Tornadoes and Hail in South Dakota, May 12, 2022

Area Forecast Discussion
National Weather Service Aberdeen SD
153 PM CDT Thu May 12 2022

.SHORT TERM...(This Evening through Friday Night)
Issued at 152 PM CDT Thu May 12 2022

Main focus is on the convective potential this afternoon and first
half of the evening.

A 999mb surface low is currently located over south central SD
(western Lyman County) and a warm front stretches northeast into
central Hyde/Hand counties and then eastward along a old outflow
boundary from morning convection eastward across northern Beadle
County and to just south of Brookings. North of the warm front,
skies are mostly cloudy and temperatures are in the mid 60s, but
south of the warm front, temperatures are in the lower 80s with
dewpoints in the upper 60s and lower 70s. As the upper trough in WY
and shortwave in sw NE lift to the northeast this afternoon, expect
both the low and warm front to move north. While things are pretty
stable north of the warm front and old outflow boundary, already
seeing a CU filed stretching from Hyde/Hand counties and south
towards Chamberlain. That area almost seems to be showing a greater
area of convergence and potential hints of reduced CIN on the latest
SPC MesoA data. So may need to watch that area a little more closely
over the next couple hours. Otherwise, expect things to develop
around the Lyman county area around 21Z, close to the surface low
and in the area of clear skies, which is supported pretty well in
the CAM and WoFS output. With ample instability (MLCAPE of 3-3.5k
J/kg at 18Z) and effective shear of 50kts, expect them to quickly
become severe with significant hail (steep mid level LRs and SHIP
values already rising into the 3-4 range), damaging winds and
potentially a few tornadoes. Will need to closely monitor the low
level fields for tornado potential in this initial storms, as latest
trends do show some favorable low level curvature in the hodographs,
especially the closer you get to the warm front. So as any discrete
storms that initial develop push north fairly quickly towards the
front, there will be an increased tornado threat. Right now, that
threat is initially greatest from northern Lyman north to US 83 and
eastward to US 281. With additional development possible eastward
along the warm front, could see the northern storms evolve into more
of a cluster of storms and increasing the wind threat and still a
threat for tornadoes into northeastern SD.  Farther south, expect
additional storms to develop southward along the cold front into
Nebraska. The expectation is for these storms to become linear with
time and move northeastward across southeastern SD. That QLCS will
likely push into the southeastern part of our CWA during the late
afternoon and early evening. Damaging winds, potentially
significant, will be the main threat, but with 0-3km bulk shear
values of 35-40kts to the northeast, will need to monitor for
potential QLCS mesovortexes too. Finally, there remains some concern
for flooding, but with the overall faster movement of the storms,
think the threats will be limited to areas that have already
received ample rain over the last couple of weeks.

With the tight pressure gradient behind the intensifying low (down
to around 990mb by 12Z as it reaches ND/Sask/Manitoba border area),
we'll see some potentially gusty west-southwest winds across much of
the area tonight. Some uncertainty on how deep we'll mix with the
bulk of the strong winds aloft occurring during the overnight hours
(900mb winds to 40kts and 850mb winds to 50-55kts) and limited low
level cold air advection to help steepen the low level lapse rates.
The best opportunity for mixing into the stronger winds aloft
appears to be over north central SD, which has shown some
consistency over the last few model runs. This is tied to a pocket
of colder 925-850mb temperatures helping to increase low level lapse
rates in that area. With the expectations of seeing at least some
advisory level gusts, will issue a wind advisory for parts of north
central SD for tonight into Friday morning. The pressure gradient
will diminish during the late morning into the afternoon on Friday,
as we see the low weaken and lift northeast, and a weak high
pressure ridge from a high in srn MN and IA moves over the eastern
area.

Tomorrow afternoon, wrap around moisture from the surface low in
Canada and a weak shortwave, may lead to some diurnally aided
showers and maybe a few rumbles of thunder tomorrow afternoon.
Instability is pretty limited (a couple hundred J/kg of MUCAPE)
though, so think thunder potential is low overall. Largely kept the
slight chance for showers over central SD, but could see them sneak
a little farther east in the evening before dissipating.

.LONG TERM...(Saturday through Thursday)
Issued at 152 PM CDT Thu May 12 2022

Upper ridge pattern is dominant this period. Weather is expected to
be relatively quiet this weekend. Starting Tuesday, a shortwave
trough will pass through with some precip possible Tuesday night
into Wednesday. Thursday's upper level pattern is more uncertain
with a ridge or a trough possible based on clusters. On to the
specifics!

Saturday upper level pattern looks to transition from a ridge to
more zonal flow as the low over Canada moves across to the north.
Shortwave energy reaches down into the area from this low, since the
region remains relatively dry this energy will most likely go
unused. Clusters for Sunday show the upper level trough and
associated low over Canada moving to the east. An upper level ridge
is moving into the region. Monday the general trend for the clusters
has been an upper level ridge still moving east towards the area.

Tuesday starts to get a little more active. The overall upper level
pattern will be a ridge but pockets of energy move into the area as
an embedded shortwave trough with a surface low make their way
across the region. As this shortwave moves through, moisture
increases. Abundant WAA in the region as a result of southerly mid
level winds will increase the probability of precipitation Tuesday
night into Wednesday. The best WAA in lower levels looks to be
around 06Z Wednesday just ahead of that surface low which passes to
the south. Totals most likely less than 0.1 inches.

For Thursday, uncertain on upper level pattern, could be an upper
level ridge, an upper level trough, or more zonal flow. GFS and
Canadian look to be leaning towards an upper trough.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1236 PM CDT Thu May 12 2022

Terminals KABR,KATY,KPIR,KMBG

A low pressure system is sitting over south central SD, with a
warm front stretching to the east across east central SD. North
and west of the low and warm front, seeing plenty of low stratus
and expect that to continue for at least a few hours at all of the
TAF sites. As the warm front lifts north, should see some rising
ceilings during the afternoon. Thunderstorms are expected to
develop this afternoon near the Pierre area, then rapidly lift to
the northeast. The storms will depart the area during the early-
mid evening period. Behind the storms, gusty west-southwest winds
are expected for parts of the area, which will continue into
Friday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

SHORT TERM...SRF
LONG TERM...KK
AVIATION...SRF

Hazardous Weather Outlook...UPDATED
National Weather Service Aberdeen SD
1223 PM CDT Thu May 12 2022

MNZ039-046-SDZ005>008-010-011-017>023-036-037-051-131200-
Traverse-Big Stone-McPherson-Brown-Marshall-Roberts-Edmunds-Day-
Faulk-Spink-Clark-Codington-Grant-Hamlin-Deuel-Hyde-Hand-Buffalo-
1223 PM CDT Thu May 12 2022

This Hazardous Weather Outlook is for west central Minnesota,
central South Dakota, north central South Dakota and northeast
South Dakota.

.DAY ONE...This afternoon and tonight.

This afternoon and evening severe storms are anticipated. Large hail
up to the size of golf balls, damaging winds in excess of 70 miles
per hour, and isolated tornadoes are possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed. Weather spotters are
encouraged to submit reports to the National Weather Service in
Aberdeen. The public can submit reports on our web page, Facebook
page, or our Twitter feed.

SDZ003-004-009-015-016-033>035-045-048-131200-
Corson-Campbell-Walworth-Dewey-Potter-Stanley-Sully-Hughes-Jones-
Lyman-
1223 PM CDT Thu May 12 2022 /1123 AM MDT Thu May 12 2022/

This Hazardous Weather Outlook is for central South Dakota and
north central South Dakota.

.DAY ONE...This afternoon and tonight.

Isolated severe storms are possible this afternoon. Hail and wind
are the main threats.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be requested. Weather spotters are encouraged
to submit reports to the National Weather Service in Aberdeen. The
public can submit reports on our web page, Facebook page, or our
Twitter feed.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1120 AM CDT THU MAY 12 2022

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

1225 AM     HAIL             6 SW OACOMA             43.75N 99.48W
05/12/2022  E1.00 INCH       LYMAN              SD   PUBLIC

&&

NWS ABR

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1125 AM CDT THU MAY 12 2022

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

1235 AM     HAIL             9 SW OACOMA             43.71N 99.53W
05/12/2022  E0.75 INCH       LYMAN              SD   PUBLIC

&&

NWS ABR

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1151 AM CDT THU MAY 12 2022

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

0100 AM     HAIL             6 N OACOMA              43.88N 99.41W
05/12/2022  E1.75 INCH       LYMAN              SD   PUBLIC

            HAILED GOLFBALLS FOR ABOUT 15 MINUTES. WIND
            GUSTS OF ~50MPH.

&&

NWS ABR

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE ABERDEEN SD
116 PM CDT THU MAY 12 2022

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

1225 AM     HAIL             6 SW OACOMA             43.75N 99.48W
05/12/2022  E1.00 INCH       LYMAN              SD   PUBLIC

1235 AM     HAIL             9 SW OACOMA             43.71N 99.53W
05/12/2022  E0.75 INCH       LYMAN              SD   PUBLIC

0100 AM     HAIL             6 N OACOMA              43.88N 99.41W
05/12/2022  E1.75 INCH       LYMAN              SD   PUBLIC

            HAILED GOLFBALLS FOR ABOUT 15 MINUTES. WIND
            GUSTS OF ~50MPH.

0113 AM     HAIL             8 ENE RELIANCE          43.92N 99.45W
05/12/2022  E0.88 INCH       LYMAN              SD   PUBLIC

            FACEBOOK MESSAGE.

0350 AM     TSTM WND GST     1 SW TIMBER LAKE        45.42N 101.09W
05/12/2022  M69 MPH          DEWEY              SD   MESONET

0355 AM     HAIL             4 S STONE BRIDGE        44.55N 97.05W
05/12/2022  E1.25 INCH       HAMLIN             SD   TRAINED SPOTTER

            FROM EMAIL.

0402 AM     TSTM WND GST     4 ENE GLENCROSS         45.47N 100.86W
05/12/2022  E70 MPH          CORSON             SD   FIRE DEPT/RESCUE

            CORRECTS PREVIOUS TSTM WND GST REPORT FROM 4
            ENE GLENCROSS. ESTIMATED 70 MPH WIND GUSTS.
            LARGE, OLD COTTONWOOD TREE DOWN.

0410 AM     HAIL             ESTELLINE               44.58N 96.90W
05/12/2022  M1.00 INCH       HAMLIN             SD   TRAINED SPOTTER

0423 AM     TSTM WND GST     4 ENE POINSETT COLONY   44.66N 96.82W
05/12/2022  M49 MPH          DEUEL              SD   MESONET

            MESONET STATION 47 BRANDT (SDDOT).

0436 AM     HAIL             1 W MOBRIDGE MUNICIPAL  45.55N 100.42W
05/12/2022  E0.50 INCH       WALWORTH           SD   PUBLIC

0438 AM     TSTM WND GST     TUNERVILLE              44.89N 96.68W
05/12/2022  M46 MPH          DEUEL              SD   MESONET

            MESONET STATION 291 4N ALTAMONT (SDDOT).

0439 AM     HAIL             2 ENE LANTRY            45.03N 101.38W
05/12/2022  E1.00 INCH       DEWEY              SD   PUBLIC

0443 AM     TSTM WND GST     5 WNW POLLOCK           45.93N 100.39W
05/12/2022  M59 MPH          CAMPBELL           SD   PUBLIC

            PWS FROM MESONET.

0456 AM     HAIL             DEMPSTER                44.63N 96.95W
05/12/2022  E1.00 INCH       HAMLIN             SD   PUBLIC

            FACEBOOK REPORT.

0517 AM     TSTM WND GST     5 SW JAVA               45.45N 99.96W
05/12/2022  M56 MPH          WALWORTH           SD   MESONET

            MESONET STATION 313 SD RWIS SELBY 4 MILES
            EAST OF US 12/83.

0535 AM     TSTM WND GST     1 SW BOWDLE             45.44N 99.67W
05/12/2022  M64 MPH          EDMUNDS            SD   MESONET

            SDSU MESONET.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
217 PM CDT THU MAY 12 2022

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

1145 PM     HAIL             13 NW IONA              43.68N 99.61W
05/11/2022  E1.00 INCH       LYMAN              SD   PUBLIC

&&

NWS ABR