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000
FXUS63 KFSD 150333
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1033 PM CDT Sun Apr 14 2024

.KEY MESSAGES...

- Highs in the 70s and 80s continue Monday. These temperatures
  in combination with dry fuels, low relative humidity values,
  and gusty southeast winds will result in near critical to
  critical fire weather conditions across our area.

- A Fire Weather Watch has been issued for Monday, excluding Brule,
 Gregory, and Charles Mix counties in South Dakota.

- High confidence in rainfall arriving Monday night and
  continuing into Wednesday. Area average rainfall totals are
  expected to reach between 0.50" and 2.00" by Wednesday
  morning, with isolated pockets of over 2 inches.

- Isolated to scattered severe thunderstorms are possible with showers
  and storm activity Monday night and Tuesday. The greatest
  threat with the strongest storms will be large hail, but
  isolated damaging wind gusts and a tornado or two cannot be
  ruled out.

- Cooler temperatures and breezy conditions are expected
  Wednesday through Friday.

&&

.DISCUSSION...
Issued at 244 PM CDT Sun Apr 14 2024

CURRENT/TONIGHT: Sunny skies and highs in 70s to low 80s have made
for quite a pleasant day across the region. Expect much of the same
through the late afternoon and evening, as wind direction gradually
becomes easterly. Should see gusts pick up in areas west of I-29
after midnight, with values ranging between 20 to 25 MPH. Lows
during this time look to remain fairly mild, as temperatures only
fall into the 40s to lower 50s. Similar to the last forecast
package, have maintained slight PoPs in areas west of the James
River prior to and shortly after daybreak in response to a quick
moving upper level wave. That being said, quite a bit of dry air
still exist in the lowest levels, so don`t expect to see much if
anything in the way of accumulations. Rather, the better chances for
seeing QPF remain across central South Dakota.

MONDAY: Broad WAA and modest ridging lift across our area ahead of
an advancing upper level low near the Rockies. This will result in
another warm and breezy day here for the region, as highs rise into
the 70s to lower 80s. Increasing SPG and fairly robust LLJ should
yield gusts between 30 to 40 MPH, with perhaps a few locations
flirting with advisory level winds if more efficient mixing can be
achieved. In regard to precipitation, have trimmed back PoPs quite a
bit to keep us largely dry during the daylight hours, as CAMs
continue to show a slower arrival time for the aforementioned low
pressure. Thus, expect the combination of dry, warm, and breezy
winds to promote widespread elevated fire danger across our area -
more on this below into the Fire Weather Section.

MONDAY NIGHT: Sfc warm front and low pressure edge closer to the
region Monday night, causing precipitation and convective chances to
return. As noted in the previous discussion, upper level support
continues to wane the further northeast you go in the Plains. Slower
onset times have also complicated matters a bit, with most CAMs now
showing showers/thunderstorms arriving to the MO River Valley around
7 PM at the earliest. While there is a decent amount of deep layer
shear (~40kts) in place, sounding profiles remain fairly capped in
the lower levels. Nonetheless, can`t rule out the possibility of
seeing a few elevated storms initially, with the potential to become
more surface based later in the evening as we become centered in the
warm-sector. SPC`s latest Day 2 Outlook does maintain a Slight Risk
(Level 2 of 5) along and just north of the MO River Valley, with a
Marginal Risk (Level 1 of 5) encompassing our area elsewhere. Thus,
expect the greatest severe threat to remain along the MO River and
mostly south of I-90 with scattered multicells tracking northeast
into the areas south of I-90. Given the steep mid-level lapse rates
in place, expect large hail to be the primary hazard, with damaging
winds and an isolated tornado being a secondary threat.

TUESDAY: Widespread rain chances (>80%) are expected heading into
Tuesday as the upper level low moves over Nebraska/Kansas. Winds
will be fairly breezy during this time, and highs notably cooler and
temperatures only rise into the 60s under cloudy skies. Still a bit
hesitant that some of our area may become dry-slotted during the
afternoon - however, this will largely depend on the track of the
low which continues to wobble. Nonetheless, should see wrap
around/deformation precipitation return Tuesday evening through
Wednesday, allowing beneficial rains to be seen by all for this
event. In fact, latest ensembles continue to show a high (70-90%)
chance of > 1" of rain for areas near and east of I-29 by Wednesday
afternoon, with a moderate-high (50-80%) chance of > 1" west of I-
29. Isolated pockets of 2-3+ inches are certainly possible as well,
especially considering storms will be able to tap into precipitable
water values at the top 3% of ensemble guidance for this time of
year. In regard to severe weather, latest SPC Day 3 Outlook does
include Marginal Risk (Level 1 of 5) for portions of our area,
mainly along and east of the James River. That being said, still
have low confidence in the timing of severe weather (i.e., morning
vs afternoon) as this will largely depend on how the track evolves.
For now, would expect those across NW Iowa stand the best chances
for seeing any strong to severe storms - but will continue to
monitor trends in the meantime.

WEDNESDAY AND BEYOND: Model consistency begins to wane during the
latter half of the work week, with most guidance showing quasi-zonal
flow returning as an upper level low deepens over Canada. Next best
chance for precipitation looks to occur Wednesday night into
Thursday, as a quick moving shortwaves dives southeastward across
Northern Plains. Otherwise, expect largely dry conditions to prevail
for the remainder of the extended period. Cooler, more spring-like
temperatures return during this time, with highs generally in the
50s and lows in the 20s to 30s.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1032 PM CDT Sun Apr 14 2024

Clear skies and light easterly winds begin the TAF period. Winds
along and west of the James River will become a bit breezy tonight
as the low level jet (LLJ) strengthens. This will lead to low level
wind shear (LLWS) across this area. Thus, have included LLWS in
KHON`s TAF for a few hours tonight.

Winds continue to strengthen out of the southeast tomorrow with
gusts between 25-35 knots expected, strongest west of I-29. Mainly
clear skies persist through the morning and afternoon hours before
the chance for showers and storms return to the area tomorrow
evening. Showers and storms look to develop south of the Missouri
River tomorrow evening and push northwards into the area. Have
included mention of showers in KFSD and KSUX as confidence is
highest in these TAF sites seeing rain. While thunder is possible
with the rain, have omitted any mention of thunder in TAFs as timing
and location of storms may still change. Will continue to monitor
trends but mention of thunder will likely be needed once confidence
increases in storm location and timing. The showers and storms will
finish out the TAF period.

&&

.FIRE WEATHER...
Issued at 244 PM CDT Sun Apr 14 2024

Very high fire danger is expected to prevail across the region
Monday as breezy southeasterly winds cause relative humidity values
to fall into the lower 20s. Gusts during this time look to range
between 30 to 40 MPH, with perhaps a few isolated gusts as high as
45 MPH. Thus, with dry fuels still in place, have decided to issue a
Fire Weather Watch for portions southeastern South Dakota,
northeastern Nebraska, northwestern Iowa, and southwest Minnesota
after collaboration with neighbors. We strongly encourage you to
exercise caution with any activity that may cause a spark, as fires
can spread quickly under these conditions!

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Monday morning through Monday evening
     for SDZ038>040-052>056-058>062-064>071.
MN...Fire Weather Watch from Monday morning through Monday evening
     for MNZ071-072-080-081-089-090-097-098.
IA...Fire Weather Watch from Monday morning through Monday evening
     for IAZ001>003-012>014-020>022-031-032.
NE...Fire Weather Watch from Monday morning through Monday evening
     for NEZ013-014.

&&

$$

DISCUSSION...SST
AVIATION...Meyers
FIRE WEATHER...SST