135
FXUS63 KBIS 290923
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
423 AM CDT Wed May 29 2024

.KEY MESSAGES...

- Severe storms are possible later in the afternoon and early
  evening today, especially in the western two tiers of counties
  along the ND/MT border. Hail up to the size of ping pong
  balls and 70 mph winds are the primary threats.

- With this storm complex, there is an 80 to 90 percent chance
  of a wetting rain (a tenth of an inch or more) for all of
  western through central ND, including the James River Valley.

- Breezy to windy conditions are expected today, especially in
  the southwest and south central portions where winds could
  gust up to 45 MPH.

- Temperatures will generally be near average through the period,
  although may be slightly below on Thursday and Friday and
  slightly above this weekend into early next week. Periodic
  shower and thunderstorm chances continue through the first
  half of next week.

&&

.DISCUSSION...
Issued at 423 AM CDT Wed May 29 2024

The primary forecast challenge remains the potential for severe
weather later this afternoon and evening.

For the day today, breezy to windy conditions are expected across
the CWA with the strongest winds in the southwest and south
central. Winds may approach advisory level. However, gusty
winds are primarily gradient driven as the area is sandwiched
between surface high pressure over Ontario and elongated low
pressure from eastern Alberta down through eastern Montana.
Winds aloft aren`t impressively strong and a low-level
inversion looks to remain in place through the day today
limiting mixing heights. Thus in collaboration with neighbors,
opted not to issue any headlines for winds today. With
southeasterly surface flow and western ND centered under a
thermal ridge, expect above average temperatures in the low 80s
over the west, while near average temperatures in the low 70s are
expected in the central and east.

In regard to severe weather, not a ton has changed over the past 24
hours. That said, there has been one change that is along the
lines of what the previous shift mentioned in regard to any
tornado threat. The threat remains slightly greater than zero
(primarily in the far west), but seems very limited. This is
primarily due to increased confidence in storm mode rapidly
becoming more linear and lower model guidance output in regard
to low level SRH.

In regard to storm mode, the thought persists that with limited deep
layer shear and said shear vectors quickly becoming parallel with
the frontal boundary, any window for supercellular development
is limited. This will result in storms rapidly clustering then
quickly taking on a more linear mode. The threats in this case
remain a narrow window in the later afternoon/early evening for
ping pong ball size hail before rapidly becoming primarily a
wind threat. The western two tiers of counties in the state
really are the most favorable areas for severe weather. Areas
further east may see a sporadic lower end severe wind gust
(around 60 mph) through the evening.

After midnight, the severe threat should have mostly ended as
showers and thunderstorms continue moving eastward through the
night. Showers and thunderstorms will continue across much of the
forecast area Thursday morning before ending from west to east
Thursday afternoon and evening. Mostly dry conditions are then
expected Thursday night through Friday morning.

As has been the case recently, this break in the shower and
thunderstorm activity does not look to last long. A parade of
shortwaves continues as the next wave passes through the area
Friday through Friday evening. This one looks fairly weak only
generating slight chances for showers and thunderstorms. A more
organized wave then looks to pass through sometime Sunday
through Sunday night. Additional waves are then possible through
the middle of next workweek. High temperatures Thursday and
Friday should be near to slightly below average. Beyond that,
forecast highs are near to slightly above average into the
middle of next workweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1253 AM CDT Wed May 29 2024

Southeasterly winds will pick up through the remainder of the
night and during the day Wednesday. This will result in breezy
to windy conditions across the entire area with some gusts up to
45 kts possible in portions of the far southwest. Otherwise, VFR
ceilings and visibility will prevail through most of the TAF
period. However, by mid to late afternoon Wednesday, showers and
thunderstorms will begin entering western North Dakota mostly
from Montana. Thunderstorm confidence is high in the western two
tiers of counties during the evening. Therefore, added TSRA to
the Williston and Dickinson TAFs towards the end of the period.
Per usual, reduced ceilings and visibility are possible with any
thunderstorms that develop. And with these storms, gusty and
erratic winds in excess of 50 kts are one of the main threats.

&&

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

&&

$$

DISCUSSION...Telken
AVIATION...Telken