172
FXUS63 KFGF 291730
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1230 PM CDT Sun Jun 29 2025

.KEY MESSAGES...

- Scattered thunderstorms are expected Monday afternoon.
  Lightning and hail to the size of nickels would be the main
  threats with stronger storms.

- Severe thunderstorm chances return Independence Day (Friday)
  into next weekend to parts of the region.

&&

.UPDATE...
Issued at 1230 PM CDT Sun Jun 29 2025

Showers have ended across the area with clearing skies observed
across much of eastern North Dakota and northwest Minnesota.
Temperatures have climbed into the upper 70s to low 80s with
breezy northwest winds. Overall, the forecast remains on track
early this afternoon.

UPDATE
Issued at 631 AM CDT Sun Jun 29 2025

Isolated to widely scattered light showers (sprinkles) are still
ongoing over parts of northwest MN. Otherwise, most locations
are starting the day dry with areas of mid to high cloud cover.
Minor adjustments were made to near term trends.

&&

.DISCUSSION...
Issued at 332 AM CDT Sun Jun 29 2025

...Synopsis...

An open mid level trough is moving over the Northern Plains, with
the main center over the Canadian prairies. Deeper moisture and
instability have been pushed to the southeast while a weak cold
front is moving through the region. Elevated instability and
at least some lingering moisture/forcing will support isolated
to widely scattered showers and a few rumbles of thunder today,
but impacts will be minimal. The mid level trough eventually
deepens to the east Monday and cyclonic northwest flow brings a
period of scattered showers and thunderstorms through the
afternoon. Ridging is expected to dominate the pattern over the
Northern Plains Tuesday through Thursday, with seasonably warm
temperatures and much lower chances for measurable
precipitation. As this ridge flattens ensemble clusters show a
shift to westerly or low amplitude southwest flow across the
Northern Plains by Friday which persists through the weekend,
and the pattern may become more active once again as a result.
In addition, the increase in BL moisture and heights across the
central US raises the potential for heat impacts. Though current
NBM keeps heat risk in the moderate category late week into the
weekend. 75th percentile of NBM members would support the
potential for higher impacts.

...Strong storm potential Monday afternoon...

The signal for scattered convection is consistent with guidance
with higher coverage for showers shown to be closer to the
deepening trough in our northeast during peak heating based on
NBM and HREF. While drier NW BL flow keeps BL in the upper 50s
and lower 60s, ML CAPE is still shown by guidances to increase
to the 1000-1500 J/KG range during the afternoon. While
effective shear may be 30-35kt in some areas, CAPE profiles will
tend to be skinny and marginal as mid level lapse rates are
weak (less than 7 C/km). This lowers the risk for severe
convection, but may support a few strong cores and hail to the
size of nickels during the afternoon period. The coverage of
lighting activity (30-50%) does raise the potential for impacts
to outdoor activities during the afternoon even if hail becomes
less of a concern. Loss of peak heating and decoupling will
result in shower/thunderstorm activity quickly ending early
evening.

...Severe thunderstorm potential Independence Day weekend...

The shift to west or southwest flow would allow for a return to
higher BL moisture return and higher instability as progressive
waves move into the region. These specific shortwaves carry
lower predictability and individual ensemble members show high
variance in timing/evolution that ultimately will impact
evolution of any severe risk in our region. All machine learning
systems have at least a signal for severe risk (5%) across the
Northern Plains and our CWA with some (FengWu/Pangu) showing 15%
contours by Friday within parts of the region. At this range
predictability is too low to zero in on specific
impacts/coverage, however anyone with plans for the holiday
weekend should monitor updates.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1230 PM CDT Sun Jun 29 2025

VFR conditions prevail at all sites through the period. Look for
an increase in cloud cover with the potential for a scattered
shower or thunderstorm during the late overnight hours into
Monday morning. Better chances are in the forecast further into
Monday, primarily for KBJI, with slightly lower chances at KGFK
and KFAR. Will continue to update as confidence grows, but at
this time, projected coverage looks too inconsistent to include
in the TAFs.

&&

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

&&

$$

UPDATE...Lynch/DJR
DISCUSSION...DJR
AVIATION...Lynch