479
FXUS63 KFSD 050334
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1034 PM CDT Fri Oct 4 2024

.KEY MESSAGES...

- Critical fire danger continues along and west of the James
  River. A Red Flag Warning has been issued for this area and
  remains in effect until 8 pm this evening.

- Near critical to critical fire danger is expected for
  tomorrow. A Red Flag Warning is in effect tomorrow along and
  west of I-29 and a Fire Weather Watch has been issued east of
  the interstate.

- Little to no precipitation expected into the next week. This
  along with warmer than average temperatures and periodic
  breezy conditions keep the focus on fire weather.

&&

.DISCUSSION...
Issued at 308 PM CDT Fri Oct 4 2024

Surface high pressure continues to slide off to the east this
afternoon. With the high off to the east, southeasterly return flow
will set up and begin advecting in higher low level moisture into
the area. However, this will mainly occur during the evening and
overnight hours. The surface pressure gradient will tighten through
the rest of the afternoon hours, leading to stronger winds up to
around 30 mph along and west of the James River. The breezy winds
along with relative humidity (RH) values down to around 25% is
resulting in critical fire danger conditions. As such, a Red Flag
Warning has been issued and is in effect until 8:00 pm this evening.
While mainly quiet conditions are expected for the overnight hours,
the southeasterly return flow will persist as the SPG tightens
across the forecast area. The breezy winds will keep low
temperatures much warmer then what we have seen over the past few
days with lows falling only down to the 50s. The warm low
temperatures will preclude any frost development.

A strong upper level wave will push through the Northern Plains
tomorrow, dragging a strong cold front tied to the wave through the
forecast area. No precipitation is expected along or behind the
front but this will lead to another day of near critical to critical
fire danger across the area. More details can be found in the fire
weather section below. The low level jet will remain strong ahead of
the front which will lead to a quick uptick in winds tomorrow
morning. A relative lull in winds is expected right as the front
comes through before winds turn out of the northwest and
restrengthen. The strongest winds are expected across parts of
central South Dakota where gusts up to 45 mph are expected. Winds
will wane through the evening hours as mixing wanes. Low
temperatures overnight will fall to the 40s overnight.

Sunday will be a much cooler day across the Northern Plains as 850
mb temperatures cool to the upper single digits. Mixing this to the
surface will result in a seasonable day with high temperatures
mainly in the 60s to up to about 70 degrees F. Breezy northwest
winds will persists through with gusts up to about 25-30 mph.
the breezy winds may lead to some elevated fire danger across
the area. More details can be found in the fire weather
discussion.

The rest of next week looks quiet as upper level ridging builds into
the Northern Plains from the southwest CONUS. This will result in a
return to above average high temperatures in the 70s and 80s. With
upper level ridging in place, no rain is expected. There could be
additional chances for fire danger next week but details remain
uncertain as of now.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1030 PM CDT Fri Oct 4 2024

VFR conditions expected through the period with primary focus on
incoming cold front for Saturday. This could result in some LLWS
tonight ahead of the front, likely most prevalent west of I-29
including KHON.

South to southeasterly winds ahead of the front Saturday will
gusts 20 to 30 kts with winds taking on a more west to
northwesterly direction behind the front and continuing to gust
AOA 30 kts.

&&

.FIRE WEATHER...
Issued at 308 PM CDT Fri Oct 4 2024

Southeasterly winds have picked up behind a departing surface high
pressure system. This has lead to gusts up to around 25-30 mph,
mainly along and west of the James River. Dew points remain in the
low 30s while high temperatures have warmed to the upper 60s and
70s. This has resulted in low relative humidity (RH) values down to
25%. As such, have issued a Red Flag Warning for this same
area. The Red Flag Warning remains in effect until 8:00 pm this
evening.

The low level jet (LLJ) will ramp up this evening and will keep
breezy southerly winds going throughout the night. The southerly
winds however will advect in higher low level moisture with dew
points (Tds) moistening into the 50s. This will raise overnight
RH values up to 60-90% which will keep fire danger temporarily
at bay. A strong cold front will begin to push through the area
during the morning hours tomorrow. A quick uptick in winds is
expected ahead of the front during the morning hours before
winds enter a relative lull along the front itself. As winds
turn to out of the northwest behind the front, they will
restrengthen where gusts up to 45 mph is expected. The strongest
gusts will lie across central South Dakota and occur mainly
during the morning hours before very slowly weakening during the
afternoon hours. Humidity will quickly drop behind the front as
dew points fall to the upper 20s and 30s while highs warm to
the 70s and 80s. RH levels down to about 15-25% is expected
across the forecast area, lowest across southeastern South
Dakota. There is a some uncertainty though for locations east of
I- 29 as humidity will not drop as fast in this area and result
in a smaller window of near critical to critical fire danger.
As such, have expended the Fire Weather Watch to include all
areas in southwest Minnesota and northwest Iowa. Locations along
and east of I-29 have been upgraded to a Red Flag Warning. Both
the Warning and Watch are in effect from 11 am to 8 pm
tomorrow.

Sunday will be a cooler day with seasonable highs in the 60s to
perhaps up to around 70 degrees F. Despite the cooler high
temperatures, breezy northwest winds will persist with gusts up to
around 25-30 mph. Tds will remain in the 30s which will contribute
to lower RH values, down to around 25-35%. The lowest RH will lie
along the Missouri River. The lower humidity and breezy winds will
result in another day of high fire danger across the area.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from 11 AM to 8 PM CDT Saturday for
     SDZ038>040-050-052>071.
MN...Fire Weather Watch from Saturday morning through Saturday
     evening for MNZ071-072-080-081-089-090-097-098.
IA...Fire Weather Watch from Saturday morning through Saturday
     evening for IAZ001>003-012>014-020>022-031-032.
NE...Red Flag Warning from 11 AM to 8 PM CDT Saturday for NEZ013-
     014.

&&

$$

DISCUSSION...Meyers
AVIATION...Kalin
FIRE WEATHER...Meyers