Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 110932
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
332 AM CST Mon Dec 11 2017

.SHORT TERM.../Today through Tonight/
Issued at 332 AM CST Mon Dec 11 2017

The forecast concern is focused on the clipper system anticipated
to bring blustery winds later this morning and into the afternoon
hours. The biggest change to the forecast was increased winds
several knots across the western half of the forecast area as the
strong PV anomaly punches into the state by around 15z this
morning. Should see some stout initial gusts exceeding 40 knots
across the west and can expect the blustery winds to persist into
the afternoon hours with the strong mixing developing. Winds atop
the mix layer range from 35-45 knots. Utilized the ARW but the
latest NAM, RAP, and HRRR are in fairly good agreement with the
winds coming in stronger than previously anticipated. With the
increase in winds and wind gusts today, issued a wind advisory for
western portions of the forecast area. Cannot rule out some gusts
to 45 mph at locations east of this advisory area, but seems to
be a limited time frame if they do occur. The other concern was
precipitation chances but this system lacks any significant depth
of moisture as the strong PV anomaly pushes south across Iowa
today. Have mainly rain mentioned today with no ice introduction
into the column and surface temperatures warming to above freezing
by the time the mainly forcing moves through the area.

.LONG TERM.../Tuesday through Sunday/
Issued at 332 AM CST Mon Dec 11 2017

Large amplified trof over the eastern United States will persist for
the rest of the week as several short waves drop into the backside
of the trof.  The first of these will arrive on Wednesday with a
cold front diving through the state during the day.  Winds will pick
up in the wake of the front with cold advection and tight pressure
gradient aiding the strong winds.  In addition, near surface mixing
will also help in momentum transfer of the stronger winds aloft.
Strongest forcing will remain to the northeast of the state with
precipitation likely staying in Minnesota and Wisconsin.  Thermal
ridging ahead of the front will be across the state to start the day
with unseasonably mild temperatures, especially in the south before
the cold air arrives by later in the day.  The colder air will
remain across the state on Thursday with a weak reinforcing
shortwave passing through the state later in the day.

The upper pattern tries to become a bit more zonal toward next
weekend as the eastern trof become much less amplified.  This should
allow warmer air into the state by next weekend with temperatures
above normal.  However, there remains a decent amount of uncertainty
with models having a difficult time resolving the numerous
shortwaves in the flow both spatially and temporally into the
weekend.

&&

.AVIATION.../For the 06Z TAFS through 06Z Monday night/
Issued at 1125 PM CST Sun Dec 10 2017

Main forecast concerns for this TAF period continue to be cloud
cover, precipitation, and winds. Alberta Clipper is moving into
North Dakota now with clouds and light precipitation moving over
eastern North Dakota and Minnesota. This precipitation should
stay north of the area with ceilings above any restrictions
tonight into early Monday morning. High confidence that clouds
will increase with bases lowering into MVFR restrictions over the
northern terminals from mid-morning into early afternoon. These
same terminals also have the best chance for rain and/or snow late
morning into the afternoon. Farther south at KDSM and KOTM,
confidence is lower now on whether MVFR ceilings will arrive. For
now, have maintained high end MVFR at KDSM while removing MVFR
restrictions at KOTM. Winds will also become gusty from the
northwest in the morning and persist through the afternoon into
the evening. MVFR ceilings will give way to VFR conditions at all
terminals in the evening hours as well.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 10 AM this morning to 6 PM CST this evening
for IAZ004-005-015-023-024-033>035-044>047-057>059-070>072-081-
082-092-093.

&&

$$

SHORT TERM...Podrazik
LONG TERM...Cogil
AVIATION...Ansorge



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