Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 142104
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
304 PM CST Sun Jan 14 2018

.SHORT TERM.../Tonight through Monday/
Issued at 304 PM CST Sun Jan 14 2018

Initial shortwave trough has impacted the southern forecast area
much of the day and will continue to push southeastward into the OH
valley region this evening. Stronger upper trough digging through ND
will continue to dig southeastward through the forecast area
tonight, with the upper low closing off and remaining in place
across the region into Monday. At the surface have an area of low
pressure stretching from far SW Ontario through nrn MN and into NE
SD. Strong southerly flow in advance of this system with WAA in
place today and moisture advection. Band of snow oriented along the
sfc trough axis and ahead of it in vicinity of the baroclinic zone
aloft, with a westward extent along the cold front moving through SE
ND and wrn SD. As the low drops southeastward into the state this
evening, the area of snow to move through from northwest to
southeast bringing a burst of fairly intense snowfall to the
forecast area. Snow already beginning to move into far northwest
Iowa, and should continue to translate southeast through midnight.
Expect a brief period of 1-3 hours where visibilities drop to around
1-2 miles or less with the snow. Given the brief burst of snow,
expect a quick 1-2 inches, especially in the northeastern half of
the forecast area. As the snow tapers off, northwest winds are
expected to pick up behind the cold front. Strong sfc pres gradient
in place, with an isallobaric push toward 06-09z across much of the
area, far south 09-12z. Bufkit winds showing 25 to 30 kts in the
mixed layer which given the strong CAA should allow much of these
winds to transfer to the sfc. Therefore expect sustained winds
behind the front of around 25 mph, with gusts possible to 35-40 mph.
This should result in some areas of blowing snow late tonight into
early Monday. Some concern as to how low visibilities may be reduced
given the fact that the strong winds will occur after the end of the
snow. Therefore expect mainly vsbys into the 2-5 mile range with the
winds, and more widespread drifting of snow across roads into Monday
morning. Even though winds stay up into Tuesday afternoon/evening,
the snowpack should blow itself out, with the snow becoming
compacted sometime late tonight into early Monday. Therefore just
kept the BLSN mention in through 18z Monday.

Temperatures to fall with the increasing winds tonight behind the
front, will send wind chills falling late tonight into the 20s to
30s below range. These low values continue into Monday, with a few
hours where they may rise above wind chill advisory/warning
criteria. However values will dip again into Monday evening,
therefore have upgraded the north into a Wind Chill Warning starting
late tonight, and expanded the advisory to the south across much of
the forecast area.

.LONG TERM.../Monday night through Sunday/
Issued at 304 PM CST Sun Jan 14 2018

Another surge of cold air to filter southward into the forecast area
as the upper trough continues to wobble across the area aloft. This
should result in a blanket of low stratus in place and possibly some
flurries in the cyclonic flow pattern aloft Monday night into
Tuesday. Additionally, winds to remain up through Monday night into
Tuesday with the arctic air in place. This will keep wind chills in
the 20s below to 30s below range into Tuesday morning as
temperatures drop into the 5 below to 15 below range Tuesday night.
Therefore continued the wind chill headlines into Tuesday morning.

Upper trough to begin to shift eastward late Tuesday with some
moderation in temperatures expected for mid-week and upper ridging
across the central US. Therefore have dry conditions for Tuesday
into Friday, with temperatures warming each day. Expect temps into
the 30s and 40s toward Friday as WAA picks up ahead of deepening
southwestern US upper trough. This system will eject northeastward
through the central US and is on track to bring the next widespread
chance of precipitation to the state. Currently temperatures will
hover around freezing and could bring a rain/snow mix to much of the
forecast area for mainly late Saturday into Sunday.

&&

.AVIATION.../For the 18Z TAFS through 18Z Monday afternoon/
Issued at 11590 AM CST Sun Jan 14 2018

Very light snow with MVFR to low VFR CIGS in place this afternoon.
Gusty southerly winds at times. This evening another wave of snow
to move through with VSBYS dropping to around 1 mile at times
with the snow. Winds to shift around to the northwest tonight, and
increase to become strong and gusty. Some BLSN possible
especially in the north. Right now have highlighted with low
VFR/MVFR VSBYS.


&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from 3 AM Monday to noon CST Tuesday for
IAZ027-028-038-039-044>050-057>062-070>075-081>086.

Wind Chill Warning from 3 AM Monday to noon CST Tuesday for
IAZ004>007-015>017-023>026-033>037.

Wind Chill Advisory from 3 PM Monday to noon CST Tuesday for
IAZ092>097.

&&

$$

SHORT TERM...Beerends
LONG TERM...Beerends
AVIATION...Beerends



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