902
FXUS63 KBIS 120254
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
954 PM CDT Mon May 11 2026

.KEY MESSAGES...

- Critical fire weather conditions expected again on Tuesday
  across central North Dakota, including the James River Valley.

- Strong winds expected across central North Dakota Tuesday
  morning through the afternoon.

- Windy conditions and low humidity values through the rest of
  the upcoming week may lead to daily critical fire weather
  conditions.

&&

.UPDATE...
Issued at 954 PM CDT Mon May 11 2026

Winds are generally beginning to diminish as deep mixing eases
and the boundary layer begins to decouple. Some countering of
this trend is occurring in north central ND, where low-level
cold air advection and surface pressure rises (on the order of 4
mb/3 hours) are strongest. That may result in an area of gusts
closer to 40 mph persisting/translating east-southeast into
parts of the James River Valley overnight, albeit with some
uncertainty in peak speeds after 06z given the nocturnally-
reduced mixing. The low- and midlevel wind maxima following that
same spatial pattern will eventually be mixed to the ground
level in a more uniform manner by early Tuesday morning, which
is what`s driving the Wind Advisory for parts of central ND and
the James River valley then. In western ND, winds will continue
diminishing overnight.

As winds diminish, blowing dust has become less of an issue with
ASOS/AWOS visibilities across western ND and eastern MT returning
to 10SM as of 0230z. Some sensors continue to report scattered
to broken cloud layers not shown on satellite, likely reflecting
dust particles that remain aloft in the residual mixed layer
above the ground level.

Given observed trends in winds in most areas and humidity values
that are increasing as mixing subsides, we will let the Red Flag
Warning for this evening expire as scheduled at 10 pm CDT/9 pm
MDT. The Red Flag Warning for parts of the area on Tuesday
remains on track, with no changes.

UPDATE
Issued at 730 PM CDT Mon May 11 2026

The main change with this update was to include blowing dust in
the forecast through this evening in western ND based on recent
satellite, ASOS/AWOS trends, and web cameras. Notable amounts
of blowing dust are being transported into the area on post-
frontal northwest winds. Deep mixing to between 600 and 700 mb
with low-level lapse rates around 10 C/km in parts of west
central and northwestern ND, in a low-level cold air advection
regime, and with a 100 kt jet streak aloft atop that deeply-
mixed air mass is contributing to wind gusts of 40 to 50 mph in
western ND as of early this evening. Given expected gradual
decreases in mixing depth and related winds between 02z and 04z,
and some variation spatially and temporally in the strongest
winds, we have not issued a Wind Advisory given the short
duration of the event. However, the winds and continued low
humidity will continue to cause critical fire weather conditions
the next few hours. The primary surface cold front is just east
of the Highway 83 corridor in central ND as of 00z, and is
expected to continue shifting eastward. High-based thunderstorms
in north central and northeastern ND have formed ahead of the
front in the Rugby area, and additional high-based showers and
isolated storms are occurring in the cyclonic flow of the post-
frontal regime in northwest/north central ND and southern Canada
as well. Given the very dry boundary layer and strong flow aloft,
strong, gusty, and erratic winds are possible with this activity
before it diminishes by late evening, too.

&&

.DISCUSSION...
Issued at 330 PM CDT Mon May 11 2026

Warm, dry, and windy conditions are expected across western and
central North Dakota throughout much of the workweek. Fire
weather concerns will remain the primary forecast challenge
through this period, and will be discussed at length in the Fire
Weather section below.

A shortwave trough is traversing the northern Plains today,
with an associated surface low moving across the southern
Canadian Prairies. With the strengthening surface gradient, and
with very dry conditions allowing for much of the area to become
fully mixed out to 500mb, strong southerly winds from 25 to 30
MPH and gusts up to 45 MPH are expected this afternoon. Late in
the afternoon, winds are expected to start veering to the
northwest as a cold front extending off the aforementioned
surface low moves across the region, starting in the northwest
and dropping to the southeast through the evening. A brief lull
in winds can be anticipated ahead of this FROPA, but will then
again strengthen along and behind the cold front as CAA
increases. With the best alignment of the CAA and the best
pressure rises found across the area late this evening and
overnight, and with the development of moderately strong, 40 to 45
knot mid level jet across central North Dakota overnight, it is
expected that at least breezy northwest winds will persist
overnight into Tuesday morning across central North Dakota.

Also for today, much of western and central North Dakota will
fall into the warm and somewhat "moist" sector of the surface
low this afternoon, promoting the seasonable warm highs in the
70s to mid 80s. With this, CAMs continue to advertise model
MUCAPE values around 750 - 1000 J/KG become available ahead of
the FROPA this afternoon, which could allow for the development
of isolated showers or thunderstorms through the early evening.
With how dry the near surface layer will remain through this
period, the little rain that does reach the ground is likely to
be associated with convective processes. In any case, whether or
not precpitation reaches the ground or it becomes virga, gusty
and erratic winds can be anticipated where it occurs. Notably,
a strong to marginally severe thunderstorm is not out of the
question late this afternoon and evening as a fairly well
sheared environment develops across central North Dakota, with
model values around 45 to 55 knots. An interrogation of model
soundings during this period indicates that the most unstable
parcels will be found elevated over a fairly robust capping
inversion through much of this period which, along with the
skinny CAPE profile advertised by the CAMs, would suggest that
greatest potential hazard for any strong to marginally severe
storm would be strong winds approaching 60 MPH.

Another windy, dry day is on top for western and central North
Dakota on Tuesday. Considering the LLJ across eastern North
Dakota, the tight pressure gradient, and the well mix boundary
layer, the gusty northwest winds that persisted overnight are
expected to strengthen through the morning into the early
afternoon, becoming strong from 25 to 35 MPH and gusting as high
as 45 MPH for most areas east of Highway 83. These strongest
winds are expected to diminish through the late afternoon and
evening as LLJ exits to east, and as the surface gradient
continues to relax. With this in mind, we have issued a Wind
Advisory for much of central North Dakota from 7 AM to 7 PM CDT.
Winds to the west of Highway 83 will be somewhat lighter, but
still breezy to windy with sustained speeds around 15 to 20 MPH
and gusts up to 30 MPH. By the early overnight period, fairly
light and variable winds are expected across western and central
North, Otherwise, for Tuesday, a slightly "cooler" highs in
broadly in the 70s are anticipated in the post frontal
environment.

Northwesterly flow is expected to be come reestablished over
the forecast area on Wednesday as an upper level ridge shifts
over the Great Plains. With this, another very warm day is
expected for western and central North Dakota, with highs
broadly forecast in the mid 70s to lower 80s central to the
lower to mid 80s west. A close low is progged to again cut
across the southern Canadian Prairies early Wednesday, with lee
cyclogenesis set to produce another surface low to the west of
the forecast area early Wednesday morning. With the tightening
of the pressure gradient ahead of this low, winds are expected
to reorganize out of the south southeast and strengthen through
the afternoon, allowing for speeds around 25 to 30 MPH and gusts
up to around 40 MPH in the west. Mainly dry conditions are
expected on Wednesday, though some isolated rain showers are
possible in the evening and overnight as the attendant warm
front ahead of the low system lifts across the west.

Very windy conditions are then on tap on Thursday as the
aforementioned low lofts a cold front across the forecast area.
With the increased CAA along and behind the front, and with
model soundings indicating mixing well up into 700-750mb, it can
be anticipated that winds from a strong mid level jet will find
their way down to the surface. In this scenario, much of
western and central North Dakota could find itself easily within
Wind Advisory criteria for Thursday, if not borderline High
Wind Warning criteria across portions of the northwest. The EFI
for winds during this period is approaching 0.9 across the
north, with a notably shift of tails along the International
Border. Some uncertainty remains however, with cluster analysis
revealing a minority of model members (approximately 40 percent)
advertising a much more diffuse and open way aloft, resulting
in a weak LLJ and thus weak winds overall. Will need to monitor
this period over the next few days.

Uncertainty continues to build into the forecast Friday into
the weekend regarding the potential for both winds and rain.
Ensemble members are fairly split between two scenarios, one
where a transient upper level ridge passing through the region,
promoting drier conditions with more limited winds, while the
other favors a more zonal flow pattern which would allow chances
for precpitation across much of the forecast area heading into
the weekend. In either scenario, there is greater agreement in a
transition into a more active precpitation pattern by the late
weekend into early next week a more robust long wave trough is
advertised by the ensemble to move across the Great Plains.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 954 PM CDT Mon May 11 2026

VFR conditions are expected to prevail across western and
central ND for the 00z TAF cycle. Northwest winds will
gradually diminish in western ND overnight, but will remain
elevated in central ND with gusts of 25 to 35 kt. Northwest
winds on Tuesday will gust up to 40 kt in central ND and the
James River Valley.

Some dust remains aloft after being lofted this afternoon and
early evening, but is expected to gradually disperse overnight.

&&

.FIRE WEATHER...
Issued at 954 PM CDT Mon May 11 2026

The Red Flag Warning for this evening is being allowed to expire
as humidity values increase and winds slowly decrease in most
areas.

With the lingering low level jet and strong pressure gradient
lingering across eastern North Dakota Tuesday morning, northwest
winds expected to again strengthen through the afternoon, again
becoming sustained from 25 to 35 MPH and gusting as high as 45
MPH by the late morning and through the afternoon. Winds will be
a little more tame further to the west, though still elevated
from 15 to 20 MPH gusting as high as 30 MPH. Though somewhat
"cooler" in the afternoon, with highs more broadly in the 70s,
conditions across the forecast area will remain very dry.
Minimum relative humidity is expected to again drop as low as 15
to 20 percent west of Highway 83, from 20 to 25 percent along
and south of I-94, and from 25 to 30 percent north of I94. The
greatest overlap of strong winds and low RHs is expected across
much of central North Dakota into portions of western North
Dakota, where critical fire weather conditions are again
expected for Tuesday. Expansion of critical fire weather
conditions further west is not out of the question if the winds
become stronger than forecast, but confidence in such a
scenario is not currently high. Winds are expected to rapidly
diminish through the early evening, becoming light and variable
overnight, as the low exits further into the Great Lakes region,
accompanied by the low level jet and allowing the surface
gradient to relax.

Critical fire weather conditions remain likely across North
Dakota Wednesday through the end of the week. Minimum relative
humidity is expected to drop as low as 15 to 20 percent across the
west Wednesday, and across the southwest and south central on
Friday, while being only as high as 20 to 30 percent elsewhere
each day. Breezy to windy conditions can be expected across the
west on Wednesday, while windy to very windy conditions are
possible across much of North Dakota on Thursday and Friday. At
least some chances for precpitation begin to build into the
forecast as we head into the weekend, with widespread low to
medium chances for rain late Saturday through Sunday.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 9 PM CDT Tuesday for NDZ003>005-
011>013-021>023-025-035>037-046>048-050-051.
Wind Advisory from 7 AM to 7 PM CDT Tuesday for NDZ005-012-013-
022-023-025-035>037-046>048-050-051.

&&

$$

UPDATE...CJS
DISCUSSION...Adam
AVIATION...CJS
FIRE WEATHER...Adam