Severe Thunderstorm Warning 174, NWS Bismarck, ND

Area Forecast Discussion
National Weather Service Bismarck ND
339 PM CDT Tue Aug 6 2024

.KEY MESSAGES...

- Showers and thunderstorms to return later today through
  tonight. Isolated strong to severe storm is possible across
  the west, with hail up to half dollar size and wind gusts up
  to 70 mph.

- Showers and thunderstorms could linger into Wednesday,
  although the threat for severe weather is low. Limited chances
  for precipitation are then expected until later this weekend.

- Below normal temperatures are expected for the rest of this
  week, especially Thursday and Friday with low temperatures
  forecast in the 40s and high temperatures in the 60s and 70s.

&&

.DISCUSSION...
Issued at 339 PM CDT Tue Aug 6 2024

There still remains a conditional isolated severe weather
threat through tonight, although timing remains uncertain.
Inverted surface trough over Montana has set up a warm front
across ND with a cold front currently in Canada. At the meeting
point of it all in Canada there are currently strong to severe
storms that have formed. As this system progresses two items of
interest will be monitored for severe weather. The first being a
conditional severe threat along the warm front. This is where
the better instability is, although this instability is modest.
This threat mainly occurs in the northwest late this afternoon
through this evening. The second area of interest will be
monitoring the progression of the severe storms currently in
Canada. The right moving bunkers vector for these would try to
bring these storms into ND mid to late this evening. As usual,
storm mode will play a big role in storm hazards. With high
amounts of shear and nearly straight hodographs, large hail will
be the biggest concern. Decided to increase the hail size to
half dollar. If more discrete cells can form perhaps golf ball
hail is possible, although the shear vector is not quite
perpendicular to any boundary. High DCAPE and 0 to 3 KM shear
also have decided to raise the winds to 70 MPH. If storms delay
to more along the cold front linear storm mode could help
increase these winds. SPC has maintained a Marginal Risk for
western ND. Those in the west and perhaps the north should be
weather aware through tonight. Otherwise look for mild lows
tonight near 60 degrees tonight. As the trough becomes more of a
surface low tonight, widespread rain will push across the state
tonight with a few embedded thunderstorm. Any areas that see
precipitation chances diminish could see patchy fog again,
although confidence was not high enough to include in the
forecast at this time. Wednesday will see cooler temperatures in
the 60s and 70s behind the passage of the weak cold front.
Showers and thunderstorms will continue to push eastward through
day diminishing in the evening. SPC does clip our southeast
with a Marginal Severe weather risk. This area is delayed until
later in the day for the passage of the front. Shear will still
be abundant. If enough instability can be found then perhaps an
isolated severe storm is possible. Winds will generally shift to
the north on Wednesday, and may be breezy at times.

Thursday through Saturday, a large upper level low lingers
across the Great Lakes Region while a ridge flattens in the
west. The result will be a cool northwest flow across the area.
Breezy winds may be found on Thursday as well. Precipitation
chances look minimal given the dryer nature of this flow. What
is of interest is the cooler temperatures found in this pattern.
Highs on Thursday look to be in the 60s, warming into the 70s
through Saturday. Low temperatures could also be quite low, with
widespread 40s forecast. ECMWF EFI values are still quite
elevated through the end of the week. NBM 10th Percentile
forecast even brings upper 30s to some western areas Thursday
night into Friday morning. Something to monitor going forward.
Later this weekend into next week clusters indicate a return to
southwest flow, which can bring some more active pattern. A
strong trough pattern is not particularly showing up in the
clusters although NBM returns pops to the area. This southwest
flow could warm temperatures somewhat and possibly back to near
normal readings.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1253 PM CDT Tue Aug 6 2024

Lingering low clouds, and the development of more low clouds and
precipitation, could bring periods of MVFR to IFR at times
during the forecast period. Currently many sites are
experiencing VFR conditions, although a swath of low MVFR clouds
remains in western ND. These are slow to erode and may linger
through this afternoon, possibly impacting the KDIK TAF. Later
today through tonight, showers and thunderstorms are expected to
develop along with more low clouds. An isolated strong to
severe storm is possible in the west. Cloud ceilings could be
MVFR to IFR heights tonight into Wednesday morning.
Precipitation becomes more scattered later Wednesday morning,
while low clouds could linger. Winds will be southerly today,
turning to the north on Wednesday.

&&

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

&&

DISCUSSION...Anglin
AVIATION...Anglin

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