Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 161204

National Weather Service Des Moines IA
704 AM CDT Sun Oct 16 2016

...Updated Aviation Discussion...

.SHORT TERM.../Today/
Issued at 349 AM CDT Sun Oct 16 2016

The main focus for today was on the dense fog lingering
through the mid morning and then temperatures this afternoon. The
dense fog axis extends from the northeast corner of the forecast
area along Highway 20 southward to the Missouri border. A sharp
gradient has set up along the Highway 20 corridor and not likely
expand much northward as a weak boundary has set up over northern
Iowa. However, the boundary has appeared to retrograde slightly
northward allowing for the dense fog to spread to just north of Fort
Dodge. Regardless, expanded the Dense Fog Advisory to include the
Highway 20 corridor and extended it until 14z. Low confidence in
further expansion northward due to the uncertainty of how far north
the aforementioned boundary moves. The humidity remains across the
forecast area today and with the fog likely to dissipate by 15z over
the advisory location, decent mixing develops towards midday into
the afternoon. Even with the low stratus hanging around for much of
the day, temperatures should have no trouble rising well into the
70s to around 80 today with enough WAA and the warm start this
morning. Leaned closer to the NAM for the maximum temperatures.

.LONG TERM.../Tonight through Saturday/
Issued at 349 AM CDT Sun Oct 16 2016

Warm advection will be underway at the beginning of the period as
southerly flow increases across the state ahead of approaching
surface trof. Theta-E advection will also accompany the warmer air
and this will lend itself to a few showers and storms in the far
north this evening, however the bulk of forcing and strongest
advection will quickly lift northward into MN and WI along with
any potential precipitation by late tonight. Pressure gradient in
the west will be quite weak overnight as with light winds and
ample low level moisture, fog is once again expected in these
areas late tonight with the potential of seeing localized dense
fog once more. Warm sector will be across the state on Monday with
warmest readings in thermal ridge just south of IA. Expect near
record highs across the southern half of Iowa where deep southwest
flow and proximity to the thermal ridge will push readings to
between 85-90 degrees by afternoon.

Surface front will pass through the state on Monday night with
bulk of forcing remaining well north of Iowa closer to track of
surface low and upper system. Therefore, frontal passage will
likely be dry across Iowa as cooler air arrives. The cooler
readings will continue into the later half of the work week
although not as cool as previous forecast. This is mainly because
both GFS and Euro deepen trof farther into the eastern United
States with main thermal trof remaining north and east of the
state. The threat for rainfall will be minimal through the end of
the week with only a few slight chances of precipitation around
mid week with passage of upper trof.


.AVIATION.../For the 12Z TAFS through 12Z Monday morning/
Issued at 704 AM CDT Sun Oct 16 2016

LIFR/IFR visibility and ceilings due to fog will continue to
impact ALO, DSM and possibly FOD and OTM through around 15z. The
stratus looks to lift with the winds increasing later this morning
into the afternoon. Fog looks to develop again tonight into Monday
morning and have introduced MVFR visibility and ceilings past 06z


Dense Fog Advisory until 9 AM CDT this morning for IAZ027-028-



SHORT TERM...Podrazik
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