974
FXUS63 KFGF 152016
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
316 PM CDT Sat Jun 15 2024

.KEY MESSAGES...

- Storms will arrive in the Devils Lake Basin and northern Red
  River Valley late tonight. They will be weakening as they move
  east, but a few isolated storms could still produce hail to
  quarter sized and 60 mph gusts.

- A few isolated storms could develop in northwestern Minnesota
  Sunday afternoon and produce ping pong ball sized hail and 60
  mph winds before quickly moving east.

- Additional thunderstorms will move into southeastern North
  Dakota and west central Minnesota late Sunday night and
  continue into Monday. A few isolated storms could again bring
  some quarter sized hail and 60 mph winds gusts, but the main
  impacts with this system will be heavy rain and flash flooding
  into Tuesday.

&&

.DISCUSSION...
Issued at 316 PM CDT Sat Jun 15 2024

...Synopsis...

Southwesterly flow throughout the period sets up an active
pattern for the Northern Plains, with a bit of a break
currently. Main upper trough out over MT tonight will lift into
Canada and help push a surface trough into the Red River Valley
by tomorrow morning. Our western counties currently have some
decent ML CAPE developing but the effective shear is around 25
kts or less and there is little forcing until later tonight when
the trough approaches. HRRR and other CAMs have been fairly
consistent on not bringing storms into our northwestern counties
until late tonight, most likely after midnight. There will be a
weakening trend, but HREF still has some good updraft helicity
tracks still moving into the Devils Lake basin into the northern
RRV. Overall, no changes to the messaging for severe weather,
but did adjust to highlight later timing.

Tomorrow, there is some differences in how far east the trough
axis moves before peak heating hits, with a few of the CAMs
breaking out strong to severe cells in our far eastern counties.
Most of the HREF UH tracks are right along or just east of our
CWA border, but cannot rule out a quick hail report up to ping
pong ball sized and 60 mph winds before it is DLH`s problem. The
bigger issue Sunday night will be with a shortwave lifting from
the southwest into the eastern Dakotas, with surface low
pressure developing to our southwest. A boundary will push north
into our southern counties, and there is some question of how
far north it will get. There is a good chance for some elevated
instability Sunday night and into Monday as this boundary hangs
around the area, with quarter sized hail and 60 mph winds still
the main threats. However, with the 850mb jet bringing lots of
moisture and PWATs nearly 3 to 3.5 standard deviations above
normal, the main issue for Sunday night into early next week
will be heavy rain. Set up for storm motion is also parallel
along the frontal boundary which will be ideal for training.
Probabilities of over 3 inches are over 50 percent in many
locations in west central MN, and probs for over 4 inches are
over 20 percent, which is high chances for that much rain. WPC
has upgraded the excessive rainfall outlook to moderate, and
will upgrade messaging. The main surface trough will be moving
out on Tuesday, and much will depend on how Monday plays out but
with at least some instability and plenty of moisture, heavy
rain and severe potential will continue until the system finally
pushes out Tuesday night.

There should be a bit of a break with surface high pressure on
Wednesday, but active pattern continues for the end of the week
and into the weekend with southwesterly flow continuing and
additional shortwaves coming through. Additional rainfall could
cause impacts given how much is expected early in the week, but
predictability is low for placement of greatest rain amounts as
well as strength of storms at this point. Thus, will focus on
the more immediate concerns.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1242 PM CDT Sat Jun 15 2024

VFR conditions, but some MVFR and then IFR as a trough of low
pressure comes into the Red River Valley tonight, starting in
the more western TAF sites this evening and spreading eastward
as the night goes on. Improvement by the end of the period in a
similar west to east direction by mid-day tomorrow. Some
weakening convection coming through, but uncertain how much will
make it to our airports, so just have VCSH at KDVL for now.
Winds will shift from a southerly direction with gusts around 25
kts this afternoon. Decreasing a bit to around 10 kts and going
to a southeast and then southwest and finally west to northwest
as the trough axis moves through by tomorrow morning. Winds will
pick up the the end of the period with gusts to around 20 kts
again.

&&

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

&&

$$

DISCUSSION...JR
AVIATION...JR