099
FXUS63 KABR 271926
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
226 PM CDT Thu Jun 27 2024

.KEY MESSAGES...

- A significant round of thunderstorms is possible from late this
  afternoon in western South Dakota through late this evening in
  central South Dakota. Large to very large hail, damaging winds
  and a few tornadoes will be possible. There remains an Enhanced
  Risk (3 out of 5) for severe weather West River and a
  Marginal/Slight Risk (1-2 out of 5) for locales farther east.

- There is a Marginal Risk for severe weather (1 out of 5)
  covering much of the forecast area on Friday. There may be a
  few ongoing thunderstorms heading east out of the forecast area
  Friday morning, but the main potential for severe weather looks
  to accompany a cold front working through the region Friday
  afternoon.

- Another opportunity for showers and thunderstorms will arrive
  later Sunday into Monday (30-70% chance of measurable rain).

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 223 PM CDT Thu Jun 27 2024

At 2 PM CDT, skies are partly to mostly cloudy, except portions of
the far western CWA where stable layer stratus clouds have been
being eroded over the past several hours with daytime
heating/mixing. Temperatures under the clouds have been holding in
the 60s to low 70s, while the clear/sunny areas have been warming
into the 80s. Showers have been moving off to the east-northeast
only to have additional showers regenerate within the maximized zone
of mid-level WAA forcing/low level moisture advection underneath
continued favorable upper level jet quadrant lift. Eventually, the
elevated shower potential over northeast South Dakota/western
Minnesota will diminish, but now, maybe not until early evening.

Got a couple of upper waves of interest to keep an eye on for the
rest of this afternoon through late tonight. The first upper wave is
approaching western South Dakota right now. This would probably be
the low that initiates preliminary (more sparse coverage)
supercellular convection across western South Dakota which then
moves toward the west river forecast zones in this CWA between ~23Z-
01Z. There is a local effect (lee-of-the-Black Hills surface
low/trof) that will need to be monitored for localized enhanced
tornado potential (low level backed wind field/large-curve hodograph
and preferred low level shear/CAPE values) throughout
Perkins/Corson, Ziebach/Dewey, Haakon/Stanley counties if any
convection moving off the Black Hills should make it that far east,
along with potentially very large hail (2.00-2.75in?) and strong
damaging winds (inverted V-soundings and high DCAPE forecast) in
excess of 70 mph. Later this evening, attention will turn to the
cold front-forced convection currently back over central Montana.
That`s the second upper wave of interest. Models depict strong
linear convective (straight line wind) storm potential rolling
across western/central North Dakota with the southern tail
potentially extending down into north central South Dakota by 03Z
this evening. After 05Z, models trend convection down in
coverage/intensity as storms work east into a more stable
environment.

This second upper circulation will push a wind shift/frontal
boundary through the CWA on Friday, and hi-res CAMS and much of the
GSM suite of output are beginning to pick up on convective potential
over this CWA along the frontal boundary by early Friday afternoon.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 223 PM CDT Thu Jun 27 2024

The weekend will be dominated by the cooler temps on Saturday and a
rebounding upper ridge, with more showers and thunderstorms entering
the forecast Sunday evening through Tuesday morning.

As the ridge rebounds, warmer air will return Sunday ahead of the
next system. The flow aloft is very progressive, as the ridge gives
way to southwest flow ahead of the next trough. It looks like
several rounds of showers and thunderstorms will be possible Sunday
night through Tuesday with the active flow.

The flow slowly switches to northwest flow, with a warming trend
through the week. Chance of showers and thunderstorms look possible
again Wednesday evening and Thursday as another weaker wave tracks
across the northern plains. Highs in the 80s look to prevail Monday
through Thursday with an unsettled pattern.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1228 PM CDT Thu Jun 27 2024

Terminals KABR,KATY,KPIR,KMBG

There is a mix of MVFR (central/north central South Dakota) and
VFR (northeast South Dakota) cigs over the region. This is
expected to persist over the next 24 hours, with the potential for
MVFR cigs to develop/move into northeast South Dakota by early
this evening. There are also showers, with embedded thunder at
times, ongoing across northeast South Dakota that are forecast to
persist for several more hours into this afternoon. Dry conditions
over central/north central South Dakota should persist until early
this evening when thunderstorms that develop today out closer to
the Black Hills move into central/north central South Dakota, and
potentially into northeast South Dakota later tonight. Some storms
this evening could produce large hail and strong damaging winds.

&&

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

$$

SHORT TERM...Dorn
LONG TERM...Scarlett
AVIATION...Dorn