Hail and Damaging Winds in North Dakota, August 4 to 5, 2019

Area Forecast Discussion
National Weather Service Bismarck ND
1013 PM CDT Sun Aug 4 2019

.UPDATE...
Issued at 1013 PM CDT Sun Aug 4 2019

Convection has been slow to develop across the region with the
negative effects of a capping inversion and weak overall ascent.
That may change in the near future as a shortwave over
southwestern Saskatchewan slides over Montana. Regional radar
shows thunderstorms currently in our northwest to north-central in
an increased region of DCVA. Additionally, thunderstorms continue
to form off a stationary boundary over eastern Montana and western
North Dakota.

As the overall setup transitions from one that was diurnally aided
earlier in the evening to one with more synoptic forcing due to
the aforementioned shortwave support...this may favor the northern
portions of the state over the southern for increased convective
and possibly severe activity. The steep midlevel lapse rate plume
extends towards the International Border which has contributed to
500-1000 J/kg of MUCAPE. Given strong midlevel flow with around
50 kts of effective bulk shear elevated storms with a severe
hail/wind threat will be possible, though still very uncertain,
overnight.

UPDATE Issued at 601 PM CDT Sun Aug 4 2019

Early this evening, a weak surface front was placed from eastern
Montana through McKenzie county and eastward into central North
Dakota, becoming more diffuse further east. A thunderstorm has
formed along this boundary in eastern Montana and is tracking
towards Golden Valley and Slope county. With ample effective deep
layer shear and steep midlevel lapse, this convection should be
moving through an environment that allows some sustainability with
a possibility for a severe threat even with less than ideal
boundary layer moisture.

Further east...the atmosphere is characterized by greater boundary
layer moisture with surface dewpoints in the 60s in central ND to
the low 70s in the James River Valley. However, the convectively
processed airmass from earlier thunderstorms left moderate
inhibition as observed by the 21Z KBIS observed sounding. Given
those two factors, significant uncertainty exists in convective
initiation further east especially given the diffuse surface
pattern. Visible satellite imagery shows no indications of cumulus
development as of 2330Z and thunderstorm activity may be delayed
until the arrival of thunderstorms initiated further west. One
potential for initiation earlier in the evening in the south-
central through south-east may be from the presence of several
outflow boundaries currently detected on KBIS/KABR radars. While
conditional, a risk for supercells and severe weather would
arise in this area given the CAPE/shear parameter space.

&&

.SHORT TERM...(This evening through Monday)
Issued at 315 PM CDT Sun Aug 4 2019

After the morning and early afternoon convection across west
central and southwest North Dakota modified the airmass,
questions arise about the stability and suitability for severe
convection there. Will release a 21Z sounding to see the nature of
the airmass.

Otherwise will generally follow the latest CAM trends and look
for convective initiation from east central Montana through west
central North Dakota along some leftover outflow boundaries and a
relative moist plume with surface dewpoints in the lower to middle
60s. Sunshine has allowed temperatures to warm into the upper 80s
southwest but dewpoints have fallen there into the lower 50s. So
current thinking is thunderstorms move southeast increasing in
intensity as they move into south central and southeast North
Dakota this evening and overnight.

Monday will see surface high pressure move over the region with
generally dry air. Highs will be in the upper 70s to lower 80s.

.LONG TERM...(Monday night through Sunday)
Issued at 315 PM CDT Sun Aug 4 2019

The extended period will generally see a northwest flow regime
through the week with several weak shortwaves producing some
slight chances for thunderstorms. The best chance will be toward
the weekend when an upper low will move inland and bring backing
flow aloft, to teh southwest, better moisture return. Highs will
generally be into the 70s and lower 80s this week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 601 PM CDT Sun Aug 4 2019

Thunderstorms are expected to develop across portions of
western/central North Dakota this evening. High uncertainty in
timing/location however as thunderstorm development has been
delayed so mention was left to VCTS for now. Otherwise VFR
conditions expected at all TAFs.

&&

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

UPDATE...AE
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...AE

Hazardous Weather Outlook
National Weather Service Bismarck ND
1018 PM CDT Sun Aug 4 2019

NDZ001>005-009>013-017>023-025-031>037-040>048-050-051-060330-
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-
1018 PM CDT Sun Aug 4 2019 /918 PM MDT Sun Aug 4 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...Tonight

Scattered thunderstorms are expected across western and central
North Dakota tonight. A few may be severe with large hail up to
the size of half dollars and 60 mph winds.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Special Weather Statement
National Weather Service Bismarck ND
809 PM MDT Sun Aug 4 2019

NDZ031-032-050300-
Golden Valley ND-Billings ND-
809 PM MDT Sun Aug 4 2019

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN GOLDEN VALLEY AND
SOUTHWESTERN BILLINGS COUNTIES UNTIL 900 PM MDT...

At 809 PM MDT, a strong thunderstorm was located 11 miles southeast
of Sentinel Butte, or 16 miles southeast of Beach, moving east at 35
mph.

Penny size hail and wind gusts to 40 mph will be possible with this
storm.

Locations impacted include...
Fryburg.

LAT...LON 4684 10383 4694 10323 4668 10324 4668 10383
TIME...MOT...LOC 0209Z 260DEG 28KT 4676 10373

EDWARDS