Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 200931

Area Forecast Discussion
National Weather Service Aberdeen SD
331 AM CST Mon Feb 20 2017

.SHORT TERM...(Today through Wednesday Afternoon)
Issued at 305 AM CST Mon Feb 20 2017

Showers, along with a few thunderstorms are ongoing over the eastern
CWA where a decent 40-50 kt LLJ is located. The LLJ will push into
western MN by 12Z or so with showers ending for a brief period of
time. A surface low and associated cold front will track eastward
across the CWA today with additional showers expected. While 925
MB temps will drop behind the cold front, good northwesterly
mixing winds should produce highs in the 50s and low 60s. The
upper level flow patten becomes nearly zonal over the region with
more than one surface low pressure system crossing the Northern
Plains on Tuesday. These lows should pass through the region dry
with only good mixing winds expected. Highs should once again warm
into the 50s and 60s. This appears to be the last warm day in a
while as all models show a low pressure system and upper level
trough crossing the region Tuesday night through Wednesday. This
system will bring cooler temperatures back into the region with
highs cooling off into the 40s and 50s on Wednesday. The NAM and
GFS both suggest a good chance of pcpn, with the WAA Tuesday night
and with the surface cold front on Wednesday. Have introduced
pops Tuesday night and have increased pops over forecast builder
on Wednesday. While the pcpn should be all liquid, wouldn`t be
surprised if a few flurries are mixed in Wednesday morning. It`s
still winter after all.

.LONG TERM...(Wednesday Evening through Sunday)
Issued at 305 AM CST Mon Feb 20 2017

The main challenge in the extended remains the end of the week storm
system that will be impacting the region. Models continue to trend
the low farther south and east, and current snow accum progs reflect
that. When the precip first arrives late Wednesday night/early
Thursday there may be some light snow across south central SD, but
this will quickly transition to a mix of snow and rain during the
daytime hours. Temps will be cooler, but still top out in the mid to
upper 30s. Behind the sfc low Thursday night there will be an influx
of colder air as the upper trough swings into the Dakotas. Precip
will change over to all snow. Right now it looks like accumulations
across the north will be little to none with perhaps a few inches
across the southern cwa through Friday evening. Trends on snow
accumulations continue to show a decrease.

A longwave trough will set up over much of the contiguous U.S.
Thursday night through the end of the extended. This feature will
return temperatures to more typical levels for the end of February
with highs in the upper 20s and 30s. There are no strong signals for
precip after the first system exits, but shortwave activity through
the upper level flow could generate some showers early next week.


.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1137 PM CST Sun Feb 19 2017

A low pressure system continues to move into the region, with
southerly winds and warm moist air streaming in ahead of this low.
A 30 to 40 KT low level has set up across eastern South Dakota.
Therefore low level wind shear is mentioned in the KABR and KATY
TAF sites. Current radar imagery is showing scattered light rain
showers across parts of western and central South Dakota. Showers
are expected to increase in coverage and spread east across the
region through early Monday morning. Isolated thunder is also a
possibility. CIGS and VSBYS could be reduced temporarily under any
stronger showers or thunderstorms, most likely at the KABR or
KATY sites. Also can`t rule out patchy fog development across the
region early this morning. Winds will switch to the northwest as
the associated cold front works from west to east across the




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