Akaska, South Dakota Weather Forecast Discussion

445
FXUS63 KABR 141841 AAC
AFDABR
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
141 PM CDT Sun Sep 14 2025
.KEY MESSAGES...
- Pockets of fog with reduced visibility to less than a half mile
  will linger through the morning.
- Marginal Risk (threat level 1 of 5) for severe storms across
  the forecast area, mainly for this afternoon, with a Slight Risk
  (threat level 2 of 5) north of a line from Mobridge to
  Gettysburg to around Ipswich.
- The strongest storms this afternoon will be capable of
  producing hail of around 1 inch in diameter. A couple of
  tornadoes will also be possible this afternoon. Storms that
  develop will also be capable of creating strong winds to around
  60 mph and heavy rain.
&&
.UPDATE...
Issued at 128 PM CDT Sun Sep 14 2025
Tornado Watch now in effect for portions of north central and
northeast South Dakota until 9 PM CDT. ~500-1000J/kg CAPE and
30-35kts of deep layer shear. 0-3km CAPE where tornadic
thunderstorm is happening is around 100J/kg and there is no lack
of surface vorticity in that area. Believe it or not, that`s not
even the most favorable low-level environment for land-
spout/mini-supercell-type tornados right now. The James River
valley (Brown/Spink Counties) eastward is where the better
environment is just now. So much rain has fallen across the
Missouri River valley, flood warnings have been issued as well.
Also, see below for an aviation forecast discussion for the 18Z
TAFs.
UPDATE Issued at 1015 AM CDT Sun Sep 14 2025
Showers with moderate to heavy rainfall at times continue to move
northward across central SD. Still expect an uptick in areal
coverage of showers/storms later this afternoon, with a low end
potential for severe storms. Will be keeping an eye on the
possibility for an isolated weak tornado or two as well as the
low-level atmospheric conditions will be somewhat favorable as the
surface low rotates northward. Made some adjustments to PoPs to
match radar trends. Also still dealing with areas of dense fog
along and west of the James River. Had earlier this morning issued
an advisory and will let that ride until 16Z.
&&
.DISCUSSION...
Issued at 426 AM CDT Sun Sep 14 2025
Fog remains a concern, particularly east of the MO River.
While at 09Z, ASOS locations remain around 3 miles of higher with
visibility, area webcams are showing pockets of visibility likely
less than a half mile. While the showers and more abundant clouds
over central SD will act to disrupt some of the lower level
moisture, areas east of a line from around Ipswich to Miller will
keep similar conditions through daybreak. As with the last several
days, some pockets of the fog will linger through late morning.
Ongoing showers and thunderstorms are currently diminishing over
central SD. However, resurgence is expected, especially as we move
into the afternoon hours. This will be as the initial surface low
broadens across SD and a reinforcing low nears from the south. This
low will be over south central SD 15-18Z today (near/south of Jones
County). Expect the low to slide north to near MBG by 03-06Z Monday.
The severe weather threat will remain near and east of the surface
low, with an SPC Marginal Risk for our forecast area today, and a
Slight Risk over portions of north central SD (mainly north of a
line from Mobridge to Gettysburg to around Ipswich).
The area of current showers and a few storms is in an area of lower
DCAPE values around 200 J/kg. Winds are less of a concern than
yesterday morning. LCL heights are however low at 500-750 m. Morning
fog/low clouds will help keep LCL heights lower. Plenty of moisture
remains with dewpoints in the mid to upper 60s this afternoon and
even RH values remaining above 50 percent (above 70% over much of
the area west of the MO River where more stable conditions will
exist on the back side of the low). Unlike the last few days when
evening and overnight storms have been more common, afternoon storms
are likely, before diminishing this evening as the low exits and we
lose daytime heating. Shear in the lower LCL environment is the main
concern northeast of the low, where daytime heating and potentially
some pockets of sun, will help create convective development. A
couple of tornadoes will be possible this afternoon. While there is
a 5% chance of a tornado within 25 miles of a point in the Slight
Risk area of north central SD, with a 2% chance across much of the
rest of the forecast area (excluding our far eastern SD and western
MN counties). The strongest storms will also be able to produce hail
of around 1 inch in diameter, strong winds to around 60 mph and
heavy rain. Heavy rain will be a concern if storms move over the
same area.
Fog may be more abundant Monday morning than what we currently are
forecasting (mainly over Leola Hills and north of PIR), especially
across areas that receive significant rain during the day today.
A trough of low pressure lingering across our area through at least
Tuesday will mean a continuation of our unsettled weather pattern.
We`re still looking at significant changes for Wednesday on, with
high temperatures around 5-10 degrees cooler than what we`ve been
experiencing lately. The 6-hourly chances for precipitation finally
drop to around 20% or less Thursday night through Saturday evening.
Not to say that there won`t be precipitation, but chances are much
lower than the last few days.
&&
.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 128 PM CDT Sun Sep 14 2025
Terminals KABR,KATY,KPIR,KMBG
A mix of VFR/MVFR cigs is expected to persist for much of the TAF
valid period at KPIR/KMBG and KABR. KATY, for now, is expected to
hang on to a predominantly VFR forecast.
Showers and thunderstorms will continue to develop all over the
forecast area. All four terminals could see convection between now
and 00Z. There is the potential for additional showers overnight,
especially at KMBG.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...10
DISCUSSION...06
AVIATION...10

NWS ABR Office Area Forecast Discussion