114
FXUS63 KABR 120605
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
105 AM CDT Sun Jul 12 2026

.KEY MESSAGES...

- A dangerous and prolonged heat wave will continue today through
much of next week with near record to record temperatures expected
and heat index values warming into the triple digits each afternoon.

- An Extreme Heat Warning for north central SD and a Heat Advisory
for parts of central and northeast SD and west central MN remain in
effect through Tuesday.

- The combination of humidity dropping below 20%, wind gusts of 20-
35 mph, and drying fuels may lead to elevated fire danger concerns
over the western portions of Corson and Dewey Counties this
afternoon. Elevated fire danger concerns are possible again Monday
afternoon along and west of the Missouri River.

&&

.DISCUSSION...
Issued at 100 AM CDT Sun Jul 12 2026

A dangerous and prolonged heat wave is the main concern in the
forecast as high temps will range in the 90s to the lower 100s today
through next Friday, hottest across central SD. The entire central
CONUS is under an impressive highly amplitude ridge that stretches
well into northern Canada. Just to give an idea on how anomalous
this is, heights run between 596-599 dam over the Northern Plains
through Tuesday night which runs in the 99-100th percentile per
climo for 500mb heights for this time of year. NAEFs indicates this
is about 2 to almost 3 standard deviation above climo. Under this
ridge the 500mb high that has been over the Southwest will stretch
northeastward and expand over the entire central CONUS (and even
eastward) through the middle of next week. By the end of next week,
not much change in the ridge aloft (heights a tad lower) with the
ridge actually retrograding westward by the weekend. With the region
under the heat dome aka subsidence occurring, no precip is expected
at least through the end of next week, worsening drought conditions
for some locations that have not received rain in the past week or
so, especially over portions of north central SD. As what the
previous shift mentioned, high pressure at the surface will not be
directly overhead and more off to our southeast Sunday through
Tuesday and another one forming to our north/northwest over central
Canada midweek.

With southerly flow under the ridge, 700-850mb temps also will run 2
to 3 standard deviation above climo per NAEFS today through all of
next week. Our hottest days will be today-Wednesday where 700mb
temps are forecast to range from +13 to +16C and 850mb temps +25 to
+30C during these days with the warmest temps over north central SD.
This runs in the 95-100th percentile range per climo at these
heights (GEFS/GEPS/ENS). This results in maxTs widespread in the mid
90s to the lower 100s this afternoon through Friday with potential
highs reaching up to 106 over north central SD today-Wednesday.
However, NBM 5.0 vs 5.2 do vary a bit in MaxT due to the ongoing
warm bias of the Canadian model in the 5.0 version with a spread of
1 to 3 degree across the CWA. For example, NBM 5.0 has a high of 98
today at KABR and 5.2 has a high of 96. This seems to be the case as
well through much of next week where a 1-3 degree spread remains. So
a bit lower confidence on how warm our maxTs will get each afternoon
across the CWA. The 25-75th spread becomes quite high for the end of
next week, on the order of 8 to 10+ degrees due to lower confidence
on the exact intensity and position of the ridge aloft. For example,
25th percentile is 92 degrees and 75th is 106 degrees for KABR. Not
much relief overnight as lows will range in the 70s with our warmest
nights being tonight/Monday morning and Monday night/Tuesday
morning. As for record temps Mobridge will be within 1 degree of
record high today through Tuesday. Also Mobridge and Sisseton are
forecast to be above for record high mins for Monday morning and MBG
again Tuesday morning. Dewpoints will range in the mid to upper 50s
to the upper 60s/70s, muggiest over eastern SD/western MN. Luckily
where the highest dewpoints are, are offset from where the hottest
temps will be, therefore, heat indices will be near actual
temps so still quite hot, between 100-105. The Excessive Heat
Warning for north central SD and the Head Advisory for central
and portions of northeastern SD/western MN continue through
Tuesday evening due to heat indices above 100 each afternoon.
This will most likely be extended further out in time. As of
now, Clark, Codington, Hamlin, Deuel do not reach the 100 degree
apparent temp threshold for a headline as of now.

Winds will also remain breezy under the heat dome with overall gusts
between 20-35 mph this afternoon and again Monday afternoon.
Again as mentioned NBM 5.0 is several knots higher than 5.2 so a
bit lower confidence again on max winds. This combining with
relative humidity dropping to 25% or less along and west of the
Mo River this afternoon (under 20% over north central SD) and
west of the James River Monday afternoon may lead to elevated
fire danger concerns. Looking at Geocolor from earlier today,
Corson, Dewey, and northern portions of Stanley County are dry
as areas east of the Mo are quite green due to the previous
rains, so lower humidity and gustier winds in this area are ok
for now. With the criteria borderline and collab with other
offices, went ahead and issued an SPS for Corson/Dewey Counties
for this afternoon and will wait and monitor the trends for a
potential headline for Monday.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1220 AM CDT Sun Jul 12 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will prevail at all terminals the next 24 hours.
South to southeast winds will turn gusty between 20-25 kts by
late morning through the afternoon.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Heat Advisory until 7 PM CDT /6 PM MDT/ Tuesday for SDZ005>008-
     010-011-017-018-021-033>037-045-048-051.
     Extreme Heat Warning until 7 PM CDT /6 PM MDT/ Tuesday for
     SDZ003-004-009-015-016.
MN...Heat Advisory until 7 PM CDT Tuesday for MNZ039-046.

&&

$$

DISCUSSION...MMM
AVIATION...Vipond