622
FXUS63 KUNR 142317
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
517 PM MDT Sat Sep 14 2024

.KEY MESSAGES...

- Very warm through Tuesday with elevated to areas of critical
  fire weather conditions
- A few stronger thunderstorms, mainly afternoon/evening,
  expected through Sunday
- Pattern change mid to late next week with cooler and wetter
  conditions

&&

.DISCUSSION...(This Evening Through Saturday)
Issued at 101 PM MDT Sat Sep 14 2024

Water vapor shows upper trof along the Pac NW coast and
southwest flow through the Northern Plains, with distinct short
wave over western SD. At the surface, trof extends from southeast
MT through west central SD. Active thunderstorms ongoing across
portions of western/central SD in association with the short wave.

Scattered thunderstorms, a few strong to severe, will gradually
shift east of our zones by early this evening. Fairly gusty
southerly winds have developed over south central SD early this
afternoon, and may increase further this evening as low level jet
lifts through central SD.

Next short wave arrives later Sunday for another round of
thunderstorms late in the afternoon and evening. MLCAPE will be on
the order of 1000-2000J/kg along and east of a developing surface
trof over far western SD, with just enough shear for a few
stronger storms. However, the later nature of storm development
could limit the amount of stronger storms. Temps will soar into
the 90s south/east of the Black Hills as thermal ridge moves
overhead. Another very warm and breezy day expected Monday, but
storm chances may be more confined to central SD.

Upper trof works through the western CONUS early next week, and
into the Plains mid to late week. This will bring a gradually
cooling trend along with increasing chances for showers/storms.
The first robust wave ejects through our area late Tuesday and
Tuesday night for potential widespread precip. The next
substantial wave may arrive Friday into Saturday, although
confidence that far out not very high. Either way, a definite
pattern change to wetter/cooler conditions is on the way as next
week progresses.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening)
Issued At 510 PM MDT Sat Sep 14 2024

Thunderstorms will dissipate this evening. Some patchy fog with
MVFR/IFR conditions may form across north central SD early Sunday
morning. Thunderstorms are expected over SW SD late Sunday
afternoon and evening with gusty winds and small hail possible.
Otherwise, VFR conditions are expected through the TAF period.

&&

.FIRE WEATHER...
Issued At 256 PM MDT Sat Sep 14 2024

.DISCUSSION...Critical fire weather conditions have developed
across portions of northeast WY into southwest SD this afternoon,
with southwest winds gusting around 30 mph and RH around and
below 10 percent. Conditions should slowly improve this evening.
Elevated to near critical fire weather conditions expected again
Sunday through Monday (possibly stretching into Tuesday),
especially over northeastern WY and far southwest SD where daily
minimum relative humidities will dip to 10-20%. The strongest
winds both Sunday and Monday look to be east of the Black Hills,
so probabilities for widespread critical fire weather conditions
over northeast WY and far southwest SD is relatively low at this
time, but will be closely monitored. A wetter and cooler pattern
is likely to develop mid to late next week.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 7 PM MDT this evening for SDZ322.
WY...Red Flag Warning until 7 PM MDT this evening for WYZ315-317.
&&

$$

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