Severe Thunderstorm Warning 104, NWS Sioux Falls, SD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
652 PM CDT Tue Aug 6 2019

.SHORT TERM...(This Evening through Wednesday)
Issued at 306 PM CDT Tue Aug 6 2019

The atmosphere looks like it will get organized tonight and bring a
very good chance for severe weather. An upper level wave will move
from eastern MT into northern SD this evening and should spark
thunderstorm development in south central ND and north central SD
from about 22-0z. The area of development will likely see CAPE
values close to 2000 J/kg with good deep layer shear, likely 40 to
50 knots from the surface to 6 km. The latest model soundings show a
favorable environment across central and eastern SD as these storms
move southeast. While the instability upstream is decent the shear
will likely be a driving factor in maintaining the stronger updrafts
as well as new ones this evening. Areas from around the James Valley
west will see the higher instability and the better chance for large
hail. Later in the night, after about 5z, the threat should turn a
little more towards wind. A favorable shear profile with deep nearly
unidirectional winds suggest the potential for very strong winds.
The surface to 3 km bulk shear vector is oriented from about 330
degrees and should be favorable for a couple of QLCS tornadoes if
any component of the convection becomes linear. Time will tell but
at this time the highest threat for severe weather should be from
about 9 pm to 2 am CDT. As the storms shift east they will gradually
move away from the better instability so as they approach Interstate
29 there should be a downward trend in coverage and intensity late
tonight.

Some residual thunderstorm activity will be possible in northwest IA
on Wednesday morning but severe weather is not expected with this.
Skies will be partly cloudy as high pressure builds south and winds
turn to the north and northeast. Highs will be seasonally warm in
the lower to mid 80s with dew points in the 60s, so a touch humid.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 306 PM CDT Tue Aug 6 2019

There will be a small chance for thunderstorms near the Missouri
River Wednesday night which is near the low and mid level thermal
gradient and location of a weak upper level wave. Severe weather
looks unlikely. Temperatures will cool overnight with high pressure
building. Lows in the mid 50s near Brookings to lower 60s along the
Missouri River.

Thursday should prove to be another seasonally warm day with
temperatures a bit below normal. Upper level ridging will build
across the area and should keep conditions dry.

Friday night into Saturday will see this ridge break down a bit and
the chances for thunderstorms will return as a decent mid level wave
moves through. Warm advection will increase as the low level jet
increases and this should bring a round of thunderstorms to the
area. A few severe storms appear possible.

Flow remain favorable for both near to below normal temperatures as
well as occasional thunderstorm chances Sunday into Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 650 PM CDT Tue Aug 6 2019

High clouds will increase this evening as thunderstorms approach
from the northwest. During the late evening and early overnight,
several strong storms are possible west of a KHON to KMHE to KYKN
line, with heavy rain, large hail, and brief strong wind gusts up
to 50 kt. Storms move south of the area by the early morning
hours. Surface winds shift to northerly during the day Wednesday
as a weak cool front moves in.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

SHORT TERM...08
LONG TERM...08
AVIATION...VandenBoogart

Hazardous Weather Outlook
National Weather Service Sioux Falls SD
710 PM CDT Tue Aug 6 2019

SDZ038-039-050-052>054-057>061-063>065-068-069-080015-
Beadle-Kingsbury-Gregory-Jerauld-Sanborn-Miner-Brule-Aurora-Davison-
Hanson-McCook-Charles Mix-Douglas-Hutchinson-Bon Homme-Yankton-
710 PM CDT Tue Aug 6 2019

This Hazardous Weather Outlook is for central South Dakota, east
central South Dakota, south central South Dakota and southeast
South Dakota.

.DAY ONE...Tonight.

This is an enhanced risk of severe thunderstorms this evening into
the early overnight. A few of these storms may be capable of large
hail up to 2 inches in diameter and wind gusts up to 80 mph. The best
chance for these storms should is between 9 pm and 1 am CDT.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed after 9 pm.

IAZ001-012-020-031-MNZ071-097-098-NEZ013-014-SDZ040-055-056-062-066-
067-070-071-080015-
Lyon-Sioux-Plymouth-Woodbury-Lincoln-Pipestone-Rock-Dixon-Dakota-
Brookings-Lake-Moody-Minnehaha-Turner-Clay-Union-
710 PM CDT Tue Aug 6 2019

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa, southwest Minnesota, northeast Nebraska, east central South
Dakota and southeast South Dakota.

.DAY ONE...Tonight.

A few thunderstorms will move into the Interstate 29 corridor after
11 pm CDT through 2 am CDT. An isolated storm could produce hail up to
the size of quarters and wind gusts up to 60 mph.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

IAZ002-003-013-014-021-022-032-MNZ072-080-081-089-090-080015-
Osceola-Dickinson-O'Brien-Clay-Cherokee-Buena Vista-Ida-Lyon-Murray-
Cottonwood-Nobles-Jackson-
710 PM CDT Tue Aug 6 2019

This Hazardous Weather Outlook is for northwest Iowa, west central
Iowa and southwest Minnesota.

.DAY ONE...Tonight.

A few thunderstorms are possible east of I-29 through the overnight
hours, with brief heavy rain and lightning being the primary threats.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
901 PM CDT TUE AUG 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0857 PM     HAIL             6 SSW CHAMBERLAIN       43.73N 99.35W
08/06/2019  M1.00 INCH       BRULE              SD   TRAINED SPOTTER

            HAIL STONES HAVE BEEN INCREASING IN SIZE
            OVER THE PAST 5 MINUTES.

&&

AT

PRELIMINARY LOCAL STORM REPORT...CORRECTED TIME OF REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
901 PM CDT TUE AUG 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 PM     HAIL             6 SSW CHAMBERLAIN       43.73N 99.35W
08/06/2019  M1.00 INCH       BRULE              SD   TRAINED SPOTTER

            HAIL STONES HAVE BEEN INCREASING IN SIZE
            OVER THE PAST 5 MINUTES.

&&

AT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
902 PM CDT TUE AUG 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0857 PM     HAIL             8 SSW CHAMBERLAIN       43.71N 99.38W
08/06/2019  M1.00 INCH       BRULE              SD   TRAINED SPOTTER

&&

AT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
913 PM CDT TUE AUG 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0855 PM     HAIL             11 S CHAMBERLAIN        43.65N 99.32W
08/06/2019  M0.88 INCH       BRULE              SD   TRAINED SPOTTER

            REPORTED NICKEL SIZE HAIL BEFORE THE RAIN
            STARTED, THEN NOTHING BIGGER THAN PEA-SIZE
            SINCE THEN.

&&

AT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
933 PM CDT TUE AUG 6 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0928 PM     HAIL             18 S PUKWANA            43.52N 99.17W
08/06/2019  M1.00 INCH       BRULE              SD   TRAINED SPOTTER

&&

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