014
FXUS63 KUNR 282307
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
507 PM MDT Sun Apr 28 2024

.KEY MESSAGES...

- Rain/showers gradually end from west to east across western and
  south central SD late today and tonight.

- Near to above average temperatures return for the first half of the
  week, with chances for showers and gusty winds Monday night
  into Tuesday.

- Cooler and unsettled weather develops for the middle and latter
  parts of the week, with some higher elevation snow possible.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 245 PM MDT Sun Apr 28 2024

Current surface analysis shows low pressure system centered over
western IA right now, with another area of low pressure over
southeast AB and a warm front extending south across eastern MT
into WY. Upper level analysis shows low located over south central
SD, moving slowly northeastward. Swath of rain and showers
extends west and northwest of the low to the Black Hills area,
with the heaviest rainfall today being just east of the Black
Hills into portions of central SD. Further west, a good amount of
sunshine has been noted across much of northeast WY. Temps this
afternoon range from the 40s over much of western SD to around 60
over Campbell County, WY. Some 30s have been noted over the Black
Hills, with a few flurries over some of the higher elevations.
Winds have mostly been from the north to northeast at 10 to 15 mph
this afternoon.

Rain/shower activity will gradually shift eastward out of western SD
late today and tonight, exiting far eastern areas later tonight.
Additional rainfall amounts will be on the light side. Weak ridging
aloft builds over the region later tonight and Monday, with warm
front sliding eastward across the area during the same time. Highs
will reach into the 60s to around 70 degrees in most areas.
Humidities will drop to 15 to 20 percent in the afternoon across
southern portions of northeast WY to extreme southwest SD as
southwesterly winds develop, but sustained speeds are not expected
to exceed 15 mph or so. A few showers could develop over the Black
Hills in the afternoon.

The rest of the week looks to be unsettled at times as a series of
systems cross the region in near zonal flow. The next one arrives
Monday night with the associated upper low passing north of the
area. Shortwave energy passing south of the low will bring chances
for showers to most of the area Monday night into Tuesday. Temps
could become cold enough for a little light snow over the higher
Black Hills. Drier air will move into the area on Tuesday on the
southwest side of the system behind a cold front, with humidities
dropping to 15 to 25 percent across northeast WY and much of western
SD. Gusty west-northwest winds will develop, especially across far
northwest SD, where chances for winds reaching advisory criteria
(gusts over 45 mph) are near or above 50 percent at this time.

Another upper level trough is progged to move farther south across
the region Wednesday night and Thursday. Medium range models differ
some on the track of this system, with GFS further south than the EC
and Canadian. Better chances for beneficial rainfall still look to
be across southern portions of the forecast area, but this potential
will likely shift some across the area with time. Depending on the
track, temps could become cold enough later Wednesday night and
Thursday for some accumulating snow across at least the higher
elevations of the Black Hills and possibly northeast WY as well. Yet
another system could bring showers Friday night and Saturday, with
the potential for snow across at least the higher elevations. As far
as temperatures go, near to slightly above temps Monday through
Wednesday will become near to below average later in the week and
into next weekend.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 505 PM MDT Sun Apr 28 2024

Light rain with widespread MVFR/IFR conditions will slowly
improve tonight across western South Dakota. Some fog is possible
overnight across the South Dakota plains, but should remain east
of KRAP. Northeastern WY will remain mostly VFR through the
period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...26
AVIATION...JC