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Area forecast discussion
National Weather Service Des Moines Iowa
537 PM CST Fri Dec 13 2019

Discussion.../tonight through Friday/
issued at 334 PM CST Fri Dec 13 2019

The wintry mix of precipitation from this morning and early
afternoon has moved east of Interstate 35 and is diminishing in
areal coverage. Impacts this afternoon have been limited by rising
Road temperatures which have responded to solar radiation that has
penetrated the cloud cover. By mid afternoon, Road temperatures have
risen above freezing south of Highway 20 and in the area that was
receiving freezing rain. Farther north the precipitation type has
been mainly light snow.

A cold front over South Dakota will pass through the state this
evening and will have a trailing stronger push of cold advection
that will arrive after midnight. A broad area of stratus will
accompany the colder air overnight. In addition to the stratus,
areas of fog will also be possible. As of now, drizzle does not
appear to be much threat with the saturation layer expected to
remain relatively shallow. Did maintain a freezing drizzle mention
over the far east for a short period overnight where better moisture
depths are achieved.

Saturday will be cold as Canadian high pressure begins to move into
the state. High temperatures Saturday will be in the single digits
north to the 20s south. Saturday night will be quite cold north with
good radiational cooling conditions setting up. Overnight lows of 5
to 10 below are expected north to around 10 above far south.

The next system to impact the region will arrive late Sunday
afternoon and persist into early Monday as low pressure develops
over the Southern Plains with a deformation band of snow developing
in vicinity the stronger Theta-E advection north into Missouri and
into far southern Iowa. The x factor with this system will be the
aforementioned Canadian high pressure that will remain situated over
southern Minnesota/northern Iowa during this period and will create
a significant amount of dry air to overcome and will set the
northern edge of the precipitation band. Current probabilities in
the forecast are likely over stretched north of Interstate 80,
mainly accounting for a northern buffer zone, but expect will be
able to contract these pops further south over the next few forecast
for the focus of light snow chances. Some accumulations will be
possible in Iowa but the greater impacts still look to be south from
Kansas, northern Missouri and into Illinois.

Quiet and cooler weather will follow for Monday and Tuesday with
high temperatures remaining in the teens and 20s and overnight lows
in the single digits and teens. Thermal ridging is on track for mid
next week which will bring warmer temperatures mid to late next week.


Aviation.../for the 00z tafs through 00z Saturday evening/
issued at 537 PM CST Fri Dec 13 2019

Generally poor aviation conditions overnight into Saturday morning
with low ceilings and visibilities. A cold front will pass
through the state tonight with strong northwest winds on the
backside. This will help visibilities improve but ceilings will
remain IFR to MVFR into Saturday morning. Some improvement in
ceilings is then expected into Saturday afternoon with mostly VFR
conditions by the end of the period.


Dmx watches/warnings/advisories...none.


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