mph are possible with today's strongest storms, along with
hail up to the size of golf balls. Tornado risk continues to be
present but overall generally low. Storm scale influences will play
the biggest role for tornado risk as hybrid clusters could show more
supercell characteristics in the presence of increased low level
shear from nearby outflow boundaries.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1239 PM CDT Thu Aug 21 2025

MVFR conditions prevail where showers and thunderstorms are
occurring this afternoon, with VFR conditions elsewhere. A cold
front continues to work to the southeast this afternoon,
bringing additional thunderstorm activity to most of the TAF
sites. A few storms could become severe, with wind gusts and
large hail being the primary risk. An isolated tornado cannot be
ruled out. Winds shift to the west and northwest this evening
following the frontal passage.

&&

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

&&

DISCUSSION...Lynch
AVIATION...Lynch

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