969
FXUS63 KBIS 291632
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1132 AM CDT Mon Apr 29 2024

.KEY MESSAGES...

- A few lingering rain and snow showers will persist in the
  Turtle Mountains area and southern James River Valley into
  the early afternoon.

- An active weather pattern will be over the region through next
  week, with daily chances for precipitation and slightly below
  normal temperatures.

- Critical fire weather conditions will be possible across
  southwest and portions of far south central North Dakota
  Tuesday afternoon through early Tuesday evening due to strong
  westerly winds and low relative humidity.

&&

.UPDATE...
Issued at 1132 AM CDT Mon Apr 29 2024

No significant changes are needed for this update. Morning fog
has now dissipated. Much of the precipitation has also
dissipated, but some light rain and possibly snow will continue
into the early afternoon mainly around the Turtle Mountains and
southern James River Valley. Cloud cover will be slow to clear
this afternoon, and erosion from the west may not reach the
Highway 281 corridor prior to sunset. The high temperature
forecast for this afternoon was lowered by a few degrees from
central into eastern North Dakota.

UPDATE
Issued at 839 AM CDT Mon Apr 29 2024

A band of more persistent precipitation continues along a
corridor between Highway 83 and the Turtle Mountains through
the James River Valley. A few surface observations continue to
indicated snow as a type, particularly near and in the Turtle
Mountains from near Bottineau to Rolette. The expectation
remains that precipitation will continue to slowly diminish and
drift eastward through the morning.

Dense fog continues to impact areas from around Tioga to
Dickinson to Mott. Webcams show signs that the fog is beginning
to dissipate.

UPDATE
Issued at 650 AM CDT Mon Apr 29 2024

For this morning update, added areas of fog to the west through
the mid morning due to visibilities at a number of sites in
that region dropping to 1/4 mile or less behind the low cloud
deck. Other than that and some minor updates to the sky grids,
the forecast remains on track at this time. Showers are
beginning to diminish over central North Dakota, with
observations from weather stations and webcams showing light
snow falling over portions of the James River Valley and north
central. Some minor snow accumulations can also be seen on DOT
webcams in this area.

&&

.DISCUSSION...
Issued at 420 AM CDT Mon Apr 29 2024

This morning, an upper level low and associated surface low
continues to progress across the the central Plains, eventually
lifting into the northern Great Lakes region by the early evening
period. Wrap around precipitation, falling mainly as light rain
showers, continues over much of central North Dakota at this time,
through is expected to begin to exit to the east northeast by around
noon today. As surface temperatures begin to approach freezing over
portions of the James River Valley this morning, periods where this
rain becomes mixed with snow will become possible. With dewpoints
remaining at or above freezing, however, little to no accumulations
are anticipated to occur if at all. Along with these showers, a
broad area of low clouds lingers over much of the forecast area this
morning, though not stretching far enough west to reach the Montana
border. This continued clearing in the west as the cloud deck moves
to the east northeast will allow for periods of patchy fog to become
possible over the west this morning, as well as subfreezing low
temperatures. Otherwise, winds are expected to remain fairly light
and variable through the morning, while high temperatures today are
expected to range from the upper 40s in the east central where the
remains mostly cloudy, up to the mid 60s where the sky becomes
mostly sunny to partly cloudy.

An active pattern then continues through much of the week, with
upper level pacific low organizing over the Canadian Prairies late
today into early Tuesday, before it and an associated surface
systems pushes into the forecast area by late Tuesday morning. With
the passage of this system, gusty winds approaching advisory
criteria are expected to developing across portions of the southwest
Tuesday afternoon. These winds, along with the intrusion of much
drier air promoting relative humdities down to around 18 percent
over portions of the southwest, lead to increased fire weather
concerns in this area Tuesday afternoon (see Fire Weather
Discussion. More showers are also anticipated with this system,
pushing broadly from west to east through the early afternoon before
swinging northward by late Tuesday night as the upper level low
stalls over southern Manitoba. This initial wave of precipitation
could see portions of the north exceed more than 0.5" by late
Tuesday night (20-40% chance). While light precipitation could
linger over the International Border, the rest of the forecast area
should dry out for Wednesday.

A series of energetic shortwave are then expected to swing around
the stalled low first late Wednesday night into early Thursday
morning then again Friday into Saturday, promoting off and on
chances (30-50%) for rain each day conditions dry out by Sunday. All
told, we could anticipate another 0.25" to 0.75" of precipitation
through this period, though there remains a lot of discord between
ensemble members at this time with regards to how slowly the system
progresses out of our area.

Temperatures this week remain broadly at or slightly below
seasonable normals, with highs in the lower 50s to mid 60s and
lows from the lower 30s to lower 40s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 1132 AM CDT Mon Apr 29 2024

MVFR ceilings will continue across central and eastern North
Dakota this afternoon, with slow improvement from west to east.
KBIS and KMOT are likely to improve to VFR conditions by this
evening, but KJMS could see MVFR ceilings continue into tonight.

Another round of MVFR to IFR clouds with precipitation chances
will begin to move into the western terminals of KXWA and
potentially KDIK by early Tuesday morning, and will progress to
the remaining TAF sites beyond the end of the 12Z TAF period.
Winds will remain light and variable for the rest of the day
before strengthening and becoming south southeasterly this
evening into tonight.

&&

.FIRE WEATHER...
Issued at 420 AM CDT Mon Apr 29 2024

Critical fire weather conditions are possible Tuesday afternoon
through early Tuesday evening over southwestern and portions of
south central North Dakota. Minimum relative humidity values as
low as 18 percent along with strong westerly winds with sustained
speeds around 30 mph and gusts up to 45 mph in this area.

Previous near-critical fire weather concerns north of the fire
weather watch have diminished with the latest model runs.
Minimum relative humidities in the upper teens and lower 20s are
now more strictly bounded by the already existing watch area,
along with an overall lowering of wind speeds supported by model
soundings. As such, previous mentions of near-critical fire
weather concerns in the area north of the fire weather watch and
bounded on the north by Lake Sakakawea and the Missouri River
have been removed.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Tuesday afternoon through Tuesday
evening for NDZ031>033-040>045.

&&

$$

UPDATE...Hollan
DISCUSSION...Adam
AVIATION...Adam
FIRE WEATHER...Adam