682
FXUS63 KFGF 012333
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
633 PM CDT Sat Jun 1 2024

.KEY MESSAGES...

- There is a level 2 out of 5 risk for scattered severe storms
Sunday afternoon and evening for the entire region. Hazards include
hail half dollar size or larger, wind gusts 60 MPH or greater, and
tornadoes are possible.

- More showers and thunderstorms possible mid-week next week. Low
chance of severe storms.

&&

.DISCUSSION...
Issued at 243 PM CDT Sat Jun 1 2024

...Synopsis...

Satellite this afternoon shows clear skies, and dry air above us for
now. This will change into tomorrow as a 500mb shortwave digs into
the area, giving us the chances for severe weather. After this, a
negatively tilted 500mb trough with a 300mb jet streak enters from
the west with more precipitation chances in tow for Tuesday night
into Wednesday. Cooler temperatures at 850mb suggest we will see a
slight cool down with this system, and it does look like to end the
week we will have highs in the upper 60s.

...Sunday Severe...

For the severe risk, we are in a slight risk
(level 2/5) for severe storms from the SPC. Timing is becoming
more clear, at least slightly. Paintballs from the CAMs show
convection beginning in our area in the Devils Lake Basin around
2 PM. But some factors still in the air are exact track of the
cold front and the speed of the forcing, as this will have a lot
to say in what storm mode we primarily see. There is plenty of
moisture for this system to play with, with PWATs exceeding 90%
of sounding climatology in some areas. So, we have all the SLIM
ingredients for severe weather: Wind Shear (winds turning with
height/increasing speed with height, critical angles on
soundings in the southern valley in the range to suggest
streamwise vorticity near the surface), Lift (thanks to the cold
front), Instability (>1500 J/kg of MLCAPE, 3CAPE only about 50,
so that could be better), and Moisture.

Right now, a few scenarios still exist. The main difference with
these scenarios is timing. The first is discrete cells get ample
time in the warm sector before the cold front comes in. Cells along
and south of I-94, where the most favorable tornado environment
exists, would need to be watched extremely closely. These discrete
cells will merge with clusters north of this area and become linear
as the system is pushed by the cold front into Minnesota. The
primary threat in this scenario would be tornadoes and large hail,
with these discrete cells capable of producing golf-ball sized hail.
Nearly all CAMs show some discrete cells ahead of the main forcing.
Ones in the southern valley would need to be watched especially
close for tornadic development (with the environment there being
minimally capped, values of 200 m2/s2 effective storm relative
helicity, and sufficient 0-1km shear in forecast soundings), whereas
the better hail environment is in the north (where MUCAPE is
maximized with lower 0C and -20C levels than in the southern
valley).

Second scenario is the cold front speeds up, and there are not many
discrete cells in the warm sector. This would lead to more of a wind
threat (possibly 70 MPH?), but still leave the threat of tornadoes
and large hail. In this scenario, the threat for winds would be
across the area, rather than in the Red River Valley and into
Minnesota like in the first scenario.

With either scenario, Sunday is definitely a weather aware day. Make
sure you know where to go when a warning is issued and have multiple
ways to receive those warnings.

...Precip mid-week...

Into mid-week, our next chance for precipitation comes, with a
negatively tilted trough. At this time, not seeing a whole lot of
evidence to support severe storms in our area. But, clusters show a
range around 0.5" of QPF for this event, with some showing pockets
near 0.75". WSUP Probabilities show 20 - 30% chance for an inch or
more in the Devils Lake Basin with this system, and a widespread 60 -
 80% chance of seeing greater than 0.25" in eastern North Dakota and
northwestern Minnesota. We will continue to monitor for more precise
amounts of precipitation, as exact track of the low, moisture, and
timing have yet to reach a consensus in the guidance.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
Issued at 632 PM CDT Sat Jun 1 2024

VFR conditions prevail this evening with mostly clear skies and
westerly winds. Look for winds to diminish later this evening
before becoming light and variable overnight. A southerly shift
in the winds is expected shortly after sunrise, with wind speeds
in the range of 15 to 20 knots, gusting up to 30 knots. The
primary concern for Sunday will be scattered morning showers,
followed by the chance for strong to severe thunderstorms during
the afternoon.

&&

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

&&

$$

DISCUSSION...AH
AVIATION...Lynch