Special Weather Statement, NWS Aberdeen, SD

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
915 PM CDT Sat Jun 19 2021

.UPDATE...
Issued at 850 PM CDT Sat Jun 19 2021

One or two showers/thunderstorms have popped up over the CWA in
the last few hours, mainly along a boundary across the far
northern CWA. Meanwhile, the most significant thunderstorms
remain across western South Dakota, in an atmosphere with around
1000 j/kg of ML CAPE and 45+ kts of effective shear. Much less
favorable environment over our CWA. Progs are barely squeaking
out 500 J/KG of most unstable CAPE over our area. So severe threat
remains low. Regardless, still expecting to see an increasing low
level jet and better forcing as the upper level trough
approaches. So it is logical to expect shower and thunderstorm
activity to increase in areal coverage overnight. Made some slight
adjustments to the POP forecast, but overall seems to be
capturing the general trends well.

UPDATE Issued at 638 PM CDT Sat Jun 19 2021

See the updated aviation discussion below.

&&

.SHORT TERM...(This Evening through Sunday Night)
Issued at 244 PM CDT Sat Jun 19 2021

A surface high pressure is producing mild temperatures and low dew
points across the CWA this afternoon. There is some weak moisture
return ongoing over southwest SD where dew points are climbing
into the upper 40s and 50s. Better instability is noted over
western Nebraska where a mid level shortwave is producing
convection. Various CAMS suggest this convection will track
eastward tonight, or well south of the CWA. Another shortwave
embedded within northwesterly flow aloft should bring showers and
thunderstorms into this CWA later this evening and into the
morning hours on Sunday. Weak convection over eastern MT, western
ND around 0Z should track east-southeast overnight with the
northeastern portion of the CWA having the best potential for
pcpn, mainly after 6Z. Based on consistency with the past few
hours of the HRRR and RAP, have lowered pops over the southeastern
CWA throughout tonight, but have maintained higher pops over the
northeast CWA.

Low clouds and cooler temperatures can be expected behind the storm
system on Sunday. With a cloudy sky, isolated to scattered storms,
have lowered highs a few degrees, or closer to the 25th percentile
of the NBM. Winds will be gusty from the north with gusts of 30 to
35 mph possible.

.LONG TERM...(Monday through Saturday)
Issued at 244 PM CDT Sat Jun 19 2021

A somewhat amplified upper trof will exist over the eastern CONUS
early in the period. However, the amplitude of the pattern will
gradually modify through the period, such that the below normal
temperatures early in the week are expected to rebound somewhat by
mid to late week. At that time a mid-level thermal ridge will again
expand across the Northern Plains, with a consequent increase in
surface temps, likely going back above normal. Another bit of energy
may dive into the Northern Plains late in the week, with another
cooldown expected. Temperatures, like mentioned before, will start
the period below average, but then should soar back above by mid-
week.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 638 PM CDT Sat Jun 19 2021

Terminals KABR,KATY,KPIR,KMBG

Starting to see isolated convection develop along the WY/SD
border this evening. Short term model guidance suggest this
activity will remain scattered and continue to track east,
reaching the KMBG/KPIR TAF sites around the 04Z-06Z time frame,
and the KABR/KATY sites after 06Z. Any thunderstorms could produce
MVFR conditions. Could see MVFR CIGS hang across the region into
Sunday morning across eastern South Dakota. Meanwhile frontal
boundary will switch winds from the south to northwest through the
day Sunday.

&&

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

UPDATE...Serr
SHORT TERM...SD
LONG TERM...TDK
AVIATION...Serr

Hazardous Weather Outlook...UPDATED
National Weather Service Aberdeen SD
1213 PM CDT Sat Jun 19 2021

MNZ039-046-SDZ004>011-016>023-034-036-037-201715-
Traverse-Big Stone-Campbell-McPherson-Brown-Marshall-Roberts-
Walworth-Edmunds-Day-Potter-Faulk-Spink-Clark-Codington-Grant-Hamlin-
Deuel-Sully-Hyde-Hand-
1213 PM CDT Sat Jun 19 2021

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.

Thunderstorms will be possible later tonight. Lightning will be the
main threat.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SDZ003-015-033-035-045-048-051-201715-
Corson-Dewey-Stanley-Hughes-Jones-Lyman-Buffalo-
1213 PM CDT Sat Jun 19 2021 /1113 AM MDT Sat Jun 19 2021/

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

.DAY ONE...This afternoon and tonight.

A few strong to severe thunderstorms are possible this afternoon and
into the nighttime hours.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

SD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1222 AM CDT SUN JUN 20 2021

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

1159 PM     NON-TSTM WND GST 13 N VIVIAN             44.12N 100.30W
06/19/2021  M56 MPH          LYMAN              SD   MESONET

            MESONET STATION RFPS2 VIVIAN 13 N.

&&

MC

Special Weather Statement
National Weather Service Aberdeen SD
1230 AM CDT Sun Jun 20 2021

SDZ035-048-051-200600-
Hughes-Buffalo-Lyman-
1230 AM CDT Sun Jun 20 2021

...A SHOWER WILL AFFECT SOUTHEASTERN HUGHES...EASTERN LYMAN AND
BUFFALO COUNTIES...

At 1228 AM CDT, a shower was located near Oacoma, or 7 miles north of
Chamberlain, moving east at 45 mph.

Wind gusts of 50 to 55 mph are possible with this shower.

Locations impacted include...
Lower Brule, Fort Thompson, Oacoma, Kennebec, Reliance, Shelby, Iona,
Cedar Creek Rec Area, Crow Creek Housing, Tailrace Rec Area, Joe
Creek Rec Area, Lyman, Medicine Butte, Counselor Creek Boat Access
Area, Dude Ranch, Lake Sharpe, Etbauer Hill, Gann Valley, Byre Lake
and Lees Corner.

LAT...LON 4377 9965 4373 9967 4375 9968 4376 9968
      4376 9969 4372 9972 4374 9976 4371 9975
      4370 9986 4367 9987 4370 9996 4420 9994
      4419 9893 4394 9893 4393 9936 4386 9931
      4367 9947 4365 9936 4350 9930 4350 9963
TIME...MOT...LOC 0528Z 276DEG 37KT 4388 9933

Connelly