Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 270913

Area Forecast Discussion
National Weather Service Aberdeen SD
413 AM CDT Thu Apr 27 2017

.SHORT TERM...(Today through Saturday Afternoon)
Issued at 412 AM CDT Thu Apr 27 2017

Stratus deck continues to slowly slide southwest through the CWA and
has now moved into KPIR. Quite a few hi-res models have picked up on
this and offer up a slower clearing trend today. Followed the GLAMP
closely for sky cover trends today as it seems to have a good handle
on current situation. It appears after sunrise there should be a
slow erosion from west to east, with some breaks within the main
cloud deck as well. Therefore, expecting mostly cloudy skies for
eastern areas today while central SD eventually clears out. This
will also have a huge effect on temperatures as sunny areas across
central SD rise into the 50s while the eastern CWA remains in the
upper 30s and 40s. Still some cooler temps aloft today over eastern
areas as well.

Looking at some pretty cold temperatures settling in the next couple
nights as the surface high remains over the area with generally
light winds. Lows will be in the 20s for most areas and have dropped
MinT`s a few degrees from previous forecast and SuperBlend. Will
have to watch cloud cover as models show some residual moisture
between 925-850mb tonight. Then for Friday night things appear
mostly clear but soundings do suggest some degree of high cloudiness
could affect the area, therefore keeping temps up slightly perhaps.

As for precipitation, the short term is largely a dry period. The
system for late tonight and Friday barely glances the area, with
only the far southwest fringe of the CWA seeing slight chances for

.LONG TERM...(Saturday Evening through Wednesday)
Issued at 412 AM CDT Thu Apr 27 2017

As the period opens, a large low pressure system is progged to be
gathering strength over the four corners region of the swrn CONUS,
while dry high pressure is in control of the weather picture over
this CWA.  By Sunday evening, the swrn CONUS system should be
lifting north-northeast across the central plains, bringing some
precipitation chances to mainly the eastern third of the cwa. The
precipitation chances likely stick around through Monday while the
upper circulation begins to pull away into the Great Lakes Region.
Not gonna get too excited about snow accum potential just yet with
this system since it is still out there in day 4.5 to day 5.5
timeframe of the 7 day forecast. Current model solutions available
at the time this AFD is being written seem to suggest there is the
potential for a few inches of snowfall Sunday night into Monday (May
1st). Then, while this low is working north across the country`s mid-
section, a pronounced upper level longwave ridge is building along
the west coast, so once this upper low exits stage "east", the upper
flow pattern becomes one of chilly northwest flow, perhaps with a
couple of smaller transient mid-level shortwaves embedded within the
pattern. This time of year, more efficient surface insolation can
sometimes lead to cold air "instability" showers when mid-level
impulses work through in these northwest flow patterns. So, in
addition to trends/changes in the Sunday night/Monday system, will
also want to continue monitoring for the potential for this
"sleeper" instability shower scenario mid to late next week, given
their shorter predictability horizon. Likely colder than normal
airmass is still influencing temperatures as the period opens. By
the end of the period, deterministic and ensemble thermal progs
would have temperatures at or above climo normal.


.AVIATION...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1243 AM CDT Thu Apr 27 2017

MVFR cigs will remain over the central and eastern CWA overnight and
into the morning hours before lifting to VFR levels and moving off
to the east during the early afternoon. VFR conditions will then
prevail through the remainder of the TAF period.




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