256
FXUS63 KBIS 220330
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
930 PM CST Thu Nov 21 2024

.KEY MESSAGES...

- Below average temperatures through next week with highs
  mostly in the 20s and 30s, and lows mostly in the single
  digits to teens above zero. Even colder temperatures possible
  to start next week, though uncertainty remains higher.

- A 80 percent chance of additional accumulating snow this
  weekend in the north, with much lower chances south. There is
  a 50 percent chance of at least 4 inches of snow mainly along
  the Canadian Border.

&&

.UPDATE...
Issued at 930 PM CST Thu Nov 21 2024

Patchy fog has developed over portions of north central into
northwestern North Dakota, mainly along the northern shore of
Lake Sakakawea. For this forecast update, has added in patchy
fog a little earlier than previously forecast to account for
this development. With dewpoint depressions and winds rapidly
diminishing all along the Missouri River south of the lake, more
patchy fog is anticipated to develop later this evening.
Otherwise, we have slightly adjusted the sky grids to account
for the latest satellite trends.

UPDATE
Issued at 545 PM CST Thu Nov 21 2024

Quiet weather is found over western and central North Dakota
this evening. We have made some minor updates to the sky grids
to account for the latest trends with the high based stratus
moving in across the west. Otherwise, the forecast remains on
track.

&&

.DISCUSSION...
Issued at 112 PM CST Thu Nov 21 2024

A quasi-shortwave ridge and higher pressure is over us
currently. A lot of moisture from the atmospheric river event
happening on the west coast is crating all the clouds in the
state. Tonight we lowered temperatures a few degrees using the
25th percentile of the NBM since it will be light winds with
snowpack. With the cloud cover being mostly the high cirrus,
strong radiational cooling should take effect.

Our next snow making system will move in Friday night. A far
Northern Rockies low will slide east off the mountains. The
latest run of the models now has the path north of North
Dakota. The north will still see snow, but the amounts have
changed. Now there seems to be no possibility of 6 inches. Just
the northern tier of counties have a 50 percent chance of 4
inches. More uncertainty now exist. Will it shift again?
Different models have a closed low at 500mb and some have an
open wave. So the intensity is also now in question. We will
continue to wait and see if we need a Winter Weather Advisory
for those few counties or not. Sunday and Monday look breezy
with a tightened pressure gradient, so look for our coldest wind
chills yet.

Next week on the backside of this system northwest flow will
dominate, bringing much cooler below average temperatures.
Multiple shortwaves will also move through next week. These
could bring light snow, but nothing major. High temperatures
could be in the single digits, but the NBM spread is about 20
degrees for this time period. Low temperatures could be below
zero across the north all of next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 930 PM CST Thu Nov 21 2024

VFR ceilings and visibility are mainly expected through much of
the 00Z TAF period. MVFR to IFR ceilings will begin to move
into northwestern North Dakota late Friday afternoon, spreading
south and east to other terminals beyond the end of the TAF
period. Additionally, patchy fog is possible late tonight into
tomorrow morning along the Missouri River and across southern
North Dakota, though confidence is too low at the time of this
update to add visibility reductions to any given terminal.
Otherwise, light snow is possible across the Canadian Border
Friday morning. Light and variable winds are expected to
persist overnight, before organizing out of the north through
the afternoon on Friday.

&&

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

&&

$$

UPDATE...Adam
DISCUSSION...Smith
AVIATION...Adam