Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 221151 AAA

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
551 AM CST Wed Nov 22 2017

Issued at 548 AM CST Wed Nov 22 2017

See below for an aviation forecast discussion for the 12Z TAFs.


.SHORT TERM...(Today through Friday Afternoon)
Issued at 356 AM CST Wed Nov 22 2017

An area of low pressure, currently over Alberta will track
southeastward across the region today. Warm air advection
associated with this system could bring light pcpn to the
northeast portion of the CWA. With a substantial dry layer to
overcome, have removed most of the pcpn in this CWA. Warmer
temperatures will move into the region today with highs ranging
from the mid 30s, in western MN, to the upper 50s and low 60s,
west of the Missouri Valley.

An upper level ridge, along with southwesterly winds will usher in
much above warmer temperatures into the region on Thursday. Highs
should reach the upper 40s, in northeast SD, to the 60s and 70s,
along and west of the Missouri Valley. Timber Lake and Pierre could
see record to near record high temperatures on Thursday. The warm
airmass will remain over the region Thursday night with low only in
the 30s and 40s. These low temps are 20 to 25 degrees above normal
for this time of year. A cold front crossing the region on Friday
will bring a slight chance for rain, along with gusty northwest
winds. Sustained winds of 25 to 35 mph with gusts exceeding 45 mph
will be possible on Friday. A wind headline will likely be needed in
the near future.

.LONG TERM...(Friday Evening through Tuesday)
Issued at 356 AM CST Wed Nov 22 2017

The CWA is sitting under northwest flow aloft until Monday when a pv
anomaly moves into the central CONUS, forcing heights to respond by
becoming southwest aloft. The flow pattern remains swrly aloft until
the system is clear of the CWA. So, the general trend of a dry
weather forecast through Monday continues. Beyond that, there are
some precipitation chances mentioned in the forecast. Tonight`s 00Z
GFS/ECMWF models depict a low pressure system undergoing lee-side
intensification and track a surface low out of northeastern Colorado
into western/northwestern Iowa Monday night and on over into
Wisconsin Tuesday.  Both models are generating more than 0.25 inches
of water equivalent now, and both models have noted a considerable
trend downward in temperatures during the Monday night into Tuesday
time period, and also have some support from the 00Z Canadian
solutions regarding low level thermal progs. Obviously a lot can
change between now and next Tuesday. There are still way more
questions than answers regarding how this potential day 6/day 7
weather scenario will play out. Still too far out to start
"bracketing" potential snowfall amounts. However, at least this go
round, there is a signal for some snow potential early next week.
Will have to continue monitoring forecast trends for said timeframe.

As far as temperatures go, if the 00Z deterministic/ensemble output
is halfway accurate, much of the forecast period should be much
above late November climo normal. In fact, some of the NAEFS
Ensemble SA table 850hpa temperature anomaly guidance tonight has a
good portion of Sunday into Monday between 1 and 2 standard
deviations above normal. Referencing the earlier mentioned cool down
showing up in the 00Z models for Monday night into Tuesday: this is
a notable downward trend in forecast temperatures, and it`s likely
that in-house extended temperature guidance (which is typically
slower to respond to "significant" swings in model-progged
temperatures) is too warm for the current low level-modeled thermal
progs. If the models become persistent with cooling things down
below freezing Monday night and Tuesday, will probably see guidance
catch up within the next day or two.


.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 548 AM CST Wed Nov 22 2017

Expect good VFR at all four terminals over the next 24 hours.




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