611
FXUS63 KUNR 201710
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1110 AM MDT Fri Sep 20 2024

.KEY MESSAGES...

-Very warm today, with strong dry cold front moving through
 tonight producing gusty northwest winds

-Cooler this weekend

-Critical fire weather conditions today across parts of northeast
 WY and southwest SD, with elevated fire weather conditions
 elsewhere. Elevated fire weather conditions continue through
 Saturday

-Mainly dry conditions for the next week or so

&&

.DISCUSSION...(Today Through Thursday)
Issued at 107 AM MDT Fri Sep 20 2024

Water vapor shows upper ridge across the southern/central Plains
with trof digging into the Northern Rockies. At the surface, lee
trof is deepening across MT, with high covering northeast WY and
western SD. Skies are clear and winds light early this morning.

Upper ridge will amplify into the Northern Plains today as upper trof
continues to dig through the Northern Rockies. Lee trof will
deepen further and shift into the western Dakota in the afternoon.
Thermal ridge peaking overhead will result in highs in the 80s to
lower 90s, warmest east and south of the Black Hills.

Upper trof will shift southeast into the Northern Plains tonight,
driving a strong a cold front through the region. 3hr pressure
rises of 3-5mb will result in period of gusty northwest winds late
tonight through Saturday morning and may near advisory criteria,
especially along the eastern slopes of the Black Hills. Highs on
Saturday will be in the 60s to lower 90s. Surface high settles
into the region Saturday night and should result in lows into the
30s from northeast WY through the Black Hills into northwest SD,
with 40s further south. Dry conditions with similar highs in the
60s to lower 70s Sunday, warmest in the west as return flow
ensues.

Another dry trof moves through early next week and will keep temps
near average. Models are relatively consistent building a ridge
back into the Rockies and eventually the Plains mid to late next
week, resulting in a trend to warmer temperatures. Precip chances
should remain low for the next week or so.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 1109 AM MDT Fri Sep 20 2024

VFR conditions will continue through the forecast period.
Northwest winds will increase tonight behind a cold front, with
gusts over 30 knots possible, strongest from KRAP eastward into
western SD plains.

&&

.FIRE WEATHER...
Issued At 107 AM MDT Fri Sep 20 2024

Very dry air will work back into the region today, especially
northeast WY and southwest SD where min RH`s will be well down
into the teens. At the same, surface trof moving into the region
combined with deep mixing will result in some gusty westerly winds
to near and above 30 mph for this same area. The result will be a
period of critical fire weather conditions. Elevated fire weather
conditions are expected elsewhere. A strong cold front will move
through tonight and Saturday morning, resulting in a period of
gusty northwest winds and more elevated fire weather conditions.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 8 PM MDT this evening for SDZ320>322-325-
     326.
WY...Red Flag Warning until 8 PM MDT this evening for WYZ315-317.
&&

$$

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