Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 231154 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
654 AM CDT FRI SEP 23 2016

.UPDATE...
Issued at 652 AM CDT FRI SEP 23 2016

See below for an updated aviation forecast discussion.

&&

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 334 AM CDT FRI SEP 23 2016

The early morning weather map showed a tight pressure gradient
overhead, with high pressure set up along the Manitoba/Ontario
border and low pressure organizing organizing across southwest WY to
CO. Plenty of low level moisture remains, some pockets of DZ and
visibilities dropping to around 2SM or less across portions of the
area, and especially over the higher terrain east near Summit.

Much of our weather will be dependant on the movement of the sfc low
to our southwest. Look for much warmer air and a line of clearing to
invade the southern third ofthe CWA late this afternoon. The steady
easterly winds will shift out of the southeast across the entire
area by 18Z, with the bulk of the warmer air in the form of 850MB
temps of 18-24C remaining across the southern half of the state
until closer to 00Z Saturday. The sfc low is expected to shift
northeastward, and stretch from western SD to eastern CO by 00Z this
evening, before focusing across western ND from 12-18Z Saturday.
Expect a strengthening low level jet to form tonight with 925MB
winds of 40-45kt. Despite this, limited moisture in the dry slot
will result in limited shower/thunderstorm activity.

Expect thunderstorm chances to be on the increase Saturday as the
cold front swings in from central SD. Skinny MLCAPE values jump up
to near 750-1000J/kg from 15Z on east of ABR, with strong sheer. The
focus for strong to possible severe thunderstorms will hug the SD/MN
border through 21Z, before shifting into western MN. The marginal
SPC risk for Saturday afternoon looks reasonable for now, although
it may be upgraded later today. Will include the potential for
strong to severe storms in the HWO for Saturday afternoon east. The
sfc low will slowly exit across southern Manitoba Saturday night,
with breezy westerly and eventually northwesterly winds lingering
through the day Sunday. 850MB temps will fall to 3 to 7C Sunday as
wrap around moisture attempts to sneak across the northern counties
thanks to the 500MB low sliding across ND/Manitoba bringing a
sizable trough across the Plains States.

.LONG TERM...(Sunday Evening through Thursday)
Issued at 334 AM CDT FRI SEP 23 2016

Right now, there is good agreement in the gsm 00z solutions. The 00Z
gfs has come more in line with the ecmwf regarding departure of an
upper low track/timing on Monday and Monday night. Superblend pops
basically dry out during said timeframe. Beyond that, model trends
are all basically the same, building/drawing an upper level ridge
into the region for the middle to latter portions of the upcoming
week. The gfs, canadian and ecmwf solutions all separate some low
pressure energy out of the current western CONUS upper level
longwave trof and tuck it back across the far swrn CONUS through
Tuesday. Even though all three gsm deterministic solutions are
reloading another western CONUS trof this upcoming week, the gfs and
canadian are slower to lift this swrn conus energy out onto the
central/northern plains. The ecmwf lifts this energy out faster
while developing this western CONUS longwave trof, bringing small
precipitation chances to this cwa mainly Thursday/Thursday night,
while the gfs trend is similar, just slower, bringing small
precipitation chances to this cwa Friday/Friday night which is just
beyond the scope of the current 7-day forecast.

Temp-wise, not much change in the extended period superblend
guidance. Agree with the previous shift that even though this
upcoming week is not jam-packed full of anomalous cold low level
air, any night time periods between Monday and Thursday that contain
clear/mostly clear skies and generally light winds will have the
potential to experience low temperatures cooler than current
guidance, especially in the typical cool-spots and low lying areas.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday Morning)
Issued at 652 AM CDT FRI SEP 23 2016

A mix of mvfr/ifr cigs and vfr/sub-vfr visbies is expected
to persist across the region this morning, with some
improvement expected as the day wears on, particularly at the
KABR, KPIR and KMBG terminals. As a warm front gradually pushes
to the north, drizzle/fog is supposed to eventually be replaced
by a partly sunny sky and scattered shower/thunderstorm
potential. By early this evening, most of the area should be
experiencing vfr flying conditions, with perhaps a return to some
shower/isolated thunderstorm chances by mid-morning on Saturday.
Look for breezy easterly surface winds today to gradually become
south tonight before switching around to some component of
westerly wind on Saturday.

&&

.ABR Watches/Warnings/Advisories...
SD...NONE.
MN...NONE.
&&

$$

UPDATE...Dorn
SHORT TERM...KF
LONG TERM...Dorn
AVIATION...Dorn



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