189
FXUS63 KUNR 262030
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
230 PM MDT Thu Sep 26 2024

.KEY MESSAGES...

- Dry weather, much warmer than average temperatures, and elevated
  to critical fire weather conditions continue through the weekend.

- Cooler to start next week, then warming again.

&&

.DISCUSSION...(This Evening Through Thursday)
Issued at 230 PM MDT Thu Sep 26 2024

Current surface analysis shows cold front from central ND to
northwest SD to far northeast WY, moving slowly to the southeast.
Surface trough is in place from north to south across central SD.
Upper level analysis shows ridge now to the east of the region,
with a shortwave trough located over the northern Rockies, moving
to the northeast. Skies are sunny with unseasonably hot temps,
mostly in the 90s across the plains, with 80s over the Black
Hills. Some daily high temp records will be broken, including in
the Rapid City area. The strongest winds are toward central SD,
near the surface trough, with gusts to 40 mph from the south to
southwest. Further west, areas of breezy conditions from the west
to northwest are noted, especially near and behind the front. With
very low humidities, red flag or near red flag conditions are
affecting much of the area this afternoon.

Dry and warm weather continues through the rest of the week and the
upcoming weekend as southwest US ridge builds back north and east
across the region. Shortwave trough passes well north of the region
tonight into Friday as cold front slowly moves southeast into this
evening, stalls out tonight over southern portions of SD, and then
shifts back north and east on Friday. Friday will be about 10
degrees cooler in most areas, but still well above average for late
September. However, temps will rise again over the weekend, with
Sunday temps similar to today. Elevated to at least near critical
fire weather conditions can be expected Friday through Sunday, with
Sunday the most favorable day for critical fire wx conditions.

The next cold front will likely arrive sometime Sunday night, with
much cooler air accompanying that one, along with gusty winds.
Associated upper level trough will slide across the northern Plains
late Sunday night and Monday, but system looks moisture starved.
Chances for any rainfall still look to be 10 percent or less at this
point. High temps will finally drop back to near average levels,
mostly 60s and lower 70s, for Monday and Tuesday. Zonal flow
aloft/weak ridging will develop behind the trough toward midweek,
with above average temps returning for at least Wednesday. Latest
ensemble output is showing good potential for another upper trough
and cold front arriving sometime late week and this one could bring
at least a chance for pcpn.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1106 AM MDT Thu Sep 26 2024

VFR conditions are expected through the TAF period. Locally gusty
south/southwest winds will persist into the afternoon ahead of a
cold front, mainly across southwestern into south-central South
Dakota. As the front sags southward and mixing picks up, winds
will shift NW this afternoon with gusty winds continuing through
the evening.

&&

.FIRE WEATHER...
Issued At 230 PM MDT Thu Sep 26 2024

Red flag or near red flag conditions are in place across much of
the area this afternoon, especially over the northeast WY and far
western SD plains. Passing surface trough and cool front are
bringing breezy west to northwest winds in these areas, with
humidity values in the low to mid teens. Conditions will start to
improve toward sunset.

Some cooler air and slightly higher humidity are in place for
Friday, but elevated fire weather conditions are expected in many
areas Friday into Saturday and likely near critical over portions of
northeast Wyoming. Very warm to hot conditions return over the
weekend, especially on Sunday. Sunday looks to be the most favorable
day for red flag potential as south to southwest winds increase
ahead of approaching cold front. Minimum humidity is forecast to
drop into the teens in most areas. Will continue to monitor
potential over the next couple of days. Another dry cold front will
bring much cooler conditions, higher humidity, and gusty winds into
early next week.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning until 7 PM MDT /8 PM CDT/ this evening for
     SDZ321>335.
WY...Red Flag Warning until 7 PM MDT this evening for WYZ314>317.

&&

$$

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