Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 302338 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
638 PM CDT Sun Apr 30 2017

.UPDATE...
Issued at 627 PM CDT Sun Apr 30 2017

The current forecast for this evening looks good overall. Based on
radar trends, have increased pops in the SE portion of the CWA,
including the Watertown area where light rain is occuring. Have
removed pops for a few hours for areas along and west of the James
River Valley where the temp/dew point spread is greater than 15-20
degrees.

&&

.SHORT TERM...(This Evening through Monday)
Issued at 351 PM CDT Sun Apr 30 2017

Main forecast challenge in the short term remains the storm system
centered to our south across the Central Plains this afternoon. It
is forecast to track northeastward tonight and tomorrow across Iowa
and then into Wisconsin tomorrow afternoon. So far today, there has
been an initial band of precip(mostly rain) that has pushed
northward out of SE South Dakota and SW Minnesota and now just
entering our SE corner of our CWA.

The challenge with this system remains the surface temperature
forecast, precip phase change and snowfall accumulations. Feel that
after perusal of all the latest model guidance from the 12Z
solutions, the SE corner of the CWA still stands the best chance at
accumulating snow that could total between the 5-7 inch mark. The
caveats in all this coming together like we expect are the surface
temp and the time duration the precip will be falling when
temperatures are cold enough to support snow. So, the precip falls
initially as just rain this evening before changing to a mixture
sometime closer to midnight before becoming all snow sometime during
the early morning hours tomorrow. The areas under the current Winter
Storm Warning are still in line to receive the highest snowfall and
will not make any changes to headlines at this time. A transition
back to a mixture around mid morning Monday before ending as just
rain Monday afternoon. As this system pulls away, another one enters
the picture quickly from the northwest during the day Monday. This
should mainly affect areas west of the James valley with generally
lighter rain showers or possibly a thundershower or two.

Temperatures will remain dependent on cloud cover versus sunshine
during the daytime. Cooler readings can be expected east underneath
that precip/cloud shield with highs in the 40s to near 50 degrees.
Highs from the James valley and points west should reach the low 60s.

.LONG TERM...(Monday Night through Sunday)
Issued at 351 PM CDT Sun Apr 30 2017

The early part of the long term is where most of the action can be
found during the period. As the strong storm departs during the
short term, a major pattern amplification begins to take place. A
ridge building over the western CONUS forces s/w energy southeast
across the region both Tuesday and Wednesday. The combination of
energy aloft, and mlcapes pushing 1k j/kg should spell at least
afternoon showers both days, with maybe some thunder thrown in,
particularly on Wednesday.  Beyond Wednesday, it should turn dry as
the mid level ridge continues to build and slowly progress east from
the western CONUS and into the central CONUS.  As might be expected,
once the ridge pushes east, temperatures will be on the uptrend,
with above normal readings expected by next weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 627 PM CDT Sun Apr 30 2017

KATY will see rain change over to snow tonight through Monday
morning with accumulations possible. The snow will bring MVFR and
possibly IFR conditions. Northerly winds will remain gusty around
25 kts overnight and Monday at KATY. VFR conditions are expected
to prevail at KABR, KPIR and KMBG through this forecast period as
these terminals will remain by in large unaffected by the low
pressure system moving into the Upper Midwest tonight and Monday.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory from 10 PM this evening to noon CDT
     Monday for SDZ008-022.

     Winter Storm Warning from 10 PM this evening to noon CDT Monday
     for SDZ020-021-023.

MN...Winter Weather Advisory from 10 PM this evening to noon CDT
     Monday for MNZ039-046.

&&

$$

UPDATE...SD
SHORT TERM...Vipond
LONG TERM...TDK
AVIATION...SD



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