847
FXUS63 KBIS 131135
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
635 AM CDT Thu Jun 13 2024

.KEY MESSAGES...

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

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

&&

.UPDATE...
Issued at 635 AM CDT Thu Jun 13 2024

Broad surface high pressure continues expanding into western
North Dakota, with winds already starting to become a bit breezy
across the north as the surface pressure gradient begins to
tighten. Some high-res guidance is still advertising a few
scattered showers and a thunderstorm or two in the Turtle
Mountains area this afternoon, so will keep our low POPs in with
this update. Going forecast looks good.


&&

.DISCUSSION...
Issued at 416 AM CDT Thu Jun 13 2024

Overall quiet weather continued early this morning, as surface
high pressure was centered well northwest of the forecast area.
Aloft, a shallow shortwave trough was passing through the
central Canadian Prairies, but far enough north to keep any
associated precipitation north of the International Border. To
our south, an impulse embedded in zonal flow was passing through
northern South Dakota, with a few showers and thunderstorms
ongoing just south of the state line. Otherwise, mostly sunny
skies and light winds persisted across western and central North
Dakota, with morning lows in the mid 40s to lower 50s.

As the previously mentioned trough to our north continues
pushing east through the day today, there is a low (20%) chance
for showers and thunderstorms in the Turtle Mountains region.
Otherwise, the remainder of the forecast area will be dry and
mostly sunny, with a continued northwest breeze. Expect highs
in the lower 70s to lower 80s.

Meanwhile, a deep cut off low is centered off the coast of
southern California, while a secondary closed low and troughing
are off the coast of British Columbia. As the southern low gets
absorbed into the mean flow pattern and the northern trough
starts to push inland, flow aloft over the central CONUS will
turn southwesterly through the weekend. Blended POPs show
precipitation chances increasing from southwest to northeast
through the day Friday as a surface low and warm front approach
the Dakotas. The latest SPC outlook for Friday has almost
entirely removed any severe potential for our forecast area,
with higher probabilities across southeast Montana into South
Dakota. Although deterministic guidance is showing sufficient
instability and shear for more substantial thunderstorms, the
lack of upper forcing will likely keep storms limited until late
Friday night, when instability decreases.

It could be a different story on Saturday, as a surface low and
cold front associated with an upper wave approach the area from
the west. For right now, it does look like there will be a break
in precipitation during the day Saturday ahead of this wave,
with latest NBM POPs already advertising medium to high
precipitation chances Saturday evening and overnight, highest
across northwest and north central North Dakota. A Marginal Risk
(level 1 out of 5) has been introduced for the majority of
western and central North Dakota. Deterministic guidance is
already advertising 1000-2000 J/kg of MLCAPE and 0-6km shear
around 40 knots, with southerly low-level flow advecting in dew
points in the 60s. Saturday will also be the warmest day of the
weekend from the low-level warm air advection through the day,
with forecast highs generally in the 80s, and highs around 90
are possible in the southwest. It is worth noting that the
current expectation is for strong to severe storms to develop in
Montana before moving into western North Dakota in the evening
and early overnight hours. Our main concern at the moment is the
additional threat from nocturnal storms on a summer weekend, so
we want people to start thinking about where they would shelter
if they were in a tent or camper on Saturday night.

Sunday begins a cooling trend as cooler air filters into the
region, with a break in precipitation but breezy northwest winds
likely behind the front. Ensemble guidance still has varied
solutions regarding when a more substantial shortwave trough
moves through, but there is still consensus in the active
pattern continuing through the start of the work week, with
blended POPs already up to 50 to 70% late Monday into Tuesday.
Highs are also favored to stay in the 60s to lower 70s Monday
and Tuesday, before a slight warming trend starts midweek. By
the time we get to Wednesday, there are significant differences
among ensemble members regarding the synoptic pattern, the
placement of the upstream trough axis, and how far to the west
ridging over the eastern CONUS can extend.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 635 AM CDT Thu Jun 13 2024

VFR conditions expected at all terminals through the TAF period.
Mostly clear skies will prevail today and tonight, with breezy
northwest winds developing late this morning, diminishing to
become light and variable tonight.

&&

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

&&

$$

UPDATE...Jones
DISCUSSION...Jones
AVIATION...Jones