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

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FXUS63 KEAX 132324

National Weather Service Kansas City/Pleasant Hill MO
524 PM CST Wed Dec 13 2017

Issued at 248 PM CST WED DEC 13 2017

Very strong northwesterly winds are expected to diminish through the
late afternoon and evening hours as the pressure gradient slackens,
strongest winds aloft shift to the east of the area, and to a lesser
extent, mixing height decreases. Will keep the advisory going but
it`s possible it can be canceled before it expires at 00Z.

The focus in the short term will then shift to another upper-level
shortwave trough, evident on water vapor imagery and 1.5PVU pressure
level plots, in northern Alberta and Saskatchewan, Canada. This
system will rapidly shift south-southeastward into the Northern
Plains and eventually track over the area as it phases with a
broader scale trough digging into the Four Corners area. Models have
been consistent in moving very light QPF into northeastern KS and
northwestern MO as the upper wave approaches and moves through.
Forecast soundings show saturation aloft through about -15C with
a subcloud dry layer of several thousand feet. Thus, it looks like
there will be a small chance for light precipitation to reach the
ground in northeastern KS and northwestern MO, mainly northwest
of I- 35. Surrounding this area, sprinkles or flurries look
possible and may persist throughout the overnight period.

With that upper low diving into the Southwest, variability with the
models increases markedly early next week. While there is a general
agreement that the area will be in northwest flow, there is a large
amount of uncertainty with the strength and position of the western
ridge and the strength of the eastern trough. This has a significant
impact on what happens through the middle of the country and if a
more significant pattern change can occur or if we continue to see
these fast moving upper-level shortwave troughs moving through. By
Wednesday into Thursday next week, the GFS is nearly completely
out of phase with the pattern over the eastern Pacific and the
east coast compared the ECMWF. Given the uncertainty with the
pattern, have made no change to the extended forecast as
confidence is low.


.Aviation...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 519 PM CST WED DEC 13 2017

MVFR stratus will approach the terminals by the late evening hours
from the northwest. This should persist over the area until
Thursday afternoon. VFR conditions look to return by the end of
the forecast period, though mid-level cloud development will
continue to increase as a short-wave trough crosses through the
region. While a light wintry mix is possible by late Thursday
afternoon and evening, not anticipating significant impacts at
this time.




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