Special Weather Statement, NWS Bismarck, ND

Area Forecast Discussion
National Weather Service Bismarck ND
412 PM CDT Sun May 23 2021

.SHORT TERM...(This evening through Monday)
Issued at 400 PM CDT Sun May 23 2021

Will expect the convection until closer to 6 PM CDT to be
showers based on CAPE and mid level lapse rates less favorable
now, becoming more favorable later across the south, and, this as
storms approach from northwestern South Dakota.

The severe threat for this evening remains basically along and
south of North Dakota Highway 200. Mesoanalysis continues to show
increasing favorability for severe weather as CAPE increases and
0-6km shear values reach to near 50kts. As far a the risk of
tornadoes, there is some with 0-1km Storm Relative Helicity
favorable for at least a few tornadoes south of Dickinson and
southwest of Bismarck.

As far as the storm mode and overall severe risk, indications
continue to be that with the deep layer shear vectors orientation
to the front, any discrete cells with a primary hail risk will
fairly quickly transition to more multicellular / linear modes.
This would transition the risk to damaging wind supported by 1,000
J'kg of downdraft CAPE along and south of Interstate 94 from the
Heart River Valley through the James River Valley. Concern has
gone to QLCS tornado formation with storm lines needing to be
watched closely for tornado development. Storms should be
progressive, however, with very high Precipitable water values
there will be heavy rainfall rates, though maybe short lived for a
given location. Another concern for heavy rain will be any
pivoting of a convective line with the pivot over the same area
leading to prolonged rain.

The H5 wave that triggers the convection will be exiting the
forecast area close to daybreak Monday. In cyclonic flow both at
the surface and aloft on Monday a few pop up instability showers
will be possible.

.LONG TERM...(Monday night through Sunday)
Issued at 341 PM CDT Sun May 23 2021

The closed H5 low over Manitoba into Wednesday swings a few H5
waves through with continued small chances for showers. Milder on
temperatures as weak ridging pokes into the southern forecast
area. By mid week the next H5 low appears on the western horizon
and the area comes under southwest flow aloft with higher shower
chances then.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 400 PM CDT Sun May 23 2021

MVFR to IFR ceilings most TAF sites for the first half of the
forecast period, this in low clouds and patchy fog. Thunderstorms
will move into the southwest part of the forecast area and spread
north and east into Sunday night. There is a risk of +TSRA at all
TAF sites and +TSRAGR at KDIK and KBIS. Conditions will be
improving after 24/0600Z.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...JPM
LONG TERM...JPM
AVIATION...JPM

Hazardous Weather Outlook
National Weather Service Bismarck ND
309 PM CDT Sun May 23 2021

NDZ001>005-009>013-017-023-025-242015-
Divide-Burke-Renville-Bottineau-Rolette-Williams-Mountrail-Ward-
McHenry-Pierce-McKenzie-Wells-Foster-
309 PM CDT Sun May 23 2021 /209 PM MDT Sun May 23 2021/

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

.DAY ONE...This Afternoon and Tonight

Isolated thunderstorms through the period. The main hazards will
be pea size hail and wind gusts as high as 40 mph. Heavy rain is
possible from the stronger storms.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Patchy frost is possible both Wednesday and Thursday mornings,
otherwise the probability for widespread hazardous weather is
low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report severe weather by phone at
701-223-4582 or on NWS Bismarck social media.

NDZ018>022-031>037-040-043-046>048-050-051-242015-
Dunn-Mercer-Oliver-McLean-Sheridan-Golden Valley-Billings-Stark-
Morton-Burleigh-Kidder-Stutsman-Slope-Bowman-Emmons-Logan-
La Moure-McIntosh-Dickey-
309 PM CDT Sun May 23 2021 /209 PM MDT Sun May 23 2021/

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 thunderstorms are forecast after 6 PM CDT and to
continue through the night. A few of the storms from 6 PM to
midnight could be severe with large hail up to half dollar size
and damaging wind gusts as high 65 mph. Heavy rain is likely with
these storms.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Patchy frost is possible both Wednesday and Thursday mornings,
otherwise the probability for widespread hazardous weather is
low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report severe weather by phone at
701-223-4582 or on NWS Bismarck social media.

NDZ041-042-044-045-242015-
Hettinger-Grant-Adams-Sioux-
309 PM CDT Sun May 23 2021 /209 PM MDT Sun May 23 2021/

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

.DAY ONE...This Afternoon and Tonight

Scattered thunderstorms are forecast the rest of this afternoon
and tonight. A few of the storms will be severe with large hail
up to half dollar size and damaging wind gusts as high as 70 mph
until midnight. Isolated tornadoes are possible until 10 PM CDT.
Heavy rain is likely with the storms.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

Patchy frost is possible both Wednesday and Thursday mornings,
otherwise the probability for widespread hazardous weather is
low.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report severe weather by phone at
701-223-4582 or on NWS Bismarck social media.

JP Martin

Special Weather Statement
National Weather Service Bismarck ND
448 PM CDT Sun May 23 2021

NDZ018>022-031>037-040>048-050-051-232300-
Dunn-Mercer-Oliver-McLean-Sheridan-Golden Valley-Billings-Stark-
Morton-Burleigh-Kidder-Stutsman-Slope-Hettinger-Grant-Bowman-
Adams-Sioux-Emmons-Logan-La Moure-McIntosh-Dickey-
Including the cities of Killdeer, Halliday, Beulah, Hazen,
Center, Garrison, Washburn, Underwood, Wilton, Turtle Lake,
Mcclusky, Goodrich, Beach, Medora, Dickinson, Mandan, Bismarck,
Steele, Tappen, Jamestown, Marmarth, Mott, New England, Elgin,
Carson, New Leipzig, Bowman, Hettinger, Fort Yates, Selfridge,
Solen, Linton, Strasburg, Napoleon, Gackle, Lamoure, Edgeley,
Kulm, Wishek, Ashley, Oakes, and Ellendale
448 PM CDT Sun May 23 2021 /348 PM MDT Sun May 23 2021/

...THUNDERSTORMS WERE DEVELOPING OVER WESTERN SOUTH DAKOTA AND
WERE PUSHING NORTH...

Thunderstorms continued to develop in western South Dakota at 445
PM CDT, and were pushing north. Storms will be crossing into
southwestern North Dakota between now and 545 PM CDT, from Bowman
to Hettinger and North Lemmon, this is along Highway 12.

Some of these storms could be severe with hail up to half dollar
size and wind gusts as high as 70 mph. A tornado watch is in
effect until 10 PM CDT for Hettinger County, Adams, Grant and
Sioux counties, where isolated tornadoes will be possible. Heavy
rainfall rates should be expected with the storms.

Some safety rule reminders for you include, keep an eye on the
sky and an ear to your National Weather Service. Move inside to a
safe place when threatening weather approaches or when warnings
are issued for your area. The safest place to be in a tornado is
below ground level, in a basement. If you do not have a basement
go to an interior room on the lowest level of the building, into a
bathroom, or closet.

JP Martin

Special Weather Statement
National Weather Service Bismarck ND
449 PM MDT Sun May 23 2021

NDZ044-232315-
Adams ND-
449 PM MDT Sun May 23 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN ADAMS COUNTY UNTIL
515 PM MDT...

At 449 PM MDT, a strong thunderstorm was located near Shadehill, or 8
miles south of Lemmon, moving north at 35 mph.

Penny size hail and wind gusts to 50 mph will be possible with this
storm.

This storm will remain over mainly rural areas of southeastern Adams
County.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

A Tornado Watch remains in effect until 900 PM MDT for southwestern
North Dakota.

LAT...LON 4614 10235 4615 10200 4595 10200 4595 10230
TIME...MOT...LOC 2249Z 182DEG 31KT 4582 10212

HARGROVE