Hail and Damaging Winds in North Dakota, September 2, 2019

Area Forecast Discussion
National Weather Service Bismarck ND
910 AM CDT Mon Sep 2 2019

.UPDATE...
Issued at 909 AM CDT Mon Sep 2 2019

A cluster of showers and thunderstorms is currently moving through
north central North Dakota, while some stronger, more discrete
thunderstorms are just over the western border in
Sheridan/Roosevelt/Daniels Counties in Montana. Thinking that if
these cells stay discrete as they move into the forecast area,
this could be the start of our severe threat..mesoanalysis
currently has effective bulk shear in excess of 60 knots in
portions of western North Dakota, which is more than favorable for
supercells. However, instability is lacking a bit, and widespread
cloud cover over the state is prohibiting the start of any
diurnal destabilization. This is where much of the forecast
uncertainty lies, but if skies begin to clear and discrete cells
form, there's not a lot standing in the way of them quickly
becoming strong to severe. Increased wind speeds a bit in line
with observations, otherwise no changes to the current forecast.

UPDATE Issued at 615 AM CDT Mon Sep 2 2019

No major changes made this update. Some showers and isolated
thunderstorms have developed across far northwest North Dakota
this morning. This area of precipitation will continue to move
eastward and additional storms are expected to form along the warm
front this morning.

&&

.SHORT TERM...(Today and tonight)
Issued at 318 AM CDT Mon Sep 2 2019

A shortwave trough will amplify as it moves east southeast through
southern Alberta and Saskatchewan, reaching the northern Plains by
early this evening. Downstream from this feature, a warm front
will advance northeast across northwest ND through northeast SD
by early evening. A cold front will extend southward from the low
through the western Dakotas and advance east during the evening.

A moist warm sector will reside south of the warm front. Surface
dewpoints will range from the mid 60s to upper 70s F beneath steep
mid-level lapse rates associated with the eastward expansion of
an elevated mixed layer (EML). Warm air at the base of the EML
will result in a substantial cap in warm sector during the day.
Theta-e advection along a southerly low-level jet will contribute
to northeastward destabilization this afternoon and evening with
MUCAPE increasing from 2000-3000 J/kg north of the warm front.
Some isolated storms this morning may have a marginal hail threat,
but the main severe threat is expected during the afternoon into
the evening hours when forcing for ascent associated with
approaching shortwave trough and attendant strengthening low-
level jet will result in development of storms north of the warm
front over northern ND. These storms will be elevated, but
effective bulk shear from 50-60 kt and a favorable thermodynamic
environment will support a few supercells with large hail the
initial primary threat. Storms may eventually evolve into an MCS
with primary threat transitioning to damaging wind during the
evening and overnight as activity continues southeast along
instability gradient into the James Valley and eastern ND. Given
favorable low-level hodographs, a conditional threat will exist
for a couple of tornadoes with any surface-based storms that can
develop on the warm front. However, current indications are that
the warm sector will probably remain capped thus limiting the
potential for surface-based storms.

.LONG TERM...(Tuesday through Sunday)
Issued at 318 AM CDT Mon Sep 2 2019

A few chances for precipitation and seasonable temperatures
highlights the extended forecast.

Tuesday will be dry and cooler than Monday after the storms roll
through, with forecast highs in the low 60s to low 70s.

Temperatures will warm up some for Wednesday and Thursday with
more scattered showers and thunderstorms possible, before cooling
down to the 60s for the weekend. The next chance for widespread
precipitation comes Friday evening and chances continue through
the weekend though the long-term models differ widely on just how
much  the are will receive and how long it will stick around.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 615 AM CDT Mon Sep 2 2019

MVFR to IFR conditions have developed over much of North Dakota
this morning in response to rapid increase in moisture from the
south. Conditions should improve from west to east this morning as
a warm front passes through. Thunderstorms are expected at KJMS
this evening and nearby at KMOT/KBIS this morning and afternoon.

&&

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

UPDATE...MJ
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...AJ

Hazardous Weather Outlook
National Weather Service Bismarck ND
911 AM CDT Mon Sep 2 2019

NDZ001>005-009>013-017>023-025-031>037-040>048-050-051-031415-
Divide-Burke-Renville-Bottineau-Rolette-Williams-Mountrail-Ward-
McHenry-Pierce-McKenzie-Dunn-Mercer-Oliver-McLean-Sheridan-Wells-
Foster-Golden Valley-Billings-Stark-Morton-Burleigh-Kidder-
Stutsman-Slope-Hettinger-Grant-Bowman-Adams-Sioux-Emmons-Logan-
La Moure-McIntosh-Dickey-
911 AM CDT Mon Sep 2 2019 /811 AM MDT Mon Sep 2 2019/

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

.DAY ONE...Today and Tonight

Severe storms are possible Today/tonight. Hail up to golf ball
size, 70 mph winds and a few tornadoes will be the main threats
with any severe storms that do develop.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed today.

MJ

Special Weather Statement
National Weather Service Bismarck ND
1005 AM CDT Mon Sep 2 2019

NDZ001-021545-
Divide-
1005 AM CDT Mon Sep 2 2019

...A STRONG THUNDERSTORM WILL AFFECT WESTERN DIVIDE COUNTY UNTIL 1045
AM CDT...

At 1004 AM CDT, a strong thunderstorm was located 9 miles southwest
of Westby, or 19 miles east of Plentywood, moving east at 30 mph.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Winds gusts to 45 mph are also possible with this storm.

Locations impacted include...
Fortuna, Alkabo and Writing Rock State Historical Site.

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.

LAT...LON 4893 10358 4863 10351 4863 10401 4864 10405
      4886 10405 4888 10404
TIME...MOT...LOC 1504Z 268DEG 25KT 4874 10414

HEINERT

Special Weather Statement
National Weather Service Bismarck ND
1043 AM CDT Mon Sep 2 2019

NDZ001-021615-
Divide-
1043 AM CDT Mon Sep 2 2019

...A STRONG THUNDERSTORM WILL AFFECT DIVIDE COUNTY UNTIL 1115 AM
CDT...

At 1042 AM CDT, a strong thunderstorm was located 10 miles east of
Writing Rock State Historical Site, or 19 miles southwest of Crosby,
moving east at 35 mph.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

Wind gusts to 50 mph and pea size hail are also possible with this
storm.

Locations impacted include...
Crosby, Fortuna, Alkabo, Writing Rock State Historical Site and
Ambrose.

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.

LAT...LON 4864 10307 4864 10403 4895 10404 4900 10321
TIME...MOT...LOC 1542Z 266DEG 31KT 4875 10363

HEINERT