715
FXUS63 KABR 230026
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
726 PM CDT Thu May 22 2025

.KEY MESSAGES...

- Rain and weak thunderstorms move back in Friday and linger into
early next week, especially west of the James River Valley.

- A very slow warmup will take place through the next several days
with daytime highs returning to the 50s and 60s through early next
week.

&&

.UPDATE...
Issued at 725 PM CDT Thu May 22 2025

Patchy frost has been included around the James River Valley from
around 09-12Z as temperatures drop into the mid to upper 30s
before higher clouds near from the west. Another potential for
this area will be patchy fog, as more of the CAMs are picking up
on a reduction in visibility. Patchy fog may need to be added to
the forecast still this evening. Otherwise, the forecast remains
in good shape with light rain entering our far southwestern
counties by 09Z and all of central SD by 12Z Friday. The eastern
edge of the precipitation shield remains in question and will
continue to be updated for Friday afternoon.

&&

.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Issued at 244 PM CDT Thu May 22 2025

Surface high pressure supports drier conditions after a long stretch
of rain over the past few days. Scattered cumulus in place will
dissipate this evening, leading to clear skies in the early
overnight hours. The break from the rain won`t last long, as the
next round of showers moves in early Friday morning supported by an
upper level shortwave. Rain is expected to enter the forecast area
over central and north central South Dakota by 09-10Z Friday and
will slowly progress eastward through the day. Incoming clouds ahead
of this rain will keep the Missouri River Valley low temperatures up
in the 40s this morning, while lows east of the river fall into the
upper 30s.

Most of the rain will stay west of the James River Valley, and the
heaviest rain is expected over central South Dakota. Short range
ensemble forecasts indicate a 80-90% chance of 0.25" over central
South Dakota and a 30-50% chance of 0.5". Previous forecasts
indicated that areas east of the James Valley would see no rain out
of this event, but there is an increasing signal in the CAMs for
some light showers to sneak further east and drop a couple
hundredths of rain. Sub-severe thunderstorms will be possible with
this system, mainly over central South Dakota in the morning. Shower
chances will diminish heading into the late evening and overnight
hours Friday with the progression of the wave moving the rain out of
the area.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 244 PM CDT Thu May 22 2025

The upper flow through the course of the weekend into the first half
of next week will feature a relatively disturbed pattern across our
region as a number of different features come into alignment to give
portions of our area persistent opportunities for precipitation. An
upper low/trough extending westward from New England and the Great
Lakes to the northwest into Ontario will gradually drift south into
parts of the Upper Midwest/Northern Plains this weekend. This will
combine with a shortwave trough shifting east out of the Northern
Rockies/Northern High Plains Saturday into Sunday leading to
rainfall chances from the James Valley and points west on Saturday
and from about the Big Sioux Valley and points west on Sunday. By
far, the highest PoPs, 50-70%, are splayed out across central and
western South Dakota this weekend. Our northeast zones look to
mostly escape any rainfall chances. Best probabilities of seeing at
least a half inch or more of rain from late Friday through late
Sunday are confined to our west and southwest zones, basically from
Eagle Butte to Gann Valley and points south and west. Here, they
currently sit at around a 40-60% chance of seeing that type of
rainfall.

The combined upper trough or what may end up being an upper low will
persist across the Upper Midwest/Great Lakes Region the early to
middle portion of next week. This is expected to maintain daily
chances for precipitation across our area. At this point, PoPs don`t
look all that substantial and neither does the anticipated rainfall
from them. Rainfall probabilities Mon-Wed next week of seeing
rainfall greater than a quarter of an inch sit at a low end range of
20-40% across the entire forecast area. Temperature trends will
continue to feature cooler than normal readings thanks to mostly
cloudy skies and rainfall through the first half of next week.
Although, there are some hints at a gradual warming trend beginning
the middle of next week which would get us back to around normal for
late May.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 725 PM CDT Thu May 22 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue through the period at both ABR and
ATY. Over central SD, VFR conditions will erode to MVFR during the
daytime hours Friday. The highest chance of MVFR to potentially
high end IFR conditons (ceilings) will be at PIR, where most of
the precipitation is expected. There is a 24% chance of 0.5" of
rain or more through 00Z Saturday, while only 3% at MBG.


&&

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

$$

UPDATE...06
SHORT TERM...BC
LONG TERM...Vipond
AVIATION...06