744
FXUS63 KFGF 051049
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
549 AM CDT Sun May 5 2024

.KEY MESSAGES...

- Organized thunderstorms are likely Monday through Tuesday,
  with a conditional threat of strong to severe thunderstorms
  south of I-94 Monday afternoon/evening.

&&

.UPDATE...
Issued at 547 AM CDT Sun May 5 2024

Very patchy fog has developed. The worst visibilities that have
been observed is 1/2SM, and it only lasted for a half hour. This
will improve over the next 1-2 hours and should present little
to no impacts.


&&

.DISCUSSION...
Issued at 135 AM CDT Sun May 5 2024

06z surface analysis indicates a surface high over the Devils
Lake Basin with an attendant surface ridge stretching down
through Minnesota. This has created near calm winds at the
surface. Dew point depressions across the area are between 2 and
6 degrees and there doesn`t appear to be a whole lot of
spatial patterns to it. For this reason, patchy fog is likely to
develop in some spots overnight tonight, but the probability for
widespread fog is very low. For today, dry conditions are
expected with mostly clear skies. Afternoon cumulus clouds may
form, but showers are very unlikely to develop today.

Attention then turns to a very strong extratropical cyclone that
will develop over the central and northern plains Monday afternoon
and evening. With strong synoptic scale forcing due to strong CVA,
there is high confidence in a broad swath of convection. MUCAPE
values in advance of this system range in the 250-750 J/kg range, so
thunderstorms are likely to develop, especially along the surface
theta-e front. With shear very good thanks to strong low-level and
mid-level flow, a brief window of strong to severe storms may
develop along a thin surface warm sector. Near surface backing in
advance of the surface front will allow for a small area of enhanced
streamwise vorticity (although this would end up being highly
dependent on storm motion, which is very uncertain due to frontal
orientation). This would create an environment conducive for low-
topped supercells, which if it were to arise would bring the threat
for damaging wind gusts (exceeding 58 mph) and tornadoes. A lot of
this hinges on near surface destabilization, which will be very
difficult without stronger differential temperature advection and
diurnal heating.
Because of all of these uncertainties, the official SPC outlook
keeps us out of severe potential. This will be something to
monitor over the next day.

What is highly confident is widespread showers and thunderstorms
will impact the region Monday and Tuesday. The bulk of the
heavier rainfall rates will be tied to thunderstorms, primarily
south of Highway 200. Rainfall amounts of at least 0.10" are
expected, with the potential to cross 0.50" in some locations
with thunderstorms. The chances for rain continue through the
week before we see a pattern shift to drier conditions.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 547 AM CDT Sun May 5 2024

VFR conditions will prevail for the TAF period. Isolated MVFR to
IFR visibility due to fog may impact any TAF site, but the
duration should be an hour at most. This will improve after 13z
to VFR for the remainder of the period. Winds today will
eventually become southerly, peaking after 00z.

&&

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

&&

$$

UPDATE...Perroux
DISCUSSION...Perroux
AVIATION...Perroux