584
FXUS63 KBIS 221435
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
935 AM CDT Tue Apr 22 2025

.KEY MESSAGES...

- Rain continues across the north with some snow mixing in
  across the far north. Rain should linger across the north
  through the afternoon.

- Breezy westerly winds are expected this afternoon and
  evening.

- There are chances for rain associated with weak systems
  Thursday into Friday morning, and Saturday into Sunday
  morning. A more substantial system is expected to arrive
  Sunday night through Monday.

&&

.UPDATE...
Issued at 930 AM CDT Tue Apr 22 2025

The rain and snow continue in the north central around the
surface low. Updated PoPs with the latest NBM data to narrow in
where the precipitation is falling. We also added near critical
fire weather wording for the far southwest and south central
since they got little rain yesterday and humidities will be
around 25 percent today.

UPDATE
Issued at 629 AM CDT Tue Apr 22 2025

Rain and low clouds continue to stretch across the north,
exiting the James River Valley by now. Some snow has also begun
to mix in across the far north, where temperatures begin to
approach freezing. Also slightly bumped the wind speeds up for
the afternoon and evening today, given the enhanced mixing
possible in the drier air. Winds are still expected to be sub-
advisory level. Otherwise, only changes were made to the PoPs
and sky coverage to better reflect radar and satellite imagery.

&&

.DISCUSSION...
Issued at 305 AM CDT Tue Apr 22 2025

Rain continues this morning, in a band extending from Divide
County southeast to Dickey County, slowly rotating
north/northeastward as the surface low tracks off towards
northern Minnesota. These showers will continue slowly tracking
northeastward through the morning and into the afternoon, before
fully departing in the north in the evening. Additional
rainfall totals across the James River Valley and the north are
expected to be anywhere from a tenth of an inch to a quarter
inch, with parts of the far north potentially seeing an
additional half inch of rain. Elsewhere, we can expect to see
some generally clear skies and breezy conditions through the day
today, with sustained westerly winds around 15 to 20 mph, with
gusts to around 30 mph. If winds can mix down in the
afternoon/evening, which some short-range high-res models
suggest could happen despite the high mixing layer forecast for
that period, we could see a few sporadic gusts to around 40 mph
at times. In general, though, winds should remain below advisory
criteria. Minimum relative humidity values get down to around
25 percent in the far south, though with the recent rains that
moved through, fire weather concerns should be minimized for the
most part. Highs will range from the lower 40s in the northwest
to the mid 60s southeast, especially in places that see more
clearing. The overnight period will be cooler, in the wake of
the trough to our northeast, with lows in the mid 20s to lower
30s.

Zonal flow aloft takes over Wednesday, with a generally dry and
overall mild day expected. Highs will be in the 50s, with
partly cloudy skies and light winds. Flow turns more
southwesterly Wednesday night, leading us into a more active
flow pattern through the end of the week and into the weekend.
An impulse of shortwave energy will pass through the Northern
Plains Wednesday night into Thursday, leading to surface
cyclogenesis to our south. The surface low will stay to our
south, but the associated rain will reach into the southern half
of the state, resulting in a roughly 15 to 30 percent chance
for rainfall totals over a quarter inch. Highs once again remain
in the 50s.

Zonal westerly flow aloft and surface high pressure may result
in a brief dry period Friday, with highs remaining in the 50s
and slightly breezy southeasterly winds. Once again, a shift to
southwesterly flow aloft Saturday will bring a more active
pattern to the area, with more rain arriving Saturday afternoon
into Sunday. Probabilities for exceeding a quarter inch of rain
are lowest with this system, hovering around 15 percent. High
temperatures begin to increase with the continued southwesterly
flow, now in the upper 50s to lower 60s.

The next substantial, organized precipitation event is expected
Monday into Tuesday. An exceptionally deep surface low with a
stacked upper level trough will deepen to our south, before
tracking northeastward through the Northern Plains. Models have
come more into agreement with the track of this low as of recent
runs, with chances already exceeding 60 percent across much of
the area. NBM probabilities of exceeding a quarter inch of rain
already range from 40 to 60 percent across the entire area as
well. Long range guidance suggests the possibility of some
convective activity with the leading push of this rain as well,
though its too far out to tell if the ingredients needed for
severe potential will line up. Windy conditions can also be
expected with this low as well, given the rather strong surface
pressure gradient. Beyond this system, heading into next week,
models diverge quite a bit, though in general, a slight drying
trend is being hinted at for now.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 629 AM CDT Tue Apr 22 2025

At the moment, VFR ceilings are present across the southwest
and far southcentral, while MVFR ceilings are present in the
James River Valley. KJMS will see MVFR ceilings through 16z.
IFR ceilings are possible across the north, where low stratus
has continued to linger along with light rain/snow. IFR
conditions will continue through the morning, before ceilings
lift to MVFR as chances for rain decrease through the afternoon
and evening. Breezy west-northwesterly winds are expected to
pickup during the daytime hours today as well, with sustained
speeds around 15 to 25 kts, and gusts up to 35 kts.

&&

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

&&

$$

UPDATE...Smith
DISCUSSION...Besson
AVIATION...Besson