Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 180332
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1032 PM CDT Sun Mar 17 2024

.KEY MESSAGES...

- Winds will be lighter for Monday afternoon out of the west to
  southwest. However, humidity levels remain low, 20-25%. This
  will result in High to Very High grassland fire danger Monday
  afternoon. High to Very High grassland fire danger persists
  through Wednesday.

- Colder air drives south Tuesday into Wednesday. This has a
  high chance of bringing near to below normal temperatures
  from Wednesday through next weekend.

- A more active weather pattern will set up by Thursday through
  next weekend. Model agreement is still poor so low confidence
  in timing of precipitation and related impacts. Those with
  weekend travel plans will want to begin to monitor the
  forecast as precipitation is more favored to be snow than
  rain.

&&

.DISCUSSION...
Issued at 310 PM CDT Sun Mar 17 2024

THIS AFTERNOON: Clouds will continue to thin out, and we will have a
mostly clear night. Gusty winds quickly subside after sunset. Lows
tonight will be mid to upper teens.

MONDAY: The surface pressure gradient (SPG) eases as surface high
pressure builds in from the northwest overnight. By sunrise winds
will be northwesterly around 5-10 mph with occasional gusts of
15 mph. As the high pressure moves southeast after noon, winds
will become westerly, then southwesterly. Conditions will be
very dry at the surface with dew points in the single digits,
and the corresponding relative humidity (RH) in the 20-25%
range. Bufkit soundings and ensemble cloud models indicate
afternoon mid to upper level stratus development. This could
work to limit highs somewhat to the 40s and low 50s. Though
grassland fire conditions will be in the High to Very High
category, the cooler temps and lighter winds should limit rapid
fire growth. But caution is still advised with sources of
ignition, as fuels are cured and ready to burn. Lows for Monday
night will be in the upper 20s to mid 30s.

TUESDAY: As a northern stream clipper system digs from the Canadian
Prairie into the Great Lakes Monday night, a cold front slides
through early Tuesday. This brings notably cooler air aloft for
Tuesday, but we should see one last mild day with highs in the 50s
and some 60s.

Expect stronger winds Tuesday than Monday with breezy northwest
winds gusting in the 20s Tuesday afternoon. High to very high fire
danger persists Tuesday afternoon across the region as gusty winds
combine with humidity levels below 30%. Model profiles suggest an
afternoon cumulus field would likely develop before we could mix
down enough dry air and stronger winds to develop critical fire
weather conditions, but this will be something to continue to
monitor given recent propensity to mix drier/windier than expected.

WEDNESDAY: A northwesterly upper jet streak pushes a colder, drier
Arctic High into the Northern Plains Tuesday night into early
Wednesday. Despite weakening winds, this should drop temperatures
into the teens and 20s Wednesday morning. Cold air advection aloft
and northerly flow during the day will make for a chilly day with
highs remaining colder than normal for this time of year - in the
30s to mid 40s. Even drier air brings continued elevated fire danger.

THURSDAY: A low to moderate (30-60%) chance for snow develops late
Wednesday night through Thursday as a mid level wave brings a band
of snow somewhere in the Northern Plains. At this stage, ensemble
guidance favors snow accumulations residing north of a line from
Huron and Madison SD to Windom MN with the heaviest amounts (maybe
up to a few inches of snow) even further north in North Dakota, far
northeast South Dakota, and west central Minnesota. However, there
will certainly be minor shifts in the system track over the next few
days. This combined with complex forcing associated with both an
inverted sfc trough and mesoscale Fgen forcing suggest those
traveling will want to monitor this period.

FRIDAY AND BEYOND: The Northern Plains is favored to remain on the
cool side of a quasi-stationary thermal gradient draped from the
Northern Rockies into the Central Plains and Ohio Valley/Southeast
next weekend. Although northwest flow turns more zonal by Friday,
proximity to the northern jetstream favors near to below normal
temperatures through the weekend.

As a longwave trough treks into the West, an early look into next
weekend and the following week favors periods of moderate or
occasionally high chances for precipitation. Precipitation during
this period is favored to be snow moreso than rain, but there is
very poor agreement in timing the progression of a complex series of
upper waves or details at this time.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1032 PM CDT Sun Mar 17 2024

Again looking at a broader area of stratus which will sag south
across the forecast area into early Monday. At this time, ceilings
expected to remain largely VFR, though like last night into early
Sunday, we could see brief periods of MVFR ceilings, along with
a few flurries as the cloud layer resides in a thermal range
favorable for ice production.

Breezy north winds accompany the stratus as well, with
occasional gusts 20-25kt. Winds are expected to gradually
decrease and swing around to the west later tonight-Monday
morning, with occasional gusts to around 20kt through the latter
half of the TAF period.

&&

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

&&

$$

DISCUSSION...AJP
AVIATION...JH


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