Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 241140 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
640 AM CDT Sun Mar 24 2024

.KEY MESSAGES...

- Models continue to trend snowfall amounts downward across much
  of the region, but highest totals still reside over northeast SD
  (especially Coteau area) into west central MN where a foot or
  more is possible.

- Light snow tapers off Monday night into Tuesday across
  northeast South Dakota and west central Minnesota. Stronger
  winds also subside during this time curtailing any concerns for
  blowing snow and reduced visibilities.

- Cold temperatures persist through midweek before modifying
  toward the end of the week. A couple of weak disturbances may
  affect the region late in the week with the next opportunity for
  precipitation.

&&

.UPDATE...
Issued at 630 AM CDT Sun Mar 24 2024

Aviation discussion updated below for the 12Z TAFs.

&&

.SHORT TERM /TODAY THROUGH MONDAY AFTERNOON/...
Issued at 411 AM CDT Sun Mar 24 2024

Current radar imagery continues to show snow moving into central SD,
with KPIR reporting -SN since about 230am CDT. Will continue to keep
an eye on P-type through the morning hours, but it does appear
probabilities for mixed precip have lowered vs 24 hours ago. 12Z P-
type meteograms from the ENS show less than 10% chances for mixed
precip from Philip, to Chamberlain, up through Watertown. NBM probs
for freezing rain are generally around 30% or less for the far
southern CWA bordering FSD. Ice accums forecast has come down a bit
and shifted south, but still potentially around a tenth from the
Lyman county bootheel over towards the ABR/FSD CWA border across
east central SD.

As for the snow, models continue to trend accumulations downward.
This is reflected in HREF membership accumulation output,
deterministic output, as well as various probs for specific amounts
within NBM/HREF/etc. A southward shift has been noted with the
highest QPF axis, and this puts central/north central SD with lower
accums forecast than say, 24-48 hours ago. In fact, after today,
there are some solutions that don`t give central/north central much
more snowfall at all as focus shifts to eastern/southeastern SD into
western/southwestern MN. Highest totals in our CWA continue to be
areas east of the James River, especially in the Coteau/upslope
favored areas, where amounts in excess of a foot are still forecast.

There was a change to headlines, which included changing
Lyman/Buffalo to a Blizzard Warning for collaboration purposes along
the southern CWA border. PotBlowing snow output isn`t as high as one
would like to see to upgrade to blizzard, but close enough
nonetheless, and there should definitely be some impacts down that
way in regards to reduced visibility. Same can be said elsewhere
over the eastern CWA once the wrap around snow begins moving in, but
will let later shifts upgrade if need be. Was getting nervous about
the continued southward shift and a bit hesitant to do much to
headlines until 12Z data starts coming in. If one were to believe
the 00Z deterministic EC, central SD does not even receive much more
snow after today! That said, one can also likely consider dropping
headlines earlier across central SD, but will also leave that for
later shifts once the storm starts progressing a bit and we get
better agreement on an ending time in models.

&&

.LONG TERM /MONDAY EVENING THROUGH SATURDAY/...
Issued at 411 AM CDT Sun Mar 24 2024

This period will begin on Monday night with both deterministic and
ensemble model guidance agreeing on taking the sfc low track farther
south and east of our region than they were progging 24 hrs prior.
Now, it appears the low will be located somewhere in the vicinity of
central Iowa at the beginning of this period. It`s then forecast to
track northeast into west central Wisconsin Tuesday morning and then
on over Lake Superior Tuesday night into Wednesday.

Precipitation chances will be ending from west to east Monday night
into Tuesday. Basically, there will be a good chance for light snow
continuing along and east of the James Valley Monday night and then
tapering off across the northeast corner of South Dakota and west
central Minnesota during the day Tuesday. A tight pressure gradient
across the area initially Monday night will gradually relax going
into Tuesday allowing the stronger wind gusts to subside. Given the
anticipated storm track farther removed from our area, tempered wind
speeds from the inherited NBM values Monday night through Tuesday. A
sfc ridge of high pressure is set to build into the area toward
midweek. This will help to reinforce a colder than normal air mass
across the region. With a new snow pack on the ground, temperatures
will be rather cold for late March. In fact, NBM guidance
probabilities remain fairly high(30-60 percent) for seeing subzero
overnight lows Tuesday night into Wednesday morning for north
central and parts of northeast South Dakota. The air mass will
modify toward the end of the week as the potential for the next
disturbance moves closer to the region. Models continue to remain at
odds as far as what make of where these systems will track, thus
creating low confidence. Will continue to advertise the inherited
slight chance PoPs late Thursday through Saturday and watch how the
trends play out going forward.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 630 AM CDT Sun Mar 24 2024

Terminals KABR,KATY,KPIR,KMBG

MVFR/IFR CIGs/VSBY are forecast through the TAF period, due to
SN/+SN and eventual BLSN snow (later in the period). There may be
a lull in SN this afternoon, with possibly a return to VFR VSBY
(will adjust TAFs as necessary), although MVFR/IFR CIGs are
forecast to remain.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Storm Warning until 7 AM CDT Tuesday for SDZ007-008-011-
     019>023.

     Winter Storm Warning until 7 AM CDT /6 AM MDT/ Tuesday for
     SDZ003>006-009-010-015>018-033>037-045.

     Winter Storm Warning until 1 AM CDT Monday for SDZ048-051.

     Blizzard Warning from 1 AM Monday to 7 AM CDT Tuesday for SDZ048-
     051.

MN...Winter Storm Warning until 7 AM CDT Tuesday for MNZ039-046.

&&

$$

UPDATE...TMT
SHORT TERM...TMT
LONG TERM...Vipond
AVIATION...TMT


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