Special Weather Statement, NWS Bismarck, ND

Area Forecast Discussion
National Weather Service Bismarck ND
257 PM CDT Tue Jul 20 2021

.SHORT TERM...(This evening through Wednesday)
Issued at 257 PM CDT Tue Jul 20 2021

The short term forecast is highlighted by hot temperatures and
chances for showers and thunderstorms that continue through the
night and end in the east tomorrow afternoon.

This afternoon, the synoptic pattern was characterized by ridging
placed over the Northern Rockies while a closed low was spinning off
the coast of British Columbia. Water vapor imagery showed a
shortwave moving through the mean flow over Montana and into North
Dakota. At the surface, a low has developed as expected in eastern
Montana, with a surface trough extending to the south and a weak
quasi-stationary frontal boundary extending to the northeast into
northern North Dakota. Showers and a few isolated thunderstorms
have been ongoing through the morning and into the early
afternoon.

Winds this afternoon have exceeded expectations in the southwest,
with wind gusts up to 40 mph reported at the Bowman Airport and Sand
Creek RAWS site in Slope County. These also have reported a
minimum relative humidity of 17 and 18 percent, respectively,
although the most recent observation has brought up humidity a few
percent. The Red Flag Warning continues until midnight. Winds are
breezy to windy across the rest of the southern part of the
state, but humidity has managed to stay a bit higher. Temperatures
as of 19 UTC range from the mid 70s in the northwest, which have
been cloudy and showery all day, to the mid 90s in the south
central.

As the previous shift noted, the probability for severe
thunderstorms is low. The latest model guidance does have deep layer
shear of around 40 knots across most of the west and north central,
but instability looks lower than it did earlier today, with guidance
advertising only around 500 J/kg of MLCAPE. Forecast soundings
continue to show a modest amount of capping, which could also limit
convection. If there was to be a strong to severe thunderstorm, the
best chance would be in the northwest, but at this point thinking
that chance is pretty low. Will message scattered showers and
isolated thunderstorms that will likely be non-severe.

The chance of showers and thunderstorms spreads east tonight
following the progression of the surface trough, and using the NBM
for timing and spatial coverage. The latest guidance does have
slight chance PoPs lingering in the James River Valley Wednesday
afternoon, before the low finally pushes east of the forecast area.
Wednesday will be another hot day, with forecast highs in the mid
80s north to mid 90s south.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 257 PM CDT Tue Jul 20 2021

The extended period is highlighted by continued hot and mostly dry
conditions.

Thursday currently has the hottest forecast highs of the extended,
with highs around 100 in the southwest and 90s elsewhere. The best
chance for scattered showers and thunderstorms looks to be Thursday
night into Friday as a shortwave and attendant surface low move
through the region. This should somewhat flatten out the upper
ridging on Friday as the upper air pattern becomes dominated by
broad ridging extending across the majority of the CONUS. The
Northern Plains will be placed under the center of that ridge, with
quasi-zonal flow expected across the region through the rest of the
extended period. Temperatures will be relatively stable during this
time per the latest NBM, with highs generally in the mid 80s north
to mid 90s south. Dew points will be lower, in the 40s and 50s, as
we transition to low-level northwest flow which will advect in drier
air. Chances for precipitation look low.

NAEFS guidance shows low- and mid-level temperatures above the 90th
percentile through next week, and paired with the 8-10 day cluster
analysis showing broad ridging persisting, there is high confidence
in our current stretch of above average temperatures continuing
through the end of the month.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1248 PM CDT Tue Jul 20 2021

Overall VFR conditions through the 18Z TAF period. Scattered
showers and thunderstorms are possible across western and northern
North Dakota this afternoon and evening, so included VCTS at
KXWA/KMOT with this update, and VCSH at KDIK. Chances spread east
overnight tonight but are lower confidence in timing and location.
South winds are gusting to 30 kt southwest and 25 kt south central

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until midnight MDT tonight for NDZ031-032-040-
043.

&&

SHORT TERM...MJ
LONG TERM...MJ
AVIATION...MJ

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Special Weather Statement
National Weather Service Bismarck ND
448 PM MDT Tue Jul 20 2021

NDZ031-202315-
Golden Valley ND-
448 PM MDT Tue Jul 20 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN GOLDEN VALLEY COUNTY
UNTIL 515 PM MDT...

At 448 PM MDT, strong thunderstorms were clustered over Carlyle, or
18 miles south of Beach, moving northeast at 35 mph.

Nickel size hail and wind gusts to 55 mph will be possible with these
storms.

Locations impacted include...
Beach, Golva, Sentinel Butte and Alpha.

Very heavy rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4698 10404 4696 10361 4694 10361 4663 10377
      4663 10380 4658 10380 4654 10382 4654 10404
TIME...MOT...LOC 2248Z 212DEG 29KT 4665 10402

HAMILTON

Special Weather Statement
National Weather Service Bismarck ND
542 PM MDT Tue Jul 20 2021

NDZ043-210015-
Bowman ND-
542 PM MDT Tue Jul 20 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN BOWMAN COUNTY UNTIL
615 PM MDT...

At 542 PM MDT, a strong thunderstorm was located 8 miles west of Mud
Buttes, or 29 miles southwest of Bowman, moving northeast at 30 mph.

Wind gusts to 50 mph will be possible with this storm.

Locations impacted include...
Mud Buttes.

LAT...LON 4605 10404 4619 10366 4619 10365 4594 10356
      4595 10404 4602 10405
TIME...MOT...LOC 2342Z 243DEG 28KT 4599 10395

Telken