491
FXUS63 KBIS 151656
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1156 AM CDT Sun Jun 15 2025

.KEY MESSAGES...

- Potential for severe storms late this afternoon through tonight,
  with greatest chances over southwestern and parts of south
  central North Dakota.

- Active pattern with periodic shower and thunderstorm chances
  during the workweek into next weekend. A few severe storms are
  possible, more notably later in the week.

- Overall temperatures remain around average for this time of
  year.

&&

.UPDATE...
Issued at 1135 AM CDT Sun Jun 15 2025

Convection is still bubbling around the James River Valley,
but looks to be exiting for the most part. Otherwise, remnants
of convection over northeast Montana earlier this morning
continues to push through western ND. There is some congested
cumulus and orphaned anvils over west central ND where there is
some increasing instability aloft on top of a currently stable
boundary layer. Overall, we do expect a relative minimum in
convection as we move through the afternoon hours. However,
given the instability and a being within a southwest upper flow,
even though we see building upper heights, can`t rule out an
isolated thunderstorm. Generally went with some broad brushed
slight chance pops through much of the afternoon until we picked
up a blend of the NBM and ConsShort to depict the increasing
thunderstorm threat late afternoon and through the evening from
the west.

UPDATE
Issued at 917 AM CDT Sun Jun 15 2025

No significant changes to the going forecast. Currently,
convection associated with a weak shortwave and modest warm
advection over the James River Valley is tracking eastward. With
a nose of MUCape from eastern SD into the JRV would support
additional convection before exiting the JRV later this morning.
Back to the west, convection over NE Montana is dissipating as
it approaches the ND border. We`ll see how convection over
eastern Montana behaves as the impulse associated with it
pushes into ND. In general, we do expect it to struggle as upper
level ridging builds over the area ahead of a stronger wave
that will be the main culprit for convection later today and
tonight. Previous shift had a good handle on the ongoing
convection so just some minor tweaks to sky cover with this
update.

UPDATE
Issued at 657 AM CDT Sun Jun 15 2025

Two main areas of convection continue over our area, with one
over northwest North Dakota and the other along the South Dakota
border of south central North Dakota. CAMs are greatly
struggling with handling these, but it looks as if they should
keep moving along towards the east for the next couple of hours.
Precipitation chances therefore have been adjusted.

&&

.DISCUSSION...
Issued at 318 AM CDT Sun Jun 15 2025

Current surface analysis places low over the central Rockies
with high over northeast Ontario. Upper level analysis places
trough off the west coast with rather flat ridge centered over
the northern plains. A modest short wave pushing through the
ridge continues to bring convection to northeast Montana, while
an increasing low level jet has been increasing coverage of
convection over South Dakota, which is starting to nudge across
the state line into southwest/south central North Dakota.
Otherwise, light east/southeast low level flow continues to
usher moisture into the area, with some visibility reductions
noted over south central North Dakota/James River Valley.

For today, initial concern will be aforementioned storms that
area trying to lift into southern portions of our area thanks to
the low level jet. For now it appears that any severe should
remain south of the border where the stronger instability is
noted, but will have to keep an eye on this over the next few
hours to see if a stronger one tries to sneak into our area. In
the meantime, will also have to keep an eye on the activity
over northeast Montana which continues to slide to the east-
southeast and should approach our border around sunrise. CAMs
continue to struggle with how to handle this activity along with
the activity nudging in from South Dakota. Thereafter, a
variety of little short waves sliding through keeps low chances
for showers/possibly a storm in the forecast over much of the
area through the day.

As we push into late day into the evening hours, a rather stout
short wave deepens over Montana as it approaches our area. In
the meantime, light southeasterly low level flow continues to
gradually usher moisture into the area. By late afternoon/early
evening, CAPE values of around 2-2.5 kJ/kg are expected
throughout southwest and south central North Dakota, with
notably elevated 0-6km bulk shear values of around 45-50kts.
With the approaching wave and variety of boundaries expected
from earlier convection, the potential is there for some late
afternoon/early evening discrete storms to develop, in which
large hail will be the main threat. With that said, still
expecting the more widespread convection to initiate over the
higher terrain of Montana and push into the area later tonight,
and slide through overnight in more of a clustered storm mode
with strong winds being the main concern, especially if we were
to get an MCS to develop.

As we get into Monday the potential is there for this system to
still be passing through our area, with the possibly of severe
weather continuing. Some additional showers/storms may develop
again later in the day/evening, though with a diminished severe
threat.

As we go through the work week we remain in a pattern with a
variety of short waves passing through bringing a near daily
chance for showers and thunderstorms, typical for this time of
year. As for severe threat, latest machine-learning guidance
brings lesser chances for severe for Tuesday into Wednesday,
with increasing chances later in the week. Temperatures remain
seasonable.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1135 AM CDT Sun Jun 15 2025

Expect periods of MVFR ceilings early this afternoon, but
ceilings are expected to lift above MVFR around mid afternoon.
Later today thunderstorm chances will be on the increase from
west to east. Some of the storms may become severe, with large
hail and strong wind gusts, especially over southwest North
Dakota later this evening and overnight. In addition, ceilings
will again lower, especially over southern and eastern areas.
Areas of fog may also develop late tonight into Monday morning.

&&

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

&&

$$

UPDATE...TWH
DISCUSSION...JJS
AVIATION...TWH