Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 090005
AFDDMX

AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
605 PM CST Thu Dec 8 2016

.SHORT TERM.../Tonight through Friday/
Issued at 336 PM CST Thu Dec 8 2016

Fairly benign period before we transition to a more active one. High
pressure will nose into the region tonight and slowly push East
through Friday night.  There is a stratus deck over the Northeastern
third or so of the state that will continue to shift off to the East
as the high moves in and the upper flow becomes less influenced by a
short wave that is exiting.  I did keep some flurries in the far
East/Northeast through early evening...until that wave is far enough
East.  On Friday...despite a high moving in...there will be a a far
amount of moisture around and as we transition to some weak warm
advection ahead of the next system...we should see a fair amount of
mainly mid to high level cloud cover which will negatively impact
temps again.  Late morning into the evening some very weak mid level
forcing comes across which could produce some flurries across
Northern sections of Iowa but this really won`t be much different
from today.  Temps were nudged a degree or two lower mainly due to
cloud cover.

.LONG TERM.../Friday night through Thursday/
Issued at 336 PM CST Thu Dec 8 2016

Our system for Saturday through Sunday looking in a little better
agreement between the models though subtle differences still exist.
One main difference from a couple of days ago was that it now does
look like it will give us two shots of snow.  The first to come
Saturday into Saturday night across the North.  The main forcing
with this segment remains North of Iowa but does extend to about
Highway 20.  As previously discussed we will likely need headlines
out in the next couple of forecast issuances if models continue to
trend the way they are going.  We will be fairly warm on Saturday so
the snow that does occur will be a little wetter than what we will
see in later periods.

Sunday into Monday models differ on the location of the surface
features but they all drag a short wave across Iowa late Sunday
through Sunday night along with colder air.  The forcing with this
will be broader across Iowa and with the colder air...snow ratios
will be a little higher.  Much of central Iowa should see some light
snow during this period with an inch or two possible before
daybreak.

Monday into Tuesday will be a relative quiet period but a cold front
will push across the region Monday night into Tuesday.  This system
may be interesting.  While models right now are not advertising much
in the way of qpf...i believe this will change but in any
event...given the boundary...strength of the cold air and forcing
from a non descript shortwave that the models disagree on at the
moment...we should likely squeak out some light snow and with snow
ratios quite high it will be fluffy and accumulations will occur.
The question becomes when does the really big push of cold air and
wind come in.  We will really get cold for Tuesday night and
Wednesday...likely accompanied by stronger winds ahead of the
biggest push which could loft the light fluffy snow.

Cold temperatures will remain in place for the remainder of the week
with highs in the single digits and teens and lows above and below
zero.  Wind chill headlines may be needed around mid week if things
trend the way they are looking right now.

&&

.AVIATION.../For the 00Z TAFS through 00Z Friday evening/
Issued at 604 PM CST Thu Dec 8 2016

Confidence is only medium at best through the period due to MS
Valley stratus caught in broad low level cyclonic flow with the
back edge passing through TAF sites. Most likely scenario shows
MVFR ceilings staying in place through at least the evening at
KMCW/KALO and then becoming less likely at KOTM/KDSM/KFOD in that
order. Confidence in VFR rises area wide into Fri, but diminishes
again somewhat toward KFOD when MVFR conditions may return late in
the period. Most likely conditions are to remain VFR through 00z
however.

&&

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

&&

$$

SHORT TERM...FAB
LONG TERM...FAB
AVIATION...Small


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