051
FXUS63 KBIS 172052
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
352 PM CDT Sun Aug 17 2025

.KEY MESSAGES...

- Isolated to scattered showers and thunderstorms in the east
  through this evening, then isolated thunderstorms possible across
  the west tonight. The threat for severe weather is low.

- Patchy to areas of fog possible tonight into Monday morning.

- Isolated thunderstorms possible Monday through Monday evening.
  A strong to severe storm is possible across south central
  North Dakota with the main hazards being hail to the size of
  ping pong ball and wind gusts to 60 mph.

- Warming and dry trend expected through mid week. Some moderate
  heat impacts are possible.

&&

.DISCUSSION...
Issued at 352 PM CDT Sun Aug 17 2025

Upper level wave will push eastward and out of the state
tonight. Weak instability close to this wave could bring some
shower and thunderstorm activity across the east through this
evening. Being displaced from the wave combined with a lack of
shear, severe weather is not expected. Some CAMs have isolated
thunderstorm activity in the west overnight tonight along an
axis of instability. The lift for this looks limited, thus just
put in slight chances. If a storm can develop, modest shear
could bring a strong storm although the chance for severe
weather looks low. Winds will become calm tonight and with
lingering high dewpoints will bring RH values near 100%. This
could bring patchy to areas of fog to much of the CWA tonight
into Monday morning. Lows tonight will generally be in the mid
50s to mid 60s. The axis of instability moves over central ND on
Monday. A weak warm front also looks to set up Monday warming
temperatures back into the 80s for most areas with light winds
also expected. Either weak disturbances in the westerly flow
aloft or this frontal boundary at the surface could bring
isolated thunderstorms in the axis of high cape. Either one of
these disturbances would provide weak lift, thus the confidence
in thunderstorm formation is low. The potential is there for an
isolated severe storm if one can develop. SPC currently has a
Marginal Risk (level 1 of 5) in south central portions. CAPE is
high yet shear is modest. Storm mode would be multi cluster to
perhaps supercell. Thus the main hazards would be ping pong ball
size hail and 60 mph winds. Monday night, thunderstorm activity
will diminish and another night of light winds and high RH
values could return patchy to areas of fog. Given the similar
setup to tonight have added fog mention in for Monday night into
Tuesday morning as well.

A broad ridge aloft then looks to settle in over the state
Tuesday. This will bring further warming temperatures in the 80s
to perhaps 90s in the west. Heat Risk could even reach the
moderate level in some western areas. Even with some afternoon
instability, ridge aloft should cap any chances for
thunderstorms Tuesday. After a mild and dry night Tuesday night,
further warming and generally dry conditions will be expected on
Wednesday. Widespread mid 80s to mid 90s are forecast, with
perhaps some upper 90s in the west. This could bring more
widespread moderate to perhaps isolated major Heat Risk across
the CWA. Breezy southerly winds may also be found, as well as
some lower RH in the west. Fuels are likely too green for any
fire danger across the area. Surface low and perhaps a cold
front could return shower and thunderstorm chances Wednesday
night into Thursday morning. Thunderstorm activity could then
linger into Thursday with some cooler temperatures possible in
the north behind the mentioned front. Depending on timing of
this front there could be at least some isolated severe weather
chances as well.

Late next week into next weekend looks mainly dry and cool as
northwest flow is forecast to remain across the area. Cooler
highs in the 70s with lows in the 40s and 50s are forecast.
Perhaps some breezy northwest winds may also be found in this
pattern next weekend. These temps and winds are dependent on
how this northwest flow pattern sets up, although NBM
temperatures spreads are currently small indicating higher
confidence in this pattern change.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1259 PM CDT Sun Aug 17 2025

Isolated showers and thunderstorms may still be found through
this afternoon across central and eastern portions, with perhaps
some isolated showers and thunderstorms across western portions
tonight. Confidence was to low to include precipitation mention
in TAFs at this time. Low clouds may linger today for most
sites, with some improvement forecast in the west. These low
clouds may then return tonight into Monday morning for most
sites. These clouds could have MVFR to IFR ceilings at times.
Easterly winds will also become light and variable tonight into
Monday morning. Light winds and increased humidity could also
bring some fog tonight into Monday morning, but confidence was
too low to include in the TAFs at this time.

&&

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

&&

$$

DISCUSSION...Anglin
AVIATION...Anglin