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000
FXUS63 KUNR 131732
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1132 AM MDT Sat Apr 13 2024

.KEY MESSAGES...

- Warm with elevated fire weather conditions this weekend and near
  record high temperatures in some areas today.

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

&&

.DISCUSSION...(Today Through Friday)
Issued at 312 AM MDT Sat Apr 13 2024

Current surface analysis shows a warm front located across the
western Dakotas into the central Plains, with a weak cold front
across northern MT to the Pacific NW. Upper level analysis shows
ridging from the Rockies into the Plains, with low pressure off
the CA coast. Skies are partly cloudy early this morning with very
mild temps in the 40s and 50s, with some 60s along the northern
and eastern slopes and adjacent foothills of the Black Hills.
Winds are south to southwest in most areas, breezy in some areas
toward central SD.

Ridge will continue to progress eastward over the Plains this
weekend, bringing the warmest weather of the season so far. Highs
will reach the 80s across much of the western and south central SD
plains today, with 70s over northeast WY and the Black Hills. At
least a few locations will approach record highs for the day,
including Rapid City. The weak front to the northwest of the region
will slowly move southeast across the area later today and this
evening. Not expecting much weather with the frontal passage, but
the front will move across the Black Hills area during peak heating
and there could be enough energy aloft to help trigger a few showers
and storms along it from northeast WY to southwest SD from mid
afternoon into the early evening. MUCAPE values are progged up to
around 500 j/kg, but shear is forecast to be rather weak, so
anything that develops should not be strong, but brief gusty winds
would be possible. Slightly cooler air expected behind the front for
Sunday, but still well above average, with highs in the 70s and
lower 80s. Breezy south to southeast winds will develop on Sunday,
with southwesterly winds across northeast WY. The warm, dry, and
somewhat breezy conditions will produce elevated fire wx conditions
in many areas today and Sunday, especially across western SD today
and northeast WY on Sunday.

Monday still looks to be a transition day as the ridge moves east of
the region and a strong trough moves across the Rockies. Warm
conditions will persist in most areas, with highs ranging from
mostly 60s over northeast WY and the Black Hills to the 80s toward
south central SD. Embedded upper low moving across the southwest US
and Four Corners regions will track through the central/southern
Plains Monday night and Tuesday. Though the heaviest rainfall still
looks to mostly stay south and east of the forecast area with the
upper low, relatively strong northern stream energy within the
trough will bring good chances for showers and some thunderstorms
across our area from Monday afternoon into Tuesday. Ensemble data
still supports the best chances for rainfall from the Black Hills
east-northeastward across the SD plains, with 40 percent or higher
potential for a quarter inch or more of rainfall in many areas,
though convective nature of rainfall will make the heavier rainfall
potential more hit and miss. Isolated stronger storms look possible
later Monday into Monday evening (marginal risk for severe) as
MUCAPE values are progged to reach 500 to 1000 j/kg from the Black
Hills area to central SD, with at least modest shear across the
area, especially east of the Black Hills. Gusty northwesterly winds
will develop on the back side of the system later Monday night and
especially Tuesday, with advisory criteria wind potential near or
above 50 percent across a good portion of the western SD plains. The
system will then track quickly east of the region later Tuesday and
Tuesday night, with somewhat drier conditions into midweek. However,
medium range models continue to show a secondary low moving
somewhere across the northern Rockies to the northern Plains/south
central Canada midweek. Depending on how far north this system
ultimately tracks, it looks like our area will mostly be on the dry
side of the system, with the better chances for additional pcpn in
the form of light rain and snow mostly from northeast WY to the
northern Black Hills and northwest SD Wednesday and Thursday.
Blustery winds will likely persist into late week as well.
Temperatures through the week will gradually become colder, with
near to below average temps from Wednesday through Friday. Dry and
eventually warmer weather could return over the weekend.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1131 AM MDT Sat Apr 13 2024

Isolated showers and thunderstorms are possible between 21Z this
afternoon and 02Z this evening. VFR conditions are forecast
through the TAF period.

&&

.FIRE WEATHER...
Issued At 312 AM MDT Sat Apr 13 2024

Though green-up is progressing across the area, a period of
elevated fire weather conditions is expected across much of the
western SD plains this afternoon as humidities drop to 15 to 20
percent in most areas. Northwest winds behind a weak cold front
will gust to around 25 mph across northwest into west central SD,
with a few locations possibly reaching near critical fire wx
conditions briefly. On Sunday, elevated fire weather potential
will shift mostly into northeast WY, as southwesterly winds
develop in the afternoon and humidities drop to near 15 percent in
many areas. A few locations will could be near red flag for a
period later Sunday afternoon. Will continue to monitor potential
for any fire weather headlines.

&&

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

$$

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