939
FXUS63 KBIS 282056
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
356 PM CDT Sun Apr 28 2024

.KEY MESSAGES...

- High chances (60 to 90 percent) for rain across south central
  North Dakota from around the Missouri River and east into the
  James River Valley late this afternoon through tonight, with
  medium chances (30 to 50 percent) elsewhere across central
  North Dakota. Dry across western North Dakota.

- Light rain may become mixed with, or briefly change over to
  light snow late tonight into early Monday morning central.
  Patchy fog is possible late tonight into early Monday morning
  west.

- 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 225 PM CDT Sun Apr 28 2024

A surface and upper level will lift from the central Plains this
afternoon, into the northern Great lakes region by Monday
afternoon. Current radar reflectivities can be seen over
southeast North Dakota and extending west in to far south
central North Dakota and then back down to the southwest to the
Black Hills and south into far southwest South Dakota.
Precipitation lifting northward through eastern South Dakota and
Minnesota will continue to wrap back west into central ND and
this deformation zone will remain over central ND tonight.
Heavier rain amounts up to around three quarters of an inch are
possible over portions of the southern James River Valley before
all is said and done Monday. While amounts will not be as
impressive back over the south central, respectable amounts of
a tenth of a third of an inch are possible from around Bismarck
and Linton, north and east to Harvey and Carrington. Late
tonight a rain snow mix or even a period of all snow can not be
ruled out with some very light accumulations possible on grassy
surfaces. With dewpoints remaining at or above freezing, impacts
are not expected. Precipitation tapers off over central ND on
Monday with highs ranging from the 60s in the west with much
more sunshine, to the lower 50s over the James River Valley
which sees clouds through much of the day. A period of patchy
morning fog is possible in the west as lower clouds don`t make
it out that far. Morning lows will also drop below freezing over
portions of the west.

An active weather pattern continues Tuesday through the end of
the forecast period as another upper level low tracks from the
west coast, across the Rockies and into the northern Plains
region before stalling and continuing to spin over the Northern
Plains into the Canadian Prairie Provinces.

The initial wave and attendant surface system tracks through
the forecast area on Tuesday with scattered showers expected
along the surface boundary. The main impact from this system
though will most likely be fire weather related with strong
winds and low humidities expected southwest (See Fire Weather
discussion below). Wind highlights may also be needed over the
southwest Tuesday afternoon. It looks like a little break in the
action is possible Wednesday before shower chances increase
again Thursday into Friday as another shortwave swings through
the forecast area, around the initial wave that stalls just to
our north. Some wrap around moisture will probably keep
lingering light precipitation chances across the north on
Saturday as the entire system lifts slowly north.

Temperatures will remain around normal through the forecast
period. Normal late April highs are around 60 and normal lows
are in the low to mid 30s. Daytime highs this week will vary
from the lower 50s to upper 60s. Lows will range from the upper
20s to lower 40s.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1203 PM CDT Sun Apr 28 2024

Widespread rain with MVFR to IFR and some LIFR ceilings
continues over far south central into the James River Valley to
begin the 18Z TAF period. This area of precipitation will mostly
impact KBIS and especially KJMS tonight into Monday morning with
rain possibly mixing with snow for a period around 12Z Monday
into the forecast later today and this evening and remain
through 18Z Monday. Fog is also possible with the rain with
visibilities generally in the 2-6SM range.

Farther to the north and west. Scattered MVFR ceilings to begin
the 18Z TAF period at KDIK and KMOT should lift/dissipate early
this afternoon. Late tonight into Monday morning lower ceilings
and visibilities will work their way north and west to impact
these sites, with a period of MVFR to IFR ceilings possible at
each site. Southwest ND, including KDIK will see a better chance
of some IFR-LIFR visibilities in patchy fog Monday morning if
lower ceilings don`t expand that far west. The north central,
including KMOT should see more widespread stratus, possibly
MVFR to IFR late tonight into Monday morning with periods of
light rain. At this time northwest North Dakota, including KXWA
is expected to remain VFR with lower clouds not quite reaching
this area.

Surface flow through the period is generally 5 to 15 knots with
a southeast to east flow today shifting to a north to northwest
flow by Monday.

&&

.FIRE WEATHER...
Issued at 225 PM CDT Sun Apr 28 2024

Critical fire weather conditions are possible Tuesday afternoon
through early Tuesday evening across southwest and portions of
south central North Dakota. Minimum relative humidity values are
expected to drop as low as 18 percent, with westerly winds around
30 mph and gusts to 50 mph.

North of the fire weather watch and bounded to the north and
east by Lake Sakakawea and the Missouri River near critical
fire weather conditions are possible Tuesday afternoon.

More uncertainties remain over the near critical area. Namely
the potential for a wetting rain Tuesday morning. Lower wind
speeds and higher humidities should also limit the rate of
spread of any fires that may ignite. The rates of spread are
forecast to be highest over the far southwest Tuesday afternoon
and the Duration of fire weather conditions has dropped a bit
as you approach the big Lake and the Missouri River. If forecast
winds/humidities would worsen, we would still have the time on
the overnight shift tonight to add additional counties.

&&

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

&&

$$

DISCUSSION...TWH
AVIATION...TWH
FIRE WEATHER...TWH