466
FXUS63 KBIS 260324
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1024 PM CDT Wed Jun 25 2025

.KEY MESSAGES...

- An isolated thunderstorm is possible across the west tonight.
  Patchy fog may also form tonight into Thursday morning.

- Isolated strong to severe thunderstorms are possible in the
  far northwest on Thursday.

- Isolated to scattered severe thunderstorms are possible on
  Friday over most of western and all of central and eastern
  North Dakota. All hazards are possible.

&&

.UPDATE...
Issued at 1024 PM CDT Wed Jun 25 2025

Remnants of thunderstorms in Montana from earlier this evening
are now pushing across southern North Dakota. The chance for
severe weather has diminished as instability is limited.
However, there could be some isolated thunderstorms in the west
tonight with lingering elevated instability and modest mid
level lapse rates. Look for the wave associated with this wave
to push eastward tonight bringing some isolated to scattered
showers. Abundant low level moisture could also bring some low
clouds and perhaps fog tonight into Thursday morning. Overall
the forecast remains on track, yet made some updates to PoPs and
weather types to limit thunder mention.

UPDATE
Issued at 657 PM CDT Wed Jun 25 2025

Strong to severe thunderstorms in Montana are getting close to
ND, with one severe storm currently in Bowman county. The rest
of the evening will see decent instability in the west, with
decent shear in the southwest. The wave associated with this
convection may cause limited lift through the evening, keeping
the severe thunderstorm threat limited. The shear vector is well
aligned for some isolated supercells, bringing hail to golf
balls and winds to 60 mph as the main threat. Overall made some
minor changes to PoPs based on current radar trends.

&&

.DISCUSSION...
Issued at 202 PM CDT Wed Jun 25 2025

Showers have exited the James River Valley. Isolated showers and
a few thunderstorms remain across the far north and continue to
track off to the north and east. Farther to the west, scattered
thunderstorms are developing over northeast Montana in an area
of moderate instability but generally weak shear. Better shear
is situated farther east, along the ND/MT border and into
central ND. The main question for late this afternoon/evening is
with a generally slow eastward propagation, will these storms
catch up with the better Shear to the east. Current SPC
Mesoanalysis shows the better effective shear will linger over
the southwest this evening, which northeast convection could
catch up to. Also developing convection later this afternoon
over southeast Montana into western South Dakota and NE Wyoming
may move into this area of higher bulk shear over southwest ND.
Confidence is relatively low, but should either area of
convection hold together long enough, we could see a few strong
to possibly severe storms in southwest ND. Currently, it looks
like the highest instability remains over Montana, and the
higher shear remains over southwest ND. Convection that
develops over Montana and holds together to make it into ND
could be capable of producing hail to the size of ping pong
balls and 60 mph winds.

On Thursday and Friday, we remain within a broad southwest
upper flow. Thursday, a frontal boundary becomes established
over eastern Montana and pushes into western North Dakota, most
likely Thursday evening, but possibly as early as the late
afternoon in the far west. We will once again become moderately
unstable with MLCAPE of 1000-2000 J/KG but only modest bulk
shear of 20 to 30 knots. Isolated thunderstorms are possible
along the surface boundary Thursday afternoon, which currently
looks to be over eastern Montana. There could be some discrete
supercells initially, but as convection moves into North Dakota
the atmosphere becomes more capped. Supercells would normally
necessitate larger hail, but with the current forecast position
of the boundary, will limit the hail to Quarter size, as was
the case with the previous shift. CAMS also currently dissipate
convection as it pushes into North Dakota. Will need to monitor
however.

By Friday, it looks like moderate to possibly strong
instability is forecast to develop across much of western and
central North Dakota with sufficient deep layer shear for
supercells to develop as mid-level flow strengthens. At this
time it looks like very large hail and damaging winds would be
the main threat. A tornado or two can not be ruled out however.
On Saturday the severe potential may linger over south central
and into eastern North Dakota, with another day of strong
instability and strong shear. The eventual location of the
surface boundary will play a big part in the amount and
intensity of thunderstorm activity over our forecast area, with
a better severe potential probably farther to our south and
east, but stay tuned as this may change.

Drier and cooler conditions return late in the weekend and into
early next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 657 PM CDT Wed Jun 25 2025

Widespread MVFR to IFR conditions expected tonight through
Thursday morning, with conditions improving through the day
Thursday. This evening, a few showers and thunderstorms may
enter into western North Dakota this evening, then become
isolated through tonight. Confidence in showers or thunderstorms
at TAF sites is too low to include at this time. A push of low
level moisture will bring low clouds and perhaps fog tonight
through Thursday morning. This is expected to bring MVFR to IFR
conditions for most sites, with perhaps LIFR conditions in any
fog that may form. Most sites are then expected to see ceilings
and visibility improve to MVFR or perhaps low VFR conditions
through the day Thursday. Some showers and thunderstorms may
return late in the TAF period across the west.

&&

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

&&

$$

UPDATE...Anglin
DISCUSSION...TWH
AVIATION...Anglin