897
FXUS63 KBIS 290600
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
100 AM CDT Sun Jun 29 2025

.KEY MESSAGES...

- Scattered showers and an occasional thunderstorm are possible
  along the North Dakota-South Dakota border overnight.

- Much quieter weather is expected Sunday into Tuesday, with
  slightly cooler and less humid conditions.

&&

.UPDATE...
Issued at 1258 AM CDT Sun Jun 29 2025

Over the past couple hours, and area of scattered showers with
infrequent lightning developed just to the north and east of
Bismarck. This activity has since become more isolated and was
moving through the northern James River Valley at the time of
this writing. Elsewhere, only the far northern extent of anvil
from severe storms along and north of the Black Hills has
crossed the border into far southwest North Dakota. However,
explosive growth of convection over the past half hour has been
observed in northwest South Dakota, and now extends as far north
as the middle of Perkins County. Still think it is more likely
that the strongest storms will remain south of the stateline.

UPDATE
Issued at 945 PM CDT Sat Jun 28 2025

The showers and occasional rumbles of thunder over western and
central North Dakota have diminished at the time of this mid
evening update. Isolated weak reflectivities linger over
portions of north central North Dakota, though with these being
associated with mid based clouds, and and with a dry near
surface layer, little to no precipitation is expected to reach
the ground. Have tweaked the sky grids by incorporating the
latest satellite observations, but otherwise the forecast
remains broadly on track.

UPDATE
Issued at 645 PM CDT Sat Jun 28 2025

Isolated to scattered showers and a few rumbles of thunder can
be found over the forecast area at this time. With CIN
increasing across western and central North Dakota, further
strong to severe storms such as those previously found over the
James River Valley this afternoon are not generally anticipated
this evening. Showers are generally anticipated to diminish
across the forecast area through the mid to late evening. For
forecast updates, have blended in the latest satellite imagery
and model runs into in the sky cover. Overall, the forecast
remains on track.

&&

.DISCUSSION...
Issued at 216 PM CDT Sat Jun 28 2025

Currently, a cold front was situated from far northeast ND into
the James River Valley. A very unstable airmass is situated over
eastern ND, with a finger of instability extending back
southwest into far south central ND. Effective shear in the
northern JRV is around 25 knots, but does increase to 40-50
knots over south central ND. An isolated severe thunderstorm has
developed over far northeast Foster county, and into southwest
Eddy county. Another storm had developed a little northeast of
Jamestown. Effective shear will be increasing later this
afternoon and into this evening. We could see a few hours,
through around 00 UTC where a strong to severe thunderstorm is
possible, mainly over the JRV. As the cold front moves east and
we lose our strong daytime heating, the severe threat will
subside. Back to the west, convection has developed over far
northeast Wyoming into west central SD. This is within an area
of ascent ahead of a shortwave over southeast Montana.
Convection is expected to expand over western SD tonight and
track to the east. At this time, it appears the best forcing
will remain south of the border, but we continue to maintain a
chance of thunderstorms along the SD border tonight.

Sunday we cool off and dry out. Highs are expected to range from
the upper 70s north to the mid 80s south. A strong upper level
jet beneath a digging upper trough should provide enough support
to keep a chance of showers and thunderstorms along the
International Border. Severe storms are not expected Sunday.

Monday and Tuesday are expected to be mostly dry with highs
mainly in the 70s Monday and climbing into the 80s Tuesday. An
isolated shower or thunderstorm can not be ruled out in far
eastern portions of central ND due to the position of the
digging upper trough.

A progressive upper flow is in store for the middle through the
end of the work week with periodic chances of thunderstorms.
Although there isn`t currently a strong signal for severe
weather during this timeframe, given the time of year, daily
highs in the 80s and dewpoint into the 60s, strong to severe
storms can not be ruled out.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1258 AM CDT Sun Jun 29 2025

Isolated showers and perhaps an occasional thunderstorm are
possible overnight, primarily across southern North Dakota.
Additional scattered showers could move into northern North
Dakota Sunday evening. The probability of RA is not high enough
to mention in any TAFs at this time. VFR conditions are
expected to prevail through the forecast period. West-northwest
winds will increase to around 15-20 kts on Sunday, with gusts
as high as 30 kts across the north.

&&

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

&&

$$

UPDATE...Hollan
DISCUSSION...TWH
AVIATION...Hollan