839
FXUS63 KBIS 220017
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
717 PM CDT Fri Jun 21 2024

.KEY MESSAGES...

- Chance of showers and thunderstorms (ranging from 20% south to
  70% north) return Saturday. A few afternoon or evening storms
  mainly over central North Dakota could be strong to severe,
  with the main expected hazards being quarter sized hail and 60
  mph winds.

- Temperatures increase through the weekend, topping out in the
  80s north to lower 90s south on Monday, then slightly cool to
  the upper 70s to upper 80s through next week.

- Mostly on and off chances for precipitation (ranging from 20
  to 40%) last through next week, with the best chances for
  showers and thunderstorms on Monday and Thursday.

&&

.UPDATE...
Issued at 717 PM CDT Fri Jun 21 2024

The Minot radar has returned to service.

A tricky forecast persists this evening through tonight. There
remains a few showers in far north central ND and the eastern
forecast area. However, most organized rain has moved off to the
east. Under low ceilings, patchy drizzle and reduced visibility
is occurring in random parts of the forecast area. Based on
model forecast soundings, patchy drizzle is expected through the
night and into Saturday morning ending from west to east.
Updated PoPs based on the latest radar trends and removed
thunder chances through this evening.

&&

.DISCUSSION...
Issued at 248 PM CDT Fri Jun 21 2024

Some pop-up showers that originated in far eastern Montana have
moved into western and central North Dakota, congealing into a large
area of showers covering much of south central North Dakota. Some
rumbles of thunder are possible with this area of showers, but its
not expected to intensify much more than it already has. Some
additional pop-up showers and isolated thunderstorms have formed
across the north as well, moving into Canada and bringing about some
short-lived locally heavy downpours of rain. Given the lack of
instability and forcing across our area, severe development is not
anticipated through the rest of the evening and into tonight. Weak
surface high pressure is analyzed over northeastern North Dakota,
while an inverted surface trough sits to our southwest across
Wyoming. Aloft, southwesterly flow persists around the southern edge
of a trough, helping bring about the weak forcing needed for the
current showers. Temperatures across the south were kept pretty cool
due to the overcast decks that built in through the morning, with
highs only reaching into the mid 60s in some areas. These showery,
cloudy conditions are expected to continue into the overnight hours,
though the chances for precipitation decrease to around 25 to 50
percent through this period. Lows tonight remain largely in the 50s.

Saturday sees the arrival of a quick moving shortwave aloft,
swinging through the southern edge of the aforementioned trough and
helping bring about another wave of showers and thunderstorms. With
warmer temperatures filtering in, instability is forecast to
increase through the afternoon and evening hours, mostly across
central North Dakota and the James River Valley. Current
deterministic analysis suggests a large area in that region of 1000
to 2000 J/kg of MUCAPE, while the northern half of that region sees
a narrow corridor of 40 to 50 kt 0-6 km bulk shear. As a result, the
SPC has outlined much of our northern areas with a Marginal Risk
(level 1 of 5) for severe weather. For the few brief hours that
these ingredients line up, any storm that forms could certainly
strengthen and produce 60 mph wind gusts and quarter sized hail, but
given how marginal the ingredients themselves are, the risk for this
will remain somewhat low. Otherwise, Saturday is expected to bring
in the beginning of a brief warming trend, with highs in the mid 70s
to lower 80s expected.

Sunday and Monday will continue the warming trend as a thermal ridge
builds in from the southwest, helping raise temperatures into the
mid 80s and lower 90s by Monday. Flow aloft on Sunday will shift to
northwesterly as a ridge quickly builds into the area as well,
resulting in a fairly dry and mostly clear day on Sunday. Flow aloft
shifts to become more zonal Sunday night, which leads into a
potentially wetter Monday.

While Monday is expected to be the warmest day in the forecast
period, it is also of particular interest due to the severe
potential across the far eastern portions of our area (most
notably in the James River Valley). Given the heat, as well as
the moisture that has continued to be transported into the area
from the south recently, instability will be plentiful, along
with more than enough shear needed to sustain strong to severe
storms. Current deterministic guidance suggests prominent
midlevel height falls, nearly collocated with an axis of modest
ML mixing ratios and MUCAPE ranging from 2500 to 3500 J/kg,
along with roughly 40 kt 0-6 km bulk shear. The main factor
reducing the confidence with this setup is the forcing needed to
get these storms going; whether that be the location of the
most prominent height falls, the location of the surface warm
front, or the location of the attendant surface low sweeping
through the area. The ingredients are absolutely there for a
risk for severe weather, but without knowing where storms will
fire off, we can not say for certain where in our area this
threat will be. Regardless, there is still a chance for sub-
severe thunderstorms and showers in the James River Valley, but
confidence is just too low to expand that chance further west
into our area.

From Monday night onward, we are expecting to enter another semi-
active and warm pattern, with mostly zonal flow aloft through the
end of next week. Ridging to our southwest will nudge some continued
warm air into our area, keeping high temperatures firmly in the mid
70s north to mid 80s south. Chances for precipitation are also
pretty spotty, with the middle of the week appearing to be fairly
dry, while the end of the week may see some slight chances of
showers and thunderstorms. However, given how weak the impulses are
that would bring us these chances for rain, confidence is fairly low
in the timing and extent of these showers. Come Friday, there are
some relatively large differences in some of the long range models,
with some solutions indicating another drier and warmer period
beneath a potent ridge, while other solutions suggest continued
zonal flow aloft with daily chances for precipitation. Taking a look
at the most recent WPC cluster analysis, it appears to be around a
60/40 split, favoring the solution that brings about the more
prominent ridge. At the very least, we can expect continued warm
temperatures in the 70s and 80s, potentially reaching into the 90s,
by the end of next week and into next weekend.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 717 PM CDT Fri Jun 21 2024

Forecasting aviation conditions remains tricky this evening
through tonight. Scattered showers continue over much of central
ND, including the James River Valley. These showers will
continue gradually moving into eastern ND over the next few
hours. However, with LIFR/IFR ceilings over most of western
through central ND, patchy drizzle, along with reduced
visibility, is occurring in random areas at random times. This
will continue through the night into Saturday morning.
Conditions will gradually improve from west to east through the
day Saturday.

&&

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

&&

$$

UPDATE...Telken
DISCUSSION...Besson
AVIATION...Telken