Area Forecast Discussion
Issued by NWS Bismarck, ND

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FXUS63 KBIS 120948
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
448 AM CDT Fri Apr 12 2024

.KEY MESSAGES...

- Warmer today and continued mild through the weekend and to
  start the work week.


- Increasing rain chances next week, especially Monday night and
  Tuesday, with greatest chances (60 to 80 percent) coming to
  central and into eastern North Dakota.

- Colder temperatures mid to late in the work week with
  lingering chances (30 to 60 percent) for rain and snow.

&&

.DISCUSSION...
Issued at 212 AM CDT Fri Apr 12 2024

Currently, high pressure is situated over central North Dakota
with low pressure off to the east and west. Skies were mostly
clear, with some high clouds approaching from the west.

Today and through the weekend our weather will be influenced by
a northern stream zonal to slightly northwest flow pattern.
Upper level ridging early today will be flattened by a
shortwave tracking across southern Canada. Mid level forcing
combined with warm advection ahead of a warm front may produce a
few showers across the north tonight into Saturday. A weak cold
front will move through the area Saturday with little more than
a wind shift expected. Surface flow will turn northerly late
Saturday into early Sunday, then eventually easterly as the
surface high behind the front slides east of the area.

Overall we are looking for a nice weekend ahead. Highs, mainly
in the 60s today, will climb into the upper 60s to upper 70s
Saturday, and only dropping slightly on Sunday. There will be
some small precipitation chances mainly across the north
tonight into Saturday (mentioned above). Winds will be breezy
today in the west, with breezy conditions sliding east
overnight. Lighter winds are then expected through the weekend.

While we are enjoying our weekend an upper level low off the
West Coast early moves onshore Sunday and then into the Southern
Rockies by early Monday. In addition, a strong northern stream
wave develops into another upper level low over western Canada
by early Monday. This will set the stage for an interesting
stretch of weather next week.

Initially Sunday night into early Monday, warm advection ahead
of developing low pressure in the lee of the Rockies, combined
with one last northern stream wave, could produce some showers
late in the day Sunday through Sunday night. The potential for
thunder looks minimal at this time but there is some elevated
instability and we are getting some low thunder probabilities.

The main show (precipitation wise) will be Monday through
Tuesday night as the southern system moves into the Great Lakes
Region and the northern stream upper low drops into the Northern
Rockies/Northern Plains region. The most favored timeframe for
thunder looks to be Monday afternoon through Tuesday morning.
Deterministic models show some elevated instability lifting into
southern ND Monday afternoon, and remaining over the far south
central/southeast into early Tuesday. Initially there is some
dry air remaining as we see upper level ridging over southern ND
ahead of the strong southern stream low. Eventually this ridging
gets pushed north and east, out of the area, but we also see
possible ridging behind this low and ahead of the northern
stream low. Therefore, a lot of uncertainty remains in how much
precipitation we see. The raw model ensemble surface low
positions are fairly well clustered tracking the low from
northeast Colorado, across Nebraska and into southern Minnesota.
The GEFS members may be a little north of the ECMWF. Latest
 runs are both a bit farther south than the ensembles. If we
are able to get some elevated convection, we could definitely
see some nice rain accumulations. If we don`t get convection, I
wonder how widespread the non-convective precipitation will be.
A lot of that will probably depend on the interaction, or lack
thereof between the northern and southern stream systems.

A cluster analysis centered on 7 PM Monday through 7 PM Tuesday
yields, from what I can tell, four separate solutions. Two with
more separation between the two systems (you can see the ridging
between them) and two without. of these two scenarios, there is
both a stronger and a weaker southern southern low. There are
also differences between the strength/position of the northern
stream low. You could possibly try and group these together
somehow, but the main thing I can see is that between the four
clusters, there is only a 10 percent difference in members
between the cluster with the most members and the one with the
least. If you could combine three somehow, you could maybe get a
better separation between solutions, but I can`t really see that
at this time. Thus at most you, if you go with two clusters you
get a 57/43 favored solution. Another thing is that if you look
at the 24 hour qpf, at 7 PM Tuesday, each cluster gives you a
completely different solutions. If anything, the south and east
would probably be favored, just looking at the 24 hour qpf from
the clusters.

As we get beyond Tuesday night, two things are apparent. Qpf is
much lighter and temperatures are much colder. Currently, the
NBM is producing high chance to likely precipitation chances
Wednesday through the day on Thursday, tapering to chance pops
Thursday night and slight chance pops Friday. Temperatures are
such that any precipitation that falls Wednesday night or early
Thursday would be at least a rain/snow mix, and possibly all
snow north and west. By Thursday evening through Friday morning,
any precipitation would likely be snow. Morning lows Thursday
and Friday will be mainly in the 20s and daytime highs in the
30s to mid 40s, quite a difference from what we will see this
weekend, so enjoy the weekend. Any accumulating snow would
probably be confined to the west and north.




&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1222 AM CDT Fri Apr 12 2024

VFR conditions are expected through the 06Z TAF period. Light
and variable winds overnight will become southerly early Friday
morning in the west, by mid morning central and in the afternoon
James River Valley. Winds will become moderate 15-25 knots in
the west and central by afternoon.

&&

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

&&

$$

DISCUSSION...TWH
AVIATION...TWH


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