032
FXUS63 KBIS 091935
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
235 PM CDT Sun Jun 9 2024

.KEY MESSAGES...

- High temperatures the next few days near normal for early
  June (normal is mid 70s). Above normal temperatures are
  expected with increasing confidence for Wednesday (80-85
  degrees).

- Widespread showers and thunderstorms (80 percent chance)
  expected Monday through Monday night. Isolated severe
  thunderstorms are possible across portions of western and
  south central North Dakota (level 1 out of 5 risk), with a
  small area with a Sight (level 2 out of 5) risk of scattered
  severe thunderstorms over Bowman and Adams counties.

- Chance for showers and thunderstorms (30 percent) return late
  Tuesday night through Wednesday, before higher chances for
  precipitation at the end of the week.

&&

.DISCUSSION...
Issued at 235 PM CDT Sun Jun 9 2024

Today, clear and calm conditions are found over most of western
and central North Dakota as broad area of high pressure at the
surface lingers over the Northern Plains. Slight chances (10 to
20%) for showers can be found across the far southwest today
ahead of a weak shortwave advects a vort max across northwestern
South Dakota. However, with ample dry air over the low to mid
levels much of any precipitation that does fall out of these
high based clouds will likely become virga. Highs today remain
slightly below seasonable normals, ranging from the upper 60s
north to the mid 70s south. Winds will remain generally light
out of the east southeast, though it will become little more
breezy across the southwest late this afternoon and evening as a
weak boundary pushes across the area.

The remnants of an upper level low over the southern Canadian
Prairies will be absorbed by an incoming pacific shortwave
overnight tonight into early Monday, pushing a deepening
attendant low center at the surface out of Wyoming and east
across the Dakotas. Increased WWA ahead of this system will
prime the environment across western and central North Dakota
for showers and thunderstorms that will start Monday morning and
last through early Tuesday. With high PoPs (70 to 90%) and
moderate PWATs, much of the forecast area is progged to have a
40 to 70% chance of exceeding 0.50" of rainfall by Tuesday
morning. With two rounds of precipitation expected, with showers
developing in the north ahead of the system, then another round
ahead of a following cold front in the afternoon, portions of
the northwest have modest chances (15 to 25%) of exceeding
1.00" in total. Convection wise, much of southwestern and south
central North Dakota has been placed under a Marginal (level 1
of 5) risk for isolated severe thunderstorms, with a small
portions of Bowman and Adams counties under a Slight (level 2 of
5) risk. Current model MUCAPE values are advertised in the
1500-2000 J/KG range across the southwest and south central,
along with strong 0-6 KM Shear of 35 to 45 knots and decent mid-
level lapse rates. The SPC and CSU machine learning have also
dialed onto a low tornado risk with the high SRH associated with
the low center`s triple point, though an interrogation the most
recent model soundings have placed our expectations of the
tornado threat as being on the lower end of low. As such, we
have begun messaging the primary hazards for the thunderstorms
Monday afternoon and evening, from around 3 PM to 11 PM CDT, as
large hail up to ping pong balls (1.50") in size and winds up to
60 MPH. A few question remain, however, with how far north the
axis of instability will penetrate, with regards to how worked
over the environment will be by the initial wave of showers and
thunderstorm Monday morning, which may help limit the risk of
the greatest hazards to far southwest and south central.
Additionally, there are some hints that the isolated severe
storms may quickly outpace the axis of instability once they
develop, which may also limit the hail potential as well, though
it is still a little early to say as such with much confidence.
Otherwise, highs on Monday are forecast from the upper 60s
north to the upper 70s south.

Showers and slight chances for thunderstorms (<20% chance) will
continue to progress eastward across North Dakota overnight
before clearing east of the forecast area early Tuesday morning.
At this point, the inciting pacific shortwave will have been
replaced by longwave ridging across the Northern Plains,
promoting dry conditions and warming temperatures through
Wednesday. While highs on Tuesday are similarly forecast the
upper 60s and upper 70s as on Monday, a penetrating axis of warm
air will see Wednesday as the hottest day of the week, with
highs forecast from the upper 70s north to the mid 80s south. A
modest shortwave will travel down the zonal flow aloft, allowing
a return of showers (20 to 40% chance) across western and
central North Dakota early Wednesday through Thursday morning.
The ensemble has resolved on a more progressive shortwave,
meaning the potential for severe weather over the northern
Plains Wednesday afternoon has been pushed mainly out of our
area, though we could see some development in the mid afternoon
over the southern James River Valley.

The passage of the shortwave on Wednesday will erode the
overall ridging pattern over the northern Plains, leaving an
increasingly southwesterly flow pattern over the forecast area
through the later half of the workweek. Temperatures will remain
roughly or slight above seasonably normals through the later
half of the week, forecast from the lower 70s north to the lower
80s south through Sunday. Conditions will remain dry through
early Friday, when a more active, northwesterly pattern
returns. Chances (30 to 50%) for showers and thunderstorms will
linger through the weekend and into early next week. While the
ensemble is fairly discordant at this point of the forecast,
some individual members have begun to hint at strong moisture
advection from the Gulf across central and eastern North Dakota
this weekend and into early next week, which may prime the
stage for a comparably spicy pattern than we have experienced
over the last week. Confidence is low at this time, however, so
we will continuing monitoring model trends over the next few
days.


&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 235 PM CDT Sun Jun 9 2024

VRF conditions are expected to begin to 18Z TAF period. Isolated
showers are possible across the southwest, but there is not
sufficient confidence in it impacting any terminals at this
time. Winds will become breezy across the west this afternoon,
but will then diminish through the evening. Overnight into early
Monday, chances for showers will push into the west, first
impacting the terminals of KXWA and KDIK then spreading to KMOT
and KBIS by 18Z tomorrow. Beyond the end of the TAF period,
showers and eventually thunderstorms will become widespread,
with strong to severe thunderstorms possible Monday afternoon
and evening.

&&

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

&&

$$

DISCUSSION...Adam
AVIATION...Adam