807
FXUS63 KBIS 110918
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
418 AM CDT Tue Jun 11 2024

.KEY MESSAGES...

- Near average temperatures are expected today. Highs on
  Wednesday will be the warmest of the week, with highs in the
  upper 70s to upper 80s. Some locations in the southern James
  River Valley could reach the lower 90s.

- Isolated showers are possible today and tonight, with
  additional showers and storms (30% chance) Wednesday night and
  Thursday. Higher and more widespread precipitation chances
  are then forecast Friday night through the weekend.

&&

.DISCUSSION...
Issued at 418 AM CDT Tue Jun 11 2024

A compact shortwave trough and closed low were analyzed over
southwest Manitoba this morning, with a frontal boundary
exiting the eastern portion of the forecast area. Breezy winds
are ongoing across the north central under the influence of a
tightened pressure gradient from the surface low. Morning lows
will be in the upper 40s to upper 50s, with limited cloud cover
to start the day.

Under the cyclonic flow aloft today/tonight, isolated showers
are possible with any impulses that move through, with blended
POPs producing slight (20%) chances across the far north and
south central this evening, and across the southwest overnight.
Both today and tonight the main caveat with rain potential is
that forecast soundings are showing high clouds bases (over 10k
feet) and a significant dry layer above the surface, so either
very light rain or virga is the most likely scenario. Highs
today will be near to slightly above normal, in the upper 70s to
lower 80s.

The synoptic flow becomes more zonal on Wednesday, with an
approaching embedded wave and a low- level thermal ridge trying
to build in. The timing of the upper wave and attendant cold
front will determine how warm temperatures get, with forecast
highs in the upper 70s northwest (where the front reaches first)
to the upper 80s southern James River Valley. It is not out of
the question that we see some highs in the lower 90s in this
area, especially if the front slows up at all. The timing of the
front will also be critical for any thunderstorm potential.
Deterministic guidance is advertising bulk shear of 40-50 knots
and MLCAPE of 1000-2000 J/kg, with CSU Machine Learning
indicating higher hail and tornado probabilities just east of
the forecast area. The Day 2 outlook has the Marginal Risk
(level 1 out of 5) just clipping LaMoure and Dickey Counties,
which seems appropriate given what current high-res guidance is
advertising.

Scattered showers and thunderstorms are possible Wednesday
night into Thursday across the far north and south as additional
impulses move through the mean zonal flow, although POPs have
been changing the past few forecast cycles as the impulses are
low predictability. A shallow ridge is progged to build in
Thursday into Friday, while a deep upper low begins developing
off the coast of the Pacific Northwest. Ensemble guidance is in
fairly good agreement on southwest flow aloft persisting across
the Northern Plains through the weekend, helping an active
pattern set up starting Friday. Blended POPs begin increasing
during the day Friday and remain relatively stable through the
weekend as the aforementioned closed low starts to sink south
across the western CONUS. Southerly low-level flow to start the
weekend does look to increase available instability, and machine
learning probs highlight persistent (but low) probabilities for
severe weather through the weekend. Temperatures are favored to
be relatively steady, with highs generally in the lower 70s to
lower 80s, before potentially a slight cool down to start next
work week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1248 AM CDT Tue Jun 11 2024

VFR conditions expected at all terminals in the wake of an
exiting system. Northwest winds will become breezy across the
north and east on Tuesday, with gusts up to 25 knots possible at
KMOT and KJMS. Winds will diminish in the evening, with mostly
clear skies.

&&

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

&&

$$

DISCUSSION...Jones
AVIATION...Jones