000
FXUS63 KUNR 121106
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
506 AM MDT Fri Apr 12 2024

.KEY MESSAGES...

- Warming trend continues into the weekend with elevated fire
  weather conditions possible in some areas.

- Unsettled, windy, and gradually colder weather expected for much
  of next week.

&&

.DISCUSSION...(Today Through Thursday)
Issued at 245 AM MDT Fri Apr 12 2024

Current surface analysis shows weak high pressure now centered
over central portions of the Dakotas and NE. A trough is located
along the lee of the Rockies, with a tighter pressure gradient to
the east across the western high plains. Upper level analysis
shows ridge axis now over eastern portions of the Great Basin into
the Rockies. Skies are mostly clear early this morning with temps
mainly in the upper 20s and 30s. Winds are mostly light and
variable.

Ridge will continue to progress eastward across the Rockies and over
the Plains over the next few days, bringing the warmest weather of
the season so far. Highs will reach the mid 60s to mid 70s today,
with mostly 70s and lower 80s over the weekend. Breezy south to
southeast winds will develop across much of the plains later this
morning, especially over western SD. A weak cool front/trough
crosses the area on Saturday, bringing a wind shift and at least
marginally breezy conditions. The trough and weak energy aloft could
be enough to trigger isolated showers and thunderstorms over at
least the Black Hills in the afternoon, with MUCAPE values up to
around 500 j/kg progged for the area. Winds shift back to the south-
southeast across much of the area on Sunday, with breezy
southwesterly winds across northeast WY. The warm, dry, and
occasionally breezy conditions could produce elevated fire weather
conditions in some areas during the afternoon hours each day.

Monday looks to be a transition day as the ridge moves east of the
region and a strong trough moves across the Rockies. Embedded upper
low moving across the southwest US and Four Corners regions late in
the weekend will move across the central/southern Plains Monday
night and Tuesday. Though the heaviest rainfall will likely stay
south and east of the forecast area, northern stream energy within
the trough will bring a good chance for showers and a few storms
across our area from Monday afternoon into Tuesday. Ensemble data
support the best chances for rainfall from the Black Hills eastward
across the SD plains, with 30 percent or higher potential for a
quarter inch or more in many areas, though convective nature of
rainfall will make it more hit and miss. Highs will range from the
60s to 80s from west to east across the forecast area Monday, with
cooler 50s and 60s expected on Tuesday. Gusty north-northwest winds
will develop by Tuesday on the back side of the system. Medium range
models become more divergent on their solutions after this system
passes the region, but generally show a trailing upper trough/low
moving across the northern Rockies/northern Plains/south central
Canada midweek. Much of the pcpn with this system could stay north
of the area, with most of northeast WY/western SD more in the dry
slot region. Colder air will accompany that system along with more
wind, with chances for rain and at least higher elevation snow
expected, especially across western and northern portions of the
CWA. There is a lot of uncertainty still on the exact track of this
system and its affects on our area, so will continue to watch
closely. Late next week looks to be cool and somewhat unsettled,
with a drier/warmer pattern toward the weekend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 506 AM MDT Fri Apr 12 2024

VFR conditions are forecast through the TAF period.

&&

.FIRE WEATHER...
Issued At 245 AM MDT Fri Apr 12 2024

Though green-up is progressing across the area, a period of
elevated fire weather conditions is possible across portions of
the western SD plains this afternoon as south to southeast winds
become breezy, with gusts of 20 to 30 mph, and relative humidities
drop to near 20 percent in some areas. Areas of elevated fire
weather conditions are possible over the weekend as well, mainly
across northwest and west central SD on Saturday and across the
northeast WY plains on Sunday, as breezy conditions develop and
humidities drop to around 20 percent in these areas. A few
locations could be near critical fire weather conditions in WY for
a brief period on Sunday. Will continue to monitor for any
possible headlines.

&&

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

$$

DISCUSSION/KEY MESSAGES...26
AVIATION...SE
FIRE WEATHER...26