Jamestown, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

569
FXUS63 KBIS 111953
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
253 PM CDT Sat Apr 11 2026

.KEY MESSAGES...

- Temperatures trend above normal for this weekend, along with
  breezy winds during the day.

- Rain showers, with a few thunderstorms, will be found at times
  this weekend into early next week.

- Active weather pattern continues next week, along with near
  normal temperatures.

&&

.DISCUSSION...
Issued at 253 PM CDT Sat Apr 11 2026

This afternoon, a deep trough and closed low were placed off the
California coast, leading to downstream southwest flow across
the Dakotas. At the surface, a broad area of low pressure was
analyzed over eastern Montana, with a moderately tight surface
pressure gradient across the forecast area that was producing
breezy southeasterly winds. There is also a large area of low
stratus that extends from the Turtle Mountains through the James
River Valley and east, and goes far enough west to be on the
edge of the Bismarck/Mandan area. Low confidence in the
progression of the western extent, but high-res guidance all
agrees on our eastern counties being socked in for the rest of
today and through tonight. Underneath this stratus are afternoon
temperatures in the 40s and occasionally some drizzle in the
eastern James River Valley. Meanwhile, western North Dakota has
plentiful sunshine and afternoon highs in the 60s and 70s.

Just upstream, we are already starting to see some scattered
convection develop with a shortwave and 300mb jet streak moving
through the mean southwest flow over Wyoming, with activity
expected to move into southwest North Dakota this evening before
expanding across the forecast area tonight. Carrying a broad 20
to 40 percent chance of showers and thunderstorms, with
deterministic guidance showing at most a few hundred j/kg of
instability available for some rumbles of thunder across the
west and central. The other main forecast concern tonight is fog
development across the eastern half of the state underneath the
low stratus, with patchy fog included in the gridded forecast
into Sunday morning.

Precipitation chances taper off Sunday morning as the upper
wave and attendant surface low exit to the northeast, with skies
clearing and winds turning more westerly and breezy. Sunday
looks like the warmest overall day of the period, with forecast
highs in the upper 50s north to the mid 70s south. We did opt to
skew up to NBM50 for forecast high temperatures and blended
down dew points just a touch, due to the west- northwest winds
forecast and the deterministic NBM being on the cool side of the
ensemble spread.

The next round of precipitation comes late Sunday through
Monday, as another wave ejects out of the trough base that will
be over the western CONUS. Some guidance wants to have a more
northern stream wave separate from the main trough, but
regardless, there`s decent ensemble agreement on precipitation
chances as latest NBM POPs are up to 60 to 80 percent across
western North Dakota on Monday. There are low to medium chances
for at least a quarter inch of QPF with this event, focused over
western North Dakota.

Temperatures stay seasonable Tuesday and Wednesday with not too
much wind, and low chances for rain focused on far southern
North Dakota as a few waves pass to our south. Focus then turns
to late in the week as a more substantial shortwave is progged
to move in from our west, bringing chances for rain and snow as
well as much cooler temperatures to end the work week. It is
worth noting all four ensemble clusters have at least some snow
associated with this system, and certainly more confidence in
the cooler air moving in, but plenty of details to be worked out
before then.

There are then hints of cooler than normal temperatures
continuing into the week 2 period and potentially beyond,
although average highs increase to the lower 60s by the end of
the month. The active pattern is also favored to continue at
least broadly across the region.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1253 PM CDT Sat Apr 11 2026

Widespread MVFR to IFR stratus deck is set in place over the
James River Valley, including KJMS, and has been expanding north
and west through the early afternoon, likely impacting KBIS for
the next few hours. Could be some areas of light rain or
drizzle underneath the low stratus as well. Expecting this to
continue through the night, with LIFR ceilings expected from the
Turtle Mountains through the James River Valley and fog
development overnight at KJMS, while terminals west should stay
mostly VFR, with the exception of potentially some lower
ceilings at KMOT/KBIS depending on how far west the stratus deck
expands. Breezy southeasterly winds will diminish tonight before
becoming westerly and breezy on Sunday. Rain showers are
possible this evening into Sunday morning, with PROB30 groups
included at KDIK and KMOT.

&&

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

&&

$$

DISCUSSION...Jones
AVIATION...Jones