000
FXUS63 KFSD 070325
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1025 PM CDT Tue Jun 6 2023

.SHORT TERM...(This Evening through Wednesday Night)
Issued at 255 PM CDT Tue Jun 6 2023

Key Messages:

1. Daily non-severe showers and storms continue today. Storms will
be capable of lightning, brief heavy rain, gusty winds, and small
hail.

2. Daily diurnally driven storms continue tomorrow with a slightly
higher possibility for a strong to severe storm.

3. Dry conditions look to make a return for this weekend and into
early next week.

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Current radar and satellite show a line non-severe storms that has
developed along the Buffalo Ridge area in southwestern Minnesota.
Aside from any weak upslope the ridge may cause, a weak convergent
boundary is present in surface obs which has contributed to
convective development. Like we have seen for about a week now,
instability remains on a somewhat modest side with CAPE values up to
around 1000-1500 J/kg. Wind shear remains poor with 0-6 km shear
values up to 10-15 knots. Although southwest Minnesota will be the
primary area for rain, could still see additional showers and storms
develop mainly along and northeast of a line from De Smet, South
Dakota to Sioux Falls, South Dakota to Storm Lake, Iowa. Given the
lack of shear, these storms will be non-severe and look to continue
for the rest of the afternoon and evening hours before nocturnal
stabilization diminishes the storms. These storms will be capable of
lightning, brief heavy rain, gusty winds, and small hail. An upper
wave will be diving southward over the midwest states this evening
which will push a cool front into the area. With the cool front
pushing westwards through the night, not impossible to see a few
showers or a weak storm persist through the overnight hours. Low
temperatures will fall to mid 60s.

Upper level ridging pulls a touch further west on Wednesday but the
previously mentioned wave will continue to dive southward. The cool
front will continue its westward movement through the day, allowing
higher moisture to fill in behind it. This will continue our daily
shower and storm chance but with a touch higher focus from along and
east of the James River. Wind shear still looks weak to poor with 0-
6 km shear in the 15-25 knot range but instability will be a bit
higher in the 1000-2000 J/kg range. This seems somewhat similar to
last Wednesday where a similar environment was in place with a low
level boundary. Storms were sparked on this boundary, which provided
a bit more coverage but again were largely non-severe. Do agree with
the SPC day 2 marginal risk as slightly stronger shear can result a
few stronger storms with higher potential for severe weather. Aside
from rain chances, highs will again warm to the 80s to low 90s while
winds remain light. The diurnally driven showers and storms will
dwindle by the evening as the boundary layer stabilizes. Low
temperatures will again fall to the 60s overnight.

.LONG TERM...(Thursday through Tuesday)
Issued at 255 PM CDT Tue Jun 6 2023

The same cool front from Wednesday will progress further to the west
on Thursday, bringing the best area for afternoon showers and storms
to along and west of I-29. Ensembles generally agree on this idea as
the GFS and Euro ensembles keep the highest dew points in this area.
The Canadian ensemble is the outlier as it only has dew points into
the 50s. Given how this ensemble is the outlier, am not putting as
much weight into its solution. The GFS and Euro ensemble both show a
50-70% chance at exceeding 500 J/Kg of instability mainly west of I-
29. With the upper ridging a bit further west, better shear from an
occluding cyclone over the northeastern US will also be pulled
further west. However, the better shear will reside east of I-29
while the better instability lies west of the interstate. This lack
of overlap between the best shear and instability looks to keep our
chances for diurnally driven non-severe storms going. Highs will
again be a touch cooler as compared to Tuesday with highs in the 80s
to low 90s expected with the warmest highs taken place towards
central South Dakota. Overnight lows will fall to the 60s.

Upper ridging progress further west on Friday, placing the forecast
area downstream of the ridge and in a more favorable position to
receive rain. Medium range guidance does show a shortwave trough
passing through the now northwesterly flow aloft. This wave looks to
bring another cool front with it as well. Ensembles are a bit more
excited for rain chances as they all show a 70-80% chance for
receiving a tenth of an inch of rain or more. Some uncertainty
remains in determining the location with the highest potential to see
rain and thus have left model blended PoPs. Highs in the 80s to low
90s and lows down to the 60s are expected.

The weekend looks to be more on the quiet side as the previously
mentioned cool front will push the better moisture south of the area
and introduce surface high pressure in its wake. Could still see
chances for rain on Saturday but ensembles show a lower probability
for a tenth of an inch or more, down to a 40-60% chance. This
incoming surface high will cool 850 mb temperatures to the mid to
low teens, resulting in near seasonable high temperatures from the
mid 70s to the low 80s.

Next week looks to be drier than previous forecasts as latest 12z
guidance has come in stronger with the southern stream jet stream.
Ensembles also agree with this solution so do think that rain
chances have decreased for early next week. On the flip side, a
return to more summer like conditions appears more likely as highs
warm back up to the 80s and low 90s. Light southerly winds will
coincide with the warmer temperatures, making for a nice start to
the work week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1023 PM CDT Tue Jun 6 2023

A scattered mid-lvl cloud deck will continue into Wednesday
morning. A few showers may drop south across western Minnesota
into Wednesday morning, casting a thicker mid-lvl cloud deck
westward.

Diurnal CU will then develop by noon, and may lead to scattered
convection through the afternoon. Considerable uncertainty remains
on where convection could form, so will leave a prob30 group in
place. For the most part winds will stay variable into Wednesday,
but may turn more easterly as mixing increases.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&

$$

SHORT TERM...Meyers
LONG TERM...Meyers
AVIATION...Dux