sd discuss
Office: FSD
FXUS63 KFSD 151105
AFDFSD
Area Forecast Discussion
National Weather Service Sioux Falls SD
605 AM CDT Wed Oct 15 2025
.KEY MESSAGES...
- Areas of fog, some locally dense, through mid morning.
- Low shower/drizzle chances remain through today and tonight,
though additional rainfall amounts will be less than a tenth
of an inch through the period.
- Warm and breezy on Thursday ahead of an incoming system that
will bring additional showers along a cold front Thursday
night into Friday.
- Temperatures fall back to near seasonal averages for the
upcoming weekend, with only low rain chances - mainly on
Saturday.
&&
.DISCUSSION...
Issued at 340 AM CDT Wed Oct 15 2025
Seeing spotty light showers and drizzle remaining across the area
very early this morning, with hi-res guidance suggesting this
continuing through at least mid to late morning. The overall trend
through the remainder of the day, however, will be for lessening
coverage with increasing subsidence as an upper level ridge
amplifies over the region. Additional rainfall amounts will average
less than 0.05" - and this would mainly occur during the morning.
Developing low pressure over CO will begin to usher warmer air
northward through the day, and temperatures this afternoon will be
15 to 20 degrees warmer than yesterday. Highs will range from the
lower to mid 60s north, to the 70s through the MO River corridor
where there may be more breaks in the clouds by afternoon.
Low pressure continues to deepen into western NE/SD tonight, and in
an increasing surface pressure gradient southeasterly winds will
begin to pick up overnight. Rainfall chances will remain low (20% or
less) for the much of tonight, though may bump up a bit (30-40%)
through our north and west later in the night as an elevated warm
front lifts to the north and a LLJ develops through central NE and
SD. It will be a milder night in response to the warm air advection
with lows in the 50s to lower 60s.
For Thursday through Friday, an upper level trough oriented through
the Rockies lifts into the Northern Plains through the period. At
the surface, the low pressure to our west lifts into ND and finally
into south central Canada by Friday, pulling a cold front through
our area as it does so. Out ahead of the front, a strong southerly
flow will result in a breezy day on Thursday, along with
temperatures climbing into the mid and upper 70s. Ensembles and
deterministic models continue to indicate the better rain chances
with this front occurring on Thursday evening as the main upper
level low ejects northward out of the trough - tracking over the
western Dakotas during this time frame and enhancing midlevel
frontogenesis west of Interstate 29. Current rainfall amounts during
this period are projected to average 0.2" to 0.3" west of I-29, with
ensembles on the lower end of this amount. Rainfall chances may
linger into Friday as the front finally sweeps through the area,
though rainfall amounts will most likely be less with appreciable
forcing weakening. With cold air advection behind the front,
temperatures will cool slightly for Friday with highs into the 60s
and lower 70s.
Much cooler temperatures push into the region for the upcoming
weekend as the upper level trough deepens over the Plains and
Mississippi Valley through the period. Could again see some low rain
chances for Saturday, with both the GFS and ECMWF showing upper
level energy tracking southeastward on the backside of the trough,
ending up in the Central Plains on Saturday. Temperatures for the
weekend look to be in the 60s, with lows in the 30s.
As we move into next week, confidence in the forecast becomes low
with increasing model divergence in solutions. While the GFS would
indicate an upper level ridge building back over our region, both
the ECMWF and Canadian have a deepening trough through the Northern
Plains for the beginning of next week. Temperatures over our area
will be dependent on which solution verifies, though it does look
like a drier period for Monday and Tuesday.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 600 AM CDT Wed Oct 15 2025
Widespread IFR/LIFR stratus expected through at least early
afternoon, with some improvement possible by late afternoon and
evening. Otherwise, areas of MVFR/IFR fog will persist through
mid to late morning, then improving by early afternoon. While
spotty showers and drizzle will occur through the morning,
chances will lessen during the afternoon into early tonight.
Although cloud coverage will lessen tonight, there could still
be areas of IFR ceilings. With a low level jet developing west
of Interstate 29 tonight, there will be a period of LLWS at KHON
overnight.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 10 AM CDT this morning for SDZ050-052-
057>059-063-064.
MN...Dense Fog Advisory until 10 AM CDT this morning for MNZ071-072-
080-081-089-090-097.
IA...None.
NE...None.
&&
$$
DISCUSSION...JM
AVIATION...JM
Office: UNR
FXUS63 KUNR 151110
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
510 AM MDT Wed Oct 15 2025
.KEY MESSAGES...
- Dense fog/patchy drizzle this morning, but patchy/areas of fog
will linger through tonight
- Unsettled through Thursday
- Isolated strong/severe thunderstorms tonight parts of
northeastern WY/southwestern SD
- Drying out this weekend with seasonal weather
&&
.DISCUSSION...(Today Through Tuesday)
Issued at 225 AM MDT Wed Oct 15 2025
08z surface analysis had high over the Great Lakes and trough
from eastern MT into central CO. Low level moist east/southeast
flow between the two feeding fog/dense fog/patchy drizzle across
much of the CWA early this morning per surface
observations/highway cameras. Water vapour loop showed upper low
spinning over southern NV with shortwave-laden southwest flow over
the northern Plains. Wave over WY creating shra/TS over
northeastern WY per regional radar loop/GLM data. Forecast concern
continues to be upper low.
Today/tonight, upper low ejects into the central Rockies. Surface
low spins up along surface trough in northeastern CO. Low level
moist east/southeast flow will continue with dense fog/drizzle
early this morning and improving visibilities late
morning/afternoon, but fog will still linger into tonight for some
folks. Current Dense Fog Headlines look good. As surface low
spins up, a narrow band of 0.5-1KJ/kg MUCAPE (SPC HREF) is
forecast to poke into the CWA from the south late this
afternoon/tonight. Given expected stratus/fog surface-based
convection developing in the CWA might be tough, but elevated
buoyancy/effective shear may be sufficient for isolated
strong/marginally severe thunderstorms (hail/wind) this evening
over southwest portions of the CWA. Otherwise, band of shra/TS
will invade the CWA tonight affecting the western half the most
with a 40-60% chance of 0.50" QPF per HREF where the band sets up.
Forecast PWATs 150-200% of normal, so locally heavy rain possible
if any training develops. Have lowered temperatures for MaxT
today courtesy of stratus/fog.
Thursday, upper low moves into southern MB with dry slot over the
eastern half of the area. Additional showers likely on the back
side over the west with any daytime heating conducive to popcorn
showers especially over northeastern WY. Temperatures will be near
guidance.
Friday into the weekend, northwest flow aloft is replaced with
upper ridge with drier weather and a warming trend. Progressive
flow early next week creates low confidence forecast as a series
of upper troughs move across the northern Plains. Typical Fall
pattern.
&&
.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 507 AM MDT Wed Oct 15 2025
Areas of fog, some drizzle, and low clouds will persist through
the forecast period with IFR/LIFR conditions, although some
improvement may occur this afternoon and early evening. A storm
system will spread rain and a few thunderstorms (hail and gusty
winds possible) into the area late this afternoon, persisting
into tonight as the precipitation moves south to north.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 9 AM MDT /10 AM CDT/ this morning for
SDZ001-002-012>014-024>032-041>044-046-047-049-072>078.
WY...Dense Fog Advisory until 9 AM MDT this morning for WYZ054-056-
057-060.
&&
$$
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Helgeson
Office: ABR
FXUS63 KABR 150817
AFDABR
Area Forecast Discussion
National Weather Service Aberdeen SD
317 AM CDT Wed Oct 15 2025
.KEY MESSAGES...
- A Dense Fog Advisory is in effect for counties around the Missouri
River until 10 AM CDT. Visibility will be reduced to around one-
quarter mile or less at times.
- Patchy/areas of drizzle are possible through at least the morning
hours across much of the area.
- Temperatures will be 10 to 15 degrees above normal Thursday
afternoon over eastern South Dakota and west central Minnesota.
- There is a 30-60% chance of showers Thursday through Thursday
evening, with highest chances over north central SD. There is a 40-
70% chance of more than a quarter inch mainly west of the Missouri
River and north of Hwy 14.
- Windy conditions (30-45 mph NW gusts) and elevated fire danger on
Saturday, then cold temperatures (near/below freezing) in the low to
mid 30s likely Saturday night/Sunday morning.
&&
.SHORT TERM /TODAY THROUGH THURSDAY AFTERNOON/...
Issued at 315 AM CDT Wed Oct 15 2025
As of 3 AM CDT, light drizzle continues across the area. Winds
are out of the east at 5-10 mph with temperatures in the mid to
upper 40s. We also have some visibilities less than a quarter mile
around the MO River this morning prompting a dense fog advisory
until 10 AM CDT.
Areas of drizzle will be possible today (exact timing and coverage
is still uncertain) with rain moving in for Thursday as a low
pressure system moves into and across the forecast area. It is
possible that a few storms could develop with maybe one or two
becoming severe over central SD but the chances for severe storms
have decreased since the previous model run. Rainfall
accumulations have a 40-70% chance of exceeding a quarter in
around and west of the Missouri River mainly north of Hwy 14 and a
50-70% chance of exceeding a half inch over far north central SD.
Relatively deep moisture remains over the area through the end of
the period which will keep a thicker layer of clouds overhead and
help keep highs today a bit on the cool side (in the 50s to low
60s) and overnight lows more moderate (in the upper 40s to low
50s). Some WAA ahead of the low will also help with these low
temps. The low will move northeast across the forecast area with a
cold front trailing behind from west to east. Due to this cold
front, high temperatures Thursday are a little uncertain across
most of the forecast area, but kept NBM for now. In general, highs
are expected to reach into the upper 60s to mid 70s.
&&
.LONG TERM /THURSDAY EVENING THROUGH TUESDAY/...
Issued at 315 AM CDT Wed Oct 15 2025
Thursday night, the surface low and mid-level shortwave trough will
be moving northward into Canada and out of the area. It appears the
frontal boundary should be quickly moving eastward into MN Thursday
evening, thus taking much of the precip chances with it. Inherited
NBM PoPs feature 20-40% chances in the evening, but quickly go
mostly dry after 06Z and into Friday morning.
Upper pattern then shows shortwave energy moving eastward across the
Dakotas on Saturday. Models are trying to generate a bit of precip
across the area, but NBM probability of measurable is generally less
than 20 percent across the region. Current forecast PoPs show
generally slight chances (20%) or dry across the region for
Saturday. What is likely the bigger story on Saturday is the
potential for 35-45 mph northwest wind gusts as a tight pressure
gradient sets up over the region. NBM probability of 24-hr max gusts
of 45 mph or greater ending at 06Z Sunday generally ranges from 40-
60% across central SD. Current forecast RH values in the afternoon
are ranging from 35 to 45 percent, so elevated fire danger for sure
on Saturday.
Will then be focusing on low temperatures Saturday night into Sunday
morning as a surface ridge axis moves through the region. While it
appears from the GEFS/GEPS/ENS pressure pattern Saturday night that
we don't lay right under the high center, the axis looks substantial
enough to the north to where winds should go fairly light,
especially in valley areas. Current NBM sky grids show clear
conditions, so we should be setting up fairly nicely for near or
even sub-freezing conditions. Cool air mass in place also with 850mb
temps from 0 to +5C. Current forecast is for lows in the low to mid
30s. NBM probability of min temps less than 32 degrees Sunday
morning is around 40-60% in the James River valley into portions of
north central SD.
&&
.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1201 AM CDT Wed Oct 15 2025
Terminals KABR,KATY,KPIR,KMBG
VISBY at KPIR/KATY appear impacted by fog and drizzle with MVFR/IFR
conditions to continue through the night. For CIGS, a mix of
MVFR/IFR is also expected. Little change through the day with
nothing to get rid of the moisture. Winds stay mainly out of the
east.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Dense Fog Advisory until 10 AM CDT /9 AM MDT/ this morning for
SDZ003-004-009-015-016-033>036-045-048-051.
MN...None.
&&
$$
SHORT TERM...13
LONG TERM...TMT
AVIATION...13
