234
FXUS63 KBIS 131832
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
132 PM CDT Sat Jul 13 2024

.KEY MESSAGES...

- Very warm temperatures are expected through the weekend, with
  a Heat Advisory in effect over Dickey and LaMoure counties
  from 1 PM to 8 PM today.

- Isolated to scattered severe storms are possible this evening
  and into the night. Hail to the size of tennis balls and
  damaging winds up to 70 mph will be the main hazards.

- Isolated to scattered severe storms will be possible once
  again late Sunday afternoon and into the evening. Hail to the
  size of golf balls and damaging winds up to 70 mph will be the
  main hazards.

&&

.UPDATE...
Issued at 121 PM CDT Sat Jul 13 2024

The weather continues to be quiet this afternoon. For the severe
risk tonight:

Southwest North Dakota got upgraded to a level 3 risk (enhanced)
for wind and hail. The rest of the risks remained the same.
Timing is tricky as the CAMs are different. It looks like
somewhere between 6pm MT and 8pm MT for storm forming or moving
in from Montana. They will then slide east and south through the
overnight. Threats are the same: 70mph winds and tennis ball
hail.

UPDATE
Issued at 958 AM CDT Sat Jul 13 2024

Scattered storms formed and moved out of the area near Rugby in
the last few hours. So PoPs were reduced since they moved east.
Sky cover was blended with a few different models to get an
accurate forecast based on real time observations. There seems
to be a surface low in the central part of the state that the
clouds are rotating around around.

UPDATE
Issued at 631 AM CDT Sat Jul 13 2024

There are still a few storms hanging around the north central
this morning, mainly from along a line just north of Minot
Air Force Base to Rugby. While these storms are not very
impressive on radar, one NDAWN site near Rugby reported a 65 mph
gust and another DOT station reported a 57 mph gust. So, as
these little storms are collapse, a decent push of wind may
accompany them. For now, we will issue an SPS to account for
this threat. For this update, just updated precipitation chances
for the next few hours based on the latest radar observations
and trends.

&&

.DISCUSSION...
Issued at 327 AM CDT Sat Jul 13 2024

Several shortwaves were noted on water vapor satellite imagery
early this morning, moving through the region in nearly zonal
flow aloft given the flattened ridge overhead.

The strongest wave continues to move across northern North
Dakota and another across the south. The northern wave has led
to a cluster of storms generally along and north of Highway 2.
While the severe weather threat has diminished, the Minot Air
Force base did report a 68 mph wind gust with this cluster as it
moved overhead. So, an occasional pulse up to severe levels
through the morning is not out of the question. The southern
wave has been producing a few isolated storms over the far south
central. This activity will have the potential to mainly
produce sub-severe hail and frequent lightning. Thunderstorm
activity should continue to diminish across the north and south
over the next few hours.

Surface high pressure will move into the region later today,
keeping most of the afternoon dry and capped. Moisture will
continue to surge into the region, leading to widespread
dewpoints in the upper 60s to the lower 70s. High temperatures
will range from the lower 80s northwest, to the low to mid 90s
over the James River Valley. Eastern LaMoure and Dickey counties
will see the best overlap of high dewpoints and temperatures,
leading to some apparent temperature values into the triple
digits. Thus, the Heat Advisory for these two counties later
this afternoon is in good shape.

The next chance for severe weather than arrives this evening and
into the overnight hours as the next wave rides down the ridge
popping back up to our west. The best chances for a few
supercells and/or bowing segments will be across the west and
south, where the RAP suggests we will see a nocturnal
environment characterized by MUCAPE values ranging from around
700 to 1700 J/kg and deep layer shear in the 50 to 60 knot
range. With plenty of instability and very strong shear, hail to
the size of tennis balls and damaging gusts to 70 mph seems
like a reasonable worst case scenario. Especially initially,
when storms may be a bit more discrete as they move into western
North Dakota from eastern Montana in the mid to late evening.
Storms should mainly move out around 12z Sunday morning, give or
take a few hours.

Modest ridging will lead to mainly dry conditions for the first
part of the day on Sunday. However, the next wave will approach
from the west in the late afternoon and evening hours,
flattening the ridge again. Another round of severe storms is
possible during this time frame given an environment
characterized by MLCAPE potentially greater than 3000 J/kg and
deep layer shear in the 45 to 55 knot range. Storm coverage is a
bit uncertain but most CAMs produce storms. The best chances for
severe storms will generally run along and east of a line from
the northwest corner of the state, to just east of Bismarck, and
down to the South Dakota border over Dickey county. Hail to the
size of golf balls and damaging winds to 70 mph will be the
main threats. Sunday will be another hot and humid day with
highs ranging from the lower 80s in vicinity of the Turtle
Mountains, to the mid to upper 90s southwest. Dewpoints will
only be in the mid 50s to lower 60s over the hottest areas, so
it does not appear that we will reach any Heat Advisory
criteria on Sunday.

Most of the precipitation will move out on Monday, but we could
maybe see a few lingering showers or storms across the northeast
early in the day as we transition back into northwest flow
aloft. We will also cool down a bit on Monday with highs
forecast to range from the lower 70s in the vicinity of the
Turtle Mountains, to the low to mid 80s southwest. These cooler
temperatures will remain in the forecast through midweek before
the western ridge starts to nudge closer and we warm back into
the lower 80s to lower 90s again by the end of the week and into
next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 130 PM CDT Sat Jul 13 2024

VFR except maybe MVFR in thunderstorms overnight. This afternoon
will be mostly clear skies with winds up to 15kts from the north
in western ND, and from the southeast in eastern ND. Overnight
there will be scattered severe thunderstorms in the west and
south central, maybe the central, through about 10z. Winds will
be gusty in thunderstorms. Sunday should start with mostly
clear skies and winds from the east.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for NDZ048-051.

&&

$$

UPDATE...Smith
DISCUSSION...ZH
AVIATION...Smith