Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 121819
AFDSGF

Area Forecast Discussion
National Weather Service Springfield MO
1219 PM CST Thu Jan 12 2017

.SHORT TERM...(Today)
Issued at 329 AM CST Thu Jan 12 2017

An Arctic cold front will continue to slide south through
southern Missouri this morning. The temperature contrast on either
side of this front is quite remarkable. Temperatures ahead of the
front are in the middle 60s across south-central Missouri with
temperatures in the lower teens across far northwestern Missouri.

Temperatures will certainly be quirky today depending on where you
are at across the Ozarks. Temperatures will fall this morning
across southern Missouri behind the front. Areas north of the I-44
corridor will see falling temperatures early this morning with
some recovery this afternoon.

This front will encounter a weakly unstable air mass across
south-central Missouri. This opens the door for a few showers and
possibly a thunderstorm. We will also have to watch for some
patchy drizzle development behind the front. We are not sure if
the low level moist layer will be deep enough to support this, but
it is something worth watching...especially if temperatures remain
below freezing until late this morning across west-central
Missouri.

.LONG TERM...(Tonight through Wednesday)
Issued at 329 AM CST Thu Jan 12 2017

This front will then continue to march south this evening before
stalling from northeastern Texas into far northern Mississippi.
Cold air advection will continue behind this front across the
Ozarks as Arctic high pressure strengthens across Minnesota.

By late this evening, a low level jet and isentropic upglide will
commence across southern Missouri as upper level low pressure digs
south along the central California coast. We are expecting
precipitation to break out across far southern Missouri and begin
spreading north into the Highway 60 corridor by sunrise. We have a
hunch that this precipitation may start sooner than some models
are indicating...possibly even before midnight over parts of
southern Missouri.

Precipitation type will largely be freezing rain (or freezing
drizzle) tonight as the freezing line should make it at least to
the Missouri/Arkansas border. Our hunch is that it will actually
make it farther south into northern Arkansas. There may be a few
pockets of sleet mixed in as there will be some weak instability
available.

That band of precipitation will then slowly lift north through
the Missouri Ozarks Friday morning and into Friday afternoon. The
amount of additional re-development south of that band is
somewhat in question as lifting mechanisms become a bit more
questionable. Even at that, very light precipitation still remains
a good bet south of that initial band.

That freezing line may nudge a bit north during the day Friday,
but we remain very skeptical of some model output and their
aggressive northward surge to the freezing line. With northeast or
east-northeast surface winds in place, cold air advection will
continue and likely offset latent heat release of ice accretion.
We are therefore expecting the threat for freezing rain to
continue over most areas with the possible exception of far
southern Missouri during the day on Friday.

Synoptic scale lift will then begin to increase again from Friday
night into Saturday. The fate of the freezing line will be a key
player in precipitation type and continued ice accretion
potential. We continue to go on the colder side of models
regarding surface temperatures. Surface pressure gradients do
become weaker which will decrease cold air advection potential.
This may allow latent heat release from ice accretion to warm
temperatures and slowly nudge that freezing line north across
southern Missouri. However, confidence in its location still
remains low for Friday night and especially Saturday.

That upper level low will then swing out towards the Ozarks from
Saturday night into Sunday which should support the true surface
front beginning to shift north. This should result in rising
temperatures across the area and a changeover to rain over all
areas. Central Missouri will see the latest changeover, but we are
thinking they should be all liquid by midday Sunday. We may even
see some thunderstorms as we head into Monday.

At this time, we expect the highest storm total ice accumulations
to occur roughly along and north of a Pittsburg, Kansas to
Stockton to Rolla, Missouri line. This corridor will likely see a
solid 0.50" to 0.75" with some areas pushing an inch of ice
accumulation. South of this region, areas along and north of the
Highway 60 corridor should see amounts in the 0.25" to 0.50"
range. It should be noted that the Highway 60/Interstate 44
corridors are the general area of least confidence as that
freezing line will likely be meandering across this area. Areas of
far southern Missouri should see amounts from a thin glaze up to
two tenths of an inch as the changeover to rain will occur much
sooner.

After collaboration with neighboring offices, we have decided to
maintain the Winter Storm Watch for now. We want the 12Z models
and the higher resolution/rapid refresh models to get a better
handle on that front and air mass before making final decisions
on warnings/advisories. Unless something drastically changes, we
expect any warnings and advisories to be issued by around midday.

Once this system exits the region, we are expecting generally
quiet conditions for Monday and Tuesday of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1214 PM CST Thu Jan 12 2017

Shield of low MVFR to IFR cloud cover is being persistent.
Expectations are for the clearing line to finally make it to I-44
this afternoon. This would bring improvements to the Joplin and
Springfield terminals briefly this evening. The Branson area will
likely see cloud cover remain however. Flight conditions will
slowly deteriorate after midnight however as a storm system moves
into the Ozarks region. This will bring freezing rain and MVFR/IFR
ceilings to the region after midnight and last through Friday
afternoon.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...Winter Storm Watch from midnight CST tonight through Saturday
     afternoon for MOZ055>058-066>071-077>083-088>096-098.

KS...Winter Storm Watch from midnight CST tonight through Saturday
     afternoon for KSZ073-097-101.

&&

$$

SHORT TERM...Schaumann
LONG TERM...Schaumann
AVIATION...Hatch



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