574
FXUS63 KABR 291927
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
227 PM CDT Wed Jul 29 2026

.KEY MESSAGES...

- A Heat Advisory remains in effect through this evening for central
and portions of northeastern SD and west central MN with heat
indices as high as 103 degrees.

- Western wildfire smoke may impact visibility at times across the
region through Thursday morning. Smoke may drop air quality to the
point of impacting those sensitive to smoke.

- A Marginal Risk (level 1 of 5) for severe weather is in place over
the western portions of Dewey and Corson Counties this evening
through late tonight. Wind gusts of 60 miles per hour will be the
main severe threat.

- A Slight Risk (level 2 out of 5) for severe weather is in place
over portions of south central SD Thursday. A Marginal Risk (level 1
of 5) for severe weather is in place for the rest of the forecast
area. The main hazard will be wind gusts of 60 to potentially 70 mph
and hail of one inch in diameter. Heavy rain that could lead to
localized flash flooding is also possible with any stronger storm.

&&

.DISCUSSION...
Issued at 226 PM CDT Wed Jul 29 2026

Main concern in the forecast is the ongoing smoke, both at the
surface and aloft, and the return of shower and thunderstorms
(potentially severe) with beneficial rain in the forecast across the
region late tonight through Thursday night. As of 2pm, temperatures
are in the upper 80s to around 100 with dewpoints in the upper 60s
to the upper 70s, highest James River and eastward thanks in part to
peak evapotranspiration and south to southeast winds. Heat indices
range in the 90s to the lower 100s. Went ahead and expanded the Heat
Advisory to cover the remaining forecast area with the exception of
Codington and Hamlin. Besides fair weather cumulus over central SD
and portions of NESD skies remain free of clouds with ongoing smoke
and hazy skies. Smoke from the wildfires out west will continue to
affect the region with lighter concentrations of near surface smoke
continuing through the rest of the evening and tonight before
lifting northward Thursday morning for a few hours before moving
back in mainly east of the Mo River late Thursday night/Friday
morning. This may continue to bring a reduction in visibility and
affect people who are sensitive to smoke. Periods of smoke
aloft/haze will continue through at least the end of the week.

The Northern Plains continues to be under the upper level ridge with
its mid level high over the southern CONUS and winds across the CWA
slightly west to to northwest flow. A shortwave (which originated
over Arizona) will continue to track northeastward and over Wyoming
by 00Z Thursday with a lee north to south oriented surface trough
along the western Dakotas and eastern WY/MT. The CWA will be within
the warm sector (between this and a high over MN) with ongoing south
to southeasterly winds at the surface to 850mb and ongoing moist
air. By 06Z, there really only seems to be a slight shift eastward
in the surface trough which is connecting to a low over the Northern
Rockies. By this time, the majority of the CAMs keep any convection
just to the west of the CWA. Between 12-18Z the center of the low on
this surface trough really only shifts a bit east and over south
central SD. Widely scattered showers and thunderstorms will mainly
continue along and west of the Missouri River. However, NBM is a bit
more bullish and has pops extending to the James River. Through the
afternoon and evening the surface trough will orient itself more
northeast to southwest over the eastern half of SD/NE with the
convection continuing to track eastward with additional development
of shower and thunderstorms across the entire CWA. CAMS do vary
quite a bit on timing and the location of development/storm track
through the midday Thursday. So low confidence remains, however, NBM
does a good job keeping the pops widespread due to this. Later on in
the afternoon a few of a models do show the potential of storms
clustering and eventually growing upscale/cold pool development and
forming into a line of storms extending from Nebraska through
central and northeastern SD into MN where it will track
east/southeast and hopefully out of the eastern CWA by late Thursday
night. HRRR indicates the potential for a bowing segments, however,
as of now this looks to be south and east of our CWA.

Looking at the mesoscale parameters, the low level moisture will be
abundant, as mentioned, as dewpoints will overall be in be in the
the upper 60s to the upper 70s through Friday evening. SB/MUCape
will generally be around 1000j/kg or less this evening and overnight
with values increasing by midday Thursday, ranging from 1000-2500
j/kg highest over northeastern SD. However, 21Z and after values
decrease to around 1000-1500 j/kg and diminishing even more after
sunset. However, RAP is much higher with CAPE values of 2000 to 3000
j/kg with some areas indicating 4K! This looks to be a high CAPE low
shear setup as bulk shear looks to remain below 30kts and no real
LLJ. RAP soundings indicate low level lapse rates will be steeper
whereas mid level lapse rates are not as steep with DCAPE values
above 1000 j/kg early Thursday morning but does decrease below
1000j/kg by the afternoon. So the main threat with the storms will
be damaging wind gusts of 60 to potentially 70 mph with a few storms
possibly producing quarter size hail. If the line of storms does
form/grow upscale and/or potentially bow over any part of the CWA
then wind gusts could potentially be higher. Main caveat will be the
cloud cover which could keep instability on the lower side for
Thursday as well as a cap over much of the region setting up late
tonight through the morning before breaking Thursday afternoon. A
Marginal Risk (1/5) continues over north central SD for the
convection overnight/early Thursday. A Slight Risk (2/5) for
portions of south central SD with a Marginal Risk covering the rest
of the CWA for Thursday with the main threat being damaging wind
gusts.

PWAT values will range from 1.3 to 2" with the highest amounts James
Valley and eastward. Therefore, any rain that falls could be heavy,
especially with any stronger storms or training storms, leading to
flooding. There is a slight risk of excessive rainfall for Thursday
James Valley and eastward due to the high PW`s meaning a 15% chance
of rainfall exceeding flash flood guidance within 25 miles of a
point in the slight risk. The probability of rainfall of 0.5" or
more is 50 to 90% across the entire CWA with the probability of 1"
ranging from  40 to 75%, mainly along and east of the Mo River with
the highest chances over northeastern SD, mainly Spink County and
eastward. Prob of 2" is 30-50% James Valley and eastward. Again this
will be convective so exact amounts at any one location is hard to
predict, but any rain will be beneficial to the area. NBM 25-75th
spread for the 48 hour period, ending Friday evening is quite high
ranging from 0.6 to 2 inches, highest James Valley and eastward.
This leads to low confidence in exact amounts.

Behind this shortwave, the ridge amplifies with the axis more along
the intermountain West with its mid level high encompassing much of
the southwestern US Friday through early Saturday. A large mid level
low, over the Gulf of Alaska, will track eastward across Canada and
breaking down the ridge, with the southern portion of the shortwave
possible clipping the Northern Plains early next week bringing a
chance of showers and thunderstorms associated with a fropa through
the middle of next week, however, confidence remains low at this
time as this is several days out. Temps will be cooler for the end
of the week with highs overall in the 80s for Thursday and even
upper 70s to upper 80s/90 Friday, warmest along and west of the Mo
RIver. As the ridge becomes more positive tilted for the weekend
over the CWA, warmer air moves back in with highs in the 80s to the
upper 90s/100, again warmest along and west of the Mo River.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1223 PM CDT Wed Jul 29 2026

Terminals KABR,KATY,KPIR,KMBG

VFR cigs continue through the TAF period. Both smoke at the
surface and aloft will continue in waves over the region as well
through the TAF period. This may bring slight reduction to
visibility at times, especially during the late evening and
again in the morning. Widespread showers and thunderstorms will
track west to east across the region late tonight through
Thursday afternoon. A few of these storms could become severe
with the main threat being damaging wind gusts of 60 to
potentially 70 mph.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory until 9 PM CDT /8 PM MDT/ this evening for
     SDZ003>011-015>019-021-023-033>037-045-048-051.
MN...Heat Advisory until 9 PM CDT this evening for MNZ039-046.

&&

$$

DISCUSSION...MMM
AVIATION...MMM