Silva, North Dakota Weather Forecast Discussion

623
FXUS63 KBIS 091740
AFDBIS
Area Forecast Discussion
National Weather Service Bismarck ND
1240 PM CDT Tue Sep 9 2025
.KEY MESSAGES...
- Above normal temperatures expected through the work week.
- Mostly dry with smoky skies through Wednesday, then low to
  medium chances for showers and storms late Wednesday through
  Friday.
- Higher chances for rain across the western half of the state
  this weekend, with medium chances for at least half an inch of
  rain.
&&
.UPDATE...
Issued at 1235 PM CDT Tue Sep 9 2025
Clear and quiet weather continues across the region with no
updates needed at this time. Temperatures continue to warm into
the mid 70s to lower 80s this afternoon. Low clouds continue to
move out of the James River Valley.
UPDATE
Issued at 949 AM CDT Tue Sep 9 2025
Fog continues to clear across the region as temperatures warm
up. The weather remain fairly quiet, thus no updates are needed
at this time.
UPDATE
Issued at 639 AM CDT Tue Sep 9 2025
Satellite, surface observations, and webcams show some patchy fog,
occasionally dense, across central North Dakota. But the fog is not
nearly as widespread nor as dense as model guidance had been
indicating, likely on account of greater coverage of mid to high
clouds. Otherwise, the forecast for today remains on track.
&&
.DISCUSSION...
Issued at 432 AM CDT Tue Sep 9 2025
Broad northwest flow aloft lies over the Northern Plains early this
morning with weak flow at the surface. The cyclonic flow has
maintained scattered to broken clouds through much of the night, and
a thicker anvil shield eminating from a cluster of stronger
thunderstorms near Aberdeen has entered the southern James River
Valley. These clouds are likely preventing a more widespread dense
fog event as had been advertised by numerous models. However, any
area that ends up in a clear pocket from south central North Dakota
to the James River Valley could see a period of dense fog through
the mid morning.
From today through Wednesday, an upper level ridge is forecast to
build over the Northern High Plains and slide eastward. High
temperatures each day are projected to remain near to slightly above
normal in the mid 70s to mid 80s, with a shallower boundary layer
and thicker smoke aloft inhibiting a stronger warmup. An increasing
southeasterly flow underneath the ridge will bring breezy conditions
to western North Dakota on Wednesday. After a period of anticipated
dry weather through Wednesday afternoon, a large upper low spinning
over northern California will begin to send shortwave energy
northeastward, bringing chances for showers and thunderstorms back
into the region Wednesday night. There is strong ensemble consensus
that the synoptic wave pattern will take on positive tilt by the end
of the work week, resulting in an active southwest flow over our
area. The persistent southerly return flow underneath will keep
temperatures mostly above normal Thursday and Friday, and bring in
seasonably high dewpoints in the 60s. There looks to be at least a
low potential for strong to marginally severe storms Thursday and
Friday with ensemble mean MUCAPE around 2000 J/kg, but deep layer
shear is presently only forecast around 20-30 kts.
Ensemble cluster analysis shows high confidence that the upstream
longwave trough and its embedded upper level circulations will take
on a negative tilt heading into the weekend, with the heart of DCVA
swinging into the western and central Dakotas. The NBM in turn
presents its highest chances for rain late Friday night through
Saturday night, which are still only around 20 percent in the Turtle
Mountains area but increase to around 70 percent in southwest North
Dakota. While the entire weekend is unlikely to be a washout, the
NBM does show medium chances for at least half an inch of rain along
and west of Highway 83 Saturday through Sunday. Furthermore, the
ECMWF EFI shows a signal for anomalous QPF centered over southwest
ND/northwest SD, and both precipitable water and low level specific
humidity are forecast to be in the 99th percentile to climatological
maximum range. There will likely be enough CAPE to support at least
some daytime thunderstorms each day this weekend, but there is
greater uncertainty in the shear, and therefore strong to severe
storm outlook. The increased chances for rain and associated cloud
cover lower the high temperature forecast for the weekend, but it is
still at near normal values in the 70s, albeit with a larger spread
in the median percentile distribution.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1235 PM CDT Tue Sep 9 2025
VFR conditions will continue across the region this afternoon.
Winds will be light and variable switching to southeasterly
early tomorrow morning. Breezy winds are expected across the
west tomorrow afternoon.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Hollan/Johnson
DISCUSSION...Hollan
AVIATION...Johnson

NWS BIS Office Area Forecast Discussion