928
FXUS63 KABR 020022 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
722 PM CDT Wed May 1 2024

.KEY MESSAGES...

- Rain showers over mainly south central SD will expand across the rest
  of central to northeastern SD this evening, before diminishing west
  to east Thursday. Rain totals through Thursday will range from a
  0.05 to near 0.5"(highest over north central SD).

- Active pattern continues in the extended period, with at least two
  systems affecting the region. The first (Friday afternoon and
  night) will quickly move through the southeast half of SD and bring
  generally light rainfall (0.1" or less). The next system will be
  larger and prolonged, lasting from Sunday night and potentially into
  Tuesday. Rainfall amounts may exceed 0.5" during that event (50%
  chance) and there may be a few thunderstorms on Monday (20% chance).

- Near to below normal temperatures Friday and Saturday, warming to
  above normal Sunday and Monday.

&&

.UPDATE...
Issued at 713 PM CDT Wed May 1 2024

See below for an aviation forecast discussion for the 00Z TAFs.

&&

.SHORT TERM /THIS EVENING THROUGH THURSDAY NIGHT/...
Issued at 203 PM CDT Wed May 1 2024

The weather map early this afternoon shows the surface ridge that
had dominated our area this morning shifting into western MN. There
is a trough of low pressure extending from the main surface low over
southeastern CO to another over western SD. A third low was moving
in from Canada/northern MT. Winds out of the south are beginning to
take hold across areas east of the MO River. Surface winds will
shift out of the southeast tonight as the CO low moves to central
KS/OK by 12Z Thursday and northern lows join forces over western ND
Thursday morning into the early afternoon hours.

Moisture pushing north into the area, and the assistance by embedded
waves in the southwesterly flow at 500mb, will help bring a return
of showers to mainly central SD. This moisture return is a bit
faster than previously expected, with the main focus being across
central SD this afternoon. There are 2 main areas of precipitation,
over north central SD and our southeastern Counties, with not much
in between (on the order of 0.02" through midnight). The trend is
for the northern system to become more dominant across our area,
with 0.l2-0.5" of rain over Dewey, Corson, and Campbell Counties
(highest over western Corson County).

Cooler air will remain in place, with 850mb temperatures staying in
the single digits above 0C through at least 12Z Friday. A few
readings just below 0C will be possible over north central SD right
around 12Z Friday. Highs will remain in the mid 50s to low 60s, with
lows mainly in the upper 30s to low 40s.

Rain shower chances will continue to diminish Thursday afternoon
into Thursday night as a cold front drags across the forecast area,
extending from the surface low over southern Manitoba/far
northeastern ND late Thursday night.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 203 PM CDT Wed May 1 2024

The start of the long term period (Friday) will continue the trend
over the last couple of days, with a brief period of dry weather
before another period of showers (Friday night). A surface low
centered along the US/Canadian border of ND/MN at the start of the
period will gradually lift northeast. Meanwhile, there will be upper
jet support across southeast half of SD on Friday night, as a jet
streak rounds the base of the upper ridge axis along the MT/ND/SD/WY
border. This will also be supported by a nice area of mid-level warm
air advection and q-vector convergence. All of these features come
together over southeast SD and having rainfall chances of 30-50% to
the southeast of Pierre/Aberdeen seems reasonable at this time. In
addition, instability is extremely limited (MUCAPE values