259
FXUS63 KUNR 051723
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1123 AM MDT Sun May 5 2024

.KEY MESSAGES...

-Windy across the western SD plains today.

-Cool, windy, and unsettled for much of this week.

&&

.DISCUSSION...(Today Through Saturday)
Issued at 203 AM MDT Sun May 5 2024

08Z upper level analysis has shortwave ridge across the Central
Plains, with deep upper low across northern California. Skies are
mainly clear across the Northern Plains at the moment. At the
surface, high pressure resides across the Northern and Central
Plains, with strong low pressure over Idaho. Temperatures at 2am
across the forecast area are in the 40s, with southerly winds.

Transient upper ridge will quickly shift east today as large upper
low shifts into the Great Basin area. Surface low pressure over
Idaho will move into western Wyoming today, producing a strong
pressure gradient across the Northern Plains. Southerly winds
around 30 mph with gusts to 45 mph will develop across the
forecast area by mid day, and persist into the evening hours. As
the surface low approaches the area, some showers and
thunderstorms could develop over northeast Wyoming late in the
afternoon, with precip chances shifting into western South Dakota
this evening. Widespread severe storms are not anticipated at this
time.

Upper low crosses the Rockies late tonight into Monday, with more
widespread rain showers and thunderstorms expected across
northeast Wyoming and far western SD. Rainfall amounts across
northeast WY, the Black Hills, and northwest South Dakota will
likely be half an inch to an inch on Monday. More scattered
showers and storms are expected south and east of the Black
Hills. As the strong surface trof shifts through the area, gusty
west to northwest winds are expected, which may require another
wind advisory across the SD plains. Temperatures should be cool
enough Monday night for some light snow accumulations across the
higher elevations of the Black Hills.

Strong system becomes stacked across western North Dakota by
Tuesday, with blustery conditions continuing across the area.
Precip chances become lighter and more scattered on Tuesday as the
main weather system resides north of the area. Once again, wind
highlights will likely be needed on Tuesday, especially across
northwestern South Dakota.

Upper low and main upper trof finally shifts southeast on
Wednesday, dropping back through central SD on its way out of the
Northern Plains. Unsettled weather continues with better chances
for precipitation across the SD plains. West to northwest winds
remain very breezy. Thursday will be slightly warmer with
continued chances of light rain showers and isolated
thunderstorms, along with breezy north winds.

Weather will slowly warm up and dry out toward the weekend as the
upper low finally exits the region and a ridge of high pressure
builds across the western CONUS.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1119 AM MDT Sun May 5 2024

South-southeast winds of 25 to 35 mph with gusts of 45 to 50 mph
will continue this afternoon and evening, strongest across the
western SD plains. MVFR to IFR conds will develop tonight as
moisture advects north ahead of a low pressure system. Expect
showers and isolated thunderstorms tonight with more widespread
rains across the NW half Monday.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory until 11 PM MDT /midnight CDT/ this evening for
     SDZ001-002-012>014-026-030>032-042>044-046-047-049-072-073-
     075>078.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...15
AVIATION...JC