Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 201130 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
530 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 pattern 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 12Z TAFS through 12Z Tuesday Morning)
Issued at 524 AM CST Mon Feb 20 2017

A few showers are moving through the area this morning, but are
expected to exit to the east by early afternoon. KATY is dealing
with some IFR/MVFR stratus this morning, but should improve to VFR
this afternoon. All other taf sites are forecast to remain VFR
through the period. Southeast winds will become west to northwest
behind the low but will diminish to light and variable tonight.




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