671
FXUS63 KBIS 150553
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1253 AM CDT Sat Jun 15 2024

.KEY MESSAGES...

- There is a Slight Risk (level 2 out of 5) for severe
  thunderstorms late Saturday afternoon through Saturday night,
  covering most of western and central North Dakota.

- There is a Marginal Risk (level 1 out of 5) for severe
  thunderstorms Sunday across far southeastern portions of the
  state.

- High temperatures are forecast to peak in the 80s on Saturday
  (potentially reaching the 90s in the southwest), with a
  gradual cooling trend through the first few days of next week.

- Periodic showers and thunderstorms are expected next week,
  with the best chances Monday night with precipitation chances
  ranging from 60 to 80 percent across the state.

&&

.UPDATE...
Issued at 1253 AM CDT Sat Jun 15 2024

Limited updates needed to start the overnight hours. Shower and
thunderstorms activity has become more isolated, and will
continue to do so through the night. The threat for severe
weather for the remainder of the night is overall low. Made some
minor adjustments to PoPs based on current radar trends.
Otherwise the forecast remains on track.

&&

.UPDATE
Issued at 1012 PM CDT Fri Jun 14 2024

No major changes were needed for the late evening update. We did
greatly reduce precipitation chances across much of the west and
central over the next few hours. Radar trends and most of the
CAMs suggest we will see a break in activity before the next
round of at least isolated showers and storms potentially moves
in late tonight or Saturday morning. We will continue to see
showers with a few embedded storms over our east for the next
few hours, generally along and east of a line from the northwest
corner of Wells county, to the South Dakota border in south
central McIntosh county.

UPDATE
Issued at 626 PM CDT Fri Jun 14 2024

Scattered thunderstorms continue early this evening generally
along a line from around Kenmare, southeast through Minot, and
then to the north of Jamestown. These will continue to move east
through the night. Thus far, the strongest storms were seen
over the northwest where the shear has been the most
substantial. The main limiting factor here has been instability
with MUCAPE values generally in the 500 to 1000 J/kg range and
MLCAPE values much less. Instability is stronger over the
southwest but so is the convective inhibition. Some cumulus has
been a bit agitated south of Baker, MT but this activity
appears to be struggling with inhibition. It seems unlikely that
any storms of significance will develop here at this point. We
could still see some more isolated to scattered showers and
storms later and into the overnight as there is still some
activity over south central and southeast Montana, but the
severe weather threat tonight should remain rather low.

&&

.DISCUSSION...
Issued at 129 PM CDT Fri Jun 14 2024

The main forecast challenge is the potential for severe weather
this afternoon through this weekend.

Presently, a transitory ridge is passing through the central
Dakotas with a weak trailing shortwave analyzed over eastern
Montana towards western South Dakota. This shortwave and
associated WAA will help generate showers and thunderstorms this
afternoon possibly lingering into the overnight hours.
Instability will become moderate in the west with CAPE values
around 1000 to 2000 J/kg, especially in the southwest, as Gulf
moisture advects into the area. Shear is on the lower end at
around 30 to 40 kts, but it`s enough for a few severe
thunderstorms to develop. One of the biggest limitations to
potential severe weather is that capping is quite strong in the
west. While it is progged to deteriorate, there is some question
as to whether it will break in time or not. As a result, there
is a window for severe weather mainly in the west this afternoon
and early evening, but it`s also possible storms will stay sub-
severe. The primary threats are hail up to the size of ping pong
balls and 60 mph wind gusts.

A bigger severe weather threat is possible on Saturday. Unlike today
where Gulf moisture is primarily advecting into western ND, Gulf
moisture will be present over most of the state. This will result in
mixed layer dewpoints approaching 60 degrees, thus creating ample
instability over much of the area. In the late afternoon, wind
shear looks marginal (though enough) along and south of I94,
while areas further north of I94 and west of Highway 281 are
progged to have strong shear in excess of 50 kts of 0 to 6 km
bulk shear. Moderate instability and strong shear values migrate
eastward through Saturday night. The primary forcing mechanism
looks to be a moderate shortwave along with associated surface
cold frontal boundary, which looks to begin sliding through the
area in the late afternoon. This will result in severe weather
potential in the later afternoon, through the evening, and
potentially into the early overnight hours.

In regard to potential hazards for Saturday, shear vectors are
generally parallel or between parallel and perpendicular. Overall,
this favors a more clustered event that may become linear. However,
a few discrete supercells are possible earlier on. With any discrete
supercells, hail of two inches or greater is possible. There
remains a very conditional brief tornado threat window should
any discrete cells develop. Otherwise, in a more disorganized
cluster, threats include wind gusts up to 70 mph and hail up to
ping pong ball size. Any hail threat will diminish as storms
become more linear leaving a primary threat of wind gusts up to
70 mph. Isolated gusts up to 80 mph are not out of the question.

Beyond Saturday, breezy to windy conditions are possible in the
north and west, and especially the northwest itself, as the
pressure gradient tightens between low pressure to the north
and high pressure to the southwest. One point to this is that
with strong pressure rises and moderate CAA progged in
deterministic models at this time; winds may wind up being
stronger than presently forecast. Otherwise, expect periodic
showers and thunderstorms with severe weather not out of the
question Sunday in the far southeast CWA, and Monday in the
eastern CWA.

The highest confidence for widespread precipitation next week is
Monday through Tuesday afternoon, and especially Monday night,
as deep low pressure originating in Wyoming moves through the
central/northern Plains. As a result, the entire forecast area
is already forecast for a 60 to 80 percent chance of seeing
showers and thunderstorms. This low pressure will also bring a
return of cooler temperatures. Though exact values will be
ironed out in the future, the majority of the forecast area is
favored to see highs return to the 60s Monday through Wednesday.
A gradual warming trend is then favored for the latter half of
next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1253 AM CDT Sat Jun 15 2024

Isolated thunderstorms look to be found tonight, along with
mainly VFR conditions. Breezy southeasterly winds will diminish
tonight. Saturday could see some lower clouds in the morning,
perhaps approaching MVFR ceilings to a few areas. Southerly
winds could also become breezy again for some locations.
Saturday afternoon through Saturday evening could then see
isolated to scattered showers and thunderstorms. A few may be
severe at times. Confidence in timing of these storms is
currently low to modest, although did use some VCTS at this
time. Stronger storms could also bring some brief MVFR
conditions.

&&

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

&&

$$

UPDATE...Anglin
DISCUSSION...Telken
AVIATION...Anglin