Severe Thunderstorm Warning 129, NWS Bismarck, ND

AREA FORECAST DISCUSSION
National Weather Service Bismarck ND
536 PM CDT Mon Sep 4 2023

.UPDATE...
Issued at 532 PM CDT Mon Sep 4 2023

Severe thunderstorm watch has been issued for parts of far
southwest and south central North Dakota, as well as much of the
James River Valley through this evening. The main threat continues
to be very strong thunderstorm winds, with peak gusts ranging from
70 to 90 mph, with the best chance of occurrence from Mobridge,
SD northeast through Jamestown, associated with a line of storms
moving into a more favorable environment and as a potent mid level
low swings east across the Dakotas.

&&

.SHORT TERM...(This Evening through Tuesday)
Issued at 215 PM CDT Mon Sep 4 2023

Current surface analysis places low over Manitoba with a trough
extending southward through the northern plains, while a cold
front stretches to the southwest of the low, just nudging into
extreme northwest North Dakota into eastern Montana. Ahead of the
front, temperatures have warmed mainly into the 80s and lower 90s,
while behind the front wildfire smoke is notably dropping
visibilities, with temperatures in the 50s and 60s. Upper level
analysis places staunch trough with a slightly negative tilt
stretching through central Montana into western Wyoming. A variety
of notable short waves swinging around the trough are sliding up
southwest flow which stretches through our area. A few rain
showers behind the aforementioned cold front are trying to work
their way towards northwest North Dakota, but the start of the
main show that will be affecting us is a line of storms stretching
from far southeast Montana through northeast Wyoming into far
southwest South Dakota.

For late this afternoon into tonight, aforementioned area of
storms to the southwest will continue its approach. Latest timing
of the storms bring them to the far southwest North Dakota border
around 23Z (5 PM MDT), for which most CAMs have been pretty
consistent with through the day. As the storms lift towards our
area, they will encounter an environment with CAPE values of
1000-2000 J/Kg and about 40 to 50 kts of deep layer shear, all
plenty for severe potential and large hail, particularly if we get
a few stray storms developing ahead of the main line. What
continues to catch our eye, though, is the potential for strong
damaging wind gusts. Forecast parameters for wind potential
continue to be on par with what was previously discussed early
this morning with 0-3KM shear values in the 25 to 35 kt range, and
DCAPE values of 1000+ J/kg. So, much of southwest and central
North Dakota are in play for severe weather this evening, but the
corridor of greatest concern continues to be south central North
Dakota into portions of southwest where the greatest severe
parameters are lining up. Therefore, will continue to message
potential for 70 mph gusts with an isolated 80 mph possible.
Severe threat wanes and exits by around 06Z, but showers and tamer
thunderstorms continue though the overnight into Tuesday before
gradually diminishing and departing the area.

As for rainfall amounts, NBM probabilities continue to click up,
with now a 50 to 80 percent chance of seeing an inch of rainfall
tonight through Tuesday over much of southwest and south central
North Dakota, The greatest values are around Bismarck stretching
towards Glen Ullin, Hettinger, and Fort Yates, where, when
looking at potential for 2 inches, a 30 to 50 percent chance
exists.

Now, on to a separate concern, smoke. Behind the advancing cold
front which is now pushing into far northwest North Dakota,
visibility has notably dropped off along with air quality as the
next batch of wildfire smoke makes its way into the area.
Therefore, have brought smoke into the area in line with latest
HRRR near surface smoke guidance. There is still some question as
to how the smoke will interact with the anticipated rainfall, but
earlier this summer we had an event where notable smoke lingered
around while thunderstorms were occurring. Continued having smoke
in the area through Tuesday/Tuesday night.

.LONG TERM...(Wednesday through Monday)
Issued at 215 PM CDT Mon Sep 4 2023

Near to below average temperatures are expected through this time
period. Occasional shower/storm chances develop over the area from
time to time, but based on latest parameters concern for severe is
low.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 215 PM CDT Mon Sep 4 2023

Thunderstorms will move into western North Dakota late this
afternoon, spreading east this evening. A few of these storms may
become severe with large hail and strong wind gusts. Localized
MVFR to IFR visibilities will be possible under any of the heavier
showers or storms. IFR to MVFR ceilings will also move into the
southwest and south central late in the period as a steadier rain settles
in.

In addition, areas of smoke will move into northwest North Dakota
this afternoon, spreading southeast as we go into tonight and
Tuesday. This may drop visibility to MVFR and IFR levels.

&&

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

UPDATE...NH
SHORT TERM...JJS
LONG TERM...JJS
AVIATION...JJS

Hazardous Weather Outlook
National Weather Service Bismarck ND
212 PM CDT Mon Sep 4 2023

NDZ001-002-009-051915-
Divide-Burke-Williams-
212 PM CDT Mon Sep 4 2023

This Hazardous Weather Outlook is for portions of northwest North
Dakota.

.DAY ONE...This Afternoon and Tonight

Thunderstorms are possible. Severe weather is not expected.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

NDZ003>005-010>013-017-018-031-032-051915-
Renville-Bottineau-Rolette-Mountrail-Ward-McHenry-Pierce-McKenzie-
Dunn-Golden Valley-Billings-
212 PM CDT Mon Sep 4 2023 /112 PM MDT Mon Sep 4 2023/

This Hazardous Weather Outlook is for portions of north central
North Dakota, northwest North Dakota, and southwest North Dakota.

.DAY ONE...This Afternoon and Tonight

Thunderstorms are possible this morning. Severe weather is not
expected.

Isolated severe storms are possible late this afternoon and into
the evening. The primary threats will be one inch diameter hail
and wind gusts to 60 mph.

In addition, some storms could contain heavy rainfall tonight
into Tuesday morning. This could lead to some localized flooding
concerns.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.
Please report any severe weather, which includes flooding, to the
National Weather Service in Bismarck.

NDZ019>023-025-033>037-040>048-050-051-051915-
Mercer-Oliver-McLean-Sheridan-Wells-Foster-Stark-Morton-Burleigh-
Kidder-Stutsman-Slope-Hettinger-Grant-Bowman-Adams-Sioux-Emmons-
Logan-La Moure-McIntosh-Dickey-
212 PM CDT Mon Sep 4 2023 /112 PM MDT Mon Sep 4 2023/

This Hazardous Weather Outlook is for portions of south central
North Dakota, southeast North Dakota, and southwest North Dakota.

.DAY ONE...This Afternoon and Tonight

Scattered severe storms are possible late this afternoon and into
the evening. The primary threat will be one-inch diameter hail
and damaging winds to 70 mph. An isolated storm or two may produce
wind gusts of 80 mph. Also, a few of the initial thunderstorms
could produce ping pong ball size hail.

In addition, some storms could contain heavy rainfall tonight
into Tuesday morning. This could lead to some localized flooding
concerns.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.
Please report any severe weather, which includes flooding, to the
National Weather Service in Bismarck.

Special Weather Statement
National Weather Service Bismarck ND
605 PM CDT Mon Sep 4 2023

NDZ018-019-033-034-042330-
Stark ND-Mercer ND-Morton ND-Dunn ND-
605 PM CDT Mon Sep 4 2023

...A STRONG THUNDERSTORM WILL IMPACT PORTIONS OF SOUTHEASTERN DUNN,
NORTHWESTERN MORTON, EASTERN STARK AND SOUTHWESTERN MERCER COUNTIES
THROUGH 630 PM CDT/530 PM MDT/...

At 605 PM CDT/505 PM MDT/, strong thunderstorms are located over
Richardton, or 22 miles east of Dickinson, moving northeast at 35
mph.

HAZARD...Wind gusts to 50 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of southeastern Dunn,
northwestern Morton, eastern Stark and southwestern Mercer Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT/1000
PM MDT/ for south central North Dakota.

&&

LAT...LON 4685 10268 4736 10217 4728 10171 4724 10174
      4724 10177 4721 10176 4665 10220
TIME...MOT...LOC 2305Z 208DEG 31KT 4689 10230

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...50 MPH

MDJ

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