116
FXUS63 KBIS 291739
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1239 PM 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.

&&

.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 /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1239 PM CDT Mon Apr 29 2024

MVFR ceilings are forecast to slowly erode from west to east across
central and eastern North Dakota this afternoon and evening, with
VFR conditions prevailing to the west. A low pressure system moving
across the state from west to east later tonight through Tuesday
will bring MVFR ceilings and a period of rain showers to most
terminals. Light winds this afternoon will become southeasterly
around 10-15 kts later this evening into tonight. A cold front will
then switch winds to the west Tuesday morning along and southwest of
a line from KXWA to KBIS, increasing to 15-25 kts with gusts to
around 30 kts.

&&

.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.

&&

$$

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