741
FXUS63 KBIS 212345
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
645 PM CDT Fri Mar 21 2025

.KEY MESSAGES...

- Rain and snow returns Saturday into Sunday, with medium to
  high chances of precipitation across the forecast area.
  Accumulating snow is most likely across northeast and parts of
  north central North Dakota, with a medium chance of at least
  2 inches of snow.

- There is a 30 to 50 percent chance for rain and snow Monday
  through Tuesday.

- Temperatures will slowly warm up through most of next week.

&&

.UPDATE...
Issued at 635 PM CDT Fri Mar 21 2025

Quiet weather continues across the region this evening. Some
showers are moving across eastern Montana, showers continue to
decrease as they progress eastward. No updates are needed at
this time.

&&

.DISCUSSION...
Issued at 333 PM CDT Fri Mar 21 2025

This afternoon, cloud cover was slow to diminish across the area
in the wake of an exiting shortwave, while a surface warm front
was draped northwest to southeast over the state. Northwest
winds were a bit breezy but are expected to weaken through the
evening as the surface pressure gradient relaxes. Afternoon
temperatures were quite varied over the area, with highs in the
20s north central to the upper 40s southwest.

Current forecast is overall dry tonight, with blended POPs
around 10 percent in the northwest. Some of the recent high-res
runs are advertising scattered precip, likely along a preceding
impulse, although the likelihood of any one location exceeding
0.01" of QPF is very low. We elected to keep POPs as is, but
recognize there`s a non-zero chance that an isolated location
seems some light precipitation overnight tonight. Lows will be
in the teens north and east to around freezing west.

Main forecast concern in the next few days is an approaching
shortwave trough moving through Montana and the Dakotas Saturday
into Sunday. Precipitation chances expand west to east through
the day Saturday, with rain the primary p-type, before a switch
from rain to snow Saturday night into Sunday morning. Guidance
has been consistent on this being a progressive system, so we do
not expect precipitation to linger through the whole day Sunday
before the system exits to our east. The big question is how
deep the trough gets and does it close off or not. There is one
cluster of ensemble members that favors a deeper closed low,
with subsequently higher QPF and potentially snow totals,
although the higher amounts are still over eastern North Dakota.
This scenario has 90th percentile snow amounts of 3 to 6 inches
in our eastern tier of counties, so although it is a very low-
chance outcome, worth seeing how things trend in the next 12 to
24 hours in case high-res guidance favors this solution. Message
right now is a medium chance for at least two inches of snow is
limited to parts of Bottineau and Rolette Counties, with low
chances extending from Bowbells to Carrington and the
surrounding corridor. Also advertising medium to high chances
for at least 0.10" of QPF pretty much everywhere except for the
southwest. Highs on Saturday will be warmer, in the mid 40s to
mid 50s, but won`t feel quite as nice with the precipitation
chances and breezy winds.

As the system wraps up and moves east on Sunday, expecting
strong northwest winds behind the system, especially in the
James River Valley area. There`s no signal for enhanced winds in
the ECMWF EFI, and the most robust cold air advection is
overnight Saturday into Sunday compared to during the day
Sunday, but pressure gradient and strong 850mb winds should be
enough for sustained winds around 30 mph. Even with the strong
winds, the lack of snow on the ground and overall normal snow
ratios means that blowing snow will not be much of a concern
after the event, but primarily when snow is falling.

Sunday also brings the potential for near critical fire weather
conditions, focused in far southwest North Dakota. Northwest
winds will be strong here as well, although not quite as strong
as in the James River Valley, and overlapping with minimum
relative humidity dropping to around 30 percent.

Precipitation chances return relatively quickly late Sunday
night through Monday and into Tuesday, as an embedded wave in
northwest flow, stacked with an upper jet streak, moves through
the region. The entire system is pretty weak, however, with NBM
probabilities generally low for exceeding 0.1" of QPF. The good
news is that these probabilities (and precip chances in general)
are highest over southwest North Dakota. With warmer
temperatures Monday and Tuesday, expecting rain to be the
primary p-type with this system, although could see some light
snow mixing in, especially north.

Things quiet down midweek as ridging begins to build to our
west, with temperatures warming Wednesday and further on
Thursday. Highs on Thursday are strongly favored to reach at
least 60 F across the southwest and far south central. After
Thursday, there are signs of a cooler and more active pattern
through next weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 635 PM CDT Fri Mar 21 2025

VFR conditions continue across the region as clouds scatter
out. MVFR conditions may return late tomorrow as a system moves
through the region. Precipitation is forecast to across the
state tomorrow. Mostly rain during the day transition to snow by
the end of tomorrow. Winds will continue to shift to southerly
tomorrow morning then to westerly by tomorrow afternoon.

&&

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

&&

$$

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