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000
FXUS63 KFSD 200814
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
314 AM CDT Sat Apr 20 2024

.KEY MESSAGES...

- Below freezing temperatures are expected again tonight into
  Sunday morning, potentially creating some frost/freeze
  concerns across portions of the area.

- More light rain chances (20%-50%) will return by Monday.
  However, only light accumulations are expected.

- Monday and Tuesday will be the next windy days and while many
  of the fuels are beginning to green up with the recent rains,
  afternoon relative humidity will likely fall to about 30 to
  35 percent in some locations, leading to a high fire danger in
  a few locations.

- A bit better chance for rain and thunderstorms Thursday into Friday
  with EC and GFS ensemble output indicating a 10-20 percent
  chance for an inch or more of rainfall.


&&

.DISCUSSION...
Issued at 313 AM CDT Sat Apr 20 2024

A little relief from the excessive wind today, although there
will still be some gusts around 25 mph. The surface pressure
gradient gradually slackens through the afternoon as high
pressure builds across the Western High Plains, so winds should
be a little less gusty towards late afternoon. Temperatures
aloft are just a smidge warmer, so highs should be a couple of
degrees higher than yesterday, so still on the cooler side.

High pressure builds into the area tonight so lows may be at their
coolest with a little better chance for some patchy frost.
Regardless, will likely need another freeze warning for tonight into
Sunday morning. Sunday should be a pleasant day with lighter
winds and highs in the 60s.

Sunday night into Monday low pressure aloft deepens over southern
Canada with a lead wave expected to eject onto the Northern Plains
late Sunday night into Monday. This will bring some broad mid level
warm advection through which may aid in generating scattered
showers. Generally westerly warm advection lacks a bit of moisture
and this case is no different. So then there is more reliance on the
elevated mixed layer to generate some instability and for now that
looks to be a challenge as well. Not completely out of the question
for a few showers but rainfall amounts should be spotty and on the
light side. There will be some stronger winds as this system passes
which comes as no surprise and gusts should be somewhere from about
30 to 40 mph. Fire weather should not be a major problem, but will
need to watch the trends in fuels and potential afternoon relative
humidity, but for now green up is happening with the recent rains.

Cold advection spills into the area on Tuesday as the tail end of
the system moves east. With the cold air aloft moving through some
very weak instability will be possible which could trigger a few
showers, but once again the amounts should be light. Otherwise with
the cold advection mixing will be strong and with the potential for
35 to 40 knot winds in the mixed layer it should Be a very windy
day. Will once again need to pay attention to fire weather concerns
as well as the potential for wind advisory criteria.

Tuesday night through Wednesday night should be mostly dry as upper
level ridging moves through and troughiness develops to the west.
The next system of interest moves into the area Thursday into Friday
and should bring the next better chance for rain and potentially a
few thunderstorms. Temperatures Wednesday into Friday should be near
or a few degrees above normal and with a warmer EC Ensemble
temperatures may end up another 3-5 degrees warmer than forecast.
That will be a trend to watch with the GFS potentially running on
the cool side.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 943 PM CDT Fri Apr 19 2024

VFR conditions are expected through the TAF period. Light
northwesterly winds tonight. By Saturday morning winds will
increase again, gusting around 20 kts through the afternoon.
Winds become light again on Saturday evening.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Freeze Warning until 7 AM CDT this morning for SDZ055-056-061-
     062-066-067-069>071.
MN...Freeze Warning until 7 AM CDT this morning for MNZ071-072-080-
     081-089-090-097-098.
IA...Freeze Warning until 7 AM CDT this morning for IAZ001>003-
     012>014-020>022-031-032.
NE...Freeze Warning until 7 AM CDT this morning for NEZ013-014.

&&

$$

DISCUSSION...08
AVIATION...JM