421
FXUS63 KBIS 171734
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1234 PM CDT Mon Aug 17 2026

.KEY MESSAGES...

- Low chances (20-30%) for showers and thunderstorms today.
  Isolated severe storms (level 1 out of 5) are possible in the
  southern James River Valley this afternoon.

- Low to medium chances (20-40%) for showers and isolated
  thunderstorms tonight. Severe weather is not expected.

- Low to medium chances (20-40%) for hit and miss showers and
  thunderstorms continue Tuesday through Wednesday, then only
  low chances (20%) late in the work week.

- Seasonable temperatures are expected this week.

&&

.UPDATE...
Issued at 1226 PM CDT Mon Aug 17 2026

Embedded mid level impulses in quasi-zonal flow aloft coupled
with weak instability will contribute to a chance for showers
and a few thunderstorms this afternoon and evening across
western and central North Dakota. Uncertainty is high for any
given location, so opted to keep POPs on the low side (20-30%).
Main update with this forecast iteration was to POPs and cloud
cover based on latest trends. All other forecast elements remain
on track.

UPDATE
Issued at 944 AM CDT Mon Aug 17 2026

The forecast for today remains on track. Main change was to
trend SKY and POPs with latest imagery and latest model output.

UPDATE
Issued at 552 AM CDT Mon Aug 17 2026

A small area of thunderstorms has developed just north of
Minot, otherwise it was clear to partly cloudy across western
and central ND early this morning. Made some minor adjustments
to pops and sky cover based on latest radar and satellite
imagery. Wouldn`t be surprised to see at least a little more
development through the morning as the cold front pushes farther
south and upper level instability increases.

&&

.DISCUSSION...
Issued at 221 AM CDT Mon Aug 17 2026

Currently, weak low pressure was located over the area, ahead of
an approaching cold front dropping south from Canada. Skies were
partly cloudy and last nights evening convection has mostly
dissipated except for an isolated shower over northwest ND. We
remain within a northwest upper level flow. Although modest at
best, elevated instability remains over the area with modest
shear as well. Short term guidance has been overdoing the
overnight convection and continues so. May take a look and see
how the northwest convection is going in a bit and if not much
has changed, drop from chance to slight chance early this
morning. With that said, think there is a chance of showers and
isolated thunderstorms yet this morning, but probably more like
mid to late morning as elevated instability and bulk shear aloft
continue to increase. Forecast NAM soundings from Dickinson to
Bismarck and Jamestown indicate 1000-1500 J/kg of SBCape with
30-40kts of bulk shear and little CIN, late this morning, then
instability drop pretty quick this afternoon. If you go down to
Ashley, instability increases to around 2000 J/kg with 35 to 40
knots of shear late morning, before also losing instability as
drier air moves in this afternoon. SPC has pulled the marginal
risk of severe storms (that was east of the forecast area) back
west into the far southern James River Valley. Think there is a
small window late morning into the early afternoon for a
stronger to possibly severe storm here. The main hazards would
be quarter sized hail and 60 mph winds.

After early this afternoon, the threat for severe storms looks
to be over for a while. At the surface high pressure builds over
the area tonight, but jet energy over the area may provide
enough forcing for scattered showers and isolated thunderstorms
tonight into Tuesday, with another wave bringing low chances for
scattered showers and isolated thunderstorms on Wednesday.
Severe storms are not expected at this time Tuesday through
Wednesday.

Upper level ridging over the western U.S west amplifies and
pushes east Wednesday through Friday. Northwest flow remains
over the area so a low threat for a hit or miss thunderstorm
will remain, but overall, precipitation chances will remain low
for the second half of the work week.

Temperatures remain seasonable through the forecast period.
High temperatures will generally range from the mid 70s to mid
80s. A little cooler on Tuesday and a little warmer on Thursday.
Forecast lows are expected to range from the mid 40s to mid
50s. Again, a little cooler on Tuesday, and with some upper 50s
to lower 60s later in the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1226 PM CDT Mon Aug 17 2026

A cold front will drop southeast through the area today. Winds
will shift to the northwest 10 to 15 knots behind the front,
with a slight chance of a shower or thunderstorm this afternoon
and evening. Uncertainty was too high to mention in any most
individual TAFs at this time, though did go with a PROB30 for
KXWA this afternoon with showers upstream of this terminal now.
Any shower or storm that does develop may produce locally gusty
and erratic winds. Winds turn north to northeast later today
then become light this evening. Another chance of showers and
thunderstorms mainly west and south tonight, but again,
probabilities too low for even a PROB30.

&&

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

&&

$$

UPDATE...NH
DISCUSSION...TWH
AVIATION...NH