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Area forecast discussion
National Weather Service Des Moines Iowa
327 PM CST Tue Nov 19 2019

Discussion.../tonight through Tuesday/
issued at 327 PM CST Tue Nov 19 2019

Mixing has increased this afternoon across the southwest half of
Iowa with west to northwest winds and sunny skies. This has led to
highs exceeding expectations with mid to upper 50s. In the
northeast, status has stubbornly remained with cooler readings in
the 40s. A surface ridge is currently near the Missouri River and
will pass through the state tonight. Given the proximity of the
ridge, slackening winds are expected into the evening becoming
light and variable. Some patchy fog is expected to develop with
residual moisture from the rain of last evening and have continued
the mention in the grids.

Shortwave in the southwest United States moves quickly northeast
on Wednesday with continuing warm advection and increasing
moisture advection. Clouds thicken through the day as isentropic
lift increases and temperatures topping out mainly in the 50s.
Robust forcing by the late afternoon/early evening will lead to an
expansion of rain in Nebraska into western Iowa with mean flow
advecting the precipitation rapidly north and east. The entire
forecast area has categorical pops by late evening into the early
morning hours as the strong forcing passes through the state.
Elevated instability from 100-300 j/kg shows up overnight
associated with the surface low and frontal boundary. A few
rumbles of thunder are expected in this narrow axis prior to
frontal passage during the early morning hours. Once the front
passes, precipitation should cut off relatively quickly as
subsidence and cold advection increase on the backside of the
system on Thursday morning. Some light snow remains possible in
the far northwest corner of the forecast area at this time, but
any accumulations will remain very light.

Surface ridging will overspread the state late Thursday into early
Friday keeping readings cool with some clearing. Forcing grazes
southern Iowa later Friday into Friday night associated with a
weakening upper low. However, any precipitation that may occur
will fight drier near surface air underneath the surface ridge.
This will lead to mainly virga although an isolated light shower
does remain possible. Thereafter, the weekend is expected to be
quiet with slowly warming temperatures as upper ridging builds
across the central United States. A more active pattern appears
forthcoming during Thanksgiving week and this will need to be
watched closely.

&&

Aviation.../for the 18z tafs through 18z Wednesday afternoon/
issued at 1140 am CST Tue Nov 19 2019

Stratus continues to hang tough across eastern Iowa affecting Kalo
and kmcw this afternoon. However, much of the areas will see
unrestricted ceilings and visibilities this afternoon and tonight
with west to northwest surface flow. Mid and high clouds will
drift over the state tonight with light surface winds. This may
lead to some light fog development, especially in eastern areas
tonight with MVFR to locally IFR conditions. Surface winds are
forecast to increase from the southeast on Wednesday morning as
mid level ceilings begin to increase.

&&

Dmx watches/warnings/advisories...none.

&&

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