Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 201620

Area Forecast Discussion
National Weather Service Aberdeen SD
1020 AM CST Mon Feb 20 2017

Issued at 1016 AM CST Mon Feb 20 2017

Continue to update forecast as needed for final band of rain
showers that is just east of a line from MBG to PIR. 1/4SM vis has
been reported over ATY and areas south. Updated to include
widespread fog in this area for another hour or so.


.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 18Z TAFS through 18Z Tuesday Afternoon)
Issued at 1016 AM CST Mon Feb 20 2017

MVFR ceilings/vis are pretty standard. However, ATY is dealing
with 1/4sm vis. Expect improving conditions in a couple of hours
as the deep moisture exits east and winds increase. Most locations
will get gusts of 20-25kts behind the last band of rain that is
currently set up near MBG to PIR that is moving northeast around
25kts. No more lightning is anticipated. Expect winds to diminish
to under 10kts tonight, before increasing slightly out of the
southwest during the day Tuesday.




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