668
FXUS63 KBIS 070247
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
947 PM CDT Fri Jun 6 2025

.KEY MESSAGES...

- Showers and thunderstorms on Saturday, with the highest
  chances north central (80 percent) and lowest chances
  southwest (20 percent). A few strong to severe thunderstorms
  are possible over south central and eastern North Dakota.

- Breezy to very windy conditions Saturday through Monday, with
  the strongest winds on Sunday.

&&

.UPDATE...
Issued at 940 PM CDT Fri Jun 6 2025

Diurnal cu has all but dissipated across western and central ND
this evening. There is some high level cloudiness pushing in
from the west, and expect an increase in mid-high clouds
tonight. Southerly winds have dropped off to around 5 to 10
mph. Winds will pick up in the west and north late tonight and
shift to the southwest ahead of the cold front that is forecast
to be approaching the far northwest corner of the state around
12 UTC. Only minor cosmetic changes were needed with the late
evening update. Text products will be transmitted shortly.

UPDATE
Issued at 631 PM CDT Fri Jun 6 2025

Only some minor adjustments to sky cover based on latest
satellite imagery and through the day Saturday for Aviation
purposes.

&&

.DISCUSSION...
Issued at 303 PM CDT Fri Jun 6 2025

This afternoon, broad cyclonic flow aloft dominated the synoptic
pattern, with an embedded shortwave trough placed over the Northern
Rockies area. At the surface, broad high pressure was centered over
the intersection of the Dakotas and Minnesota. Some scattered low
clouds are lingering across the south central and southeast, left
over from fog that lifted this morning. A few isolated showers
are ongoing across the southern James River Valley and
surrounding area, moving very slowly due to weak low- level
flow. Not a lot of forcing around but these are potentially from
a subtle upper level jet max, as well as mid- level vorticity
enhancement. A couple of brief funnel clouds have been reported
in northeast South Dakota from the showers there, and the SPC
mesoanalysis page does highlight the non-supercell tornado
parameter extending up into southeast North Dakota. Therefore,
cannot rule out a brief funnel with the activity ongoing in the
James River Valley, although any that develop would be weak and
unlikely to reach the ground.

HRRR smoke model continues to advertise on and off waves of smoke
aloft sweeping through the state tonight through Saturday, but still
little suggesting that smoke will be pulled down to the surface.
Primary impacts will be hazy or milky skies, but expecting
visibilities to stay near normal levels.

A deeper, closed low is progged to develop over the southern
Canadian Prairies tonight into Saturday, with the attendant cold
front moving through North Dakota through the day Saturday. Recent
CAMs runs are advertising scattered showers along and behind the
front, spreading across northern and central North Dakota through
the morning on Saturday. As the line expands east, there are some
indications of a second line of showers and thunderstorms from a
surface trough / secondary boundary close behind the initial cold
front. Some high-res guidance wants to have the stronger storms with
the second line, but unsure about the likelihood of this. We are
still carrying a mention of isolated severe thunderstorms (level 1
out of 5) across south central and eastern North Dakota. At this
point, not fully convinced we will end up with any severe storms
just because of how limited instability is in current deterministic
guidance, but we do have a tendency to get isolated severe wind
gusts out of weaker storms and even rain showers sometimes, as
stronger winds aloft get mixed down. Machine learning probabilities
for severe weather have trended down over the past day or two.

High temperatures on Saturday will range from around 70 northwest to
the lower 80s far south central. Highs in the northwest will be
earlier in the day than we typically see, before the front moves
through. Winds will be breezy across the area, southwesterly
ahead of the front and northwesterly behind the front.

As the closed low aloft deepens and sinks south Saturday night into
Sunday, winds will not diminish overnight much before increasing on
Sunday with a strong pressure gradient. The latest NBM has a 60 to
90 percent chance for wind gusts of at least 45 mph on Sunday, with
similar probabilities for sustained winds of at least 30 mph. At
this point, expecting we will need an advisory for the majority of,
if not all of, the forecast area for Sunday. It will also be
cooler in the post-frontal air mass, with highs mainly in the
60s. Scattered showers are possible through the day from the
cyclonic flow aloft, with higher chances east (50 to 60 percent)
compared to west (10 percent).

The aforementioned closed low slowly drifts east on Monday,
keeping winds breezy and temperatures still on the cool side,
with highs in the mid 60s to mid 70s. A brief ridge builds to
our west in the meantime, with temperatures warming into the
widespread 80s on Tuesday in response. Cluster analysis then
favors the ridge flattening through the rest of the work week,
with temperatures slowly cooling down to around average, and
widespread low to medium chances for showers and thunderstorms
late Tuesday night through Friday.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 631 PM CDT Fri Jun 6 2025

A cold front will move through the forecast area on Saturday.
This evening and overnight look for mainly scattered mid and
high clouds with a south to southeast surface flow 5-15 kts.
On Saturday a cold front will move through the area with winds
south to southwest ahead of the front increasing to 10 to 20
knots with some higher gusts. Behind the front, winds shift
northwest 20 to 30 its. Scattered to numerous shower and
isolated thunderstorms are expected behind the cold front with
the best chance for thunderstorms from north central into
eastern North Dakota. Locally higher wind gusts and brief MVFR
visibilities in heavy rain are possible in any thunderstorms
that develop.

&&

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

&&

$$

UPDATE...TWH
DISCUSSION...Jones
AVIATION...TWH