Tornadoes and Hail in South Dakota, August 23, 2018

Area Forecast Discussion
National Weather Service Aberdeen SD
335 PM CDT Thu Aug 23 2018

.SHORT TERM...(This Evening through Friday Afternoon)
Issued at 335 PM CDT Thu Aug 23 2018

Some initial short wave trough scattered showers/isolated storms
were lifting northeast this afternoon through north central into
northeast SD. These will continue to lift in ND through the
afternoon. The main area of convection was moving into western SD
this afternoon with a jet streak/short wave trough coming around the
base of the larger closed upper low pressure area. The surface
analyses showed a low pressure area near the PIR area with a warm
front extending south southeast from it. As this short wave
trough/upper low pressure area moves east tonight, expect showers
and thunderstorms to develop/expand eastward across our cwa. There
remains a slight risk of severe weather mainly west of the James
Valley into this evening. East of the James Valley has little to no
risk with stable ll lapse rates along with the cooler air and low
clouds. Central and north central SD will have the best chances
where low and mid level lapse rates are better along with more
sunshine and instability. Although, the deep layer shear was
marginal this afternoon generally less than 30 knots for the 0-6km
shear. Made adjustments to weather and pops through the night into
Friday. Low clouds should remain across much of the east into
Friday. Left the pops in for the eastern cwa for Friday as the upper
low pressure area moves east and winds become northwest over the
entire cwa. It will remain cooler than average across the east with
mid 70s for highs. Central South Dakota should be mostly sunny on
Friday with mid 80s for highs.

.LONG TERM...(Friday Evening through Thursday)
Issued at 335 PM CDT Thu Aug 23 2018

The main focus for this forecast period will be chances of
precipitation, mainly from the end of the week through early next
week.

Some weak upper level ridging is expected to be in place across the
Dakotas as the period begins, but it will be short lived. An upper
level trough is progged to work from the PAC NW toward our region
during the weekend. Model consensus indicates that it will be mostly
weak in nature. The surface reflection during the weekend shows a
cold front will slide through the region during the middle of the
weekend. Low end chances for showers and storms will be scattered
across the cwa by Saturday night through Sunday.

A stronger mid level trough is expected to slide into the region by
late in the weekend through Tuesday. A surface low and associated
frontal boundaries are anticipated to move through the area Sunday
night through Tuesday. Higher chances for precip will exist in our
cwa during that time. Temperature trends this period look to remain
at or above normal through early next week. After this system moves
through early next week, temperatures should cool to near to
slightly below normal for late August.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 101 PM CDT Thu Aug 23 2018

Surface front will bring a few showers and thunderstorms through
the TAF period. Some of these storms may be severe. Expect spotty
MVFR conditions associated with these storms lowering cigs/vis this
afternoon and evening.

&&

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

SHORT TERM...Mohr
LONG TERM...Vipond
AVIATION...ALD

Hazardous Weather Outlook
National Weather Service Aberdeen SD
433 AM CDT Thu Aug 23 2018

SDZ003>005-009-010-015>017-033>037-045-048-051-240945-
Corson-Campbell-McPherson-Walworth-Edmunds-Dewey-Potter-Faulk-
Stanley-Sully-Hughes-Hyde-Hand-Jones-Lyman-Buffalo-
433 AM CDT Thu Aug 23 2018 /333 AM MDT Thu Aug 23 2018/

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

.DAY ONE...Today and tonight.

Thunderstorms are possible this afternoon through tonight. A few
storms could become strong to severe late this afternoon through this
evening, mainly between the Missouri River to the James River.
Strong winds and large hail will be the main threats, along with
brief heavy rain.

.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.

MNZ039-046-SDZ006>008-011-018>023-240945-
Traverse-Big Stone-Brown-Marshall-Roberts-Day-Spink-Clark-Codington-
Grant-Hamlin-Deuel-
433 AM CDT Thu Aug 23 2018

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

.DAY ONE...Today and tonight.

Thunderstorms are possible this afternoon through tonight. A few
storms could become strong to severe late this afternoon through this
evening, mainly between the Missouri River to the James River.
Strong winds and large hail will be the main threats, along with
brief heavy rain.

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

Thunderstorms will be possible Friday. However, severe weather is
not expected.

.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.

KF