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

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000
FXUS63 KEAX 142333
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
533 PM CST Thu Dec 14 2017

.Discussion...
Issued at 305 PM CST THU DEC 14 2017

Water vapor imagery with 1.5PVU pressures overlaid shows a fast
moving clipper system diving southeast through the Central Plains.
Regional radar imagery and surface observations show a broad area of
light precipitation, light rain and some light snow at times, moving
into north central KS. Models show the upper wave weakening as it
moves into the forecast area and becoming more strung out and not as
concentrated. This results in the light QPF models show in NE and
KS, evaporating as it tracks east. This trend can be observed on
the latest radar imagery with the eastern most echos decreasing/
drying up. Given this feel that there is a small chance for some
lingering flurries and/or sprinkles to move into western portions
of the forecast area late this afternoon and this evening. Some of
this may transition east as the strung out upper trough moves
over the area.

The next system, which will bring much better chances for measurable
precipitation, will move into the area Sunday morning. With the
western upper ridge having retrograded west, off the West Coast,
a deep trough will develop over the Southwest. This will help
advect better moisture northward. Even with this better
precipitation scenario, the northward extent of precipitation
remains uncertain. But models are in good agreement bringing light
rain into southern portions of the forecast area so have placed
the highest PoPs in our south and southeast. There will likely be
a relatively sharp gradient to the northward extent of the
precipitation due to drier air filtering into the region from the
north. For now models range from dry to northwest MO getting 0.1"
to 0.2" of rain. This higher QPF is an outlier and is what`s
leading to higher PoPs in our northern and northwestern zones. For
now have only made minor tweaks to scale back PoPs in this area.
It`s likely as the Sunday time frame approaches, a tightening of
PoPs in the northward extent of the precipitation will continue.

The remainder of the forecast looks dry at this point as we return
to more of a northwesterly flow. For the later half of next week,
models show the pattern becoming more amplified. But there is
substantial differences in how deep and how progressive a trough
moving across the middle of the country is. The ECMWF and the
Canadian are in decent agreement with the upper pattern. The GFS,
while it lags the trough in the Upper Midwest, it digs a deep low
over the Baja and southern California and Arizona. Even with these
differences in the upper pattern, all three models show a very
strong cold front moving through the forecast area next Thursday.
With the considerable differences in the upper pattern, there is
quite a bit of variability in the track of the surface low and where
precipitation may fall. But there are indications that wintry
precipitation will impact the middle of the country leading into a
busy holiday travel weekend.

&&

.Aviation...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 524 PM CST THU DEC 14 2017

Although VFR ceilings are prevailing for the start of this TAF
period, MVFR ceilings are anticipated to overtake the terminals by
the pre-dawn hours on Friday. These conditions are expected to
only last through just after dawn, with partially clearing skies
by midday Friday. Look for light NW winds tonight to become more
westerly tomorrow.

&&

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

$$

Discussion...CDB
Aviation...lg



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