746
FXUS63 KBIS 091142
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
642 AM CDT Wed Jul 9 2025

.KEY MESSAGES...

- Isolated to scattered severe thunderstorms are possible late
  this afternoon and evening, and again Thursday afternoon into
  the night.

- Hot and humid conditions are expected today, with widespread
  high temperatures in the 90s.

- Temperatures will cool down to the 70s to end the work week,
  before warming back up again for the weekend.

&&

.UPDATE...
Issued at 642 AM CDT Wed Jul 9 2025

An area of showers and thunderstorms has been trekking across
north central North Dakota through the early morning hours, on
the nose of a low-level jet and in a narrow swath of uncapped
instability. Did have a few storms get pretty strong and had a
couple reports of hail around the size of nickels. SPC
mesoanalysis page illustrates that deep layer shear is very low,
as expected, only around 25 knots, so storms are more of the
pulse-type thunderstorm which is what`s been observed. Most of
the convective activity has been dying out as it moves east
through Bottineau and McHenry County area, although we are
seeing some increased lightning activity still.

&&

.DISCUSSION...
Issued at 337 AM CDT Wed Jul 9 2025

This morning, a stout upper high was placed over the Desert
Southwest, with northwest flow across the Dakotas on the
northeast side of this feature and upstream of troughing over
the Great Lakes. Further upstream, a closed low and attendant
trough are moving onto the Pac NW coast, with a secondary wave
in northern British Columbia. At the surface, high pressure was
drifting off to our east, while a low centered in the southern
Canadian Prairies had a warm front and surface trough extending
into central Montana.

It will be quite hot and humid today, with highs in the upper
80s to upper 90s, and likely seeing a few locations hit 100 F
across western North Dakota where humidity is lower and it is
closer to the low-level thermal ridge impinging on the region.
Apparent temperatures are getting close to Heat Advisory
criteria (100 degrees F), although for a relatively limited area
across central North Dakota where there is the most favorable
overlap between air temperatures and dew points. Looking
upstream across the Central Plains, we aren`t seeing dew points
exceeding 70 F, so thinking NBM dew points are reasonable.

Besides the heat and humidity, main focus of today is potential
for isolated to scattered severe thunderstorms across southwest
and central North Dakota. As the warm front moves across the
state today, deterministic guidance is advertising a weak
impulse moving through flow that turns mostly zonal by this
evening. Although there have been some concerns of capping with
such warm temperatures in the lower levels, most high-resolution
guidance has been consistent in developing convection somewhere
across southwest and into south central North Dakota, depending
on where the embedded impulse ends up tracking, late this
afternoon. As previous discussions have noted, the environment
is characterized by extreme instability but quite marginal
shear, which will likely limit the upper extent of potential
hazards with any thunderstorms that develop. A likely scenario
is that there is explosive initial development where large hail
is possible, and a tornado can`t be ruled out, especially with
any initial storms along the boundary. The lack of shear will
limit the lifespan of any storms, with severe gusts possible as
the storms collapse, with somewhat inverted V soundings due to
hot surface temperatures, and DCAPE in excess of 1500 J/kg.
There are some hints of an eventual cluster/upscale growth that
would also favor a wind threat, with current CAMs highlighting
this potential across the James River Valley and into eastern
North Dakota. Best timing window is 3 to 11 PM CDT, starting in
the southwest and ending east.

We are also carrying some low POPs across the west late tonight
into Thursday morning, with another weak impulse moving through,
but with limited instability thinking this will just be showers
and a few rumbles of thunder. Lows tonight will be in the upper
50s to mid 60s.

As the upper trough base approaches from the Canadian Prairies
on Thursday, a trailing cold front will approach from the
northwest. Some capping from warm 850mb temperatures will
likely keep convection at bay initially, although the
approaching wave and attendant cold front will provide more
robust synoptic forcing compared to today. It`s another case of
very high instability in the warm sector, but bulk shear is
forecast to be just as low, if not slightly lower, than today,
especially in the area of highest buoyancy. Shear starts to
increase as the front comes in but there doesn`t seem to be much
favorable overlap, although the one area that could potentially
see higher shear with sufficient instability would be the north
central. Some of the higher- res guidance isn`t as set on
convective development compared to global models, but thinking
there is still potential for isolated to scattered severe
thunderstorms across parts of the state Thursday evening and
into the overnight hours. We do have some questions on how far
to the southwest we could see severe storms in the area outlined
as level 2 out of 5 risk, with some guidance hinting that dew
points will be lower and temperatures will be higher than what
the NBM has. Things will also be very dependent on the timing of
the cold front. Highs on Thursday will be in the lower 80s
northwest to lower 90s southeast, with dew points in the 60s
central and east that will make it feel pretty humid for another
day.

Friday will be much cooler and less humid in the post-frontal
air mass, with highs dropping down into the 70s. There could be
a few isolated showers and non-severe thunderstorms from the
influence of cyclonic flow aloft as the upper low exits to the
east, but blended POPs are only around 10 to 20 percent and
taper off in the afternoon. We then dry out and warm up through
the weekend with zonal flow aloft dominating, with highs back
into the widespread 80s for Saturday and Sunday. Precipitation
chances return to start the work week with temperatures cooling
into midweek. NSSL machine learning guidance has some low
probabilities for severe weather Monday and Tuesday, and then
again looking further ahead to next weekend when the NBM has
temperatures warming up again.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 642 AM CDT Wed Jul 9 2025

Overall VFR conditions are expected at all terminals through the
TAF period. Some showers and thunderstorms are moving east of
KMOT early this morning, otherwise mostly clear skies to start
the day. Breezy southeast winds will continue at central and
eastern terminals while western terminals see winds shift to
northwesterly through the afternoon. Chances for showers and
thunderstorms, some strong to severe, then increase across parts
of southern North Dakota late this afternoon and into the
evening. Did include PROB30 groups at KBIS and KJMS where there
is the highest likelihood of thunderstorms, with gusty erratic
winds and large hail possible.

&&

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

&&

$$

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