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Area forecast discussion
National Weather Service Des Moines Iowa
1037 PM CST Mon Dec 9 2019

Discussion.../tonight through Monday/
issued at 319 PM CST Mon Dec 9 2019

Weather has calmed down quite a bit with our attention now
turning to cold temperatures over the next few days. The MS valley
mean trough will be our main weather influence until heights
begin rising by midweek, with two brief, minor precip windows
through that transition. More progressive and milder lower
amplitude flow will be in place to end the work week as we nudge
back to normal with brief precip chances around Thursday, and
then intermittent precip chances from the weekend into early next
week as the fast Pacific flow eventually develops a broad mean
trough across much of the Continental U.S..

Our brisk northwest winds should diminish this evening with lows heading
toward +/- zero north and the teens south. Confidence is not
great, but mentioned a short period of flurries north tonight with
low level moisture in favorable -12c or less temps. This cold
temperature regime will be in place through Wed with similar lows
and highs no better than the single digits north to lower 30s

Pops will return to the forecast Tue night when a dusting of snow
is possible as the last short wave traverses our current mean
trough. Much of the mid level forcing stays to our north, but
lower based frontogenetic and warm/Theta-E advection support may
produce a quick dusting of light snow. The next precip window will
be around Thursday when a fairly phased trough passes through the
Midwest. Models are in fairly good agreement with timing and two
primary short waves, the northern mainly driving our weather.
Forcing will be deep, but somewhat moisture starved, so northern
sections will see the pops and better potential for saturation.

By late Friday the passage of several short waves will begin lowering
heights and returning our temps back closer to normal, or just
below. This will introduce several periods with minor, low
confidence precip chances outside of a small break late Sat into
sun. The more organized lift will pass to our south sun into Mon,
but for the most part any of these precip windows will be minor.


Aviation.../for the 06z tafs through 06z Tuesday night/
issued at 1037 PM CST Mon Dec 9 2019

Few changes to going package. Another quick moving system with
little moisture is initially going to bring some mid level to
lower MVFR cigs across the northwest at kfod between 09 and 15z
with a brief period of MVFR possible at kdsm between 15-18z.
Otherwise, winds continue to relax toward 12z with a gradual shift
to west southwest aft 23z tues. A few flurries are also possible
with the lower cigs but confidence low on coverage. /Rev


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