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000
FXUS63 KEAX 050015
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
615 PM CST Wed Dec 4 2013

.SHORT TERM...(This Evening through Friday Afternoon)
Issued at 256 PM CST WED DEC 4 2013

The Arctic blast is here and it won`t be leaving any time soon. So,
the main focus will be on the snow potential. A pronounced
positively tilted upper trough extending from CA through the
Northern Plains will allow a steady flow of mid/high level moisture
to spread across the Central Plains and Mid MO Valley into Friday. A
stout upper level jet maxed out over the central U.S. will shift
southeast and intensify Thursday night/Friday and enhance the lift
for precipitation...with the bulk of it being south of the CWA.

For tonight have had to add a small area of slight chance/chance
PoPs into northwest MO and northeast KS. Last two model runs of the
NAM as well as RAP, and to a lesser extent the GFS, have developed a
narrow band of layered frontogenesis which will spread quickly
northeast from western KS later this evening. Dry sub-cloud region
and weakening trend of the forcing as it moves through northwest MO
suggest very limited QPF/snowfall, likely just a dusting.

Snow threat on Thursday has been pushed further south of the CWA so
will go dry for now. And the snow threat for Thursday night/Friday
morning will be limited to the far southern counties with PoPs
lowered some. Snow totals for Thursday night/Friday morning should
be less than an inch. The general trend of the models for the past
2-3 runs has been to shift the northern edge of the snow shield
further south due to the southern shift of the upper level jet and
better frontogenetic forcing.

Only minor changes made to the temperatures due to limited
insolation on an Arctic air mass. Temperatures will be around 20
degrees below average through the period.

.LONG TERM...(Friday Evening through Wednesday)
Issued at 256 PM CST WED DEC 4 2013

Arctic air mass will encompass a good deal of the northern and
central U.S. through the weekend. Coldest temperatures will be
Friday night when the center of an expansive surface high will
settle into the Dakotas with low-level ridging extending southward
into MO. This should allow temperatures to drop into the single
digits across the region with some areas near the IA border flirting
with the zero degree mark. Winds will be light but still enough to
send wind chill values between 0 and -10 by sunrise Saturday. Skies
will be sunny on Saturday but northeast winds will only allow
temperatures to rise into the lower 20s.

Next system of interest will track across the area in the form of a
broad upper trough on Sunday. This system still appears on track to
produce a widespread area of light accumulating snow during the day,
with most models pointing to QPF amounts around a tenth of an inch
or two. With a very cold air mass in place, snowfall ratios could be
high enough to produce a broad 1-3 inches of snow with these kinds
of QPF amounts (very preliminary thinking of course). Snowfall rates
should be light with the only real forcing mechanism being broad
isentropic ascent. Without deep synoptic forcing, frontogenetical
ascent or any other significant source of lift, snowfall rates would
seem unlikely to exceed a half inch per hour. This combined with
generally light northeast winds suggest that any impacts with this
system should be relatively minor.

Forecast beyond Sunday looks quiet, although another surge of Arctic
air Sunday and Monday nights combined with an anticipated light
snow pack should allow temperatures to drop into the single digits
once again, possibly even near zero.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 551 PM CST WED DEC 4 2013

Expect MVFR stratus to continue through a portion of the overnight
hours before it eventually and gradually dissipates. There is a very
slight chance of a brief snow shower or two at the terminals
overnight, but will consider the threat minimal enough to leave out
of the official forecast. Otherwise northwesterly winds will
continue for the entire forecast period, with perhaps an occasional
gust of 20+ knots.

&&

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

$$

SHORT TERM...MJ
LONG TERM...Hawblitzel
AVIATION...Leighton