469
FXUS63 KBIS 131115
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
615 AM CDT Sun Jul 13 2025

.KEY MESSAGES...

- Another round of smoke is expected to skim north central
  North Dakota and the James River Valley this afternoon.

- Turning cooler north on Monday but remaining hot south. Highs
  ranging from the mid 70s far north to the mid 90s far south.

- Isolated severe thunderstorms are possible across southwestern
  and central North Dakota Monday afternoon and evening, and
  again across the southern James River Valley Tuesday.

- Notably cooler mid-week with periodic chances for showers and
  thunderstorms.

&&

.UPDATE...
Issued at 615 AM CDT Sun Jul 13 2025

Quiet weather is found across western and central North Dakota
this morning. Skies are generally clear outside of the odd clump
of clouds here and there. Wildfire smoke has drained east of
the forecast area, with visibility everywhere above 6 SM at the
time of this update. Low temperatures this morning are broadly
in the 50s. Have made some adjustments to the sky grids to
account for the latest satellite trends, and to account for
another push of smoke aloft moving across the north central
later today. Otherwise, the forecast remains on track.

&&

.DISCUSSION...
Issued at 330 AM CDT Sun Jul 13 2025

Northwesterly flow is found over the northern Plains this
morning. Generally quiet weather is to be had, though near
surface smoke lingers across portions of eastern North Dakota.
Visibilities across the James River Valley have generally
improves to 10 miles plus this morning as the smoke continues
to be pushed eastward by a weak surface trough. Another round
of wildfire smoke is progged to drain into north central and the
James River Valley behind this surface trough this afternoon
through the early evening. Otherwise, dry and clear weather is
expected through the day today as high pressure bleeds into
northwestern North Dakota. With a surface low lingering over
eastern South Dakota this afternoon, the resulting tightening of
the surface pressure gradient is expected to promote breezy
northwest winds across central North Dakota, with sustained
speeds up to around 15 MPH and gusts up to 25 MPH expected to
the east of Highway 83. Otherwise, high temperatures this
afternoon are expected to peak into the 80s north up to the
upper 80s and lower 90s south.

Tonight, a slight uptick in precipitation chances (20 to 40
percent) is expected as a quasi-stationary front parks over the
International Border. With very modest MUCAPE values in the 200
to 400 J/KG range overnight, a few rumbles of thunder are not
out of the question, though the potential for strong to severe
storms remains very low. Any showers and or storms that do
develop are expected to generally diminish through the morning.
Otherwise, low temperatures Monday morning are forecast broadly
in the 60s.

The aforementioned quasi-stationary front is progged to be
lofted through the forecast area Monday afternoon as a very weak
shortwave travels through the broad zonal flow found over the
northern Plains. While quite weak, the passage of this front
should provide sufficient forcing for CI in afternoon. While
our northern counties are expected to be fairly cool Monday
afternoon, with highs in the mid to upper 70s, areas south of
Highway 2 are generally expected to peak into the upper to mid
90s Monday afternoon. Dewpoints during this time climb in the
lower to mid 60s, mainly in south central North Dakota, while
model MUCAPE values are moderate to high at the time of this
forecast cycle, broadly from 2000-3000 J/KG overall. Thus,
upscale growth of storms along the passing surface boundary is
generally expected. However, one of the more unclear parts of
this setup is the quality of the sheared environment. While
previous forecast cycles advertised sufficient Bulk shear values
to sustain convection, broadly from 45 to 55 knots across
southern North Dakota, models overall continue to trend this
down into the 25 to 35 knot range instead, generally orientated
perpendicular to the frontal boundary. If this verifies, storms
may struggle to sustain themselves for any appreciable amount of
time in our forecast area. With that in mind, we will only
advertise large hail and damaging wind gusts at this time, with
wind currently anticipated to be the most widespread hazard. SPC
has place much of southwestern and central North Dakota into a
Marginal Risk (level 1 of 5) for Monday, with the CSU machine
learning algorithm painting the severe potentially mainly across
our southern counties. Notably, the CSU ML algorithm has backed
off quite a bit with its most recent run, highlighting the
lingering uncertainty on the evolution of these storms on
Monday. Overall chances for precipitation are moderate (45 to 55
percent), with showers and rumbles of thunder lingering across
the forecast area overnight into early Tuesday. The window for
severe weather diminishes Monday evening into the early
overnight period.

Cooler weather is then on the docket through the remainder of
the workweek, with highs Tuesday through Friday broadly in the
60s and 70s as southwesterly flow lingers over the northern
Plains. A number of shortwave trough ejecting off a positively
tilted pacific trough will continue to promote near daily low to
medium chances for precipitation (30 to 60 percent) through
Wednesday. A few thunderstorms are also possible in the
afternoon and evening each day through this period, especially
on Tuesday as a slow-moving cold front cuts across southeastern
North Dakota. With an environment borderline supportive of
severe thunderstorms in the southern James River Valley in the
PM Tuesday, SPC has placed portions of south central North
Dakota into a Marginal Risk (level 1 of 5) for isolated severe
thunderstorms on Tuesday. At this time, the positively tilted
trough will be absorbed into a generally zonal flow pattern that
lingers through the end of the workweek.Lower chances (10 to 30
percent) for showers then persist through the weekend as a
majority of ensemble members (70% membership) favor flow aloft
turning increasingly southwesterly. Warmer weather is also
anticipated during this period, with high temperatures trending
broadly back into the 80s by Sunday.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 615 AM CDT Sun Jul 13 2025

VFR ceilings and visibility is anticipated at all terminals
throughout the 12Z TAF period. Chances for showers and a few
thunderstorms increase across the north this evening through
Tuesday morning. Have included a PROB30 group for -SHRA at KMOT
with this update. LLWS is possible tonight at KDIK from 7Z
through 10Z. Light winds this morning will turn northwesterly,
becoming breezy across portions of central North Dakota this
afternoon with sustained speeds up to 15 knots and gusts up to
25 knots expected through the afternoon. Winds then diminish
through the evening, veering to become southerly by the end of
the TAF period.

&&

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

&&

$$

UPDATE...Adam
DISCUSSION...Adam
AVIATION...Adam