Area Forecast Discussion
Issued by NWS Bismarck, ND

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111
FXUS63 KBIS 121207
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
707 AM CDT Sun Oct 12 2025

.KEY MESSAGES...

- Very windy today, with west to northwest winds around 30 to
  35 mph and gusts as high as 55 mph.

- Periods of rain expected in northwest North Dakota this
  morning through early evening. A few thunderstorms are
  possible in the morning, and snow could briefly mix in with
  the rain during the late afternoon and early evening.

- Much cooler to start the work week, then warming back up to
  near or slightly above average mid to late week.

- Widespread below freezing temperatures likely across western
  North Dakota tonight and northern North Dakota Monday night.

- Medium to high chances for rain Wednesday through Friday.

&&

.UPDATE...
Issued at 707 AM CDT Sun Oct 12 2025

The cold front has begun surging into western North Dakota,
producing gusts as high as 45 mph. Isolated thunderstorms are
tracking north-northeast across Williams and Divide Counties. The
main cell, which passed just to the east of Williston around 630 AM
CDT, has shown signs of pulsing intensity, and earlier in its life
span had some weak rotation aloft. Radar analysis has not supported
hail any larger than pea size, and wind gusts stronger than those
caused by the cold front have not been observed directly with
the storms. The chance of thunderstorms will continue in this
part of the state until around 9 AM CDT. Patchy dense fog has
also developed in northwest parts of the state, mainly impacting
the Tioga area. Conditions should improve either after the
passage of the cold front or perhaps sooner from thunderstorms
passing by.


&&

.DISCUSSION...
Issued at 504 AM CDT Sun Oct 12 2025

The base of a potent upper level trough is swinging across the
Continental Divide of the Northern Rockies early this morning. A
lead shortwave that is responsible for widespread rain showers
across the eastern Dakotas and western Minnesota is lifting
northeast into southeast Manitoba and western Ontario. Trailing the
lead shortwave, low level warm air and moisture advection has
maintained a broad area of widely scattered showers from the Turtle
Mountains to near Lake Sakakawea. This activity may continue to
percolate into the mid morning hours.

Farther west, rain more closely associated with the intense DCVA in
tandem with a left exit region of a strong upper jet is approaching
the North Dakota/Montana border. An initial concern through the mid
morning hours will be the potential for a few thunderstorms. This
signal has been showing up in CAMs since this morning entered their
forecast time ranges. As of 330 AM MDT, there were 2 separate but
decaying thunderstorms between Sidney and Baker. But some CAMs do
suggest a possible re-flaring of this convection as it moves into
far northwest North Dakota from around 7 to 10 AM CDT. MUCAPE as
high as 500 J/kg, steep mid level lapse rates, and increasing
effective bulk shear to around 50 kts could promote a stronger storm
or two.

A surface trough is analyzed along the ND/MT border early this
morning. The rapidly lowering mid level heights upstream will force
the surface trough into a cold front that surges across the state
from west to east this morning and early afternoon. While this is
occurring, the northern end of the surface trough is forecast to
undergo rapid cyclogenesis over the southeast corner of Saskatchewan
this morning, lift into southwest Manitoba this afternoon as a sub-
990 mb low, and occlude this evening as the parent trough catches up
to it.

The main concern from the deepening surface low pressure system is
the potential for strong winds. Strong magnitudes of cold air
advection and pressure rises look to produce an initial surge of
gusts as high as 45 mph with the frontal passage this morning,
strongest in the southwest and tapering off slightly over time and
space. As the low continues to deepen and lift northeastward this
afternoon, all of western and central North Dakota will fall under
the strong pressure gradient with sustained cold air advection,
rising surface pressure, and steep low level lapse rates. Mean BL
winds are forecast around 30 to 35 kts around midday, but should
steadily rise to as high as 40 to 50 kts by early evening. The
strongest corridor of winds is expected across northern North Dakota
this evening as an 850 mb jet wraps around the southwest flank of
the low. There is still forecast uncertainty on the magnitude of
these winds in both the HREF and among global ensembles. Given the
expected strong dynamics of this system, we are leaning our forecast
toward the higher end outcome of mean mixing potential closer to 50
kts. Due to the forecast consistency on the timing and location of
the strongest winds, we have preemptively extended roughly the
northern half of the Wind Advisory until midnight CDT tonight, and
also increased the forecast maximum gusts to 55 mph.

The timing and strength of the frontal passage will create a unique
diurnal temperature trend that varies across the state. The James
River Valley could see midday temperatures spike to near 70, aided
by compressional heating, before cooling back into the 50s by late
afternoon. Central North Dakota could see late morning high
temperatures near 60, followed by near-steady temperatures south
central and falling temperatures north central. Western North Dakota
could see a trend similar to that of central North Dakota, but
around 10 degrees cooler and with a more rapid fall in the northwest
through the afternoon.

After the initial round of rain with potential thunderstorms in the
northwest this morning, there may or may not be a brief break before
the wrap-around deformation band of precipitation consolidates this
afternoon. There is uncertainty in the southern extent of the
deformation band, from as far north as McKenzie County to as far
south as Highway 12. Regardless, the duration of precipitation will
be much longer in the northwest where there are medium to high
chances for at least a quarter of an inch of liquid. There is still
a potential for enough cooling to allow snow to mix in before the
precipitation ends during the late afternoon or early evening. This
would be most likely to occur along the higher terrain from Divide
to northern Mountrail Counties. The NBM derived probability of
measurable snow is only around 10 to 20 percent, and snowfall rates
are no longer expected to be high enough to overcome melting on
contact with the warmer ground. Aside from the deformation band,
there is low chance that a narrow band of showers could develop
along the leading edge of the vort max as it pivots through central
North Dakota this afternoon. But much of the day should remain dry
outside of the northwest.

A surface ridge axis is forecast to expand from southern Alberta
into South Dakota tonight, cutting through southwest North Dakota.
The southwest therefore has the highest odds of a hard freeze
tonight, with projected lows in the mid 20s. Upper 20s to lower 30s
are in the forecast for the rest of the western half of the state,
with mid 30s in the James River Valley. The surface ridge axis is
forecast to lift northward on Monday, leading to a dry but much
cooler day with high temperatures only in the lower and mid 40s
northwest to mid 50s southeast. By Monday night, shortwave energy
will begin to eject from the base of another deep western CONUS
trough. The northern half of the state is more likely to remain
under the influence of Canadian surface high pressure through Monday
night, which could allow for a widespread hard freeze there. The
southern half of the state may see increasing clouds and a light
easterly breeze Monday night, but there is still a 50 to 75 percent
chance of sub-freezing lows across the south.

The aforementioned lead shortwave could bring some light rain
showers to western and southern parts of the state on Tuesday. Then
after a brief period of upper level ridging Tuesday night, the
western CONUS trough is forecast to migrate into the Northern and
Central Plains and Upper Midwest mid to late week. Cluster analysis
reveals an even split among each of the GEFS and ECMWF ensemble
members between a more progressive and open wave and one that is
deeper and slower. Regardless of these timing discrepancies, this
pattern places medium to high chances for rain across the state from
Wednesday into Friday. There is very high ensemble confidence that
surface temperatures will not fall below freezing while
precipitation is falling. In fact, the NBM shows a distinct mid week
warming trend that brings high temperatures back to near or slightly
above average (50s and 60s) and low temperatures safely above
average (mid 30s to upper 40s). Another aspect of this part of the
forecast that may need monitoring is a low chance for thunderstorms
on Wednesday, as clusters representing the more progressive solution
bring 500-1000 J/kg CAPE along with 30-40 kts of deep layer shear
into the state.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 707 AM CDT Sun Oct 12 2025

Widespread low ceilings, primarily MVFR but with some IFR, are
expected across much of western and central North Dakota this
morning. South central into eastern North Dakota should improve to
VFR this afternoon, with the southwest following suit this evening.
But northwest and north central parts of the state are more likely
to maintain an MVFR ceiling through much of the night.

Periods of rain are expected in northwest North Dakota through early
this evening. Isolated thunderstorms will also impact the area until
around 14Z. There is a low chance that rain could mix with snow
during the late afternoon and early evening, but this would be more
likely to occur north of KXWA.

A cold front will surge across the state from west to east this
morning and early afternoon, shifting winds to the west-northwest.
Gusts as high as 35-40 kts are possible with and behind the front
this morning. Then expecting westerly winds sustained around 30 kts
with gusts to 45 kts across most of western and central North Dakota
this afternoon. Winds should taper off from south to north this
evening, but north central parts of the state could see even
stronger gusts closer to 50 kts early in the evening.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until midnight CDT tonight for NDZ001>005-
009>013-021>023-025.
Wind Advisory until 8 PM CDT /7 PM MDT/ this evening for
NDZ017>020-031>037-040>047-050.

&&

$$

UPDATE...Hollan
DISCUSSION...Hollan
AVIATION...Hollan