Severe Thunderstorm Warning 47, NWS Sioux Falls, SD

504 
WWUS53 KFSD 091141
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
641 AM CDT Tue Jun 9 2020

SDC035-061-087-097-091150-
/O.EXP.KFSD.SV.W.0047.000000T0000Z-200609T1145Z/
Davison SD-Miner SD-McCook SD-Hanson SD-
641 AM CDT Tue Jun 9 2020

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN DAVISON...
SOUTHERN MINER...WEST CENTRAL MCCOOK AND HANSON COUNTIES WILL EXPIRE
AT 645 AM CDT...
        
The storm which prompted the warning has weakened below severe
limits, and has exited the warned area. Therefore, the warning will
be allowed to expire.

Remember, a Severe Thunderstorm Warning still remains in effect for
portions of southern Miner county until 700 AM CDT.

LAT...LON 4350 9804 4367 9813 4390 9776 4362 9753
TIME...MOT...LOC 1140Z 243DEG 35KT 4377 9761 

$$

SG

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
450 AM CDT Tue Jun 9 2020

.SHORT TERM...(Today and Tonight)
Issued at 450 AM CDT Tue Jun 9 2020

More active weather in the short term, with concern continuing
around the short term precipitation concerns west of the James
River, the potential for marginally severe hail in the same area, a
few more severe storms in and around northwest Iowa midday through
mid-afternoon, and stronger synoptic winds later today and tonight.

Ongoing convection as expected has backed gradually westward from
the earlier corridor of severe storms from the mid evening to early
overnight hours, in response to strong frontogenetic forcing with
the jet entrance across central SD. This jet associated with the
northern portions of a full latitude trough through the Rockies/high
Plains, with a second upper wave moving toward the central/southern
Plains, which is then steering northward the remnant
circulation/moisture from Cristobal toward the mid/upper Mississippi
valley. CAMS doing a decent job with this initial precipitation
across NE/SD, and given the 40-50kt shear and elevated instability
on order of 1000 J/kg for the elevated parcels over the slowly
expanding cold pool (edge to MML/FSD/YKN by 09z) would not close
minds toward potential for a couple of marginally severe hailstones
early this morning. However, much more pressing will be the
potential rainfall over the next 1-3 hours, with now a tendency for
linearly oriented bands to start to shift slowly eastward with the
deeper convergence axis now into Brule/Gregory/western Charles Mix
county. This will work toward areas which received some heavier
rainfall earlier in the night, and will be monitoring for flash
flood potential early this morning.  However, signals for
maintaining the convection start to weaken a bit and shift eastward
through mid-morning, so will allow the flood watch to expire at 7 am.

Gradual eastward shift of the frontal precip will work into areas
that have been precipitation free during the morning, but likely to
remain below severe thresholds moving through eastern SD.
Complexity of the larger scale flow will put northwest Iowa and
southwest MN into weaker flow regime between the various pieces
during the day, but will also be the location of the lower-level
convergence by midday and early afternoon. Shear is not terribly
strong for any afternoon development, so the severe threat will be
more based on the roughly 1000-1400 J/kg MLCAPE with a decent surface-
3km component in proximity to any vorticity source due to
convergence in the weak flow field. Some marginally large hail,
water loaded wind gusts to 65 mph, and not out of the question for a
brief tornado. Potentially interfering with this will be the
influence of the Cristobal moisture into areas toward Highway 71
during the later morning and afternoon, which could act to stabilize
that area a bit more.

The main precipitation will continue to be focused along the mid-
level frontal boundary, but in a weakening state during the
afternoon and evening hours and the entire trough system slips
eastward.  Have maintained the highest PoPs in this zone, and with
lapse rates not as weakly unstable, would see mainly rain with a few
embedded storms. Precip rates, while not as high as those with
storms in current night, could bring a good quarter to half inch per
hour in a few spots. Precipitation should shift mainly east of I-29
after midnight, and be mostly ended as subsidence behind the main
upper trough settles in early Wednesday morning.

The other issue with the frontal band will be some intense
synoptic winds expected to develop. Some stronger winds already
taking shape west of the leading precipitation banding through
central SD/NE early this morning, and most models indicate
potential for winds to reach 30 to 45 kts in the mixed layer as
the system shifts eastward through tonight. Some of the higher
winds (50-60 kts) seem to be overdone by select hi-res solutions,
but certainly bears watching especially given the winds already
revealing themselves this morning. For now, have issued a wind
advisory through the mid and lower Missouri River valley for later
this afternoon into tonight where gradient is somewhat stronger,
but could see the need to expand through I-29 and eastward.
Concern keeping away from an earlier and further west/north
issuance are potential precipitation drag.

.LONG TERM...(Wednesday through Monday)
Issued at 450 AM CDT Tue Jun 9 2020

Quiet weather, other than being quite breezy on Wednesday, looks
to settle in for much of the remainder of the forecast. Deep
mixing northwest flow with temps mainly in the lower to mid 70s
appears reasonable, with only a small chance for some lingering
precip early in the day east of I-29. More generally westerly flow
into Thursday as well, with a shade warmer in the upper 70s to
around 80.

Amplifying upper level ridge to the west late in the week will help
push a weak boundary southward into the area by Friday. Not
impossible that could be in play for a high-based shower/storm as
warm advection again commences aloft, but not recognized at this
point by the blend.  Depending on the frontal location, in play for
temps to end up a shade warmer on Friday as well.  Ridge shifts
eastward through the weekend, with conditions becoming more windy.
Perhaps an isolated shower/storm late in the weekend, but nowhere
near a lock.  Warmest day likely by Monday with front moving toward
the area, and well within the thermal ridge.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1257 AM CDT Tue Jun 9 2020

Widespread precipitation around the James River valley and
westward will be hard pressed to expand too much eastward
overnight. Expansion of the cold pool likely to keep more intense
convection as well as the main thunder threat along the eastern
tier of increasing stratiform area, meaning likely just some
infrequent thunder threat around KHON. Will be a while before
precipitation actually works into KFSD/KSUX areas, which will
likely come as the synoptic boundary shifts into Iowa by early
afternoon. Winds will increase behind the surface front, likely
gusting at times to 30-40 knots through the evening.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Flash Flood Watch until 7 AM CDT this morning for SDZ038-039-050-
     052>054-057>060-063>065-068.

     Wind Advisory from 4 PM this afternoon to 4 AM CDT Wednesday for
     SDZ068>070.

     Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
     SDZ071.

MN...NONE.
IA...Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
     IAZ020-031.

NE...Wind Advisory from 4 PM this afternoon to 4 AM CDT Wednesday for
     NEZ013.

     Wind Advisory from 7 PM this evening to 4 AM CDT Wednesday for
     NEZ014.

&&

SHORT TERM...Chapman
LONG TERM...Chapman
AVIATION...Chapman

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1229 AM CDT TUE JUN 9 2020

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

1155 PM     TSTM WND GST     5 SSE CANOVA            43.81N 97.48W
06/08/2020  M56 MPH          MCCOOK             SD   PUBLIC

&&

AT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1231 AM CDT TUE JUN 9 2020

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

1155 PM     TSTM WND GST     5 S CANOVA              43.81N 97.49W
06/08/2020  M56 MPH          MCCOOK             SD   PUBLIC

            TIME ESTIMATED FROM RADAR.

&&

AT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
601 AM CDT TUE JUN 9 2020

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

0539 AM     TSTM WND GST     1 WSW PLANKINTON        43.71N 98.51W
06/09/2020  M59 MPH          AURORA             SD   MESONET

&&

JC