000
FXUS63 KFSD 081956
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
256 PM CDT Thu Jun 8 2023

.SHORT TERM...(This Evening through Friday)
Issued at 256 PM CDT Thu Jun 8 2023

On the eastern fringes of the stubborn upper level ridge axis,
earlier rainfall east of I-29 left a bit of cooler air across
portions of the area. As of 1 PM, portions of SW MN and NW IA were
starting to bounce back up into the 70s, while areas west of I-29
were already well into the 80s. For the rest of the afternoon hours,
areas west of I-29 will continue to approach lower 90s, while areas
further east of I-29 may only reach up into the upper 70s.

Our daily chances for afternoon convection returns throughout the
afternoon and evening hours, with highest chances (30%) for
scattered showers and thunderstorms looks to be along and west of I-
29, where the moisture gradient is. While these storms will remain
diurnally driven and without strong forcing aloft, given SBCAPE of
up to 2500 J/kg it will not be impossible to see a strong storm west
of I-29 produce hail to the size of quarters. As shear continues to
be displaced from the greatest instability, not expecting organized
convection either, but as we`ve seen the past couple days a strong
gust or two can`t be ruled out, but overall thunderstorms are not
expected to become severe.

Throughout the evening and overnight hours, the convection loses
instability and thus will be decreasing in coverage overnight.
Otherwise a quiet overnight period is expected, with overnight lows
in the upper 50s east of I-29, and lower to mid 60s along and west
of I-29.

Some of the earlier high-resolution guidance from this morning
(HRRR/ARW/FV3) was hinting that we could see some morning
thunderstorms on Friday, though the NAMNEST held out until the
afternoon hours. Global models show that this activity is tied to a
shortwave that will be coming down the 500 mb flow, which looks to
enter the region during the late morning / early afternoon
timeframe, thus giving more weight to the NAMNEST solution regarding
timing at least. This timeframe also makes more sense as
climatologically we generally get our showers and thunderstorms
during the afternoon and evening hours.

By the afternoon hours, we will again be pushing into the upper 70s
and lower 80s for temperatures with dewpoints in the lower 60s,
which will allow for CAPE values of up to 2000 J/kg to build across
areas generally west of I-29. Though shear continues to look weak,
25 to 30 knots of shear could lead to some semi-organized storms,
though this is likely due to various wind shifts throughout the 0-6
km column as flow aloft remains rather weak. High-resolution
guidance is showing primarily multi-cellular storms into the
afternoon hours, which makes sense. So, tend to think that storms
will fire in Aberdeens area as the shortwave moves through during
the morning hours, with a group of storms moving into our northern
counties during the early afternoon hours. Throughout the afternoon
hours, expect this group to move from N/NW to S/NE, with the primary
threat being scattered strong wind gusts to 60 mph, similar to what
the high-resolution guidance is showing. Downdraft CAPE values vary
based on the model, but up to 1000 J/kg seems reasonable.

For the evening and overnight hours, cooler air moves in aloft
though it won`t have much of an impact on temperatures just yet.
Will likely continue to see scattered showers and thunderstorms, but
chances for severe weather to continue look low. Overnight lows in
the lower 60s are expected.

.LONG TERM...(Friday Night through Thursday)
Issued at 256 PM CDT Thu Jun 8 2023

For Saturday into Sunday, cooler 850 mb temperatures will start to
be mixed down, though afternoon high temperatures will still likely
remain at or just above normal in the mid 70s to lower 80s. Our
final day of daily scattered showers and thunderstorms looks to
occur on Saturday, though severe weather is not expected. Rainfall
totals through the last 3 days will continue to range widely, with
some possibly missing out on rain entirely, and others likely
getting over an inch if they`re lucky and get a couple rounds of
these scattered showers and thunderstorms.

Upper level troughing will strengthen a surface low off to our south
overnight into Sunday, which will be tracking eastwards throughout
the morning hours. This will result in cooler air being brought into
the region, with afternoon highs largely in the 70s accompanied by
breezy northeasterly winds gusting up to 35 mph.

For the first half of the work week, the aforementioned trough
converts into a closed upper level low over the Great Lakes region,
keeping our upper level flow out of the north. Models show a surface
high developing across portions of the northern great plains, though
a passing wave could lead to scattered showers and thunderstorms by
Tuesday into Wednesday. Temperatures look to rise again into the
lower to mid 80s on Monday, with widespread mid 80s again by the mid-
week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1225 PM CDT Thu Jun 8 2023

Aside for some isolated MVFR cigs across portions of SW MN and NW
IA, largely VFR conditions out there. Cigs will lift into VFR east
of I-29 throughout the afternoon hours as heating continues, with
our daily chances for afternoon convection again possible during the
afternoon and evening hours. Highest chances (30%) for scattered
showers and thunderstorms looks to be along and west of I-29, where
the moisture gradient is. Not impossible to see a strong storm west
of I-29 produce hail to the size of quarters and/or a strong gust to
60 mph, but overall thunderstorms are not expected to become severe.

There is a chance for some morning thunderstorms on Friday, though
the better chances for thunderstorms again arrive during the
afternoon and evening hours.


&&

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

$$

SHORT TERM...APT
LONG TERM...APT
AVIATION...APT

NWS FSD Area Forecast Discussion