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300
FXUS63 KBIS 221149
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
649 AM CDT Sat Jun 22 2024

.KEY MESSAGES...

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- Cloudy this morning with areas of fog and scattered morning
  showers. An isolated thunderstorm is possible southwest and
  south central.

- There is a 20 percent (south) to 50 percent (north) chance of
  thunderstorms this afternoon and early evening. A few could
  be strong to severe. Quarter sized hail and 60 mph winds are
  the primary hazards.

- After a dry day on Sunday, thunderstorm chances return late
  Sunday night into Monday over northwest into north central
  North Dakota and again Monday afternoon into early Monday
  evening over eastern portions of central North Dakota.

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

- Mostly dry Tuesday and Wednesday. Thunderstorm chances return
  Thursday and Friday.
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&&

.UPDATE...
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Issued at 629 AM CDT Sat Jun 22 2024

Thunderstorms did hold together as they moved from Montana into
southwest ND. A line of thunderstorms from southwest Hettinger
County south through western Adams county continues to push
east. Winds gusted to around 40-45 mph at Hettinger with one of
the stronger cells. Some pea sized hail is also possible as this
line moves towards western Grant and Sioux counties in the next
hour or so. MUCape and Effective shear drop off farther east so
don`t expect stronger cells to last much longer.

We updated pops through the morning based on latest radar and a
blend of short term guidance.

We issued a SPS for dense fog for areas south and west of Lake
Sakakawea and the Missouri River, as well as Emmons county to
the east of the Missouri. We expect fog to dissipate by mid to
late morning.
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&&

.DISCUSSION...
Issued at 154 AM CDT Sat Jun 22 2024

Widespread low clouds and some fog early this morning, across
the southern half of the CWA. Currently the fog is pretty much
limited to the southwest and south central. Light rain/drizzle
continues over the south central into the James River Valley in
what looks like an area of weak low level warm advection and
moisture convergence. In eastern Montana convection is located
around Miles City and continues to move east southeast towards
far southwest ND. There is and area of around 1000 J/KG of CAPE
and 30-35 knots of effective shear situated over southwest ND,
thus there is the potential for this activity to reach the
state. On the negative side, the mid level lapse rates look to
be flattening and CIN looks to be increasing. Most CAMS have a
handle on this convection show it weakening as it moves into
ND, although some keep convection bubbling as it moves into ND.
Will continue to monitor.

For today, an upper level circulation will track across
southern Canada. At the surface there is little indication of
any frontal boundary, other than a wind shift. However, it does
look like as clouds break up and temperatures warm this
afternoon, there should be a broad area of weak to moderate
instability across the forecast area. Forecast soundings
indicate that if we reach our forecast highs, there would be a
window of opportunity for a few thunderstorms this
afternoon/early evening. If we would see thunderstorms there is
anywhere from around 30 to 50 knots of 0-6km bulk shear. From
the forecast soundings there is little if any directional shear
but there is some decent speed shear. There is a nice jet
dropping south around the Canadian circulation into the north
central as well. There are some limiting factors. In fact, they
probably outweigh the favorable severe factors. Surface heating
is a question, and thus overall instability. Although speed
shear is favorable, I`d like to see it more unidirectional. At
times we see winds backing with height. We also see surface
pressure rises moving into the west by late afternoon. CAMS are
not real consistent and are not in agreement. You could pretty
much pick an area and at least one CAM would have convection
there. If we had to pick and area most favored, it would be the
north central, closer to the upper circulation and the upper jet
dropping down. Second would probably be pretty much anywhere
except the southern James River Valley. But if convection would
hold together it very well could reach the JRV this evening. As
far as threats and coverage, we think the severe threat would
be isolated, but as mentioned it`s hard to pinpoint any one
particularly favored area. And as far as hazards are concerned,
there could be a bit more of a wind threat north central, but
overall we think a mention of 60 mph winds and quarter sized
hail could be justified pretty much anywhere and it would be
hard, at this time to go any higher with the threats. We will
message isolated to scattered thunderstorms possible this
afternoon and early evening, and a few could be severe with 60
mph winds and quarter sized hail. Later shifts can adjust if
needed.

Once convection, if it develops, ends this evening we should be
warm and dry through the day Sunday with highs from the mid 70s
Turtle Mountains to the upper 80s southwest. Sunday night into
Monday would be the next chance for thunderstorms as a shortwave
flattens the upper level ridge that moves over the are Sunday.
Currently SPC has a marginal risk for severe storms over a good
portions of west central through north central. At this time we
will message 60 mph winds and quarter sized hail. Monday will
be interesting in that as we rise into the 80s and 90s, we
become quite unstable over central into eastern North Dakota.
However we are also quite capped. Currently SPC has a slight
risk for severe storms over Much of Minnesota with a marginal
risk back into central North Dakota. This is a conditional
severe threat in that if the cap would break, severe storms
would certainly be a good bet, but currently the cap looks to be
quite strong. Will certainly need to monitor this as well as we
go forward.

After Monday, temperatures cool down a bit and it looks like we
may see a break in convection mid-week until another upper wave
moves from the Pacific Northwest and into the northern Plains,
bringing increasing thunderstorm chances Thursday and into
Friday.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
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Issued at 629 AM CDT Sat Jun 22 2024

Areas of MVFR to IFR ceilings across western and central North
Dakota. IFR-LIFR visibilities are mostly confined to southwest
and far south central ND including KDIK. Visibilities are
expected to improve by mid to late morning. Ceilings will slowly
lift mid to late morning and skies will also clear from west to
east late this morning through the afternoon. VFR conditions
are expected by mid afternoon most areas, and perhaps a bit
later over eastern portions of central ND.

Ongoing showers and thunderstorm activity should remain south of
the southern TAF sites except for a VCSH at KJMS. Then this
afternoon any convection is expected to be too isolated in
nature to include at any TAF site. The exception being the north
central including KMOT. Here we included a VCTS from mid to late
afternoon.

Generally light winds today (10 knots or less) mainly from the
east this morning and then shifting to the west this afternoon.
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&&

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

&&

$$

UPDATE...TWH
DISCUSSION...TWH
AVIATION...TWH