283
FXUS63 KBIS 131147
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
647 AM CDT Mon Oct 13 2025

.KEY MESSAGES...

- Widespread below freezing temperatures expected across
  northern North Dakota tonight into Tuesday morning.

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

- Medium to high chances for rain Wednesday through Friday.

&&

.UPDATE...
Issued at 645 AM CDT Mon Oct 13 2025

Low stratus continues to be more persistent and expansive than
expected. Latest RAP guidance suggests rapid erosion from southeast
to northwest beginning soon, but current satellite trends tell a
different story. It would seem likely that a slower but steady
erosion of clouds should commence shortly after sunrise, but
forecast confidence is low.

The cloud cover has kept temperatures near to above freezing, but
areas along the Highway 12 corridor where clouds have not reached
have fallen into the mid 20s, including 23 degrees at the Hettinger
Airport. Looking ahead, the high temperature forecast in northwest
North Dakota this afternoon has already been lowered by a few
degrees. If an appreciable retreat of the stratus is not underway by
midday, the high temperature forecast for today may be too warm
anywhere where clouds linger.


&&

.DISCUSSION...
Issued at 440 AM CDT Mon Oct 13 2025

A powerful nearly-stacked low pressure system is spinning over
southern Manitoba early this morning. Mid level flow over the region
has turned westerly, while at the surface, a ridge is expanding from
southern Alberta into the western Dakotas. North central North
Dakota remains under the influence of the tight surface pressure
gradient early this morning, with some gusts still as high as 35 mph
as of 4 AM CDT. A large area of stratus clouds has also become well
established from around Baker, MT to Bismarck to Carrington. The RAP
maintains these clouds through sunrise before a gradual
northwestward erosion through the afternoon. The stratus may prevent
temperatures from falling much further this morning, but they are
already as low as the mid 30s underneath the clouds. Meanwhile, the
cloud-free southwest part of the state has already seen temperatures
dip into the mid 20s. A Freeze Warning remains in effect for the
western half of the state until 10 AM CDT.

Canadian high pressure will increasingly exert its influence over
the region today. Aside from a strengthening easterly breeze in
southwest North Dakota late this afternoon and evening, winds will
become very light throughout the day. The high temperature forecast
for this afternoon ranges from the lower and mid 40s northwest,
where cloud cover could hang on the longest, to the mid 50s in the
southern James River Valley, where plentiful sunshine is anticipated.

Another potent trough digging into the western CONUS today will turn
flow aloft southwesterly over the Northern Plains tonight into
Tuesday. A shortwave is forecast to eject from the base of the
trough by this evening and reach the Northern Plains by Tuesday
morning. The approaching shortwave is likely to bring increasing
clouds into southern North Dakota by late tonight, which is expected
to keep low temperatures above freezing. Northern North Dakota is
more likely to see a clear sky through much of the night and will
remain in closer proximity to the Canadian surface high, allowing
overnight temperatures to fall into the 20s. There is also strong
model consensus that this wave will bring scattered showers through
the state from south to north during the day Tuesday, with upper
level divergence and low level warm air advection aiding ascent.
Only very light amounts of rain are favored on Tuesday. A cloudier
sky will keep temperatures cooler for most areas on Tuesday, with
forecast highs mostly around 45 to 50, but pushing 55 in the far
southwest.

The mid to late week forecast focuses on the evolution of the
upstream trough, which is favored to migrate over the Rockies on
Wednesday and lift into the Northern Plains on Thursday. Ensemble
cluster analysis shows two distinct solutions, each of which are
nearly exclusive to the GEFS and ECMWF ensemble, respectively. The
GEFS favors a more progressive solution with the trough opening up
as it lifts into Canada, while the ECMWF ensemble favors a slower
and deeper wave that maintains a closed upper low and lifts it more
due northward through the High Plains. Each of these scenarios do
offer some similar traits to our forecast though. The downstream
southerly return flow ahead of the trough is expected to bring
slightly warmer temperatures into the region for Wednesday, with
continued warming through Thursday for south central and eastern
North Dakota. Both solutions bring rain into western North Dakota on
Wednesday as a surface low begins to develop in Colorado. The
highest rain chances are focused around Wednesday night through
Thursday afternoon, shifting from southwest to northeast across the
state. By the time this system fully exits the area, which could be
as early as Friday or as late as Saturday, there are medium chances
for half an inch of rain across all of western and central North
Dakota. It should be emphasized that despite the time of year and
type of system, all ensemble guidance continues to show zero chance
of sub-freezing temperatures while precipitation is falling. In
addition, rainfall amounts through Thursday have the potential to be
convectively influenced, as guidance continues to show a signal for
modest buoyancy approaching 500 J/kg of MUCAPE. This amount of
thermodynamic energy combined with an advertised 40 to 50 kts of
deep layer shear may be sufficient to support a few stronger
thunderstorms. The most likely time and location for a stronger
storm appears to be Wednesday evening in southwest North Dakota,
where CSU machine learning guidance actually paints a low
probability for severe hail.

Ensembles favor a continuation of mid level troughing over the
central CONUS to start the weekend followed by a quick transition to
ridging heading into the following work week. This leaves lingering
low chances for rain on Saturday followed by a dry forecast for
Sunday. A slight warm up is possible to end the weekend, but the
thermal ridge axis is forecast to remain well off to the west. It
will still remain seasonably mild from mid week through the weekend,
with highs in the 50s and 60s and lows mostly above freezing in the
30s and 40s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 645 AM CDT Mon Oct 13 2025

MVFR ceilings will continue across most of western and central North
Dakota this morning. An erosion of the stratus from southeast to
northwest is anticipated from late morning through the afternoon,
but there is a chance it may be slower than what the current TAFs
are indicating. Confidence in the ceiling forecast beyond mid
morning is low. Outside of the low stratus, VFR conditions are
otherwise expected to prevail, and it is also possible that the
stratus could lift to a VFR height by the afternoon. A few rain
showers could move into southern North Dakota by the end of the
forecast period, but are unlikely to reach KDIK, KBIS, or KJMS until
Tuesday morning. West-northwest winds around 10-20 kts could remain
gusty this morning, but a steady weakening trend should take place
by late morning. This afternoon, lighter winds will turn to the east-
northeast in a clockwise fashion. All terminals should then see
easterly winds tonight at around 5 kts from KMOT to KJMS to 15
kts south and west of KDIK.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Freeze Warning until 10 AM CDT /9 AM MDT/ this morning for
NDZ001>005-009>013-017>023-031>036-040>047-050.

&&

$$

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