043
FXUS63 KBIS 061417
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
917 AM CDT Sun Apr 6 2025

.KEY MESSAGES...

- Dry through Monday, with below average temperatures east and
  near to above average temperatures west.

- There is a 20 to 40 percent chance of rain showers Tuesday
  through Wednesday.

- Above normal temperatures favored for the second half of the
  week, especially beginning on Friday.

&&

.UPDATE...
Issued at 915 AM CDT Sun Apr 6 2025

No major changes were needed with this forecast update. Mid/high
clouds continue moving through the state from the north, with
some small adjustments to cloud coverage being made.

UPDATE
Issued at 636 AM CDT Sun Apr 6 2025

The forecast for today remains on track. Mid to high clouds
streaming south through the region this morning will give way to
a mostly sunny sky this afternoon. Current conditions and trends
were blended in for this update.

&&

.DISCUSSION...
Issued at 322 AM CDT Sun Apr 6 2025

The Northern Plains lie under northwest flow aloft early this
morning, with a downstream trough axis extending south of a Hudson
Bay low and a highly amplified upstream ridge over the far western
CONUS. At the surface, high pressure centered well to both the north
and south leave the local area in a broad and diffuse zonal trough.
Expect mid to high clouds passing through this morning with clearing
to follow in the afternoon as flow aloft turns more northerly. A
backdoor cold front will begin entering the state from the northeast
this afternoon and progress southwestward through the evening and
tonight, reach as far as the vicinity of the ND/MT border by Monday
morning. Surface high pressure trailing the cold front will extend
into the northern Red River Valley early Monday morning. During the
day Monday, the upstream upper level ridge will begin to shift
eastward with its axis projected to reach eastern Montana by Monday
evening. This will force the cold front to begin retreating as a
westward progressing warm front by late Monday, as well as induce a
strong southeasterly return flow between the the surface high and
upstream cyclogenesis over Alberta. This pattern gives us a dry
forecast through Monday, with much cooler temperatures in eastern
North Dakota compared to the west. Highs for today are expected to
range from the 40s to lower 60s, decreasing to the 30s to 50s on
Monday. Lows tonight will mainly be in the teens east to mid 20s far
west. It does not appear winds will become light enough in time for
a longer duration of strong radiational cooling to set up, and there
could also be some clouds trailing the backdoor cold front. This
should mostly prevent overnight temperatures from plummeting into
the single digits. A northeasterly breeze around 10 to 20 mph can be
expected as the cold front moves through this evening. Then on
Monday, the southeasterly return flow could reach sustained speeds
up to 25 mph in northwest North Dakota.

A series of shortwaves are forecast to flatten the upper ridge as
they dig into the Northern Plains Tuesday through Wednesday. Initial
height falls over a lee trough could promote scattered shower
development over western North Dakota Tuesday afternoon, shifting
eastward through the evening. There is then growing model consensus
that the strongest shortwave will deepen over the region on
Wednesday, though uncertainty in the finer details of location and
amplitude is evident. This general deep layer cyclonic pattern
brings a 20 to 40 percent chance of rain showers across all of
western and central North Dakota on Wednesday. For both Tuesday and
Wednesday, there is a low potential for weak CAPE up to a few
hundred J/kg that could allow a few thundershowers to develop, but
the overall probability of thunder is not yet high enough for it to
be introduced to the forecast. The preceding upper ridge/warm front
brings warmer temperatures into the forecast for Tuesday and
Wednesday. Tuesday should see highs recover around 10 degrees across
the board, from the 40s east to lower 60s southwest. This is
followed by a forecast of mid 50 to lower 60s across all of western
and central North Dakota on Wednesday, with very low spread in the
NBM maximum temperature distribution. The forecast for Thursday has
shifted slightly cooler than previous iterations on account of the
strength of the more potent shortwave from Wednesday digging south.
The NBM has cooled its high temperature projection for Thursday into
the 50s, but that is closer to the 25th percentile of its
distribution.

Ensembles favor strong upper level ridging shifting into the
Northern Plains on Friday that may be followed by a transition to an
active zonal flow pattern at some point next weekend. This brings
well above normal temperatures into the forecast for Friday and
Saturday when widespread 60s are favored for highs, and there is at
least a 50 percent chance of reaching the 70s in the southwest. The
NBM maintains a dry forecast on Friday, followed only by a 10 to 20
percent chance of precipitation through the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 636 AM CDT Sun Apr 6 2025

VFR conditions are expected through the forecast period. Winds
will gradually turn from westerly around 5-10 kts this morning
to northeasterly around 10-15 kts through the afternoon and
evening, then become more east to southeast across the western
half of the state later tonight.

&&

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

&&

$$

UPDATE...Besson
DISCUSSION...Hollan
AVIATION...Hollan