532
FXUS63 KFGF 261930
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
230 PM CDT Sat Apr 26 2025

.KEY MESSAGES...

- Near critical fire weather conditions due to low relative
  humidity (20-25%) in northwest Minnesota.

- Severe thunderstorms are possible Sunday night into Monday
  morning. The primary hazard will be large hail.

- Additional severe thunderstorms may develop Monday afternoon.
  All hazards are possible if they do develop including large
  hail, damaging winds, and tornadoes.

&&

.DISCUSSION...
Issued at 126 PM CDT Sat Apr 26 2025

...Synopsis...

Cloud cover has begun to increase from the west as southerly
flow brings in some nice moisture content. This will at least
increase dewpoints through the afternoon and evening. Showers
may impact the area in some spots, however instability will be
limited so impacts are unlikely.

For tomorrow, increasing moisture plumes will allow for MUCAPE
to start pushing northward. This will eventually make it to our
area late tomorrow night into Monday morning, bringing a severe
thunderstorm risk to our area. This risk will arise again as the
main wave begins to eject eastward.

Regarding rainfall, there is very high confidence in at least
0.50" of rainfall across pretty much the entire CWA, with at
least a 50% chance for greater than an inch of rain. Depending
on where convection develops, there is a low chance for a band
of 1.5-2" of rainfall through the entire event. Flash flooding
appears unlikely at this time due to high rainfall rates not
training and the more 1" totals on the backside should be more
stratiform in nature.

The period after severe storms Monday will be dry as a very
large ridge will develop over the CONUS. This will tamp down
convective risk and also give us increasing temperatures. Thus,
hazardous weather is unlikely after Monday.

...SEVERE THUNDERSTORMS SUNDAY NIGHT INTO MONDAY MORNING...

Elevated thunderstorms are likely to develop in at least some
capacity Sunday night and track into our area. The bulk of
MUCAPE > 1000 remains along and south of I-94, stretching
northeastward, however the 500 isoline is fairly diffuse, so a
marginal severe risk cannot be ruled out further north.

Regardless, a 50 knot jet is likely to set up along the northern
plains and successfully support convection through the overnight
and morning hours. With the elevated nature of these storms, the
primary hazard should be hail. However, if storm mode can become
linear as some CAMs do suggest, there is marginally enough 0-3km
shear to support mesovortex development, so a marginal wind risk
could arise in the morning hours.

Flash flooding looks like a diminishing threat as training is
unlikely and the fast forward propagation of thunderstorms
should mitigate hydrological impacts.

...ADDITIONAL SEVERE THUNDERSTORMS MONDAY AFTERNOON...

Another round of severe storms will likely develop Monday
afternoon, but the scope of the threat remains in question. The
scenarios remain the same this afternoon:

1.) Lower impact/coverage of elevated embedded severe
thunderstorms with large hail as the primary threat. This
scenario remains the most favored by ensemble members.

2.) Higher impact/coverage of severe thunderstorms, including
discrete supercells capable of significant hazards. Large hail,
damaging winds, and tornadoes would be the primary hazard from
these. A subset of guidance continues to favor the I-94 corridor
in west-central Minnesota as the main location where this may
occur.

This will primarily be driven by a few factors.

A.) Cold Frontal Passage Timing: A relatively strong cold front
will be digging through the Dakotas behind this main surface
low. This will scour out low and mid-level instability, but
timing in this front is in question. Faster passage means
instability leaves the area faster.

B.) Warm frontal orientation/850 jet placement/Surface Low
Placement: This will drive our more significant hazards for
discrete supercells. Right now the sweet spot of guidance is
somewhere within west- central Minnesota, however how far
north/south does it get?

Regardless of these factors, it seems likely that at least some
severe weather threat will arise. Stay up to date on latest
forecasts as we get closer.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1240 PM CDT Sat Apr 26 2025

Ceilings will fall but should remain VFR this afternoon with
mostly south-southeasterly winds between 10 and 20 knots, with
gusts up to 30 knots possible. Tonight, as we get past sunset,
wind shear will increase and impact all TAF sites eventually.
This will peak around 35-40 knots. Ceilings will also continue
to lower after 06z, pushing into the MVFR category by 12-15z for
all TAF sites. Right now, there is a low signal for IFR ceilings
by the end of the TAF period, but confidence is too low to
include at this time.

Regarding precipitation, instability is weak so TSRA is not
expected for the TAF period at this time. The only impact from
showers should remain brief drops and no impacts to visibility
are anticipated.

&&

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

&&

$$

DISCUSSION...Perroux
AVIATION...Perroux