133
FXUS63 KABR 212052
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
352 PM CDT Fri Mar 21 2025

.KEY MESSAGES...

- Very high Grassland Fire Danger Index values are expected
Saturday, especially over portions of mainly central South Dakota
where a Red Flag Warning has been posted. Shifting winds will be
critical to any ongoing fires.

- Winds will increase out of the northwest Sunday, with gusts of 30
to 50 mph, highest over central South Dakota. Very high to extreme
Grassland Fire Danger Index values are expected Sunday, again lowest
over portions of central South Dakota.

- 40-65% chance of precip Saturday night into Sunday. This will
start as rain and transition to snow. Chances for more than 0.10" of
moisture range from 30-60%, east of the James River, with the
highest chances over far northeastern SD and west central MN.

&&

.SHORT TERM /THIS EVENING THROUGH SATURDAY NIGHT/...
Issued at 352 PM CDT Fri Mar 21 2025

While relative humidity recoveries will be 70 percent or greater
across much of the area, they will only rise into the 50 to 60
percent range southwest of Pierre and east of the Prairie Coteau in
far northeastern South Dakota and west central Minnesota.

Shower chances increase late Saturday afternoon mainly over northern
SD, with the main area of showers moving into our central SD just
prior to 00Z Sunday. CAPE and shear looks more impressive to our
south, but elevated lapse rates near and behind the surface low
along with daytime heating will help support at least a few rumbles
of thunder during the late afternoon and early evening hours. The
SPC Severe Weather Outlook accurately shows a general risk of
thunderstorms for all but our far northeastern counties for Saturday
(Day 2). We will keep the mention of thunder out of the forecast for
now, but it may need to be added for a few lightning strikes.

The main concern will be fire weather once again, with little to no
rain falling this morning and little rain the forecast. A Red Flag
Warning has been issued for our southwestern most counties Saturday
afternoon. Winds will increase through the day, and gust 25 to 35
mph over portions of central South Dakota. Relative humidity falls
into the 20 percent range. The higher winds and dry conditions will
result in elevated fire weather conditions, especially over portions
of central South Dakota. Very high Grassland Fire Danger Index
values are forecast for the entire area Saturday afternoon. Shifting
winds will be a concern for any ongoing fires. Behind a cold front
Saturday night, winds will increase and shift out of the west and
northwest.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 352 PM CDT Fri Mar 21 2025

Starting off Sunday morning, GEFS/ENS/GEPS agree well on the
position of the low over central MN with its shortwave`s axis
extending southward over the Northern Plains. GEFS is a couple of
millibars deeper on the low at 996mb compared to ENS at 999mb. By
this time the CWA will be on the backside of the low with the models
indicating ongoing precip extending from the center of the low and
westward through the central Dakotas. Mean temps across the CWA are
forecasted to range in the upper 20s to the lower to mid 30s Sunday
morning over north to northeastern SD and mid to upper 30s over
central to south central SD. NAM soundings indicating the wet bulb
temps at or below 0C for most of the area. So Ptype will be mainly
be snow, however, a few places will still see rain/snow before
changing to snow as the wet bulb decreases. NBM pops show this well
with 30 to 65% along and east of the James River with the highest
pops over and east of the Coteau through 1pm. As the low shifts
east, precip will diminish west to east through Sunday evening. Not
much in terms of moisture as probability of 24hr QPF>0.10" and
snow>1", ending Monday 12Z, shows about a 30-60% chance along and
east of the James River, highest over far northeastern SD per GEFS.
With ENS being not as deep of a low, probability is about 20-35% for
QPF and snow>1". NBM seems to indicate this well with QPF ranging
between 0.10"-0.17" and snow up to a half inch for this area.

On the backside of the low, 6hr pressure rises of 5 to 7mb will be
over the CWA at 12Z Sunday, decreasing and +2 to +4 by 18Z. This
along with CAA and steeper pressure gradients will lead to ongoing
gusty winds with NBM gusts between 35-45kts. Closer to time, NBM90th
may need to be added into the mix to show the potential for even
higher gusts. A wind headline will most likely be needed. Winds will
be diminishing from west to east Sunday night. Due to these wind
gusts during the falling snow, WSSI has Minor Impacts over the Leola
Hills and the Coteau through northeastern SD into western MN for the
potential of drifting and blowing snow, that could briefly drop
visibility at times.

Behind this system, a weak clipper will swing northwest to southeast
over the Northern Plains Monday into Monday night, bringing a chance
of rain, mainly over the western CWA. Latest NBM has 30-55% pops,
highest over north central SD. Winds do increase behind it, with
gusts of 25-35kts Tuesday afternoon, mainly over central SD. This
leads to an elevated fire danger concern. High pressure moves in
midweek with another low swinging down from the northwest for the
end of the week that could bring additional rain.

Overall Clusters indicate a +PNA pattern early next week with this
ridge shifting eastward and over the central and northern part of
the CONUS by ~Thursday. This ridge shifts east as another wave moves
in off the Pacific for the end of the week. The ridging pattern will
gradually bring in warmer air from the surface and aloft. Forecasted
highs will range in the 50s to lower 60s Monday and Tuesday with our
warmest days by the end of the week, under the ridge, with
forecasted highs in the 60s to possibly the lower 70s.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 630 AM CDT Fri Mar 21 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to prevail through tonight. Northwest
winds will increase with gusts to 30 kts today before diminishing
this evening.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Red Flag Warning from 1 PM CDT /noon MDT/ to 8 PM CDT /7 PM MDT/
     Saturday for SDZ033-035>037-045-048-051.

MN...None.
&&

$$

SHORT TERM...06
LONG TERM...MMM
AVIATION...20