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000
FXUS63 KEAX 102338
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
538 PM CST Tue Dec 10 2013

.SHORT TERM...(This Evening through Wednesday)
Issued at 336 PM CST TUE DEC 10 2013

The short version of the forecast...Cold through the work week with
a wintry mix of precipitation Friday, followed by more cold. Welcome
to winter. Now for a longer explanation...items of note for the
forecast over the next week are focused on the general amplified
pattern across the United States and the cutoff circulation spinning
around off the southern coast of California. The Hudson Bay low to
our northeast continues to hold domain over the eastern half of the
Continent, which in turn has managed to keep a broad trough across
much of the nation in recent days, allowing periodic shots of cold
air to quickly filter south. Case in point with the reinforcing cold
air, a shortwave trough digging through the Dakotas tonight will send
another cold front surging south into the Central Plains. This front
tonight will bring a clipper system to the northern Plains, with the
potential for a little snow (less than half an inch) along the Iowa
border late tonight; but more importantly for Kansas and Missouri
will be the non-diurnal temperature regime Wednesday as strong cold
air advection pushes temperatures back down into the single digit
range near the Iowa border in the afternoon. Wind chill values across
northern Missouri will be particularly brutal Wednesday afternoon as
a result with values range between zero and negative 10 degrees.
Areas farther south (south of The MO River) may have a bit of a
diurnal trend, with highs climbing into the 20s before the northerly
winds force temperatures back down. Otherwise, with a 1040mb high
following behind the Wednesday cold front, temperatures will stay
cold through Thursday, but owing to a quick and brief return of
southerly winds on the back side of the surface high temperatures
will moderate a little for the afternoon hours --highs around to
above freezing along and south of The MO River--. However, all of
this is setting the stage for Fridays wintry weather mix as the
southern California circulation kicks out across the Plains States
Friday.

.LONG TERM...(Friday through Tuesday)
Issued at 336 PM CST TUE DEC 10 2013

Focus in the later half of the forecast is squarely on the potential
for wintry weather Friday into Saturday. There are some secondary
concerns about more Arctic air surging into the Plains States late
in the weekend and into next work week, but the main crux of the
forecast will be Fridays weather as the precipitation types might
include everything, and the kitchen sink. Medium and short rage
models continue to advertise the mid-work week cold surface high
slowly sliding off to our southeast Thursday and Friday.
Simultaneously, the circulation off the southern California coast
will be opening up and quickly kicking through the central and
southern Plains, with its arrival in eastern Kansas and Missouri
Friday. The warm air advection ahead of this opening shortwave will
provide the region with a number of different precipitation types,
so while confidence in the potential for precipitation is growing
significantly, that same confidence is not applicable to
precipitation type.

Model soundings still seem somewhat suspect with respect to both the
thermal profiles aloft Friday and the timing for onset precipitation,
as models are typically not quick enough with the onset of warm air
advection driven precipitation. With that said, have kept highest
POPs focused in west central to central Missouri as the moisture
advection from the Gulf looks strongest across the Ozarks to our
south. As for precipitation type, it will depend somewhat on the time
it starts. Early Friday morning through the mid-morning hours
anything falling from the sky (solid or liquid) will freeze on
contact with the ground owing to the cold overnight lows. That
afternoon precipitation phase will become more complicated as more of
the warm nose and southerly surface winds work to lift the thermal
profiles above freezing. However, latest runs from the GFS to the GEM
and ECMWF all seem to slightly cool the afternoon temperatures
relative to previous runs, but temperatures --even when knocking
highs down owing to cloud cover and wet bulbing effects-- will still
leave areas south of Highway 36 with the potential for anything from
a cold rain to freezing rain or sleet. Temperatures will quickly fall
with sunset so any precipitation falling Friday night should quickly
transition to sleet and snow before midnight. Snow and ice
accumulations are difficult to pin down at this time owing to the
large questions on precipitation type, but some combination of snow
and ice is looking possible, especially across central Missouri.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
Issued at 534 PM CST TUE DEC 10 2013

VFR conditions expected through the night. The low level jet will
increase through this evening ahead of an approaching surface front
dropping southeast out of Nebraska. There may be a few hours of
marginal LLWS around midnight, but those low-level winds will
gradually decrease through the night.

The surface front will arrive at the terminal between 10Z and 12Z
quickly turning winds to the northwest through the day.

&&

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

$$

SHORT TERM...Cutter
LONG TERM...Cutter
AVIATION...Dux