522
FXUS63 KFSD 271657
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1157 AM CDT Fri Sep 27 2024

.KEY MESSAGES...

- Warm and dry conditions continue into early next week. Many
  areas will fall within the top 10 for the driest September on
  record, and most locations will end up within the top 5
  warmest Septembers on record.

- Occasional risks for wildfire danger continue over the
  upcoming 7 day forecast, focused mainly from early to middle
  of next week as a series of fronts push through the region.

- Precipitation risks continue to remain minimal through next
  week. Ensemble guidance supports a 10% probability of
  measurable rain around Tuesday and 20% probability of rain by
  the end of next week.

&&

.DISCUSSION...
Issued at 159 AM CDT Fri Sep 27 2024

THIS MORNING: Only a slight bit of cirrus in the skies this morning
as temperatures continue to fall into the upper 40s to lower 50s by
daybreak.  Given the light winds and cool temperatures, very shallow
fog along waterways may be possible.

FRIDAY-SUNDAY: A seasonally strong mid-lvl ridge will continue to
remain centered across the Northern Plains through the upcoming
weekend. This ridge will suppress any risk for rain through the
weekend and also bring seasonally warm temperatures over the
Tri- State area. With the heart of the 925:850 mb thermal ridge
overhead, we`ll see daily high temperatures well into the 80s
through the weekend. In fact, temperatures the past days have
run at the 75th-90th percentile of NBM guidance, likely a factor
of the growing drought conditions and continued loss of green
vegetation in the local area. While the temperatures will be 10
to 15 degrees above normal, the presence of a low-lvl ridge in
the area will keep winds fairly light through the weekend,
generally keeping fire danger risks lower. Dew points though
have trended downward each afternoon given the growing drought.

MONDAY:  The final day of September will see a fairly strong front
move through the area, pushed southeast by a deep upper trough
crossing southern Canada.  However, the cooler Canadian airmass
behind the front will only briefly knock temperatures downward
towards seasonal normals.  Temperatures Monday are still expected to
climb near or above the 80 degree mark.  Should we finish the month
with 80+ degree temperatures every day, this will place all of the
long-term climate sites in the area in the top 5 for most 80+ degree
days in September, and will likely also lead to a top 5 warmest
month of September on record.  These temperature stats are in
addition to also reaching the top 5 driest Septembers on record in
most areas. This front will bring both a period of strong
southwesterly winds ahead of it, but also strong northwest winds
behind the front in the afternoon. NBM projections support 30 knot
wind gusts at times, which when combined to drastically falling dew
points and RH, could lead to heightened fire danger in the
afternoon and evening.

TUESDAY-THURSDAY: The airmass moving southeast Tuesday will be
significantly cooler, but a 20+ degree drop from the abnormally warm
weekend and Monday temperatures only puts temperatures slightly
below seasonal normals in the upper 60s to Tuesday. Dew points
are likely to plummet behind this front, with dry downslope air
pushing RH values into the lower to middle 20s areawide. A very
progressive westerly flow then develops through the end of the
week, pushing several fast moving fronts through the Plains.
Rain chances remain on the very low side with these fronts, as
meaningful moisture just can`t work back northward. GEFS and ECE
guidance suggests just a 10% probability of measurable rain
with the frontal passage Tuesday night, and 20% probability
towards the end of the week. Temperatures rise back above normal
in most locations through Thursday.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1157 AM CDT Fri Sep 27 2024

VFR conditions expected to prevail this period. Skies will be clear
and winds will be light, going light and variable after sunset.
Winds remain light and variable through the period.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.

&&

$$

DISCUSSION...Dux
AVIATION...AJP