530
FXUS63 KBIS 110242
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CDT Wed Jul 10 2024

.KEY MESSAGES...

- Smoky skies are expected to continue through the night before
  clearing out on Thursday.

- Hot and humid conditions are expected Thursday through
  Sunday, with highs mostly in the upper 80s to upper 90s.

- Low to medium chances (20 to 40%) for showers and
  thunderstorms are in the forecast each night starting
  Thursday night and continuing through the weekend.

&&

.UPDATE...
Issued at 940 PM CDT Wed Jul 10 2024

The main change made with this update was bumping up sky
coverage for the smoke that has been filtering in from the
north. While not at the surface, it did add a bit of a haze to
the sky, and will linger around until the morning hours on
Thursday. Apart from that, just blended in the current
observations to the forecast.

.UPDATE...
Issued at 622 PM CDT Wed Jul 10 2024

Minimal changes were made to the forecast for this update. Broad
surface high pressure continues to sit across much of North
Dakota, keeping skies generally clear and winds relatively
light. Just slightly tweaked cloud coverage to account for
diurnal cumulus in the west. Otherwise, the forecast remains on
track.

&&

.DISCUSSION...
Issued at 325 PM CDT Wed Jul 10 2024

This afternoon, the synoptic pattern was characterized by troughing
over the Great Lakes Region, while a stationary heat dome was placed
across the Desert Southwest. North of this, a shallow ridge was
moving over the Northern Rockies, with sharp northerly flow in place
across the Dakotas. Broad high pressure was centered over the
region, with relatively light surface winds. Although cloud cover is
very limited, GOES GeoColor satellite imagery shows continued
smoke aloft across central and eastern North Dakota, so we do
have slightly increased cloud cover in these areas to account
for not quite full sunshine. Expect a hazy sunset tonight with
quiet weather through the night, and forecast lows in the 60s.

Flow aloft turns a bit more northwesterly on Thursday downstream of
the shallow ridge, with a stout low-level thermal ridge beginning to
build into the region. Forecast highs range from the upper 80s from
the Turtle Mountains to the James River Valley, to the mid and
perhaps upper 90s in the southwest. Southerly low-level flow will
also advect in a higher moisture air mass, with dew points in the
lower 60s across the north and central. Chances for precipitation
(20-40%) return late Thursday afternoon to the northwest, expanding
into much of central North Dakota overnight, as an upper level
shortwave moves through. Shear and instability both look marginal,
so for right now expecting showers and non-severe thunderstorms
through Thursday night, although we wouldn`t be surprised if a
storm or two ended up on the stronger side.

With flow aloft turning more zonal, HRRR and RAP forecast smoke
models agree on the bulk of smoke aloft moving out of the area by
later on Thursday. There is some uncertainty on the expanse of near-
surface smoke, with model guidance showing low but still-
present concentrations through the day Thursday due to the low-
level return flow. For now will keep out of the gridded forecast
but can`t rule out slightly reduced visibilities, especially in
our far eastern counties.

A similar pattern is expected through the weekend, with hot, humid
conditions across the area and 20-40% chances for showers and
thunderstorms in the evening and overnight hours. The highest
chances are mainly across northern and eastern parts of the
state. Machine learning probabilities are low but persistent
every day, with deterministic guidance already advertising
moderate to high instability, although bulk shear is generally
on the marginal side. Highs through Sunday will mainly be in the
upper 80s to upper 90s across the area, with a low (around 20%)
chance of highs exceeding 100 degrees F in southwest North
Dakota, focused in the Bowman and Hettinger areas. Forecast heat
indices are staying below advisory criteria, although are
beginning to get close in LaMoure and Dickey Counties on
Saturday.

There is relatively high confidence in temperatures cooling down
some next work week, but the question is how cool. The placement of
the ridge axis across the Northern Rockies, as well as the location
of the downstream trough, will determine how warm temperatures stay.
Cluster analysis reveals ensemble members are split about 60/40,
with the slight favoring towards the trough axis extending back to
the Minnesota/Wisconsin area which would bring lower heights and
cooler temperatures to North Dakota. 40 percent of ensemble
members have the trough further away, higher heights, and
subsequent warmer temperatures across the area.

If the cooler solution verifies, some locations could see highs
return to the upper 70s by the middle of the work week. Overall, the
general expectation is for highs to remain mainly in the 80s through
the work week, so much more seasonable compared to the upcoming
weekend. Blended precipitation chances stay generally in the 15
to 30 percent range through midweek.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 622 PM CDT Wed Jul 10 2024

VFR conditions are present across all terminals and will prevail
through the TAF period. Smoky skies continue across the area,
but confidence remains too low in this smoke reaching the
surface overnight. Generally light southerly winds will prevail,
potentially becoming a bit gusty at KDIK and KMOT overnight and
into tomorrow morning, with gusts up to around 20 kts.

&&

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

&&

$$

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