794
FXUS63 KUNR 261139
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
539 AM 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.

- No appreciable precipitation through the middle of next week.

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 153 AM MDT Thu Sep 26 2024

The warm, dry upper ridge over the area will shift southeastward
as an upper trough crosses to the north of the forecast area this
afternoon/evening. A surface trough, currently located over
eastern MT/WY will shift eastward into western SD today, followed
by a cold front later this afternoon.

The warm and dry weather patter will continue through the weekend
as the upper ridge rebounds behind the passing upper trough.

Much warmer than average temperatures are expected today, with
highs reaching well into the 90s across much of the plains. Some
daily high temperatures records could be broken, including in the
Rapid City area. Breezy to windy southerly winds will occur to the
east of the surface trough this morning, with winds becoming
southwesterly as the trough passes through, then later this
afternoon/evening, the winds will become northwesterly as the cold
front arrives. The very warm temperatures and dry air will drop
the minimum relative humidity percentages into the lower teens
this afternoon. Due to the expected warm, dry and windy
conditions, a Red Flag Warning has been issued for most of the
forecast area today.

Behind the cold front, Friday will be only slightly cooler, with
highs in the 80s over much of the plains. With the upper ridge
then rebounding, very warm conditions will return for the weekend
with highs in the 80s and 90s, warmest on Sunday. Elevated to
critical fire wx conditions can be expected on most days through
the weekend.

Another trough is will cross the Canadian prairie provinces this
weekend into the beginning of next week. The main energy is
expected to remain well north of the forecast area Sunday night
into Monday, so any chances for any rain look minimal at this
point. However, a passing surface cold front will bring much
cooler air and gusty winds to start next week, with highs back
closer to average levels in the 60s and lower 70s. Cooler air
could linger into Tuesday before weak ridging builds back over
the region. Above average temps are likely again for the second
half of next week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 538 AM MDT Thu Sep 26 2024

VFR conditions are expected through the TAF period. Locally gusty
south/southwest winds will persist through this morning ahead of
a cold front. Where the gusty winds do not develop, expect LLWS
east of the Black Hills through early morning. Behind the cold
front Thursday afternoon and evening, gusty northwest winds will
develop.

&&

.FIRE WEATHER...
Issued At 153 AM MDT Thu Sep 26 2024

Dry air will overspread the area today ahead of a cold front.
A surface trough ahead of the front across western SD will bring
increasing southwesterly winds later in the morning into the
midday hours before the front arrives. The cold front will cross
northeastern Wyoming and much of western South Dakota during the
midday and afternoon hours, stalling out toward central SD later
in the day. Breezy conditions, with gusts of 25 to 40 mph, look
most likely behind the front over much of northeastern Wyoming
and the northwestern into the west central South Dakota plains
during the afternoon. Over south central South Dakota, breezy
south-southwest winds can be expected during the day. Humidity
values will drop into the lower teens across much of the area.
Gustier winds may be more localized further south across
southwestern South Dakota, but some gusts around or above 25 mph
are likely there. With conditions expected to be critical or at
least near critical over the plains of northeastern Wyoming and
western South Dakota, a Red Flag Warning is in effect today into
this evening.

Cooler air and slightly higher humidity will develop for Friday,
with very warm temperatures returning over the weekend. Elevated
to near critical fire weather conditions will continue through
the period, with Sunday looking to be the most favorable day for a
return to Red Flag conditions. Another dry cold front will bring
much cooler conditions and gusty winds into early next week.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...     Red Flag Warning from 10 AM MDT /11 AM CDT/ this morning to 7 PM
     MDT /8 PM CDT/ this evening for SDZ321-323>335.
     Red Flag Warning until 7 PM MDT this evening for SDZ322.
WY...     Red Flag Warning until 7 PM MDT this evening for WYZ314>317.
&&

$$

DISCUSSION/KEY MESSAGES...10
AVIATION...Dye
FIRE WEATHER...10