Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 171128
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
628 AM CDT Sun Mar 17 2024

.KEY MESSAGES...

- High to very high fire danger is expected today, Monday and Tuesday
  with small chances (20%) for Red Flag conditions Monday and
  Tuesday.

- Cooler temperatures will drive south Tuesday night into Wednesday
  and appear to bring a period of below normal temperatures
  potentially through next weekend.

- A potentially more active pattern will set up by Thursday and continue
  into the weekend. Model agreement still fairly low so
  confidence on timing of precipitation still low as well. For
  now the Thursday system has a better chance to be more
  impactful to the north.

&&

.DISCUSSION...
Issued at 248 AM CDT Sun Mar 17 2024

Another windy day ahead with some fire weather concerns, although
with temperatures about 15 degrees colder than yesterday and highs
only reaching the lower to mid 30s in many locations fire spread
will be limited. Afternoon humidities will likely remain closer to
30 percent or higher as well. Some very weak instability at the top
of the mixed layer which is near and within the ice bearing layer
may allow for some patchy flurries or very light snow but impacts
will be very minor.

High pressure will move through tonight with weak west to southwest
flow developing on Monday. Very dry air in place may cause some fire
weather concerns, but for now winds should stay a bit below what
would be needed for rapid fire spread. We have been over performing
on winds each day so will be something to watch as afternoon
humidities will likely be 20 to 25 percent.

Tuesday will be a mild day with gusty northwest flow. Did lower dew
points a bit as we continue to mix deeper most days. For now
afternoon RH falls to about 30 percent so given gusty winds expect
another high to very high fire danger with at least a small (20%)
chance for red flag conditions.

A strong northerly upper level jet will drive colder air south
Tuesday night into Wednesday. For now the environment looks pretty
dry and for the most part low and mid level temperatures remain
warmer than the ice bearing layer, so not expecting any
precipitation with this surge of colder air. Highs on Wednesday
likely in the 30s to lower 40s.

System late Wednesday night into Thursday gaining a little traction
in the models. The right entrance region of the upper jet swings
into the area with a mid level wave moving through. A strong thermal
gradient should exist in the low to mid levels which will likely
serve as a focus for precipitation development. Still pretty far out
so not overly confident in amounts or precipitation type just yet,
plus some hints that the majority of the precipitation would be
north of the area, closer to the 800-700mb front. Saturation via the
gFS is better north, but near and south of I-90 there are hints of
weak elevated instability which could aid in producing some
precipitation but the low levels are pretty dry as well. Overall
just some low chances for now.

Friday through Sunday maintains this strong thermal gradient in the
low to mid levels which leaves confidence on the lower side for
temperatures as any fluctuations will bring the potential for large
surface temperature differences. There are also hints of a stronger
system later Sunday into Monday with very little agreement. So, next
weekend looks like a decent chance for below normal temperatures
with some decent potential for precipitation as well, mainly snow
for now.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 627 AM CDT Sun Mar 17 2024

MVFR ceilings wil be likely this morning, but by mid to late
morning they should rise slightly above MVFR. By mid to late
afternoon most of the cloud cover will scatter out and VFR
conditions are expected the remainder of the night. Northerly
winds will gust around 30 mph through the day.

&&

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

&&

$$

DISCUSSION...08
AVIATION...08


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