813
FXUS63 KABR 220152 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
852 PM CDT Mon Jul 21 2025

.KEY MESSAGES...

- There is a Marginal Risk, level 1 of 5, of severe storms late
  this afternoon into the overnight hours and again Tuesday during
  the morning and again late afternoon into the overnight hours.
  There is a Slight Risk, level 2 of 5, for severe storms over
  north central SD tonight and over mainly northeastern SD and
  west central MN Tuesday. Winds of 60-70mph and 1-2" hail will be
  the main concerns with the strongest storms.

- Heat index values will top out in the 100 to 110 range Tuesday
  over much of the area, with slightly lower values over the
  higher elevations (Leola Hills and Prairie Coteau).

&&

.UPDATE...
Issued at 844 PM CDT Mon Jul 21 2025

Expired the Heat Advisory at 8pm, with daytime heating done now.
Monitoring convective trends over western South Dakota and eastern
Montana. No changes planned at this time for the tonight period.
Looks like a rather toasty night, with low temperatures only
falling to the upper 60s to low 70s by sunrise. If thunderstorms
happen over this CWA tonight, they should be relegated to mainly
north central SoDak starting within the next few hours,
potentially working into northeastern SoDak/west central MN during
the late overnight hours. Kinda leaning in the direction of mid-
level (700hpa) temps over this CWA being too warm to support
thunderstorms tonight though, as +14C to +15C air resides over
the western half of the CWA, and likely to remain there overnight.

UPDATE Issued at 643 PM CDT Mon Jul 21 2025

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.DISCUSSION...
Issued at 408 PM CDT Mon Jul 21 2025

A persistent area of low pressure over western South Dakota will
continue to bring in rounds of showers and thunderstorms through
Tuesday. Most of the storms will be during the late evening and
overnight hours. The strongest storms will be capable of producing
quarter to golf ball sized hail and winds in excess of 60 to 70 mph.
The day 1 and day 2 SPC severe weather outlooks now include slight
risks of severe storms, for north central SD tonight and for
northeastern SD into west central MN Tuesday.

The cap of warm air aloft has been effective in keeping any shower
or thunderstorm development out of the forecast area so far this
afternoon. However, we are starting to see some indications of at
least some radar reflectivity just east of our forecast area (near
Morris) at 2050Z. We`ll continue to monitor the latest radar and
satellite imagery for additional development. However, most of our
concerns for strong to severe storms will be with what is developing
to our west late this afternoon into the evening hours, or even late
this afternoon/evening over south central SD primarily to our south.
CAMS continue to show the highest chance across ND, with some
movement over northern portions of SD/west central MN closer to
daybreak Tuesday.

Very warm air remains in place. Temperatures will only fall to near
70 degrees by daybreak Tuesday. Highs Tuesday will be mainly in the
90s, with a few 100 degree readings. PIR is expected to top out
around 8F below their all time record of 108 degrees from 1941.
Dewpoints will remain in the upper 60s and 70s through the daytime
hours Wednesday. The high dewpoints and high temperatures will bring
heat index values into the 100 to 110 degree range Tuesday, with the
highest values over south central South Dakota. Additional headlines
will likely be needed for much of the forecast area.

We`ll see some relief in the severe weather potential behind the
surface low that will trace over central SD Tuesday night and
southeastern SD Wednesday morning. The SPC severe weather outlook
still has a Marginal Risk for severe storms Wednesday over much of
our eastern counties. Highs Wednesday will return closer to near-
seasonal values, before returning to the 80s and 90s for the end of
the week and next weekend. Dewpoints will also rebound into the mid
to upper 60s Thursday and into the 70s this weekend, with the threat
of high heat index values near 100F returning to south central SD.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 643 PM CDT Mon Jul 21 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are forecast to prevail over the next 24 hours.
Guidance this evening is indicating sub-VFR stratus/fog will not
return to the region tonight, despite the southerly wind and heavy
humidity in the boundary layer. Will monitor guidance for changes,
as this seems suspect, given the only things to change over the
past 48 hours (fog/stratus each of the last couple of mornings)
are increases in heat and humidity. Short range guidance also
suggests the most probable TS solution for tonight is convection
already happening over northeast Wyoming (or convection yet to
develop over western South Dakota) will eventually organize into a
cluster of storms and move toward KMBG by 06Z, and then over
toward KABR by 08Z. So, for now, those two terminals have the
PROB30 mention for thunder over the next 6 to 12 hours.

&&

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

$$

UPDATE...10
DISCUSSION...06
AVIATION...10