Severe Thunderstorm Warning 112, NWS Aberdeen, SD

Area Forecast Discussion
National Weather Service Aberdeen SD
412 AM CDT Tue Jul 23 2024

.KEY MESSAGES...

- Elevated smoke from Canadian wildfires will filter out the
  sunshine through Wednesday. Potential exists for some of this
  smoke to become surface based today.

- Temperatures in the 90s (especially James River westward) enter
  the region as early as Wednesday and persist through the
  weekend and possibly into early next week.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 411 AM CDT Tue Jul 23 2024

Currently watching an area of showers and thunderstorms moving
southward across western MN within north-northwest flow aloft. Added
PoPs to the far northeast corner of the CWA to account for this, but
potential exists for some of this convection to backbuild southward
over the far eastern CWA through the early morning hours. Will
continue to monitor.

For the rest of the short term today, we could once again see
isolated thundershower activity develop across the eastern CWA
within broad region of instability. Did extend slight chance (20%)
PoPs further back to the northwest into Aberdeen based on the HREF
ensemble paintball (>40dBZ output) during the afternoon hours.
Wednesday appears to offer a dry forecast finally for the entire
CWA, for the time being.

Will also be focused on smoke aloft and potentially at the surface
today/tonight into Wednesday. HRRR smoke output continues to show
rather high concentrations aloft through the whole short term
period, and have continued the trend of upping sky cover slightly to
account for this. As for surface smoke potential, it's a bit more
uncertain. Higher concentrations reside across ND where there are
legit reductions in visibility to around 2SM-5SM, while we're not
quite seeing that as of yet across our CWA, at least in a widespread
fashion. HRRR surface-smoke concentrations are not overly high, and
the latest 06Z HRRR run has actually backed off slightly. Right now,
concentrations forecast don't seem high enough to warrant mention in
the grids/forecast, but will continue to monitor trends throughout
the morning/daytime.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 411 AM CDT Tue Jul 23 2024

Global deterministic and ensemble guidance continues to show a
consistent trend in the upper flow pattern later this week into
early next week. An upper ridge will build west of our region by
midweek and spill down over the top of our forecast area by Thursday
and Friday. This is in response to another upper level low moving
into the Pacific Northwest and western Canada. Hot and sultry
conditions will be the result here locally with temperatures will
above normal and high humidity values. Cluster analysis remains in
agreement indicating this building ridge across the Northern Plains
before getting pushed south by the aforementioned upper low tracking
across southern Canada this weekend. So, confidence remains at a
high level for the first half of this period in that it will feature
hot, humid and dry conditions.

The upper low to the north will more or less fill in over time going
into next week. Southwest flow aloft across our region will set up
during the upcoming weekend before becoming more zonal early next
week. We could anticipate that in this southwest flow regime,
embedded shortwave energy will be present that will track through
our region and give some of us an increased chance for convection.
It remains to be seen when and where this could occur. There may be
a developed EML set up across some part of the region that would
effectively put a cap on any thunderstorm activity. Ensembles at
this time point to high probabilities(40-80%) of 700mb temps of +12C
or warmer. These probs do wane by the end of the weekend, indicating
that if there's a cap, it will be weakening. At this point, that's
the time frame, late Saturday into Sunday, when our inherited NBM
PoPs(20-40%) are the highest. As mentioned, temperature trends will
be running fairly hot through the period. Grand Ensemble
probabilities for seeing 90 degrees or warmer remain high(50% or
greater) from the James Valley and point west through central SD
Thursday through Saturday. With dew point temperatures in the mid
60s to around 70 degrees, it's going to feel quite muggy. Heat
indices continue look to remain just shy of heat advisory criteria,
although Friday may be the day to keep an eye on as that appears to
be the hottest day in the period.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1231 AM CDT Tue Jul 23 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to start off the TAF period, until
near surface smoke and/or light fog shows up. Then, expect MVFR
VSBY in a surface smoke (FU) obscuration or light fog (BR) to
become the prevailing condition.

&&

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

SHORT TERM...TMT
LONG TERM...Vipond
AVIATION...TMT/Dorn

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Special Weather Statement
National Weather Service Aberdeen SD
418 AM CDT Tue Jul 23 2024

MNZ039-SDZ008-231000-
Traverse MN-Roberts SD-
418 AM CDT Tue Jul 23 2024

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN TRAVERSE AND
NORTHEASTERN ROBERTS COUNTIES THROUGH 500 AM CDT...

At 417 AM CDT, Doppler radar was tracking a strong thunderstorm near
Fairmount, or 13 miles north of Wheaton, moving southeast at 25 mph.

HAZARD...Wind gusts up to 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Wheaton, Tintah, Immanuel Church, Whiterock Colony, Silver Bridge,
Mud Lake Landing, and Lake Traverse.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4594 9627 4593 9625 4580 9625 4569 9661
      4593 9666 4594 9656 4597 9657 4602 9658
      4602 9627
TIME...MOT...LOC 0917Z 328DEG 21KT 4601 9652

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Vipond