330
FXUS63 KABR 031933
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
233 PM CDT Wed Jul 3 2024

.KEY MESSAGES...

- There is a Marginal Risk (level 1 of 5) for severe weather this
  evening across south central South Dakota, mainly along and south
  of Interstate 90. The main threats with the stronger storms will
  be large hail and strong wind gusts.

- Clouds, rain showers and a few weak thunderstorms, will persist
  across the area tonight and through the day Thursday, making for
  a cool and soggy Fourth of July.

- The active weather pattern of showers and thunderstorms persists
  Friday into the weekend.

&&

.SHORT TERM /THIS EVENING THROUGH THURSDAY NIGHT/...
Issued at 233 PM CDT Wed Jul 3 2024

Weak ridge ahead of a shortwave embedded within this baggy trough
responsible for fairly pleasant conditions, though there are strong
storms just south of the White river, with the elevated band of weak
convection that lifted through Jones and Lyman counties earlier
having nearly dissipated. The atmosphere generally remains weakly
unstable however, with cumulus development along the SD/ND state
line and across the Sisseton hills.

As the afternoon/evening progresses, convection in northwest/west
central South Dakota is expected to move into the western CWA,
though we cant rule out storms (non-severe) forming along and south
of the While river also drifting into the southern CWA. Convection
should be more widespread overnight, however some of the CAMS have
noticeable gaps, but eventually coalesce around the developing mid
level trough. This trough evolves into a low over eastern South
Dakota tonight and continues to drifts east. Cool air on the
backside of this feature will result in continued weak instability
for wrap around showers/weak thunderstorms.

HREF probability of 2 inches total QPF is up to 40 percent in a few
bullseyes across the James into the Coteau, but more broadly a 40-
70% chance for an inch total. NBM probabilities are lower and
focused more into the FSD CWA. GEFS plumes range between 1/2 inch to
2 inches with a choice ensemble member or two up to 4 inches.
Needless to say, not much certainty with respect to total moisture,
but it does look like low clouds and light precipitation will linger
across east river well enough into Thursday to influence evening
activities.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 233 PM CDT Wed Jul 3 2024

Clusters agree well on the 500mb low over the Upper Midwest over
MN/WI/IA area Friday morning. The only difference is that Cluster 4
(10% GEFS/20% ENS) keeps it more of an open wave. The system will be
stacked to the surface with an occluded low over the same area.
Through the day into the evening this low and its upper level system
will continue its track east/northeast. Clusters indicate lingering
precip on the back end of this system early Friday. NBM shows this
well with lingering 15-20% pops mainly over our extreme southeastern
CWA. Shortwave energy behind the low and ahead of the next system
will bring scattered rain/thunder chances through the day as
northwest flow continues. Pops increase to 25-40% during peak
heating hours/daytime instability before decreasing by sunset.
However, this incoming wave will keep pop chances of 20-30% around
and west of the Mo River late Friday night into early Saturday.
Highs for Friday will still be on the cooler side, ranging from the
mid 70s to around 80 and lows in the 50s.

This shortwave is forecasted to swing in from the northwest
Saturday. Still a little bit of a difference in the wave`s intensity
and location between the Clusters. A cold front is forecasted to
push east/southeast over the CWA through the day, associated with
the surface low in southern Canada. There is also a lee side
low/trough that develops over the Central Plains as well aiding in
daytime moisture. We see more of a split over the CWA with the
better moisture to our north and south. By late afternoon/evening
pops increase to 35-50%. Ahead of the front, temps are forecasted to
warm into the 80s and dewpoints rising in the upper 50s. GEFS
indicates SB Cape increasing to 1000-1500 j/kg over
northeastern/eastern SD into western MN and lapse rates of 6-7C are
forecasted along with marginal shear. However, GEFS seems to be the
most aggressive in the instability compared to EC which is much more
relaxed at this point. We will also be dealing with some clouds that
could hinder some stronger instability. So we will have to wait
closer to time when models agree more. CSU has a 5-15% prob of
severe over our parts of northeastern to eastern SD into western MN.
As the system moves east/southeast, ongoing chances of showers and
thunderstorms are possible, peaking Sunday afternoon (20-50% pops)
with daytime instability, highest over the James River Valley and
eastward.

By early next week, the +PNA pattern continues with the ridge
starting to push east becoming broad and over much of the CONUS.
Highs are forecasted to warm into the 80s and possibly into the 90s
by midweek.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1215 PM CDT Wed Jul 3 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions initially. Storms south of KPIR should remain south
of the terminal for most of the day, though potentially later this
afternoon/evening we could see something move towards the KPIR/KMBG
terminals. Convection will weaken but become more widespread through
the evening/overnight. Additionally, MVFR CIGS will also develop as
this low pressure system moves across the area.


&&

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

$$

SHORT TERM...Connelly
LONG TERM...MMM
AVIATION...Connelly