845
FXUS63 KFGF 240926
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
426 AM CDT Mon Jun 24 2024

.KEY MESSAGES...

- Thunderstorms will move into eastern North Dakota this
  morning, some of which may be strong to severe bringing hail
  and gusty winds.

- Additional severe thunderstorms may develop late afternoon
  into early evening within portions of Minnesota. Should
  thunderstorms develop, damaging wind gusts, large hail, and
  tornadoes will be possible.

&&

.DISCUSSION...
Issued at 252 AM CDT Mon Jun 24 2024

...Synopsis...

Current satellite early this morning reveals broad upper trough
in SK/AB into MT, with embedded shortwave impulses within the
base of upper troughing over eastern MT/western ND as well as
along northern ND. Areas of convection exist within these
shortwave impulses, helped forced by low level jet feeding weak
to moderate instability. Near the international border, high
shear is interacting with convection, allowing organization of
robust convection of which has been severe at times. Both
impulses/areas of convection will continue east within enhanced
westerly flow aloft within the base of the upper troughing. This
will drive this morning`s potential for strong to severe storms.

All guidance indicate these impulses and accompanying chance
for perhaps continued convection to push into northern/central
MN by mid afternoon (~21Z). At the surface, a surface low
pressure will tend to develop near the tri-state area of
ND/SD/MN by late afternoon, with a weak surface trough/cold
front extending north-northeastward into northwest MN. These two
surface features may provide foci for potentially additional
thunderstorm development late afternoon into evening within
northwest and west-central MN. By this time, confident amounts
of high to very high instability will exist, within sufficient
shear to organize storms. This instability and available shear
will drive severe potential late afternoon into evening within
Minnesota, including the chance for supercells.

By Tuesday, post frontal air mass and increasing surface
pressure behind the now departing upper troughing will make for
a breezy and mostly dry day. Upper ridging then builds in the
Northern Plains Wed/Thu favoring mostly dry conditions save some
smaller areas of showers and weak thunderstorms.

Getting closer to Friday, a seasonably stout upper wave moves
east along the northern tier of the CONUS providing our next
chance at more widespread and robust convection. CSU severe and
excessive rainfall probabilities increase with this wave over
our area, signaling a chance for potentially hazardous thunderstorms.


...Potentially strong to severe storm this morning...

Mid level impulses moving out of central ND will confidently
continue showers and thunderstorms into eastern ND this morning.
There will still be a chance for a few storms to become severe,
with main hazard being hail, and a somewhat muted signal for
severe winds in excess of 60 mph. There is some indication that
initial thunderstorms are outrunning better instability which is
limiting chance for severe hazards as they enter Devils Lake
basin early this morning. Still, gusty winds to 50 mph and small
hail will remain possible.

Getting toward mid-late morning, convection will likely be
ongoing in portions of eastern ND into the Red River Valley.
While instability will be on the rise, wind shear will be
tampered as early morning low level jet subdues, along with
winds aloft likely lessening in the heart of these mid level
waves.

So while overall chance for severe hazards this morning is
generally low, there could still be some strong to briefly
severe storms, with severe storms bringing hail not larger than
golf balls and winds under 60 mph.

...Potentially severe storms late this afternoon into evening...

SPC`s severe weather outlook issued at 1AM this morning
illustrates this afternoon/evening`s severe potential and
possible outcomes nicely. As such, I`m opting to not attempt
re-write a similar discussion here, but can be found at
spc.noaa.gov/products/outlook/day1otlk.html.

However, I will comment on some features locally that may
influence our severe weather potential.

First, uncertainty in how convection this morning (and
potentially still ongoing this afternoon) is lowering confidence
in important mesoscale details that would influence areas where
severe storm potential will exist, as well as hazards
associated with it. This is particularly true for portions of
west-central MN where guidance confidently suggests a highly
unstable atmosphere will exist. Should convection continue into
the afternoon, and perhaps be slower to move into this area by
00Z (7PM CDT), there is a chance for thunderstorms to
reinvigorate, become surface based, and achieve severe status
as low level jet kicks in. Given its proximity to progged
surface low pressure, locally higher low level shear would favor
potential for tornadoes and very large hail larger than 2
inches, especially if storms can stay more discrete. Should
storms be more linear, damaging wind gusts in excess of 70 mph
would be the more dominate hazard, with chance for line-embedded
tornadoes.

Closer to northwest MN, the surface trough will provide focus
for potentially additional severe storms. However, there is
question regarding sufficient amount of forcing to sustain
robust convection with the likelihood of better synoptic forcing
aloft to remain displaced in Canada, and in turn lowering
chance for low level convergence to aid in forcing for ascent.
Additionally, a lack of temperature difference between air
masses on either side of this front will lower chance for
sustained forcing for ascent. Should there be sufficient
forcing for ascent to sustain robust convection, initially
discrete supercells will develop within northwest MN capable of
all hazards (winds to 70 mph, large hail to 2 inches, a few
tornadoes). However, with wind shear generally unidirectional
wind shear, splitting supercells in close proximity of each
other may keep the window of discrete storm mode rather short,
and become clustering of thunderstorms may lower the chance for
a tornado some. Additional uncertainties exist in how this
morning/early afternoon convection may influence this area`s
environment as well.

Ultimately to say, should robust thunderstorms develop this
afternoon/evening in Minnesota, they hold a higher than normal
chance of producing severe hazards. However, confidence still
remains degraded in whether or not this unfolds. We may not know
which scenario will unfold until this afternoon.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1145 PM CDT Sun Jun 23 2024

VFR conditions prevail at all sites through most of the period.
Currently watching the progression of scattered showers and
thunderstorms in northwest North Dakota tonight. These showers
and thunderstorms are expected to move into eastern North Dakota
during the late overnight period, impacting KDVL as early as
09Z, then moving off to the east through the remainder of the
morning. Winds are expected to become southerly gradually
through the overnight hours, with wind speeds in the 10 to 15
knot range by mid morning.

&&

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

&&

$$

DISCUSSION...CJ
AVIATION...Lynch