Flash Flood Warning 1, NWS Aberdeen, SD

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
606 PM CDT Sat May 7 2022

.UPDATE...
Issued at 538 PM CDT Sat May 7 2022

Severe Thunderstorm Watch 190 has been issued; is in effect until
11 PM CDT for much of the southern/southwestern CWA. Seeing a
handful of thunderstorms developing/moving over the western
forecast zones. With modest instability (~1000-1500j/kg CAPE), but
higher end deep layer shear (45 to 55 knots), the primary threat
with any storms this evening will be large hail and damaging
winds. That being said, right now, there is some rather strong low
level 0-1km and 0-3km shear (local effect within the Lee-of-the-
Black- Hills surface trof) in place over the CWA between Mobridge
and Pierre. RAP/SPC trends would suggest this low level shear will
diminish/shift south and east over the next 4 or 5 hours. But, for
the time being (the next couple of hours), seems like there is
certainly the atmospheric support for strong thunderstorm wind
gusts given the higher LCL's/cloud-base environment.

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

&&

.SHORT TERM...(This Evening through Sunday Night)
Issued at 308 PM CDT Sat May 7 2022

Main challenge in the short term is the chance for strong to severe
thunderstorms tonight, then the chance for additional precipitation
Sunday night. An upper level trough is currently approaching the
region, and will set up over the area tonight through Sunday night,
with several rounds of shortwave energy riding across the Northern
Plains. A decent pressure gradient between high pressure to the east
and low pressure to the west has made for another windy day today.
The frontal boundary to the west will track across the area from
west to east later this afternoon and tonight, and looks to be the
focus for thunderstorm development. Moisture ahead of the boundary
is not real high, with current dewpoints in the lower to mid 50s,
but should be enough to increase precipitable water values to 1 to
1.3 inches or so. Will see a decent instability axis with the front,
with MUCAPE around 1500 J/kg and MLCAPE values around 2000 J/kg.
There will be a bit of a cap that will need to break, but models
indicate it should as the boundary approaches later this afternoon.
0-6 km bulk shear of 40-60 knots will be common along the boundary,
so with the instability and decent shear, expect there will be the
potential for some strong to severe thunderstorms along the boundary
late this afternoon and evening, with gusty winds and large hail
being the main threats. Generally expecting discrete storms with
movement to the northeast around 40 knots or so, therefore not
anticipating any hydrologic issues. Will see a break in the action
on Sunday as weak high pressure sets up over the area, then will see
a more widespread area of precipitation move in late Sunday night as
a low pressure system tracks from Colorado to Nebraska/South Dakota.
Cannot rule out a few thunderstorms as there will be a little
instability around, but anticipating more in the way of rain and not
severe weather.

Low temperatures tonight will range form the mid 40s across north
central South Dakota, to the lower 50s along and east of the James
River Valley. High temperatures on Sunday will be in the mid 60s to
the lower 70s, with lows Sunday night ranging from the upper 40s
west to the lower 50s east.

.LONG TERM...(Monday through Saturday)
Issued at 308 PM CDT Sat May 7 2022

The period begins with a persistent trough over the Pacific
Northwest with mainly southwesterly flow aloft over the region. A
low pressure system will track northeastward across the area on
Monday, bringing the potential for widespread showers and
thunderstorms, mainly during the morning hours. The Pacific
Northwest trough will dig southward along the west coast on Monday
tonight through Wednesday morning allowing for a period of dry and
warm conditions to setup over the Northern Plains. By Wednesday
afternoon, an area of low pressure should be located over Colorado
with warm air advection over much of this CWA. A few models are
trying to depict some WAA storms over the northeast CWA, or along
the edge of the 700 mb cap. Depending on model used, Wednesday night
into Thursday could be dry, or perhaps more isolated convection as
700 mb temps remain high and forcing is rather low. As of now, the
NBM appear significantly higher Wednesday night through Thursday
night then compared to some of the deterministic models. Additional
showers and thunderstorms could be possible Friday through Saturday
as an upper level trough and surface front crosses the region.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 538 PM CDT Sat May 7 2022

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail at KPIR and KMBG. VFR conditions
should prevail at KABR and KATY into the late evening before the
potential for MVFR/IFR cigs develops over those two terminals.
Guidance has KABR/KATY dipping down below VFR through at least the
morning hours on Sunday before any recovery to VFR happens.

A frontal boundary tracking into the region will stall out between
KMBG, KABR and KPIR this evening, and will be the focus for
showers and thunderstorms. Some of the storms may become severe,
with gusty winds and large hail being the main threats. Periods of
IFR/MVFR cigs and vsbys will be possible with the stronger
storms. The precipitation will exit the area overnight.

&&

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

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

Hazardous Weather Outlook
National Weather Service Aberdeen SD
424 AM CDT Sat May 7 2022

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-080930-
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-
424 AM CDT Sat May 7 2022 /324 AM MDT Sat May 7 2022/

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.

Scattered thunderstorms are expected across central South Dakota late
this afternoon, with activity pushing eastward through the evening
hours. A few storms could become strong to severe with hail being the
main threat.

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

A chance for thunderstorms exists across the area Sunday and Monday,
although the severe threat looks minimal at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

TMT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
713 PM CDT SAT MAY 7 2022

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

0701 PM     HAIL             2 SSE GETTYSBURG        44.98N 99.94W
05/07/2022  E1.00 INCH       POTTER             SD   PUBLIC

&&

RV

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
718 PM CDT SAT MAY 7 2022

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

0654 PM     TSTM WND GST     4 N AGAR                44.90N 100.08W
05/07/2022  M66 MPH          POTTER             SD   MESONET

            MESONET STATION 212 SD RWIS AGAR.

&&

RL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
730 PM CDT SAT MAY 7 2022

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

0655 PM     HAIL             TOLSTOY                 45.21N 99.61W
05/07/2022  E0.88 INCH       POTTER             SD   TRAINED SPOTTER

&&

RV