-- Discussion containing changed information from previous version are highlighted. --
860
FXUS63 KABR 231837
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
137 PM CDT Mon Sep 23 2024

.KEY MESSAGES...

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- A cold front to bring shift to winds out of the west, and a 20
  to 50% chance of light rain through this evening.

- Above normal temperatures return Wednesday through the weekend, with
  Thursday seeing the warmest temperatures (mainly in the 80s).

- Areas around the James River Valley and west will likely see
  strong wind gusts (up to 30mph) Thursday morning into the
  afternoon.
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&&

.SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/...
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Issued at 136 PM CDT Mon Sep 23 2024

The surface through currently set up across central South Dakota has
kept winds out of the south gusting 25-35 mph, with winds shifting
out of the southwest to west and high clouds have been the main
visible feature behind this feature. Radar returns have increased
this afternoon, with light showers remaining possible as the cold
front tracks near the James River by 03Z Tuesday. The trough is
nearly stacked from the surface up through 500mb, helping to enhance
shower activity this evening over northeastern SD/western MN. We`re
still expecting dry weather to return by or shortly after 06Z.
Rainfall amounts are still expected to stay below 0.10", with only a
10% chance of getting over that amount northeast of a line from
Aberdeen to Watertown.

A ridge of high pressure will build in behind the exiting trough,
with dry weather through the rest of the forecast period. While
mostly clear sky will return, mid to high clouds will still be
around through the daytime hours Tuesday. Temperatures will continue
to bottom out in the 40s both tonight and Tuesday night.
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&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
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Issued at 136 PM CDT Mon Sep 23 2024

As the upper-level ridge over Montana moves east, the area with the
highest 500mb pressure will be over central and eastern SD by
Thursday morning. The mid-levels have dry air over SD as well as WAA
Wednesday into Thursday. This dry, warm air will lead to a lack of
precipitation development at the surface. Wednesday will see
temperatures 10-15 degrees above normal, and Thursday will see an
increase in temperatures, around 15-20 degrees above normal. The
winds will be stronger on Thursday, with strong 0.5km model winds
and lapse rates Thursday afternoon into the evening hours over the
James River Valley and to the west. Cluster ensembles show these
stronger winds as well with gusts reaching over 30kts. The NBM has
stronger gusts as well, but it has the gusts weakening earlier than
the models and cluster ensembles.

As the ridge moves to the east Thursday, it will cut off an area of
lower pressure at 500mb over MO. This low pushes the high pressure
more to the north/northwest over the next couple of days as the
ridge moves east over the Great Lakes, though models vary in the
locations. At the same time, an upper-level low off the west coast
of British Columbia keeps pushing shortwaves to the east, with
models varying the location and timing. By Monday, the models show
an upper-level shortwave being moving over SD. Mid-levels keep the
dry air over SD until Saturday afternoon, which keeps precipitation
from developing at the surface. The mid-levels also have pockets of
CAA move over central and eastern SD Friday and Saturday, which
helps to cool surface temperatures. While these days will see cooler
temperature then Thursday, they will still be 10-15 degrees above
normal for this time of the year.

The ECMWF has some mid-level moisture moving into eastern SD
Saturday evening. This leads to the model showing precipitation in
eastern SD until Sunday morning, however, other models do not show
this precipitation developing. This mid-level moisture in the ECMWF
hangs around until Monday morning when the other models also show
mid-level moisture over SD. The moisture and the lift along a cold
front, will help with the development of precipitation on Monday
over central and eastern SD. The GFS shows a strong pressure
gradient along the front, which can cause strong winds to occur.
0.5km model winds show the potential for strong winds as well as
strong lapse rates over central SD. Clusters and ensembles depict
these winds being weaker than the winds on Thursday, but there could
still be some strong gusts. Mid-levels show CAA occurring Sunday and
Monday, with Sunday being 10 degrees above normal and around normal
temperatures on Monday behind the front.
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&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1230 PM CDT Mon Sep 23 2024

Terminals KABR,KATY,KPIR,KMBG

VFR conditions continue with ta 20 to 50 percent chance of showers
as a cold front swings across the area late this afternoon through
tonight. Winds gusting out of the south ahead of this front have
peaked around 30kts.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

SHORT TERM...KF
LONG TERM...Vernon
AVIATION...Parkin