Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 072058

Area Forecast Discussion
National Weather Service Aberdeen SD
258 PM CST Thu Dec 7 2017

.SHORT TERM...(This Evening through Friday)
Issued at 257 PM CST Thu Dec 7 2017

The 500mb pattern still features a trough over much of North
America, with a ridge across the western states. Continue to monitor
radar returns that are associated with mid clouds of 4K to 8Kft. The
best chance of any flurries at 20Z are southwest of Pierre.
Otherwise, dry conditions remains as the sfc trough continues to
slowly slide east across the Dakotas. This feature will be over our
eastern counties around 03Z, and exit to our east shortly after 06Z
Friday. Once again, we won`t be able to rule out some flurries, and
possibly even some brief freezing drizzle as we move closer to the
morning commute Friday and into the daytime hours. This is thanks to
dry air aloft, with the DGZ way up around 600mb and not having
enough moisture to support snow growth. Much of the sounding is dry,
so if anything does develop, it will be light. Only kept flurries in
the forecast for now, given the low potential for any precipitation.

An additional sfc trough will sink in from eastern ND and northern
MN late in the day. The best chance of seeing anything other than
flurries will be over our far northeastern counties by late
afternoon. The pressure gradient will be on the increase by the end
of the day as well. With most locations having limited snow on the
ground, and highs in the 30s during the day, have kept the potential
for blowing snow to our northwestern counties.

.LONG TERM...(Friday Night through Thursday)
Issued at 257 PM CST Thu Dec 7 2017

Will the positive pna pattern (warm ridge west/cold trof east) ever
end? Recently posted temperature outlook guidance (8-14 day and 30
day outlooks) would suggest we`ll be stuck in this pattern all the
way to beyond Christmas!

Longer range deterministic model output does suggest that there will
be a few hybrid (and moisture-starved) clipper-type systems working
through the region in this north-northwest flow regime between
Friday night and next Thursday, bringing a quick shot of light
precipitation potential to somewhere over the Dakotas and Minnesota.
Will let forecast guidance/collaboration determine where/when/how
much precipitation mention shows up in the day 2-7 forecast periods.
But, suffice it to say, not too much to get excited about, precip-
wise, in the out periods right now.

The ensemble temperature trends still support a warm up Saturday and
Sunday, before the arctic front "tug-of-war" sets up next week.
Given the forecast area`s position amid the low/mid level thermal
gradient between warmer than climo normal air to the west and colder
than climo normal air to the east, and the deterministic models`
recent propensity for flip-flopping on low level thermal progs
beyond Sunday, forecast confidence in day 4-7 high/low temperature
forecast is rather low right now. Again, will let the chips fall
where they may once forecast guidance/collaboration is completed.


.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1129 AM CST Thu Dec 7 2017

Mid to High clouds continue to move into the region, though VFR
conditions are expected to persist until late this evening. After
which KABR and KATY are expected to transition to MVFR CIGs. KPIR
and KMBG should also transition to MVFR CIGs early Friday
morning. May see some light snow flurries during the overnight
hours for eastern SD, but do not expect visibility to be affected




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