368
FXUS63 KBIS 201439
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
939 AM CDT Fri Sep 20 2024

.KEY MESSAGES...

- Expect low to medium chances (20 to 40 percent) for showers
  late this afternoon and into the night. The best chances will
  mainly be north of the Highway 200 corridor.

- After warmer temperatures today, a cooling trend is forecast
  through the weekend and into early next week. Some areas of
  frost are possible Sunday morning across the west.

&&

.UPDATE...
Issued at 939 AM CDT Fri Sep 20 2024

Clear skies and generally calm winds continue across the area
this morning, with temperatures beginning to slowly rise. No
major changes to the forecast were made with this update.

.UPDATE...
Issued at 610 AM CDT Fri Sep 20 2024

A quiet Friday morning continues across western and central
North Dakota with temperatures mainly in the mid 40s to mid 50s.
No major changes were needed for this update. Just blended in
the latest observations to the going forecast.

&&

.DISCUSSION...
Issued at 300 AM CDT Fri Sep 20 2024

Progressive low amplitude ridging will quickly cross the state
this morning, giving way to southwest flow aloft ahead of an
approaching trough from the west. Temperatures will be a bit
warmer today with highs forecast to range from the low to mid
70s north to the low to mid 80s south. Winds will be lighter
today out of the southwest, but some breezy conditions may hang
around across the northwest.

The upper trough axis will approach the Montana/North Dakota
border this evening, along with increasing cloud cover. At the
surface, low pressure will move into the southern Canadian
Prairies with a cold front extending to the south. This cold
front will cross the state from west to east through the night,
shifting winds to out of the northwest. Synoptic forcing from
the longwave trough will interact with the low and cold front,
providing enough lift for some scattered showers (20 to 40
percent chance). The best chances will be across the north
closer to the synoptic forcing, generally along and north of the
Highway 200 corridor. While instability is forecast to be weak,
RAP soundings are suggesting at least a couple hundred J/kg of
MUCAPE across the north. So there will be at least low chances
for a rumble of thunder or two.

Most of the precipitation will move out to the northeast by
late Saturday morning or early afternoon as the trough axis
moves into the Red River Valley. Winds will be on the increase
overnight and into Saturday morning behind the cold front. Most
guidance is suggesting that strong pressure rises and strong
cold air advection should filter in behind the front, along with
steep low level lapse rates (especially for the time of day).
All the ingredients are shaping up for a breezy to windy
Saturday (winds out of the northwest). For now, it appears the
strongest sustained winds will be up to around 27 mph with gusts
to 40 mph. If guidance continues to increase, we could
eventually need a Wind Advisory so it will be something to
watch. It will also be much cooler behind the front on Saturday
with highs expected to only be in the 60s across all of western
and central North Dakota.

Saturday night into Sunday morning should be coldest time frame
of the forecast period. Winds will be on the decrease under a
mostly clear sky as high pressure dominates the weather
pattern. Lows are forecast to dip into the mid 30s to the lower
40s. Some lower 30s are not out of the question across the usual
low spots over the southwest. Areas of frost will be possible
by Sunday morning across portions of the west.

We will be in northwest flow aloft through much of the day on
Sunday as a ridge axis approaches from the west. Highs will be
just a touch warmer with most areas still in the 60s. However, a
few lower 70s may be possible across the west. Winds will also
be much lighter on Sunday. The next trough moves through on
Monday which looks to be dry for now. Highs will generally range
from the mid 60s to the mid 70 on Monday and Tuesday with some
upper 70s and lower 80s returning to the forecast by mid to
late week as a higher amplitude ridge axis moves through the
region.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 610 AM CDT Fri Sep 20 2024

VFR conditions are expected through the period. A cold front
will move across the state late today and tonight, shifting
winds from out of the southwest to out of the northwest.
Northwest winds will become breezy Saturday morning. Isolated to
scattered showers will also be possible along and behind the
aforementioned front late this afternoon and tonight, but exact
locations remain unclear at this time. The best chances will
generally be across the north, potentially impacting KXWA or
KMOT.

&&

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

&&

$$

UPDATE...Besson
DISCUSSION...ZH
AVIATION...ZH