Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 170542

1142 PM CST Tue Dec 16 2014

Issued at 321 PM CST TUE DEC 16 2014

Low level ridge will drift across the area tonight which will allow
clouds to gradually scatter out. This combined with light winds will
allow temperatures to drop into the 20s overnight, possibly some
teens across northwest Missouri and northeast Kansas. Partly to
mostly sunny skies will continue into Wednesday with temperatures
rising into the middle to upper 30s.

Light precipitation is still expected to overspread the area
Wednesday night into early Thursday when a deamplifying shortwave
will track across the Plains. Thermal profiles generally look
supportive of all snow with this system, although forecast soundings
are awfully close to the 0C isotherm in the 5-10Kft layer, so it
wouldn`t be surprising to see a bit of sleet mixing in especially
south of I-70. Most models are producing a swath of 0.2" to 0.4"
across areas near and south of US-36 through early Thursday morning,
which would translate to a broad 2" to 4" across these areas given
anticipated snow-to-liquid ratios around 11:1. However, forcing with
this system doesn`t look too impressive and it`s questionable whether
these QPF amounts can be realized. Isentropic ascent ahead of this
wave will be fairly weak and there`s no real signal for any notable
mesoscale ascent. There will be a brief period of modest upper-level
divergence within a coupled upper jet and perhaps some PVA with the
main upper wave, but these sources of broad synoptic-scale ascent
alone wouldn`t normally produce 3" or 4" of snow especially in just a
4- to 6-hour period (would mean snow rates approaching 1" per hour,
and this usually requires some source of mesoscale ascent). Am
therefore going with only about half of what these models are
producing, generally 1" to 2" across all but far north central and
northeast Missouri. While not overly impressive amounts, most of this
will fall right before Thursday morning`s commute so there could
still be some noteworthy impacts from this system. Wouldn`t be
surprising to see some amounts a bit higher than this especially over
eastern KS into west central MO where a few models are hinting at
weak and progressive frontogenetical ascent around 06Z to 09Z.

Precipitation should decrease fairly quickly through the morning
hours Thursday as the primary upper wave weakens. This will result in
a loss of upper-level moisture which could favor a bit of drizzle or
freezing drizzle into the early afternoon. Lift by this time doesn`t
look impressive particularly in the lower levels where saturation
will exist, so any drizzle should be light if anything at all and
impacts to travel minimal. Temperatures look to rise above freezing
across areas south of US 36 by mid afternoon.

Models continue to trend south with the next system which will track
across the Southern Plains Friday and Friday night. This should keep
almost all of the precipitation to the south of the forecast area.
Southerly winds behind this system will bring a modest warming trend
heading into early next week with highs reaching the 40s by Sunday
and Monday. Next chance for precip will arrive with a weak front
Monday and Monday night, most of which looks to be in the form of


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
Issued at 1126 PM CST TUE DEC 16 2014

A narrow band of MVFR cigs continues to make for a tricky TAF period.
This band has slowly sagged southward this evening with erosion occurring
on the northern edge. Models are having a hard time with this shallow
layer and it is difficult to determine if it will completely erode or
just continue to push southward. Expect terminals to scatter out by
8Z with IXD being the last to scatter out closer to 10Z. BUFKIT
soundings are showing a brief window between 14-17Z where a few MVFR
cigs may redevelop. Given model uncertainty, have decided to leave it
out of the current TAF. A 5-7 Kft deck will build in by tomorrow
afternoon ahead of an upper level trough progged to move across the
region tomorrow night. Light winds will gradually shift around to the
east by tomorrow afternoon.




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