Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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FXUS63 KFSD 250341
AFDFSD

Area Forecast Discussion
National Weather Service Sioux Falls SD
1041 PM CDT Sun Mar 24 2024

.KEY MESSAGES...

- Major Spring storm continues through Monday night. All
  precipitation types likely tonight. Rain will be the main
  precipitation type through southeastern SD and northwestern IA,
  although some freezing precipitation and snow are likely near
  highway 14 and into central SD. Some trends downward in
  amounts in central SD.

- Winds will become very strong late tonight into central SD and
transition east through the day Monday. Blizzard conditions are
likely in central SD late tonight and Monday, and may shift east
Monday afternoon and night towards I-29. The main concerns will be
decreasing snow amounts towards I-29 and whether or not blizzard
conditions can occur.

- Converted the small winter storm watch to a warning for tomorrow
and cancelled the advisory for this afternoon along I-90.

- May need a small winter weather advisory in far southeast SD and
northeast NE late tomorrow afternoon into the night as the winds
kick up and an inch or so of snow is possible.

&&

.DISCUSSION...
Issued at 305 PM CDT Sun Mar 24 2024

Overall the changes to this system are not significant, but there is
a bit of a downward trend in snowfall amounts across the area.
Warmer air should wrap slightly farther to the north and west along
with some drying aloft near and west of the James River which cuts
off the ice bearing layer. This seems to be playing a role in the
decreased snowfall amounts in central SD. Along highway 14 the
potential decrease in snowfall amounts is tied to the slightly
warmer air. Also playing a role in lower snow amounts is a slight
shift southward in the highest QPF amounts.

A broad area of precipitation will develop through the evening and
bring quarter inch per hour rainfall rate potential, which is still
expected to lead to rainfall amounts of around 2 inches in some
locations. Latest trends for areas near and west of the James River
suggest that there will be a fairly long lull in activity through
the evening and early overnight. It looks like this is due to a lack
of saturation in the dendritic layer, so without convection there
may be a fairly distinct back edge tonight, leaving this area on the
lower side. Lift does appear to increase and saturation occurs late
tonight and Monday morning so the potential for blizzard conditions
is still there. Wind gusts to 50 mph still likely. Obviously the
later it goes without snow, the lower the amounts, but still appears
that 5 to 9 inches possible within the winter storm warnings and
blizzard warnings.

Late Monday afternoon into the evening the strong northwest winds
collapse eastward, but the better environment for snow remains
mostly west of I-29. This brings the potential for some lighter snow
and very strong winds to I-29 near and south of Sioux Falls. This
area may need some kind of headlines at some point in time but with
the idea that the higher snow amounts will be west of this area and
that the worst conditions will be after 6 pm, will see how trends
play out over the next 12 hours or so.

Tuesday will be a raw, cold day with northwest winds gusting to 40
to 50 mph in the morning, then 30 to 40 mph in the afternoon,
gradually tapering off from west to east. Some headlines may need to
be extended into Tuesday if blowing snow is enough of a problem as a
half an inch or so of new snow could fall east of I-29. Morning wind
chill values will likely be below zero in most locations near and
west of I-29. Highs only in the 20s, maybe a few lower 30s.

Wednesday remains on the backside of the upper level trough so still
a bit breezy and cold. Lows may fall to around zero over any deeper
snowpack with 5 to 15 above elsewhere. Highs will again be 20s to
lower 30s, expect a bit warmer in northwest IA.

Upper level ridging quickly moves through Thursday into Friday with
troughiness developing to the west. This should allow for near
normal temperatures through the weekend with periodic chances for
precipitation. The system for Friday continues to remain to the
north with the chance for any impactful precipitation pretty
low.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1033 PM CDT Sun Mar 24 2024

IFR/LIFR conditions will dominate through the TAF period. Rain
will be the predominate precipitation type through northwestern
IA, southeast SD, and portions of southwestern MN. Back to the
north and west, snow or mixed wintry precipitation will be the
most common type. Winds will be gusty overnight, increasing west
of Interstate 29 on Monday, with gusts of 40 to 50 mph leading
to blizzard conditions over that area. By Monday evening, areas
with rain will begin to transition to snow as colder air comes
into the area.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until 7 AM CDT Tuesday for SDZ039-040-
     054>056.
     Winter Storm Warning until 1 AM CDT Monday for SDZ038-052-053-
     057>059.
     Blizzard Warning until 7 AM CDT Tuesday for SDZ038-050-052-053-
     057>059-063-064.
     Winter Storm Warning from 7 AM Monday to 7 AM CDT Tuesday for
     SDZ060-061-065-068.
MN...Winter Storm Warning until 7 AM CDT Tuesday for MNZ071-072-080-
     097.
IA...None.
NE...None.

&&

$$

DISCUSSION...08
AVIATION...JM


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