Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 231713
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1113 AM CST Tue Jan 23 2018

...Updated Aviation Discussion...

.SHORT TERM.../Today through Tonight/
Issued at 322 AM CST Tue Jan 23 2018

Area of low pressure that impacted Iowa on Monday is moving into
Lower Michigan now and will continue to move swiftly northeast
today. A drying up deformation zone with light snow is over
central Iowa now and will continue to diminish quickly through 6
am as drier mid-level air arrives. A large stratus shield is
currently in place through the eastern Dakotas and western
Minnesota and extending into Iowa and Missouri. There is a clear
area that is moving south through central Minnesota. This clearing
patch is represented well by a weakness in the short term
guidance relative humidity field and should reach far northern
Iowa before rotating back to the northeast. Therefore, mostly
cloudy conditions overall today with southwest Iowa having the
best chance of clearing by this afternoon.

The gusty northwest winds will diminish through the day as the
pressure gradient relaxes and the mixed layer winds weaken.
Another shortwave will pass over Iowa tonight. This system will
be moisture starved but enough saturation may occur over southern
Iowa for a few flurries to occur. Temperatures today will be
tempered over the snow field across the north with highs in the
mid 20s while readings in the south reach the mid 30s. Lows
tonight will range from the low to mid teens north to mid 20s
south.

.LONG TERM.../Wednesday through Monday/
Issued at 322 AM CST Tue Jan 23 2018

The long term forecast period is mild and uncharacteristically
quiet for the season. From Wednesday through Friday a mid/upper
level ridge will move over the region, bringing warm and clear
weather for the most part. Temperatures will climb into the 50s at
least in our southern counties on Thursday and Friday, with
overnight lows above freezing Thursday night. There is some
question as to how the snow laid down across the northwest by
yesterday`s system will respond to this warm air advection, and
vice versa, but with such persistent warmth and sunshine believe
we will see good melting and by the end of the week temperatures
should approach the lower 40s even in that area.

By Friday a broad trough will be moving over the Rockies and
toward the Midwest, pushing a cool front across Iowa around Friday
night and moderating temperatures somewhat for the weekend. Even
so, readings should remain above normal, and it appears likely
that moisture flow and associated precipitation in advance of the
surface front will be largely shunted southeast of our area across
Missouri and Illinois, with just some low rain/snow chances
across our far southeastern counties at this time and no impacts
apparent. This system will be followed by another brief period
early next week, around Monday or Tuesday, leading to more warming
during that period.

&&

.AVIATION.../For the 18Z TAFS through 18Z Wednesday afternoon/
Issued at 1108 AM CST Tue Jan 23 2018

MVFR stratus will continue throughout much of the TAF period and
looks to even lower to IFR and possibly LIFR late tonight into
Wednesday morning. There is a break in the stratus moving south
that looks to briefly move through FOD and possibly DSM this
afternoon. Thus, a short window of VFR condition for ceilings
mentioned at FOD. Lower confidence to mention at DSM as stratus
looks to fill back in later this afternoon.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...Donavon
LONG TERM...Lee
AVIATION...Podrazik



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