680
FXUS63 KBIS 101953
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
253 PM CDT Fri Oct 10 2025

.KEY MESSAGES...

- Above normal temperatures continue through Saturday night,
  with highs in the 60s and 70s and lows in the 40s and 50s.

- Windy with increasing chances for rain this weekend. Some snow
  could mix in with the rain in northwest North Dakota Sunday
  evening and night.

- Cooler next week, with highs in the 40s and 50s and lows in
  the 20s and 30s. Dry Monday and Tuesday, then low chances
  for rain Wednesday through Thursday.

&&

.DISCUSSION...
Issued at 253 PM CDT Fri Oct 10 2025

A narrow upper ridge was placed over the region this afternoon,
in between a compact low over the Great Lakes and a deeper,
larger low off the coast of the Pacific Northwest. Surface high
pressure was centered over southeast North Dakota, with light
winds closer to this feature, while a tightening pressure
gradient on the backside of the high was leading to breezy winds
across the western part of the state. Winds will stay elevated
tonight, contributing to mild overnight lows in the lower 40s to
lower 50s, as we head into the weekend.

The aforementioned low off the west coast begins to surge
onshore tonight into Saturday morning, turning flow across the
Dakotas southwesterly. Strong southeasterly low-level flow will
help temperatures warm but also lead to a windy day, especially
central and east. High temperatures will be well above normal,
ranging from the mid 60s in the James River Valley to the upper
70s far west. As we start to get impulses ejecting from the
approaching trough base, some scattered showers could develop
tonight through the day Saturday, mainly across the far
southwest and central. Initial showers early in the morning will
be dealing with relatively high cloud bases and a modest dry
layer, so expecting little to no rain from these at first. Once
these move out late in the day, CAMs are in decent agreement on
a break in precipitation ahead of a deepening surface low and
attendant cold front in Montana.

Ahead of this front, there could be just enough instability to
produce a few thunderstorms, with bulk shear increasing as the
wave approaches. The current projected timing and some of the
extended high-res guidance would favor any thunderstorms
occurring late Saturday night into Sunday morning. CSU machine
learning has consistently shown low severe weather probabilities
on Sunday, but thinking this is valid for early in the day and
is a pretty unlikely solution due to the forecast low
instability.

As the main shortwave trough base and vorticity maximum move
into the state on Sunday, we see our overall highest chances for
precipitation in northwest North Dakota as the wrap-around
deformation zone intensifies and the nose of an upper jet streak
points into the northwest. There is good consensus on the
center of the surface low tracking from southeast Montana, from
southwest to north central North Dakota, and into Manitoba, with
the cold front extending to the south. We continue to see GEFS
ensemble members favor a slightly slower and stronger solution
compared to EC members, which have consistently shown a more
progressive and open wave scenario. Overall, however, there is
not much of a change in our thinking with this update. One of
the main messages is that we are confident in strong winds
across the state from this system, with strong cold air
advection from the front, stout pressure rises, and steep low
level lapse rates. The magnitude of the upper threshold of winds
is still in question, with uncertainty on the strength of winds
that will be available to mix down. It is worth noting that the
shift of tails on the ECMWF EFI decreased compared to previous
runs, which means there are less ensemble members with higher-
end solutions. We did blend up slightly from the deterministic
NBM but did not want to go too much higher at this juncture.

The other main message is that precipitation chances are focused on
the northwest part of the state, which is much needed as this area
is broadly around 25 percent of normal over the last 60 days. 13Z
NBM probabilities for at least 0.50 inch of QPF are anywhere from 40
to 70 percent across the northwest corner, with low probabilities
for at least 1 inch of liquid precipitation except for in Divide
County. It continues to look like much of southwest and south
central North Dakota will get dry slotted, with overall low
chances for much of this area to exceed even a tenth of an inch
of rain. There are still questions about when and where rain
will transition to snow Sunday evening, although these will
likely not be resolved until we start to get more high
resolution data. The EC ensemble has trended down just a bit,
with less of a shift of tails in the latest EFI and slightly
lower probabilities of at least an inch of snow accumulation.
GEFS and NBM probabilities are quite similar to the previous
forecast update, so still messaging a medium probability for
measurable snow in Divide and Burke Counties Sunday evening and
night, with decreasing chances to the south and east. Chances
for at least one inch of snow max out around 20 percent, and
drop to around 15 percent for 2 inches, with a few ensemble
members still coming in with some higher-end solutions. We also
do have a mention of patchy blowing snow, which is focused
across the far northwest during Sunday evening.

Even in the slower ensemble members, the Sunday system moves
northeast and washes out relatively quickly, with precipitation
chances ending early Monday morning and skies clearing through
the day. The post-frontal air mass will be chillier than our
temperatures lately, with forecast highs in the lower 40s to
lower 50s. Temperatures warm slightly for Tuesday, and
precipitation chances these two days are very low. By the middle
of the work week, cluster analysis reveals two general
solutions: one with a more progressive trough and higher
precipitation amounts (60 percent of members), and one that
favors a deeper and slower trough that keeps zonal flow over the
region through Wednesday (40 percent). By late week, clusters
are quite split on the evolution of the synoptic pattern,
although the majority of solutions are still bringing at least
some precipitation to the area. NBM POPs have trended down, with
a general 15 to 30 percent chance Wednesday into Friday.
Temperatures are favored to warm from the start of the week,
with highs back in the mid 50s to lower 60s late in the work
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1230 PM CDT Fri Oct 10 2025

VFR conditions expected at all terminals through the TAF period.
Main weather concern through the period is LLWS at all terminals
but KJMS tonight, and increasing winds on Saturday. Breezy
southeast winds will overspread the area through tonight, with
sustained winds around 15 knots through the night, before
increasing further and becoming gusty by early Saturday
afternoon.

&&

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

&&

$$

DISCUSSION...Jones
AVIATION...Jones