882
FXUS63 KBIS 200530
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1230 AM CDT Thu Jun 20 2024

.KEY MESSAGES...

- Hit or miss showers (20 to 30 percent) are possible through
  today. Better chances for showers and thunderstorms (40 to 70
  percent) return tonight through Saturday.

- A slow warming trend is expected heading into the weekend and
  early next week, with highs approaching the upper 80s and
  lower 90s by Monday.

&&

.UPDATE...
Issued at 1230 AM CDT Thu Jun 20 2024

No updates to the forecast were needed at this time. Isolated,
light radar returns linger over portions of the southwest and
north central, with a better band of showers skirting across the
northwest. There are some thunderstorms embedded in this line of
showers, though they continue to remain outside of our area and
have begun to diminish. Otherwise, scattered to broken mid
levels clouds continue to filter across the area and winds are
generally light out of the north. The forecast remains on track.


UPDATE
Issued at 909 PM CDT Wed Jun 19 2024

Isolated light radar returns continue over the northern third
of the forecast area. Overall, most of these returns are dry
(virga), although an occasional light shower or sprinkle is
possible under the "heaviest" returns. Nevertheless, these
returns continue advancing steadily northeast where they will
appear to somewhat diminish due to the Minot radar still being
down. A more significant line of scattered showers and general
thunderstorms continue in northeastern Montana. These showers
and thunderstorms are heading northeast as well and may pass
through northwestern ND. However, instability should continue to
decrease as the sun sets. Thus, while there may be a few
lightning strikes, thunderstorm activity should decrease as
well.

UPDATE
Issued at 633 PM CDT Wed Jun 19 2024

A narrow line of returns rapidly moving to the northeast extends
north of I94 from the MT/ND border to west of the Missouri
River. However, air is fairly dry and to this point, only brief
and non-measurable light rain has been observed. Otherwise, the
forecast remains on track.

&&

.DISCUSSION...
Issued at 239 PM CDT Wed Jun 19 2024

Surface high pressure is positioned across north central North
Dakota, slowly drifting east through the day, as southwesterly flow
aloft remains across the Northern Plains. Mostly clear skies and
relatively light winds are present across much of western and
central North Dakota as a result, with a few fair weather cumulus
clouds forming and moving north across the far northwestern corner
of the state. As the surface high pressure drifts east, southerly
flow across the far western portions of the state will increase
enough to provide some low chances for showers later tonight, with
the highest chances across the southwest and northwest corners (both
roughly 15 to 25 percent). CAMs don`t show much when it comes to
these little waves of precipitation, but its certainly a possibility
that some areas may see a sprinkle, and possibly even some thunder.
Probabilities for anything producing any lightning is near zero, but
not completely out of the question.

This southerly low level flow continues on Thursday, as cloud
coverage and chances for showers slowly increase across the area,
from south to north. As such, high temperatures across the south
will be tempered just a bit, with values in the upper 60s across the
south, ranging to the mid 70s across the north. With the continued
southwesterly flow aloft, messy shortwaves embedded within the flow
will lead to disorganized showers across the area. PoPs across the
the area will be in the 30 to 60 percent range across the southern
half of the area, with the highest chances arriving later Thursday
night. There will also be a corridor of increased instability just
north of the International Border, due to the warmer temperatures up
there, which could lead to some isolated thunderstorms near the
border. The highest CAPE values are positioned entirely outside of
our area, so the chance for these storms are once again rather low.

Showers and possible some thunderstorms continue through the day
Friday, covering nearly the entire area with at least a 40 percent
chance for showers by Friday evening, with the southern half of the
area seeing chances from 60 to 70 percent. Thunderstorms are once
again possible, given the marginal instability and very pronounced
shear, but the instability maximum once again resides just outside
of our area, this time to our southeast. The SPC has outlined much
of eastern South Dakota in a Marginal Risk (level 1 of 5) for severe
thunderstorms, but this risk stops right before it reaches the North
Dakota border, near the southern James River Valley region. We will
continue monitoring this situation in case some of the ingredients
needed for severe weather begin to shift north. Regardless, much of
the area will see a slight chance for some thunder Friday evening.

Saturday will see the beginning of a drying trend, as an upper level
trough to our northwest begins to shift eastward, placing North
Dakota under more of a zonal flow aloft. Model ensembles are still
not very tight from this weekend onward, but the general consensus
is that this weekend and the start of next week will be mostly dry,
with weak embedded impulses bringing low chances for precipitation
nearly daily (with chances around 15 to 30 percent). Upper
level ridging to our west may begin to slide east through Sunday
and Monday, with NBM high temperatures suggesting the
possibility for widespread highs in the upper 80s to lower 90s
by Monday. NBM spreads for Monday in particular are rather low,
which indicates increased confidence that pretty warm
temperatures are expected that day. These spreads then begin to
increase quite a bit from Tuesday onward. Despite the spreads
and uncertainty increasing during that period, the general trend
of temperatures gradually decreasing is prevalent. The
continued mostly zonal westerly flow aloft is expected to remain
through the middle of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1230 AM CDT Thu Jun 20 2024

VFR ceilings and visibility are expected at all terminals at
the start of the TAF period. Winds will generally be weak and
out of the south, though may become modestly breezy over
portions of the west this afternoon. MVFR ceilings and chances
for showers will begin to push into southern North Dakota
through this afternoon and evening, mainly impacting KBIS and
KJMS and potentially KDIK. Showers will also be possible across
the west, though there is not enough confidence to add it to the
KXWA terminal at this time. Some isolated thunderstorms will
also be possible late this afternoon through the evening.
Chances for showers, thunderstorms, and MVFR to LIFR ceilings
will become more widespread beyond the end of the 06Z TAF
period. Occasional MVFR visibilities and gusty winds are
expected where showers do fall.

&&

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

&&

$$

UPDATE...Adam/Telken
DISCUSSION...Besson
AVIATION...Adam