Damaging Winds in South Dakota, May 23, 2021

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
640 PM CDT Sun May 23 2021

.UPDATE...
Issued at 621 PM CDT Sun May 23 2021

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.SHORT TERM...(This Evening through Monday Night)
Issued at 315 PM CDT Sun May 23 2021

A warm front extending from a low pressure system centered in
eastern Colorado is currently located over the southern part of the
CWA, and has become the focus for some thunderstorm development
across the far southeast. These storms are not anticipated to reach
severe levels, and should drift out of the area by early this
evening. Attention then turns to another area of thunderstorm
development ongoing across the far western part of the state. These
are developing along the cold frontal portion of the aforementioned
low pressure system. This area of storms is expected to become much
more widespread through the remainder of the afternoon before
beginning to slide eastward. May see a stray storm or two ahead of
the line affect the far northwest part of the CWA, and due to decent
SRH and shear, Corson and Dewey counties have been included in a
Tornado Watch. The main line of storms looks to reach the western
CWA between 01Z and 03Z. As it continues eastward from there, will
see more of a wind threat develop with the storms. The storms will
weaken to below severe levels by midnight or so, then are expected
to dissipate altogether before sunrise. May see some additional
development Monday afternoon from central Nebraska to northwest
Wisconsin, which may clip the far southeastern part of the CWA.
Otherwise, dry conditions are expected Monday and Monday night.

Low temperatures tonight will range from the upper 40s west, to the
lower 60s east, with highs on Monday in the mid 70s to mid 80s. Lows
Monday night will be mainly in the 50s.

.LONG TERM...(Tuesday through Sunday)
Issued at 315 PM CDT Sun May 23 2021

Overall the upper level pattern will be a progressive zonal flow
through the long term period. Brief upper level riding will be in
place as the long term opens, followed by a closed low pressure
system, tracking from west to east across the northern plains in the
Thursday time frame. With a cool, easterly fetch and limited CAPE,
this system looks to be more of a widespread/general thunder type
event. In fact, high temperatures will struggle to reach 60 degrees
for much of the region Thursday, which is 10 to 20 degrees below
normal for this time of the year. Return flow surface winds do set
up Friday before another long wave trough sweeps across the northern
plains by the weekend. Models are surprisingly consistent through a
majority of the long term, therefore didn't deviate from blended
guidance.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 621 PM CDT Sun May 23 2021

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail at all four terminals throughout the
TAF valid period, except for the couple of hours when
thunderstorms move through the KMBG and KPIR terminals this
evening. A line of thunderstorms running from near the Black Hills
down into the Nebraska panhandle will track from southwest to
northeast across the region working through KPIR and KMBG
generally between 02Z and 04Z. In addition to sub-VFR
cigs/visbies, there could be some hail and heavy rain with these
storms. But, the bigger threat will be strong wind. While the
storms are forecast to gradually diminish/dissipate overnight as
they travel northeast into the James River valley and on toward
the border of the Dakotas and Minnesota, wind gusts in excess of
40 mph may still be possible into the early morning hours.

&&

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

UPDATE...Dorn
SHORT TERM...Parkin
LONG TERM...Serr
AVIATION...Dorn

Hazardous Weather Outlook
National Weather Service Aberdeen SD
443 AM CDT Sun May 23 2021

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-240945-
Traverse-Big Stone-Corson-Campbell-McPherson-Brown-Marshall-Roberts-
Walworth-Edmunds-Day-Dewey-Potter-Faulk-Spink-Clark-Codington-Grant-
Hamlin-Deuel-Stanley-Sully-Hughes-Hyde-Hand-Jones-Lyman-Buffalo-
443 AM CDT Sun May 23 2021 /343 AM MDT Sun May 23 2021/

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

.DAY ONE...Today and tonight.

Strong to severe storms are expected to develop this afternoon across
eastern Wyoming and western South Dakota, then move into central
South Dakota by this evening. Large hail up to golf ball size and
damaging winds in excess of 70 mph are possible. There is a threat
for a couple tornadoes as well, mainly west of the Missouri River.
The severe threat looks to diminish as storms approach the James
River later tonight.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be requested this evening. 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.

TMT