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000
FXUS63 KEAX 040010
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
610 PM CST Tue Dec 3 2013

.SHORT TERM...(This Evening through Wednesday Night)
Issued at 338 PM CST TUE DEC 3 2013

Nothing short of perfect this Tuesday afternoon with temperature
running in the upper 50s to lower 60s under abundant sunshine. That
will soon be a thing of the passed as arctic air is poised to surge
southward into the area tomorrow. Several key challenges await in the
interim, however.

For tonight, a pre-frontal trough arcing from central KS through far
NW MO will become better defined, with a pivot point near STJ as cold
air plunges through central and western Kansas. Very moist boundary
layer conditions, characterized by dew points in the 45-50F range will
be maintained ahead of the frontal zone with gradual low level
upglide in the warm sector. Once again, conditions appear favorable
for the development of dense fog after midnight, especially from I-35
and southeast. Fog could become particularly dense, possible
coincident with drizzle, across far NW MO where low level convergence
is maximized along the temporarily stalled boundary.

Surface low pressure expected to be near the Flint Hills by 12Z, will
ride NE along the inverted trough tomorrow morning, with cold air
rapidly pouring in behind it. Given the timing, have made major
upward adjustments to temperatures across portions of northeast and
central MO where readings will likely climb well into the 50s prior
to frontal passage. Elsewhere, temperatures will fall through the 40s
and 30s, although strong/gusty winds should limit the free fall from
going much further until nightfall. Although these winds should
rapidly eliminate any lingering dense fog, the rapid column cooling
and modest low level ascent post-FROPA should lead to widespread low
stratus and drizzle through afternoon.

Blustery northwest winds will continue through tomorrow night at
10-20 mph, as temperatures fall into the teens and 20s. After near 60
degree readings currently, it will feel like the single digits by
Thursday morning.

.LONG TERM...(Thursday through Tuesday)
Issued at 338 PM CST TUE DEC 3 2013

Besides the obvious, that it will be abnormally cold throughout this
period with temperatures at least 20 degrees below average, an active
pattern is expected with several upper troughs moving out of the
west within a pronounced southwesterly upper flow. There will be
several chances for precipitation and with the entire column below
freezing it will be all snow.

Thursday through Friday will bring the a couple of chances for our
first snow of the season. Two features aided by a very strong upper
jet segment, embedded/strung out 700mb vorticity lobes and layered
frontogenetic forcing will generate bands of snow. Primary challenge
will be timing/location as the 12z NAM has thrown a bit of a wrench
into the model continuity by shifting Thursday nights/Friday
mornings snow band further north than any of the models. Currently
believe it is an outlier with the ECMWF and GFS showing better
continuity. Current forecast is a model blend with a lean towards
the more southern GFS/ECMWF solutions. This results in little change
to the northern extent of the snow during this period, roughly south
of the MO Rivera. PoPs will increase southward while snow amounts
have been slightly lowered...with areas south of a Parker,
KS-Butler-Sedalia-Boonville line possibly picking up 1-2 inches by
Friday afternoon.

The next threat for any accumulating snow remains in the Saturday
evening/Sunday time-frame with a stronger upper trough lifting out
of the Southern/central Rockies and generating a more widespread
area of snow. Difficult this far out to gage how much snow as the
models paint a more general area of weak but more widespread
isentropic ascent. Certainly possible for several inches of snow to
fall over a 36 hr period starting late Saturday night.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 603 PM CST TUE DEC 3 2013

Warm and moist air continues to stream into the area, which may bring
another round of fog to the terminals later tonight. Trends over the
last couple hours show that several observation sites are already
between 7 and 10 SM, which closely resembles last night`s pattern.
Have bumped up the timing a bit for the onset of lowered VSBY to
better resemble persistence from the previous night. Expect overnight
to see lowered VSBY in the IFR range at times. Expect a gradual
improvement in the conditions post sunrise, but MVFR stratus will
hold on through most of the day. Frontal passage will take place
during the early morning hours for KMCI and KMKC, but northerly winds
in place at KSTJ indicate that FROPA has likely already occurred at
that site.

&&

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

$$

SHORT TERM...Bookbinder
LONG TERM...MJ
AVIATION...Leighton