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000
FXUS63 KUNR 211124
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
524 AM MDT Mon Sep 21 2020

.DISCUSSION...(Today Through Sunday)
Issued at 231 AM MDT Mon Sep 21 2020

Semi-active near zonal flow can be expected in the period,
supporting temps mainly above seasonal norms. Shortwave ridging
will ensue today with WAA ongoing. Smoke/haze from western wild
fires will continue impact the southern third of the FA. However,
with flow turning more SW aloft Tues, smoke will spread back into
the region once again. Dry weather is on track for most of the
week, the next chance of showers will be late Tues in the far west
as an upper trough advects across the region with an associated
sfc cool front. Otherwise, mean NE PAC upper trough will support
semi-unsettled near zonal flow across the NW CONUS with another
warm day likely Thursday ahead of the next system. A stronger
wave is progged around Sat, which could support a slightly better
chance for high based showers and storms. However, given a lack of
LL/GOMEX moisture, most places will likely remain dry. Cooler
conds look likely for the first part of next week as the western
NOAM ridge re-builds with mean troughing over the central and
eastern CONUS. The eastern extent of the ridge will determine how
much of a warm up occurs locally as well as the chances for any NW
flow impulses.

&&

.AVIATION...For the 12Z TAFS Through 12Z Tuesday Morning
Issued At 521 AM MDT Mon Sep 21 2020

Skies will be clear through Tues, although smoke will return
Tuesday morning. Light winds will become southerly as surface high
pressure moves to the east and a lee side trof develops over
eastern MT.

&&

.FIRE WEATHER...
Issued At 231 AM MDT Mon Sep 21 2020

Warm and mainly dry weather expected through the week with near
critical fire wx conditions at times. Warmer temps expected today
and Tuesday, with Tuesday and Thursday likely being the
hottest/driest days of the week. RH`s should be well down into
the teens across northeast WY and far western Tuesday and Thursday,
but at this time winds do not appear to be strong enough to
warrant fire weather headlines. Thursday will have to be watched
as much stronger WSW winds look possible, which would support
critical fire weather conds. Cold front moves through late
Tuesday night, with the next front moving through late Thursday.
Slightly cooler with a slight increase in precip chances Friday
through the weekend.

&&

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

$$

DISCUSSION...JC
AVIATION...55
FIRE WEATHER...JC