629
FXUS63 KABR 081151 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
651 AM CDT Mon Jun 8 2026

.KEY MESSAGES...

- There is a Marginal Risk (Level 1/5) for isolated severe storms
this afternoon through tonight along and east of a line from
Sisseton to Chamberlain. Main threats include hail, quarter inch in
diameter, and 60 mph winds. Heavy rain is also possible.

- There is an Enhanced Risk (Level 3/5) for severe storms for much
of central and northeastern SD into west central MN Tuesday
afternoon through Tuesday night. Main threats include tornadoes,
large to very large hail (2+ inches in diameter) and wind gusts of
70+ mph. Heavy rain is also a concern that could lead to flash
flooding.

- The threat of severe weather continues Wednesday mainly east of
a line from Sisseton to Brookings.

&&

.UPDATE...
Issued at 640 AM CDT Mon Jun 8 2026

The aviation discussion has been updated for the 12Z TAFS.

UPDATE Issued at 319 AM CDT Mon Jun 8 2026

A line of showers and thunderstorms continue to track
east/southeast at 40 mph over north central and entering
northeastern SD. Luckily, this line continues to decrease in
intensity, however, wind gusts up to 55 mph are still possible
along with cloud to ground lightning and brief heavy downpours.
Pops have been updated to show this.

&&

.DISCUSSION...
Issued at 141 AM CDT Mon Jun 8 2026

As of 1am, a bowing line (bow remaining north of the CWA) of strong
to severe thunderstorms are over north central SD into ND that has
had a history of producing wind gusts between 60-65 mph in our CWA.
It will continue to track eastward along ND/SD border. Otherwise
current temps range in the 70s ahead of the cold front and dewpoints
in the 60s.

By 12Z the cold front (and low along the boundary) will be along the
James River with these ongoing scattered showers and thunderstorms
continuing ahead of the front, east of the James River. By 18Z, this
front will track a bit east and along (or just east) of the Sisseton
Hills where it stalls out over northeastern SD/western MN through
this evening as the low and front both weaken. Behind the front,
high pressure will continue to track eastward and over much of ND/SD
by this time. Ahead of the front, temps will warm up into the upper
80s and dewpoints remaining in the mid to upper 60s. Behind the
front, highs will only reach the lower to mid 80s with drier air.
Went with previous shift and knocked MaxT down a few degrees over
central SD. CAPE values this afternoon will increase to about 1000-
2000j/kg (diminishing with sunset) and bulk shear around 30kts out
of the southwest through about ~05Z then diminishing. Overall, Cams
indicate spotty showers/storms firing up this afternoon to early
evening over eastern SD turning more into clusters or small lines,
but this looks to form east and southeast of the CWA. HRRR is less
excited about this outcome. Additional spotty convection looks
possible through early Tuesday morning. Low confidence on where the
storms will form and track due to the spotty nature. With this
marginal instability some of these storms could become severe with
an isolated threat for quarter size hail and wind gusts of 60 mph.
Therefore, the SPC has a Marginal Risk, level 1/5, for the threat of
isolated severe weather along and east of a line from Sisseton to
Chamberlain.

By Tuesday morning, the longwave trough continues over the western
CONUS with zonal to slight southwesterly flow aloft. Another strong
embedded shortwave will ride along the downstream side of the
longwave and over WY/CO with another streak over the western
Dakotas, further downstream. Its surface low develops over ~south
central MT with its strong warm front stretching eastward along the
ND/SD border (or just north). By 00Z the warm front will still
extend horizontally across the ND/SD border with its cold front
trailing north to south over western SD as the center of the low is
forecast to be over ~northwestern SD/southwestern ND by this time.
This leaves the CWA within the warm sector as winds at the surface
to 850mb will mainly be out of the south ushering in quite the warm
and moist air with highs in the 90s (to even around 100 over
portions of south central SD) and dewpoints in the mid to upper 60s.
Heat indices could be around 100-102 over portions of south central
to east central SD. Winds will also increase with a steepening
pressure gradient with gusts of 30-45 mph over much of the CWA. So a
Wind and Heat Headline may be needed.

This warm and moist air will help the atmosphere destabilize. As of
now, REFS/HREF indicate CAPE values of at least 2500 to near 3500
j/kg with potential max over 4000j/kg! Once the cap breaks, showers
and thunderstorms will develop Tuesday afternoon through late
Tuesday night/early Wednesday morning. Mid level lapse rates of 7-
8.5C/km are forecasted (supporting large hail) and bulk shear of 30-
40kts (perpendicular to front) along with a low level jet of 30-
50kts bringing in that moist air as mentioned. We will also have
higher amounts of low level SRH (100-200m2s2) and shear than what we
have seen over the past few days with severe weather. So storms that
form along and south of the warm front could become
discrete/supercells as tornadoes and large to very large hail would
be the main threat. Models do hint that as the cold front tracks
east this looks to become more of a linear setup as shear will
become more parallel to the front aka turning into a wind event
(MCS). If this line can bow out then a QLCS setup could be very
possible if we get an RIJ and 0-3 line normal shear of 30kts. Again,
a bit early for specifics. SPC has expanded the Enhanced Risk (level
3/5) for numerous severe storms mainly for our entire CWA (with the
exception of east central SD who is in a Slight Risk, level 2/5).
Portions of north central and northeastern SD are in a 5% tornado
threat with intensity of Cig1, meaning EF2+ tornadoes possible. Rest
of the CWA is a 2% tor threat. As mentioned, winds of 70+ could
occur as the storm mode turns linear. Probability of severe wind is
30-44% with cig 1 intensity over portions of north central and
northeastern SD into west central MN. Probability of severe hail
also ranges from 30-44% Cig1 mainly between the Mo and James River
meaning 2"+ inch hail possible. With ongoing PWAT values above an
inch, heavy rain would be a concern leading to flash flooding.

By Wednesday morning, the fropa is forecast to lie along the James
Valley where it will track eastward as the center of the low tracks
northeastward. Once again, highs in the upper 80s to around 90 and
dewpoints in the lower to mid 60s over eastern SD will lead to the
potential of showers and thunderstorms firing up along and ahead of
the front along and east of the Sisseton Hills in the afternoon and
evening. The SPC has highlighted a Marginal Risk (level 1/5) along
and east of a line from Sisseton to Brookings with the main threats
being quarter size hail and 60 mph wind. The threat for showers and
thunderstorms continue on Thursday on the wrap around side of this
low mainly over north central to northeastern SD/western MN. As of
now no severe weather anticipated. We finally will see quieter
weather for Friday with quite the cooldown into the weekend with
highs forecast only in the 70s.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 640 AM CDT Mon Jun 8 2026

Terminals KABR,KATY,KPIR,KMBG

Showers and thunderstorms will remain in the KABR/KATY forecast
for the initial first few hours of this TAF cycle. Drier
conditions are expected at KPIR/KMBG which is expected to
prevail through this forecast period. MVFR cigs/vsbys will be
possible through this morning at KABR/KATY with these lower
clouds breaking up by mid morning at KPIR/KMBG. KATY could see
TEMPO IFR cigs and MVFR vsbys in the heavier showers and storms
rolling over the terminal for the first couple of hours of this
forecast cycle. That activity is expected to clear out by late
morning with redevelopment of more showers and storms around the
KATY area this afternoon.

&&

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

&&

$$

UPDATE...Vipond
DISCUSSION...MMM
AVIATION...Vipond