833
FXUS63 KFGF 142127
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
427 PM CDT Fri Jun 14 2024

.KEY MESSAGES...

- Multiple rounds of showers and thunderstorms are forecast
  tonight through Tuesday.

- Saturday through Tuesday, there is potential for multiple
  rounds of strong to severe thunderstorms, in addition to
  potential flooding impacts from excessive rainfall.

&&

.DISCUSSION...
Issued at 427 PM CDT Fri Jun 14 2024

...Synopsis...

Current water vapor depicts upper ridging over the central
CONUS with an embedded, weak upper trough entrenched in richer
moisture sourced from Pacific/Baja Coast over the Intermountain
West and High Plains. Upper troughing over the northeast Pacific
and PacNW is also noted. At the surface, high pressure centered
within Minnesota is pushing east as lee troughing impinges upon
the northern High Plains, currently resulting in scattered
thunderstorms in western Dakotas.

Ensemble guidance all agrees the upper ridging building and
eventually stalling east into the eastern CONUS into Great
Lakes region. This allows upper troughing and southwest flow
aloft over the Norther Plains and Upper Midwest this weekend
into early next week. The southwest flow aloft and surface
troughing lee of the broader scale upper troughing will allow
higher moisture and instability into the region. This sets the
stage for multiple rounds of showers and thunderstorms starting
tonight, lasting through Tuesday.

...Multiple rounds showers and storms through Tuesday, some of
which will be strong to severe...

Starting tonight, thunderstorms within central ND will advect
east into eastern ND. Wind shear should be ample, although
instability is forecast to be marginal, between 500-1000 J/kg.
Thunderstorms will confidently be elevated in height this
evening into tonight. Should instability fed into convection be
on the higher end (MUCAPE around 1000 J/kg), thunderstorms would
be capable of hail up to the size of quarters given strong
shear/opportunity of organization as well as elevated nature of
updrafts deeper into hail growth zone.

This is the first of multiple rounds, with another round
expected later Saturday evening into overnight as convection
moves out of western and central ND into eastern ND. Should
storms move into our area sooner before sunset, storms have a
better chance of maintaining strong to severe characteristics,
as well as better chance for bringing damaging wind gusts. If
they come later, strong to severe storms would remain possible,
albeit more isolated in coverage. In either scenario, hail would
be the main impact.

Guidance then starts to deviate in solutions on area, timing,
and magnitude of thunderstorms (of which may still be severe).
Some ensemble guidance pushes a cold front thorugh the area
Sunday quicker, limiting severe chances to our far south/east or
even away from our area. On the other hand, some guidance
members slow the cold front, which would result in better
opportunity for organized convection holding severe
characteristics.

This also bleeds into Monday where the cold front is expected
to eventually stall within or south of our area, and perhaps
make a jaunt back northward ahead of a stronger shortwave
impulse traveling through southwest flow aloft. Should the
front push deeper into our area bringing more
moisture/instability, the chance for severe weather increases
(vice versa if the front stays stalled further south).

While holding least confidence, Tuesday also holds a chance for
organized convection as upper troughing may be slow to move away
from our area.

Not to be discounted is the flooding potential. Numerous
thunderstorms and higher rainfall rates from these rounds may
prime the area/soils to become more susceptible to flooding,
especially on Monday where guidance strongly suggests this is
the time period where highest available moisture content
interacts with forcing aloft. Additionally, if the
aforementioned stalled front orients itself more parallel to the
flow aloft (southwest-northeast), this would focus numerous,
strong thunderstorm development, of which would have the chance
to train or backbuild. Location of areas most at risk to see
flooding impacts remains uncertain at this time.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1259 PM CDT Fri Jun 14 2024

VFR conditions are forecast through 12Z. There is a low-medium
chance for scattered thunderstorms to develop in eastern North
Dakota into Minnesota between 04Z-16Z, although confidence
remains low enough to keep out of TAFs for now. Will include in
later issuances if confidence increases enough in TS impacting a
TAF site.

At around 12Z, the chance for MVFR CIGs increases within
eastern North Dakota, spreading eastward into Minnesota after
around 15Z. Winds will also be increasing out of the south
around 20kt around 15Z.

&&

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

&&

$$

DISCUSSION...CJ
AVIATION...CJ