536
FXUS63 KBIS 140926
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
426 AM CDT Fri Jun 14 2024

.KEY MESSAGES...

- There is a Marginal Risk (level 1 out of 5) for severe
  thunderstorms this afternoon through tonight, specifically
  across the southwestern portions of the state.

- There is a Marginal to Slight Risk (level 1 to 2 out of 5) for
  severe thunderstorms 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 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.

- Chances for showers and thunderstorms (30 to 80%) will remain
  through early next week.

&&

.DISCUSSION...
Issued at 425 AM CDT Fri Jun 14 2024

Surface high pressure will keep mainly clear skies as it pushes
eastward this morning. The resultant pressure gradient from this
pushing east and a developing low lee of the Rockies will bring
a breezy southeasterly flow to much of the CWA today. There does
lack upper level support and pressure rises for advisory level
winds today, although perhaps some sites get close this
afternoon if enough mixing can be had. As this low gets more and
more developed this afternoon a warm front will form and slowly
lift north. This will allow for some warming temperatures today
with most areas expected to be in the 80s. By later this
afternoon and especially through this evening showers and
thunderstorms look to develop along this front or the surface
low. These could also be aided by a quick moving mid level
shortwave. SPC has maintained a Marginal Risk in southwestern ND
for severe weather today. These areas could see strong storms
develop upstream and move into the area through this evening.
When they do so there looks to be ample CAPE and shear. Storm
mode could be discrete to perhaps multicluster. Of concern for
today is capping issues, and modest effective bulk shear up to
40 knots. Any stronger discrete cells could have ping pong ball
sized hail and wind gusts up to 60 mph. There is higher shear
values closer to the forecasted wave away from the marginal
risk, however these areas have weaker instability. An isolated
stronger storm is possible in areas with general risk from SPC
today, yet the marginal risk does still seem to highlight the
more robust severe storm environment. This evening`s storms then
become more isolated tonight. Low temperatures tonight will
generally be in the mid 50s to mid 60s.

Saturday then looks to be a warmer day with isolated to
scattered severe thunderstorms developing later in the day and
continuing through the night. Surface low moves eastward
Saturday as does the associated warm front. Much of the day
looks to be capped with limited chances for showers and
thunderstorms in the morning through the early afternoon. High
temperatures though will remain warm and generally in the 80s to
perhaps some lower 90s. A breezy southerly wind could also be
found during the day across the east. Capping could then erode
later in the afternoon and set up isolated to scattered severe
potential through much of the night. The CAMs at this point are
split on whether the cap can erode before or after the arrival
of the cold front. If this cap can erode earlier then discrete
supercells with all hazards will be possible. Cape values will
be higher than Friday, and perhaps over 3000 J/KG in some
areas. Effective Bulk Shear will also be high and over 50 knots
for some areas. Thus decided to start hail size mentioning at 2
inches, although some soundings are showing historic values at
around 2.75 inches. There could also be a brief tornado threat
with any discrete cells that can develop ahead of this cold
front as STP values are near or slightly greater than 1, LCLs
are around 1000 M, shear is abundant, and there is some
increased SRH. This is a conditional tornado threat, yet decided
to include an isolated tornado possible in our messaging. The
wind threat could be two fold. Discrete cells could have wind
around 60 mph. As the cold front moves through at night and
storms become more linear, the abundant cape, high amounts of 0
to 3 KM shear, and DCAPE near 1000 J/KG could lead to strong
winds. Decided to start at 70 MPH in our messaging today given
the timing uncertainty. Of importance will be to have a way to
receive severe weather warnings Saturday afternoon and evening,
and especially Saturday night if storms delay until the arrival
of the cold front.

Cold front then fully moves through the CWA Sunday. There could
be some lingering thunderstorms in the east during the morning
and south in the afternoon and evening. The severe weather
threat will be isolated to the southeast where SPC now has a
Marginal Risk. Large hail and damaging wind gusts will be the
main threat, although at this point the threat looks isolated.
Behind the front will be breezy to windy westerly winds. These
could reach advisory levels, especially with strong pressure
rises and strong winds aloft expected during the day.
Temperatures will cool into the 70s for most areas, with perhaps
some lower 80s lingering in the southeast. A broad trough then
looks to bring a secondary front and widespread chances for
showers and thunderstorms to start next week. A cooling trend
will be found with this front, with many areas seeing highs in
the 60s each day. As this trough lifts into Canada mid to late
week North Dakota is left in zonal flow. The result could be a
gradual warmup each day. NBM continues low chances for showers
and thunderstorms as well given proximity to the trough and for
any weak waves embedded in zonal flow.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1245 AM CDT Fri Jun 14 2024

Mainly VFR conditions will continue through the forecast
period. Clear skies and light winds will be found tonight. Winds
become south southeast, and perhaps a bit breezy, during the day
Friday. These winds should diminish somewhat Friday evening.
Chances for showers and thunderstorms return Friday afternoon
through Friday night. Confidence was only high enough to place
VCTS in select TAF sites at this time. Thunderstorms could bring
brief MVFR conditions. An isolated severe thunderstorm will be
possible in southwestern portions of the state during this time
period.

&&

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

&&

$$

DISCUSSION...Anglin
AVIATION...Anglin