Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 251700 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1200 PM CDT Tue Oct 25 2016

Issued at 1148 AM CDT TUE OCT 25 2016

See below for an aviation forecast discussion for the 18Z TAFs.

UPDATE Issued at 942 AM CDT TUE OCT 25 2016

Made a few adjustments to the wx/pop/qpf grids this morning to
capture current radar trends and latest available short-term cam
output. Also brought back slt chc T mention across portions of the
central and southeastern cwa for this afternoon into this evening.
No changes planned to winds or temperatures at this point.

UPDATE Issued at 623 AM CDT TUE OCT 25 2016

See updated aviation discussion below.


.SHORT TERM...(Today through Thursday Afternoon)
Issued at 340 AM CDT TUE OCT 25 2016

Shortwave energy currently crossing Arizona and Utah will track
northeastward into the Dakotas later this afternoon. There is decent
moisture advection ahead of this system with PWATS two to three
standard deviations above normal. Specific humidity is also fairly
high, especially along and east of the James River valley. Not
surprisingly, ESRL`s extreme probability plot highlights
northeastern SD and western Minnesota for pcpn amounts exceeding the
90th percentile. The excellent available moisture will combine with
isentropic lift associated with the shortwave to produce a much
needed rainfall event in northeast SD and western Minnesota. Based
on expected QPF amounts, record rainfall is possible in Sisseton

The system should depart the area late tonight with leftover low
stratus possible over most of the CWA. Where skies are able to clear
tonight/Wednesday morning, then fog will be possible. Felt stratus
was more likely thus have removed the mention of fog.

WAA developing Wednesday night will continue through Thursday with
highs reaching the upper 60s, to the mid 70s.

.LONG TERM...(Thursday Evening through Monday)
Issued at 340 AM CDT TUE OCT 25 2016

Mid level ridging will be dominant over the central part of the
country Thursday night through the day Friday, then gets dampened as
a shortwave trough tracks across the region Friday night and
Saturday. Ridging then builds back over the area until another
shortwave trough approaches and looks to slide through Monday night,
leaving southwest flow in its wake on Tuesday.

At the surface, the region will be situated between high pressure to
the east and low pressure to the west when the period begins, with
the low and its associated frontal boundary set to slide across the
area late Friday afternoon/Friday night. GFS and ECMWF move the
boundary through dry, while GEM brings precipitation to the western
CWA. Will stick with some small pops there for now. High pressure
will bring a return to dry conditions Saturday afternoon through
Sunday night before another system brings possible precipitation
chances late in the period.

Temperatures will be a bit of a roller coaster through the period.
Highs will be in the 60s on Friday, before cooling back into the 50s
on Saturday. Mid 50s to lower 60s will be common Sunday and Monday,
before a cooler day with highs in the 50s returns on Monday.
Overnight lows will be in the 30s to lower 40s, with Saturday night
being the coolest of the period.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1148 AM CDT TUE OCT 25 2016

Areas of rain are starting to fill in on radar across the forecast
area, but none of it is directly over a terminal yet, except
perhaps at KABR where light rain returns appear to be filling in
just southwest of the terminal moving east-northeast. Still
appears as though the chances for rain at KMBG and KPIR will only
last a few more hours, while the likelihood of rain
developing/moving over the KABR and KATY terminals will continue
to increase into this evening before diminishing later tonight.

Stratus clouds have been slow to develop this morning, although
cig/vis plots and mvfr/ifr satellite enhancement suggests there is
a slug of fog/low clouds slowly lifting/expanding northward out of
Nebraska into south central South Dakota, so it is still entirely
possible that periods of MVFR/IFR conditions will develop at some
point during the TAF valid period (especially KABR/KATY).
Wherever the western edge of low clouds ends up being later
tonight, could see some fog development (possibly KMBG/KPIR).




LONG TERM...Parkin
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