194
FXUS63 KFGF 140443
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1143 PM CDT Wed Aug 13 2025

.KEY MESSAGES...

- Scattered strong thunderstorms expected tonight across
  southeast North Dakota into Minnesota. The main hazard will
  be lightning and hail to the size of quarters.

- There is a level 2 out of 5 risk for severe thunderstorms late
  afternoon into evening Thursday. The main hazards will be
  gusty winds hail to the size of golf balls, gusts to 60 mph,
  and possibly a couple tornadoes. Uncertainty lingers on
  coverage of thunderstorms.

- There is a level 1 out of 5 risk for severe thunderstorms
  Friday afternoon within southeast North Dakota into west-
  central Minnesota.

&&

.UPDATE...
Issued at 1002 PM CDT Wed Aug 13 2025

Initial thunderstorm activity has developed into far southeast
ND (frequent lightning/heavy rain the main threats). The main
period of interest for our CWA will be later tonight as WAA
spreads north along with the LLJ and higher MUCAPE (1500-2500
J/KG). Trend is for an increase in coverage across the southern
RRV based on a consensus of CAMs and I increased PoPs
accordingly.

Due to marginal mid level lapse rates/narrower CAPE
profiles and weak mid level flow tendency will be for impacts to
be briefing heavy rain/lightning/smaller hail. There is enough
effective shear and CAPE tonight that isolated marginal severe
hail. Wind is harder to pin down with lower level inversion
advertised and less favorable low level lapse rates.

UPDATE
Issued at 630 PM CDT Wed Aug 13 2025

WAA and a relatively weak LLJ will be focus for potential
thunderstorm initiation later this evening/overnight, with the
main warm front/baroclinic zone southwest of our region.
Skinny CAPE profiles with effective shear 25-30kt may support a
few stronger storms, though the overall severe risk is low.
Brief heavy rain, lightning, and small hail will be the most
likely threats, with a low chance for marginally severe hail
with stronger storms tonight (1"). Will continue to monitor
trends.

&&

.DISCUSSION...
Issued at 135 PM CDT Wed Aug 13 2025

...Synopsis...

Broad upper ridging is noted on water vapor satellite imagery,
with a low amplitude wave moving through eastern SD as well as
within northern WY into southern MT. These will aid in low level
jet/warm air advection induced scattered showers and storms
tonight in southeast ND into MN. There is enough shear and
instability to suggest hail up to the size of quarters will be
possible, but more likely sub-severe hail will be more
prevalent if hail arises.

...Severe storm potential Thursday and Friday...

Upper forcing for ascent increases over the Northern Plains and
Upper Midwest as upper troughing migrates eastward out of the
Canadian Rockies into central Prairie Provinces. At the surface,
a fairly progressive and stout cold front through the region,
including the Dakotas. While this combined with increasing
instability potentially greater than 3000 J/kg and effective
shear on the order of 30-45kt is driving the severe storm
potential, there are still important details that remain
uncertain. Uncertainties are mainly tied to the relationship
between degree of forcing and convective inhibition lowers
confidence in storm evolution. CAMs suggest enough convergence
and surface heating should minimize convective inhibition very
near the front, although there may still be a complicating
factor of dry air entrainment to limit initial updrafts from
sustaining themselves under a weakly forced regime, particularly
south of US Highway 2 corridor.

This opens up a range of possible outcomes ranging from isolated
discrete supercells along the cold front capable of all hazards
(including hail up to golf ball sized, potentially greater as
well as tornadoes), or more clusters of storms eventually
turning into more linear feature placing high wind and hail in
the forefront of most likely hazards (relatively greater
potential within northwest MN).

The evolution of convection as well as frontal placement will
dictate Friday`s severe storm potential. Should the front be
slow to move through the area, it could stall near the tri-state
area of the Dakotas and Minnesota. This would allow severe storm
to develop near this stalled front and perhaps eventual surface
cyclogenesis near the same area. Should this occur, all hazards
would again be possible. This is what is driving the level 1 out
of 5 risk for severe storms Friday afternoon.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1143 PM CDT Wed Aug 13 2025

A low level jet (30-40kt) is building north into eastern ND and
northwest MN, and with this elevated thunderstorms are already
over parts of southeast ND. Scattered thunderstorms are expected
to continue to increase in coverage and spread north and east
with impacts most likely at KFAR through the early morning
hours (brief heavy rain/lightning the main threats with lower
risk of severe hail). There is a signal in guidance for a
period of MVFR stratus to develop in central MN during the
11-14Z period, with potential impacts at KDVL. Otherwise,
prevailing VFR conditions are favored outside of any stronger
thunderstorms that may develop in southeast ND. Thunderstorms
should end early in the morning Thursday, with the next chance
primarily in northeast ND and far northwest MN Thursday evening
(30-40%).

Southeast winds should continue to increase due to increasing
gradient and LLJ aloft, with south winds during the day Thursday
gusting 20-30kt at times in ND. A front eventually pushes into
the region late Thursday evening as gradient decreases,
shifting winds to a northwesterly direction towards 06Z in the
north.

&&

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

&&

$$

UPDATE...DJR
DISCUSSION...CJ
AVIATION...DJR