Herreid, South Dakota Weather Forecast Discussion

519
FXUS63 KABR 252255
AFDABR
Area Forecast Discussion
National Weather Service Aberdeen SD
555 PM CDT Thu Sep 25 2025
.KEY MESSAGES...
- Winds will be breezy Friday, ahead of a dry cold front passage,
with gusts of 20 to 30 mph by the afternoon.
- A prolonged period of dry, warm, and windy conditions Sunday
through at least Wednesday. Temperatures in the 70s and 80s (5 to 15
degrees above normal), with southerly wind gusts 30-35 mph, or
potentially higher.
&&
.UPDATE...
Issued at 555 PM CDT Thu Sep 25 2025
The current forecast remains on track, with little to no
adjustments expected this evening.
&&
.DISCUSSION...
Issued at 212 PM CDT Thu Sep 25 2025
As of 2pm satellite shows clear skies over the CWA with models
indicating a weak frontal boundary/trough stretched over portions of
northern/north central SD and northeastward into ND. Really only
indication of this is a more northerly wind behind the front. Temps
range in the upper 70s to the lower 80s and dewpoints in the mid to
upper 50s. No major changes to the forecast as we are still
expecting a stretch of dry weather through early next week and
warmer than average temperatures (about 5-15 degrees above average).
The only main concern will be the breezy winds Friday and several
days of windy conditions early to the middle parts of next week.
Models are still in agreement on a ridge continuing overhead this
evening as it will shift eastward overnight into early Friday. A
shortwave behind it will track west to east across central
Canada/Northern Plains Friday and Friday night with northern SD and
northward through ND within the axis of the trough by 00Z Saturday.
Its surface low is forecasted to be over central Saskatchewan Friday
morning with the axis of the surface trough southward along western
ND/SD and eastern WY/MT. Its dry cold front will sweep northwest to
southeast over the CWA late Friday afternoon through early Friday
night as the surface low occludes and tracks northeast over Canada.
A high pressure system moves in behind it and over the region for
Saturday. Steeper pressure gradients over the area plus southerly
flow and daytime mixing will bring breezy conditions to the area.
GFS/NAM soundings indicate momentum transfer to the top of the mixed
layer (running between 850-750mb) around 20-27kts with steep dry
lapse rates below it. It does look like CAA moves in later after the
fropa passing, being more offset, so this keeps winds from getting
even gustier. So kept with the trend and blended NBM/NBM90 to
indicate higher wind gust potential with overall gusts ranging from
20-30kts, highest over south central SD (mainly southern Lyman
County area).
Otherwise Clusters are in agreement with a broad slight negative
tilting ridge building over much of the CONUS with a trough over the
Pacific (and its low spinning over the Gulf of Alaska). Ensembles
indicate this ridge becoming more amplified by Monday where the
entire -PNA pattern will shift slightly eastward on Tuesday, with
the ridge becoming more neutrally tilted. Towards the middle to end
of next week, Clusters indicate this ridge will be over the eastern
half of the CONUS. A persistent surface trough/lee low will set up
over eastern MT/WY and the western Dakotas Sunday through at least
Wednesday, with the CWA within the eastern side (downstream) of the
trough. This trough leads to tighter pressure gradients over the
area and southerly flow of winds at lower levels. Add in daytime
mixing and this will bring a period of windy conditions to the CWA
with the highest gusts forecasted to be Monday and Tuesday. As what
the previous shift mentioned, winds may need to be bumped up in the
grids these days to show for higher gust potential, but was a little
weary to do that this early. As of now, latest run indicates
probability of NBM wind gusts>35 mph is 40-70% Monday afternoon over
central SD. 30-50% Tuesday afternoon, along and west of the James
River, and only 20-30% or so over the entire CWA Wednesday.
Confidence is higher on these breezy conditions but lower on exact
magnitude.
Friday`s 850mb temps will range from +18 to +22C which runs around
the 90th percentile, per ABR sounding climatology. This along with
southerly flow through peak heating (MO river and east ahead of
front) and mixing heights anywhere between 850-750mb should lead to
highs a little warmer than deterministic NBM. So I kept the trend of
blending NBM/NBM90. Forecasted highs with this blend range in the
80s, with upper 80s over south central SD to possibly even hitting
90. Cooler air moves in with the high on Saturday with temps back
down in the 70s. As this ridge builds and prolonged southerly flow
aloft and at surface is expected through Wednesday, highs are
forecasted to range in the upper 70s to the mid 80s.
&&
.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 555 PM CDT Thu Sep 25 2025
Terminals KABR,KATY,KPIR,KMBG
VFR conditions are expected over the next 24 hours. The PIR
weather observation remains unavailable, with parts on order.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...06
DISCUSSION...MMM
AVIATION...06

NWS ABR Office Area Forecast Discussion