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fxus63 kdmx 201036 
afddmx

Area forecast discussion
National Weather Service Des Moines Iowa
536 am CDT sun Oct 20 2019

..updated for 12z aviation...

Discussion.../today through Saturday/
issued at 316 am CDT sun Oct 20 2019

The fog that developed Saturday night has largely remained in place
across eastern to southeast Iowa early this morning. This is
particularly evident in the GOES nighttime microphysics rgb where
behind departing stratus the fog becomes evident - especially along
the Mississippi River valley and tributaries. At this time only a
handful of eastern sites within the cwa, including Ottumwa and
Waterloo, have seen visibilities drop below 1/4 mile. Elsewhere
across the area, drier air has prevented much in the way of fog
development.

Expect to see fog dissipate within a couple hours of sunrise as
daytime mixing commences. The surface high will slide off to the
east while a cut-off low will deepen over the north-Central
Plains and push east towards Iowa. Expect to see showers and
thunderstorms moving into eastern portions of the cwa by 18z,
spreading across the state through the overnight. While shear and
helicity parameters are quite strong, storms will struggle
thermodynamically and thus expect thunderstorms to remain non-
severe. Southern and central Iowa will clear out by Monday
morning, while northern Iowa will continue to see lingering
showers throughout much of the day in the wrap around portion of
the low. Monday will be breezy will cold air advection across the
state keeping highs in the 50s. Expect to see cold air advection
increase Monday night through Tuesday with increasing winds.
Soundings indicate northwest winds of 40+ knots at the top of the
mixed layer both days, which would push much of the area into
advisory criteria.

By Wednesday a quick shortwave scoots across northern Iowa ahead of
a larger trough to dig across the plains and into Iowa. This will
bring a strong push of cold air to the state, with highs Thursday in
the low 40s across northern Iowa and struggling to reach 50 across
the south. Quantitative precipitation forecast is fairly low with this system, however with cooler
temperatures, a rain/snow mix is possible during the overnight
Wednesday into Thursday. Any snow that does mix in should be of
no impact. Expect to see a bit of return flow with brief
rebounding temperatures into Saturday before another strong push
of colder air for early next week.

&&

Aviation.../for the 12z tafs through 12z Monday morning/
issued at 536 am CDT sun Oct 20 2019

IFR to LIFR visibility across eastern and southeast Iowa with
dense fog developing overnight. Expect this to dissipate by 14z
with continued overcast skies. Chances for showers and a few
thunderstorms late Sunday evening through the overnight. Have
kept thunder mention out of tafs for now due to uncertainty in
timing or extent of embedded convective core.

&&

Dmx watches/warnings/advisories...
dense fog advisory until 9 am CDT this morning for iaz028-039-
050-062-075-085-086-095>097.

&&

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