551
FXUS63 KBIS 060246
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Thu Jun 5 2025

.KEY MESSAGES...

- Expect a better chance (40 to 70 percent) for showers and
  storms on Saturday. A few strong to severe thunderstorms are
  possible over southeastern and eastern North Dakota.

- Near to slightly below average temperatures are favored
  through Monday, with a slight warmup expected on Saturday.

- Breezy to windy conditions this weekend into Monday,
  especially on Sunday.

&&

.UPDATE...
Issued at 945 PM CDT Thu Jun 5 2025

Rain across western and central North Dakota has greatly
diminish by the time of this mid evening update. Over in south
central North Dakota, a few lingering showers can be found as
the back edge of the system exits the forecast area. Showers have
completely dissipated across the north, where diurnal showers
had previously developed. Have made some slight adjustments to
the PoPs and Sky grids to account for the latest satellite and
radar trends, but overall the forecast remains on track.

UPDATE Issued at 635 PM CDT Thu Jun 5 2025

Scattered showers linger over south central North Dakota this
evening, with more isolated showers found in the northwest and
north central. The sporadic rumbles of thunder found in the
south central earlier this afternoon has generally ceased by the
time of this update. Have blended in the latest satellite and
model trends into the PoPs and sky cover with this update.
Otherwise, winds are generally light and variable across the
forecast area at this time, though some breezier observations up
to around 15 MPH continue to come in on the backside of the
showers in the south. Other than the slight adjustments
previously mentioned, the forecast remains broadly on track.

&&

.DISCUSSION...
Issued at 253 PM CDT Thu Jun 5 2025

A shortwave continues to move across South Dakota and southern
North Dakota this afternoon, which has led to some scattered
showers and a few rumbles of thunder, mainly south of the
Highway 200 corridor (30 to 60 percent chance). Some isolated
showers will also be possible northwest and north central given
cyclonic flow aloft, but this activity will be diurnally driven
and more of the hit or miss variety. All of this activity should
diminish or move out to the southeast by late this evening.

Expect only a few clouds overnight but some lingering smoke
aloft from Canadian wildfires may keep the sky a bit hazy. Lows
will mainly be in the 40s overnight.

For Friday, North Dakota will be in a split flow regime aloft
with a trough well to our south and ridging to our north. A
shower or two may not be out of the question, but chances are
too low to mention at this time at any one particular point. It
should be a touch warmer on Friday with highs in the 70s but
lingering smoke from the wildfires aloft may mute temperatures
slightly.

A northern stream shortwave then swings down on Saturday along
with a surface cold front, bringing a better chance (40 to 70
percent) of showers and storms to much of the area (especially
the central and east). By the afternoon hours we should see
thunderstorms develop along the cold front somewhere over the
central or in the vicinity of the James River Valley/Devils Lake
Basin. Here we could see some modest instability with MLCAPE
values in the 500 to 1000 J/kg range and deep layer shear in the
30 to 40 knot range. Thus, there is at least a chance for a few
strong to marginally severe storms along and ahead of the front
in the afternoon and early evening depending on how the setup
evolves. The first of the longer range CAMs are starting to pick
up on this activity and are suggesting a linear storm mode
along the front, but the deep layer shear vector is roughly
perpendicular to the boundary which would suggest a more
discrete storm mode. Given the marginal shear profile, would
expect a multicell to transient/marginal supercell storm type.
Strong winds and large hail would be the most likely threats.
Highs on Saturday will mainly be in the 70s again, but we could
see a few lower 80s south central or southeast ahead of the
front.

Sunday looks to be cooler and windy, with highs mainly in the
lower 60s to lower 70s. Extreme Forecast Index (EFI) values
greater than 0.8 and approaching 0.9 suggest that we could see
some advisory criteria northwest winds on Sunday behind the
front. Synoptically, this would make sense as well with some
pressure rises, cold air advection, and steep lapse rates in the
post frontal regime. Sustained values to 35 mph and a few gusts
to 45 mph certainly seem reasonable glancing at forecast
soundings. A few showers will remain possible through the day on
Sunday as much of the area remains in cyclonic flow aloft.

Ridging then starts to nudge in through mid- week, leading to
warming temperatures with highs back into the upper 70s to mid
80s by Wednesday. Low chances of showers and thunderstorms
return to the forecast Tuesday night through Wednesday, possibly
lingering into the end of the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 945 PM CDT Thu Jun 5 2025

VFR ceilings and visibility are found at all terminals to begin
the 00Z TAF period. Patchy fog is expected to develop over
portions of southwestern and south central North Dakota Friday
morning, including at the terminal of KBIS. Have included MVFR
visibility at KBIS during the mid morning with this update.
Otherwise, wildfire smoke aloft is expected to continue
including hazy skies throughout the TAF period. Winds are
expected to remain light and variable through the evening and
overnight period, before strengthening and organizing out of the
south to southeast Friday morning and afternoon. The gusty
winds will be found in the northwest, where speeds peak up to
around 15 knots and gust up to around 23 knots.

&&

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

&&

$$

UPDATE...Adam
DISCUSSION...ZH
AVIATION...Adam