Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 131138 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
638 AM CDT Fri Apr 13 2018

.UPDATE...
Issued at 633 AM CDT Fri Apr 13 2018

See updated aviation discussion below.

&&

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 348 AM CDT Fri Apr 13 2018

A very complex storm system will impact the area today through
Saturday. Snowfall amounts are concerning for counties along the
ND/SD border where less snow is highly possible. Confidence for
blizzard conditions is lowest in this area.

Currently seeing convection developing over north-central Nebraska
and far SE South Dakota. Yesterday`s 0Z CAMS had this convection 100
miles further north. This is problematic for a few reasons. First,
pcpn will likely be delayed in our northeastern CWA, which may not
see blizzard conditions until this afternoon. Secondly, our
northeast is currently seeing dry, northeasterly winds which may
hold off some pcpn as well. Our western CWA maybe be delayed for a
few hours due to warmer temps, plus slower storm progression. Areas
west of the CWA are currently seeing a decent amount of rain and
snow. Broad upper level support should remain over western and south
central SD through this afternoon, with moderate to heavy snow
expected. The combination of falling snow and very strong northerly
winds will produce blizzard conditions for the Pierre over to Miller
area today. Based on current model runs, along with radar trends,
north central SD may miss out on blizzard conditions due to lack of
snowfall.

Speaking of snowfall amounts, WPC, 3KM NAM, 6Z HRRR, and SPC`s HREF
all suggest little to no snowfall along and north of Highway 10 in
NE South Dakota. Current projected snowfall totals along the ND/SD
are 1 to 2 inches. Snowfall amounts increase substantially the further
south you go. Brown County for example, Hecla area could see about 2
inches. Mansfield area could see 7 to 10 inches.

Lastly, there is reasonable support among models for our far SE
portion of the CWA seeing blizzard conditions mainly later this
afternoon through tonight. This is when the trowal develops,
resulting in moderate to heavy snowfall. With easterly flow, the
eastern side of the Sisseton Hills could see higher snowfall
amounts.

Precipitation should diminish from northwest to southeast this
evening through Saturday afternoon.

.LONG TERM...(Saturday Evening through Thursday)
Issued at 348 AM CDT Fri Apr 13 2018

The extended opens with the impactful weekend system exiting eastern
SD. The active pattern remains in place with a series of sfc
lows/upper troughs moving through the Plains. On Monday upper
ridging will build over the region. With a deep snowpack in place,
temps may be moderated a bit, but expect some significant melting as
temps likely climb into the 40s. The next trough barrels in on
Tuesday bringing a mix of rain and snow. Timing will drive
accumulations. Current guidance suggests northeastern SD will see 1-
3 inches as the precip hits them late Tuesday night. This trough
will be followed by another ridge on Thursday. Keep an eye toward
the end of the week/next weekend. Another low is in the wings,
though it`s a little too soon to say whether this one will affect
the Dakotas or stay farther south.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 633 AM CDT Fri Apr 13 2018

Precipitation will continue spreading into the region today. The
precipitation may begin as rain or freezing rain, then will
switch over to snow in eastern SD. All snow is expected in the
west. Cigs will generally be IFR throughout this event. MVFR
vsbys, with periods of IFR, will be common with the snow as winds
gust in excess of 40 knots through this evening.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Blizzard Warning until 7 AM CDT /6 AM MDT/ Saturday for SDZ003-
     004-009-015-016-033>035-045-048.

     Blizzard Warning from 1 PM this afternoon to 7 PM CDT Saturday
     for SDZ007-008-011-018>023.

     Blizzard Warning until 1 PM CDT Saturday for SDZ005-006-010-017-
     036-037-051.

MN...Blizzard Warning from 1 PM this afternoon to 7 PM CDT Saturday
     for MNZ039-046.

&&

$$

UPDATE...SD
SHORT TERM...SD
LONG TERM...Wise
AVIATION...SD



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