093
FXUS63 KBIS 132029
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
329 PM CDT Thu Jun 13 2024

.KEY MESSAGES...

- There is a Marginal Risk (level 1 out of 5) for severe
  thunderstorms Friday evening, specifically across the
  southwestern portions of the state. Chances for showers and
  thunderstorms range from 40 to 60% across the area.

- An active pattern begins on Friday and will continue through
  the weekend into next week. Showers and thunderstorms are
  likely to be on and off, although it does not seem like any
  one day will be a washout.

- There is also a Marginal Risk (level 1 out of 5) for severe
  thunderstorms Saturday evening and overnight, covering most of
  western and central North Dakota. The chance for showers and
  thunderstorms is 60 to 80% across the area.

- High temperatures are forecast to peak in the 80s on Saturday
  (potentially reaching the 90s in the southwest), with a
  gradual cooling trend through the first few days of next week.

&&

.DISCUSSION...
Issued at 329 PM CDT Thu Jun 13 2024

Across western and central North Dakota, mostly quiet weather is
being observed, with mostly clear skies in the south, partly cloudy
skies in the north, and breezy northwesterly winds for the entire
area. Surface high pressure across Montana continues to expand east
into western North Dakota, while an upper level ridge across the
Rockies slowly builds east into the northern Plains. A trough
digging into the Great Lakes region to our northeast has provided
enough forcing to develop some scattered showers across the southern
Canadian prairies and northern Minnesota. As a result, the
northeastern portion of our area, particularly centered around the
Turtle Mountains, currently has a low (15 to 25%) chance for some
showers and potentially a thunderstorm through the next couple
hours. This trough will move east heading into the overnight hours,
decreasing the chances for any precipitation, as well as decreasing
winds to light and variable. Daytime highs will be in the 70s to
lower 80s, while overnight lows are forecast to be in the upper 40s
to lower 50s.

As the aforementioned ridge moves east through Friday, a cutoff low
near the southern coast of California is expected to meander across
the Rockies and slide northeast towards the central and northern
Great Plains. The resulting surface low and attendant warm front are
both expected to form and move east across southeastern
Montana, northern Wyoming, and the western Dakotas. The SPC has
brought the Marginal Risk (level 1 of 5) back into southwestern
North Dakota for Friday, as ample instability and deep layer
shear overlap with the forcing due to the approaching shortwave
trough to our southwest. High-res deterministic guidance
suggests MLCAPE values near 1500 J/kg with 0-6 km shear
approaching 50 kts in a narrow corridor across our southwest,
which could certainly support a few strong to severe storms.
However, the forcing required to get these storms going seems to
be slightly displaced from our area and rather short lived,
with current CAMs suggesting a brief period where strong storms
form and move east, before quickly dissipating as they enter an
unfavorable, stable environment. Otherwise, chances for
precipitation (ranging from 40 to 60%) will continue to expand
from southwest to northeast across the area into Friday night,
where showers and thunderstorms will remain possible. The
overnight hours are not expected to see any strong to severe
storms. Highs on Friday are forecast to be in the 70s and 80s,
with overnight lows near 60.

An upper level trough across the Pacific Northwest is expected to
strengthen and move east through Friday, putting North Dakota under
southwesterly upper level flow by Saturday morning. Surface flow
ahead of this trough is expected to be southerly, which is also
expected to advect plenty of moisture north, with dewpoints on
Saturday currently forecast to reach into the mid 60s. The
developing surface low pressure system and attendant cold front are
then expected to sweep across the northern Plains from the west,
helping bring about continued chances for precipitation. Heading
into the late evening hours, deterministic guidance suggests a large
area of MLCAPE around 2000 to 2500 J/kg, paired with 0-6 km shear in
the 40 to 50 kt range. As a result, the SPC has continued to
advertise a Marginal Risk (level 1 of 5) for strong to severe storms
across most of western and central North Dakota for Saturday.
Due to the front moving through later in the evening, the
current expectation is that the severe threat will largely be
late evening and into the overnight hours, bringing about the
threat of nocturnal severe thunderstorms during a summer
weekend. Outdoor safety during this event, especially for
outdoor campers, will likely be a priority for our messaging,
and we will continue to closely monitor how the forecast for
this evolves. Outside of the severe threat, chances for showers
and thunderstorms (ranging from 40 to 80%) cover our entire area
through the day, with the highest chances in the north.
Saturday is also expected to be the warmest day of the forecast
period, with widespread highs in the 80s, potentially reaching
the 90s in the southwest.

The southwesterly flow aloft is expected to then continue into next
week, carrying near daily chances for showers and thunderstorms.
Tuesday appears to be the day with the highest chances for
precipitation, with chances ranging anywhere from 50 to 80% across a
wide area, and highest values focused across the west. Sunday marks
the beginning of a cooling trend, with highs on Tuesday dipping
largely into the 60s. Winds on Sunday may be a bit breezy as
well, mostly across the west. Beyond this point, the synoptic
pattern is still a bit up in the air, with large disagreements
between models. Current ensemble guidance suggests some warming
heading into the second half of next week, with continued
chances for precipitation each day. Temperatures will largely
depend on the strength of an upper level trough to our west,
building against a ridge across the Great Lakes to our east.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1235 PM CDT Thu Jun 13 2024

VFR conditions are present across all terminals, and is expected to
continue through the TAF period. Some fair weather cumulus has
developed across the north central and southern James River Valley,
bringing some scattered 5-8 kft decks to KMOT and KJMS and
continuing through the daytime hours. Breezy northwesterly winds
will continue through the day, become light and variable across most
of the area overnight. Winds will pick back up tomorrow.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Besson
AVIATION...Besson