Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 221733 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1133 AM CST Thu Feb 22 2018

Issued at 1129 AM CST Thu Feb 22 2018

Aviation discussion updated below for 18Z TAFs.

UPDATE Issued at 1102 AM CST Thu Feb 22 2018

Delayed onset of snowfall across the CWA based on upstream radars
and latest model data. This did not affect overall snow
accumulations much as we are still expecting a general 2 to 4
inches across eastern SD into west central MN. Did section off the
northern CWA Winter Weather Advisory and changed the start time to
21Z. Other weather elements for today are generally in good shape
and no major changes to temps/winds/sky etc.


.SHORT TERM...(Today and Tonight)
Issued at 259 AM CST Thu Feb 22 2018

Temperatures across the area stalled early this evening in the
singe digits either side of zero, but looking to the south, our
soon to be source region has temperatures in the teens to around
20, so this is where we will go for highs today.

The main forecast concern in the short term is the snow potential of
course. CAMS and deterministic guidance are in generally good
agreement over the overall progression of the snow, with a somewhat
slower onset compared to previous guidance. Now look for snow to
enter the CWA from the south around late morning and north of
highway 212 after noon. Best forcing aloft, only around 5 to 10
microbars, occurs from the 21 to 03Z timeframe so headline timing
is fine. Did see an uptick in blended guidance QPF with an
expansion westwards, and as such have adjusted headlines. All
guidance, as well as SREF and GEFS plumes come in under warning
criteria so fairly confident that this will generally be a 3 to 5
inch system.

Also need to address that at times we lack saturation within the
dendritic growth zone, though only sporadically, and mainly as
profiles begin to saturate. Top down methodology has introduced
some isolated mention of freezing drizzle, however this probably
won`t be very impactful as soundings do quickly saturate.

.LONG TERM...(Friday through Wednesday)
Issued at 259 AM CST Thu Feb 22 2018

It looks as if the current long wave pattern will continue through
most of the long term forecast. Energy will continue to carve out a
western conus/west coast mid level trof, with the energy then
ejecting across the Rockies and plains.  One such pv anomaly will
move across the Central Plains on Saturday. Models have been fairly
consistent with this feature, and continue to produce some light
pcpn over mainly the eastern cwa.  Pcpn type should favor mostly
snow, although some patchy freezing drizzle looks possible both at
the beginning and end of the event. The rest of the period looks
mainly dry at this point with other systems tracking south of the
forecast area. Temperatures will likely average out near to a bit
below normal given the resident snow pack across the entire area.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1129 AM CST Thu Feb 22 2018

MVFR CIGs have arrived in KATY and expect this CIG category to
overspread the rest of the TAF sites later this afternoon into
early evening. -SN/SN will also move northward across the area
this afternoon, with IFR/MVFR VSBY and even LIFR VSBY at times.
CIGs may also dip into IFR during the peak of snowfall this
evening. Expect improving conditions after 06Z tonight and
especially by Friday morning.


SD...Winter Weather Advisory from 3 PM this afternoon to midnight CST
     tonight for SDZ005>008-010-011.

     Winter Weather Advisory until midnight CST tonight for

MN...Winter Weather Advisory from 3 PM this afternoon to midnight CST
     tonight for MNZ039-046.



SHORT TERM...Connelly
AVIATION...TMT is the U.S. government's official web portal to all federal, state and local government web resources and services.