564
FXUS63 KABR 310709
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
209 AM CDT Tue Mar 31 2026

.KEY MESSAGES...

- The first of two systems moves into central SD early Wednesday
morning bringing accumulating snow across the region through
Thursday. There is a 50 to 75% chance of more than 2 inches of snow
and a 30 to 50% chance of more than 4 inches of snow. There is a 25
to 35% chance of greater than 6 inches mainly along the eastern
slopes of the Sisseton Hills. With temperatures warming near/above
freezing in the afternoon, snow may mix with rain or transition to
all rain, decreasing snowfall amounts. So low confidence in
exact amounts at this time.

- The second system will move west to east across the region Friday
and Saturday bringing the potential for more accumulating snow and
the possibility of freezing rain. There is 25 to 60% chance of 4
inches or more of snow, with the highest percent over north central
SD and along the eastern slopes of the Sisseton Hills. There is a 25
to 45% of 6 inches or more of snow for this same area.

&&

.DISCUSSION...
Issued at 208 AM CDT Tue Mar 31 2026

The main concern will be the two systems moving across the region
midweek and again for the end of the week into the weekend bringing
accumulating snow and the possibility of freezing rain Friday.
Starting off today, the region is positioned between the exiting
cold front to our southeast and a high pressure system to our
northwest as CAA is dominant and winds will continue out of the
northwest. The strongest gusts will continue through this morning
with the better CAA and steeper low level lapse rates. Mixing layer
is quite shallow, between 900-850mb with the top of mixed layer
around 20-30kts. So wind gusts of 30 to potentially 45 mph will
continue through the late morning with winds diminishing a bit west
to east across the CWA as the CAA exits the region later on this
afternoon and high pressure system shifts a bit east. With the gusty
winds and ongoing dry fuels, the GFDI index is High to Very High
today. Afternoon RH values are forecast to drop between 25-45%,
lowest over south central SD. Luckily the stronger winds will be
more this morning over central SD and really do not coincide with
the drop in humidity this afternoon for any fire headlines at this
time.

By this evening, the high pressure system will be over northern ND
into Canada with the CWA on the southern part of this high as it
will continue to track eastward through Wednesday morning (center
over east central Ontario by 12Z). By this time areas east of the Mo
River will still be on the west/southwestern side of this high and
west of the Mo River will be to the east of an area of low over
Wyoming and its shortwave aloft. With this southwest flow aloft,
ample amounts of moisture will surge northeastward into the region
early Wednesday morning, on the upwind side of the shortwave aloft,
with RAP 1000-500mb RH between 75-95% over the CWA by 12Z Wednesday,
highest over central SD with this higher RH shifting eastwards with
the low. RAP/HiResARW/FV3 do indicate the first wave of precip, in
the form of snow, moving in over south central SD late this evening
with CAMS overall agreeing on this snow spreading north and
northeastward overnight through Wednesday morning to about the
Coteau (as the high keeps pops lower northeast of the Coteau). At
this time HREF indicates snowfall rates up to 0.75" an hour over
north central/central SD through the late morning with the snowband
probability tracker highlighting this same area of enhanced snowfall
potential. Snow/rain will continue to overspread the rest of the CWA
Wednesday afternoon, as the high continues to track east, with
widespread pops of 70-90% Wednesday evening through Thursday morning
as a secondary low then positioning itself over lee of the Rockies
in Colorado and deepens, along with the shortwave. Widespread pops
of 40-80% per NBM are forecast from 12Z Thursday through 00Z Friday
as this low will track eastward and over ~eastern KS/NE by 12Z
Thursday as the CWA will be within the north and northwest quadrant
of the low. By this time, there seems to be a bit more variability
on the position of this low and strength. For example, GEFS is a bit
further east at 1000mb and ENS is a bit west at 998mb. By Thursday
afternoon/evening, the bulk of the snow/rain will continue over the
eastern half of Dakotas into MN with precip moving in over the far
western CWA with the next system.

Latest NBM has increased QPF amounts since the last run ranging from
0.3 to 0.7" and widespread snow amounts of 2 to 5 inches, with the
possibility of 6 inches along the eastern slopes of the Coteau. 90th
percentile snowfall ranges from 5 to 8 inches, again highest eastern
slopes of the Coteau. The 25-75th spread is still quite high,
ranging from 3-4" due to uncertainty in exact amounts. Looking at
few HREF members (only going out to 7pm Wednesday) overall show 3-
5", however, HRW-ARW indicate the possibility of 6-8" over south
central SD where the NSSL and Nam Nest show a 8-10" band over north
central SD. 00Z EC run indicates a broad 6-10" east of the Mo River
and GFS 7-10" (with a foot possible over east central SD). So low
confidence in exact amounts at this time and where the heavier snow
may fall. ENS does highlight the potential of freezing rain (up to
30%) over Watertown with NBM highlighting this threat through
southeastern SD. Probability of ice>0.01" is about 20% from Clark
through Watertown and southeastward. Winds will be a bit stronger
over central SD Wednesday, with gusts to 35 mph, before diminishing
towards the afternoon. Gusts on Thursday will be up to 25 mph so
that should keep down any widespread chance of blowing snow with the
BLSN model indicating mainly drifting to isolated areas of blowing
snow over central SD Wednesday.

With this snowfall being stretched out over several days the
probability of warning criteria is 10-30% on Wednesday/Thursday
mainly over the northern portions of the Sisseton Hills through west
central MN. EC EFI for QPF is 0.6 to 0.7 east of the Mo River for
QPF and 0.5 to 0.7 for snow over north central and portions of
northeastern SD/western MN Thursday, with a SOT of zero over north
central SD. So low EFI/low SOT indicates most EC members are near
the reforecast climatology and boom potential is low. No headlines
were issued this shift per collaboration with surrounding offices
but will most likely be needed on the day shift. WSSI highlights
"Winter weather area" to "Minor Impacts" for Wed/Thurs. With how
warm it has been (highs in the 60s to 80s) and no frost depth, it
may take awhile of any sort of accumulations on roadways unless we
end up seeing more than an inch an hour snowfall rates (not
anticipated at this time). It also depends on how much rain gets
mixed into the snow as well, epically when temps warm up above
freezing Wed/Thurs afternoon. This will help decrease snowfall
totals and/or cause for melting. So still lots of uncertainties with
this system.

This busy pattern continues as a mid level low (turning into an open
wave) and its surface low moves west to east across the region
Friday and Saturday bringing more snow with it and the potential for
freezing rain and rain. EC/NBM indicates freezing rain prob between
20-40%, highest over east central SD early Friday morning through
Friday afternoon. Probability of ice>0.05" is 30-40% over east
central SD. With any freezing rain, it will be very dependent on
temperatures at this time both surface and aloft. Additional snow
amounts of 2-4" mainly along and north of Highway 12 with decreased
amounts south of here. At this time GFS members do show the
potential for dry slotting over the southern half of the CWA while
ENS does not. This is still a few days out so any shift in the track
of the low and strength will determine where the higher snowfall may
occur.

Highs for today will be cooler ranging in the 40s to around 50,
warmest over far south central SD. It will be chilly tonight with
lows in the 20s. Highs for Wednesday will range in the upper 30s to
the lower 40s, with highs in the 30s/40s through the end of the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1238 AM CDT Tue Mar 31 2026

Terminals KABR,KATY,KPIR,KMBG

VFR conditions will continue at KABR/KPIR/KMBG terminals through
today into tonight. Although, MVFR cigs will be possible at KATY
after sunrise through about midday. Also, the potential to see
brief MVFR cigs at KABR during the early-mid morning will have to
be monitored. Northerly winds will remain gusty throughout this
forecast cycle with speeds reaching up to 30 kts at times. Winds
will begin to diminish by late in the day into tonight. A few rain
showers will be possible at KMBG through the predawn hours today.
Light snow showers may enter the KPIR terminal area late in this
forecast period.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

DISCUSSION...MMM
AVIATION...Vipond