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000
FXUS63 KEAX 081516
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
916 AM CST Sun Dec 8 2013

.UPDATE...
Issued at 916 AM CST SUN DEC 8 2013

Main wave of light snow is tracking across the area at this time.
Snow amounts have generally been an inch or less although a few
reports near 2 inches have been received near the MO/IA border. Snow
forecasts still appear on track with around an inch between I-70 and
US-36, around 2 inches north of 36 with isolated 3 inch amounts near
the IA border, and a half inch or less south of I-70. Powdery nature
of the snow and snowfall rates generally a half-inch per hour or less
have prevented widespread widespread problems on the roadways
although there have been a few accidents. Main problems seem to be
on untreated roadways with fewer problems on those which have been
treated.

Other concern is patchy freezing drizzle which is occurring near and
south of I-70 where cloud tops on IR satellite do not appear to be
reaching ice nucleation temperatures. These warmer cloud tops are
slowly moving northward which suggests freezing drizzle could begin
to spread north of I-70 especially once the stronger radar echoes begin
to move out. Icing reports upstream have so far been relatively
minor, but it doesn`t take much to begin causing problems. So far
heavier echoes this far north and east have been falling more as snow
than freezing drizzle, and what freezing drizzle has fallen has not
been enough to produce a solid coating, so we opted out of a winter
weather advisory at this time. However, there is some potential for
freezing drizzle to pick up in intensity later this afternoon as low-
level convergence increases in the vicinity of a weak surface trough.
NAM has picked up on this potential while other models are dry later
on today. Will keep a close eye on the freezing drizzle potential
later today but confidence is not high enough to put out an advisory
just yet. For now a special weather statement has been issued for all
of the forecast area highlighting the different winter weather
concerns through the afternoon.

&&

.SHORT TERM...(Today and Tonight)
Issued at 404 AM CST SUN DEC 8 2013

Early this morning an upper level shortwave is moving through the
central Plains. Top down saturation is under way however dry area
near the surface has thwarted returns inability to reach the ground.
There has been light snow reported at a few locations across eastern
Kansas and western Missouri however this precipitation has been very
light in nature. Better isentropic lift with this system is located
across southern Kansas this morning and will lift northeast in the
area this morning. As the column continues to saturate, with added
isentropic lift moving into the area we will begin to see snow pick
up in intensity and begin to accumulate. Moisture with this system
is meager, with liquid QPF on the order of 0.05"-0.15". The bulk of
the accumulating snow will fall during the morning hours with the
better lift moving through the area. With liquid to snow ratios of
15:1 we should see half an inch to an inch of powdery snow across
the I-70 corridor southward and, 1"-2" north of I-70 with perhaps
even 2+" across northwestern Missouri. As we move into the afternoon
hours we lose the lift and ice crystals as dry air aloft begins to
nose into the area. However, model soundings do show moisture
occasionally nosing into the dendritic snow growth zone. With this
uncertainty, have light snow or light freezing drizzle in the
forecast for the afternoon hours. But, again the bulk of
accumulating snow will occur during the morning hours. By this
evening we will be left with mainly just patchy freezing drizzle
north of I-70 which will end by tonight as dry air builds into the
region. Highs today will be in the 20s with lows tonight ranging
from the single digits northwest to the teens elsewhere.

.LONG TERM...(Monday through Saturday)
Issued at 404 AM CST SUN DEC 8 2013

The region will still be under the influence of a positively tilted
upper trough Monday night into Tuesday. Along the edge of the upper
PV anomaly lies a very strong jet with the southern half of Missouri
situated in the right rear quadrant of the jetstreak. This will
provide good QG forcing with a strengthening temperature gradient
aloft. This enhanced area of frontogenesis will translate across the
southern half of Missouri as the upper jet moves east. Models have
been showing a light area of snow associated with these features
that may spread light snow or flurries to the extreme southern
portions of the forecast area overnight Monday/early Tuesday
morning. Little or no accumulation is expected with this band within
the forecast area as the best chances for any accumulations should
be to our south and southeast.

After Monday night, the best chances for precipitation, which are
still very low at this point, will be Friday night into Saturday.
There will be modest moisture transport into the area with a
southwesterly low level jet ahead of a deepening upper trough over
the Rockies. This may bring some light precipitation to mainly our
eastern zones. Temperatures will be near freezing at the surface so
there may be some rain early, changing to snow overnight and then
back to rain the next day. At the onset of precipitation, forecast
soundings look to have cloud ice but then lose it later as a strung
out vort max enters the area. All of this is still highly uncertain
at this point so have maintained the rain/snow mention through the
duration of precipitation chances.

Outside of the two small chances for snow and/or rain, temperatures
will be closer to normal than what we`ve seen in the last week,
though still likely below normal. The flow should become more
northwesterly to zonal. This supports a moderation of temperatures
as the coldest air retreats to Canada and into the extreme
northeastern CONUS.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 520 AM CST SUN DEC 8 2013

Light snow will continue to spread across northern Missouri with
intensities expected to increase by mid morning. Conditions within
the heaviest snow will likely be MVFR with ceilings around 1500 feet
and visibilities as low as 2 miles. There may be brief periods of IFR
but the prevailing trend will be for MVFR vis/cigs. There may also be
a period of time when light freezing drizzle mixes in with snow late
this morning and early this afternoon. Conditions will start to
improve this afternoon with VFR conditions likely developing
overnight.


&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&

$$

UPDATE...Hawblitzel
SHORT TERM...73
LONG TERM...CDB
AVIATION...CDB