369
FXUS63 KBIS 140901
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
401 AM CDT Mon Jul 14 2025

.KEY MESSAGES...

- Isolated strong to severe storms possible across much of the
  state late this afternoon through early tonight. Expected
  hazards are hail as large as ping-pong balls and wind gusts up
  to 70 mph.

- Well below normal temperatures Tuesday through Thursday, with
  near-record cold highs in the lower to mid 60s on Wednesday.

- Medium to high chances for rain tonight through Wednesday.
  The highest rain amounts are broadly expected over southwest
  North Dakota.

&&

.DISCUSSION...
Issued at 400 AM CDT Mon Jul 14 2025

Northwesterly flow is found over the forecast area this
morning. Scattered showers have developed along the
International Border, where a LLJ and a weak W-E orientated
quasi-stationary surface boundary can be found. A few rumbles of
thunder are possible later this morning a a slightly uptick in
MLCAPE is progged by the CAMs, though these are anticipated to
be quite limited in scope. Chances for showers (20 to 40
percent) will linger across the north through much of the day
today as elevated mid level winds continue to promote vorticity
across southern Canada into northern North Dakota. Quite the
temperature gradient is expected to develop this afternoon, with
highs across the north peaking only into the lower to mid 70s
and in the 90s across much of the south. Portions of far
southwestern North Dakota may even break into the lower 100s
this afternoon (~30 percent chance). With moderate to strong
CAA, gusty northwest winds with speeds up to 20 MPH and gusts up
to 25 MPH are possible in the northwest this afternoon.

Now onto the severe potential for today. Ours is a story of
three distinct (yet somewhat arbitrary) zones across western
and central North Dakota, with the best forcing found in the
southwest, the most unstable environment found in the south
central, and the highest shear found across the north. This
afternoon, a low pressure system associated with a weak
shortwave traversing near zonal flow over the northern Plains
will progged to be lofted through southwestern North Dakota.
With the enhanced vort found in the southeastern sector of this
low pressure center, dewpoints peaking in the the mid to upper
60s, and steep low level lapse rates in excess of 9.5 C/km, we
would not be overly surprised of some early CI is able to break
through the the moderate capping ain the southwest late this
afternoon/early this evening. An interrogation of model
soundings in the southwest this timeframe reveals a very dry
near surface layer. With an inverted V profile and DCAPE values
exceeding 1500+ J/KG, the primary hazard associated with any of
these early thunderstorms would likely damaging wind gusts up to
70 MPH. Some small to marginally severe hail would also be
possible, especially if these storm manage to tap into the
slightly elevated mid layer shear and become transiently
supercellular. As this system evolves through the evening, a
warm front is expected to lift across south central ND. Here
dewpoint values peak into the mid to upper 60s, while model
MUCAPE values tickle the 2000-3000 J/KG range. LCLs are also
considerably lower in this zone, around the 1000 M range versus
the 2000 M + found further west. Considering all this, the main
hazard with any severe storms that does develop in south central
North Dakota would become large hail, though damaging wind
gusts remain possible. This is especially true to a narrow
corridor north of Highway 83, where storms begin to overlap with
the higher 0- 6 KM bulk shear values found across northern
North Dakota. With this in mind, there is a brief window of time
this evening where storms could produce hail up to the size of
ping-pong balls. This area also represents the highest potential
for locally heavy rainfall, with PWAT values exceeding 1.5+
inches and possibility of redeveloping storms on the backside of
the warm front training over some locations. With all that
considered, we will advertise large hail up to ping-pong balls
in size, damaging wind gusts up to 70 MPH, and locally heavy
rainfall as the main hazards for today. SPC has kept much of
western and central North Dakota in a Marginal Risk (level 1 of
5) for isolated severe thunderstorms today, though has notably
pulled the northern extent of this Marginal south with the
latest update. While plenty of shear is found across the north,
the lack of any significant instability helps to diminish the
severe potential there.

Widespread medium to high chances for showers and embedded
thunderstorms (45 to 75 percent) are then expected to spread
across the forecast area Monday night through Tuesday as
numerous shortwaves eject off of incoming positively tilted
upper level trough. As this upper level trough begins to be
absorbed in the more general zonal flow Tuesday night through
Wednesday afternoon, chances for showers and storms are expected
to diminish from north to south. The potential for severe
weather is fairly low during this this period as we cool off
significantly, with high temperatures broadly forecast in the
60s and 70s Tuesday and Wednesday afternoon. When its all said
and done, much of the forecast area is expected to get a good
drink of water by the mid week period. Current NBM probabilities
advertises the potential to exceed 0.50 inches of rainfall
broadly from 30 to 50 percent by Thursday morning, with
the southwest possibly even exceeding an inch overall (~30
percent chance).

A return to more seasonable temperatures is anticipated through
the end of the week, with high temperatures climbing back into
the mid 70s to upper 80s range Saturday and Sunday. The current
ensemble continues to promote low to medium near daily chances
for showers and non-severe thunderstorms Friday through the
weekend, with a majority cluster of members (~70%) favoring near
zonal flow persisting across the northern Plains. Notably, a
minority cluster (~30% membership) champions the development of
upper level ridging over the northern Plains which would herald
the return of much drier and warmer weather. In this scenario,
high temperatures peaking back into the 90s would not be out of
the cards. Overall severe weather chances remains low at this
time, with neither pattern supportive of widespread severe
threats and a distinct lack of any signal for machine learning
algorithms.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 400 AM CDT Mon Jul 14 2025

Mainly VFR ceilings and visibility are anticipated at all
terminals throughout the 06Z TAF period. Scattered showers and
possibly a few thunderstorms will linger over the International
Border overnight. Have included a PROB30 group for -SHRA at
KMOT with this update. Later this afternoon and evening, more
showers and thunderstorms are expected to develop, a few of
which may become strong to severe. Have included PROB30 groups
for -SHRA at KXWA, KDIK, and KMOT and PROB30 groups for -TSRA
for KBIS and KJMS with this update. Light winds will vary with
direction overnight, becoming somewhat gusty as a low pressure
center moves across the state in the afternoon and evening.Where
thunderstorms do develop, gusty and erratic winds can be
anticipated. LLWS is expected at KDIK at the start of the TAF
period through the early to mid morning.

&&

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

&&

$$

DISCUSSION...Adam
AVIATION...Adam