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

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000
FXUS63 KEAX 211138
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
538 AM CST Wed Feb 21 2018

.Discussion...
Issued at 405 AM CST WED FEB 21 2018

The cold front and associated wintry precipitation from yesterday exited
the region overnight, leaving everyone dry with low temperatures
in the teens and low 20s. The daylight hours today will continue
to be quiet with highs approaching freezing, thanks to the north
wind.

The quiet weather will be short-lived though, as another shortwave
moves across the Central U.S. providing upper-level support for more
precipitation tonight through Thursday. Unfortunately, it will be
another round of wintry precipitation. Above-freezing
temperatures around 850 mb are going to move north across the
forecast area, with ample moisture; while at the surface, the sub-
freezing temperatures are going to remain in place, at least
until Thursday afternoon. The tricky thing about this forecast is
of course the precipitation type. With the warm nose advancing
with the majority of the precipitation, only snow isn`t likely,
at least for areas south of HWY 36. A little snow could mix in
though for areas as far south as the MO River. Right now, it looks
like sleet will be the dominate precipitation type initially, as
the warm nose temperature will be just above freezing with the
introduction of cloud ice. However, the warm nose temperatures
should increase with time, while the introduction of cloud ice
decreases, so we should see a change over to freezing rain. A
freezing rain/sleet mix is likely before we see only freezing rain
though. This scenario is different from what we saw yesterday in
that, this is a longer duration, stratiform event with less QPF
expected, which is actually more ideal for ice accretion. That in
conjunction with an additional 0.10-0.20 of an inch of ice
expected tonight, and not much, if any, melting today has lead to
a Winter Weather Advisory being issued for the entire forecast
area. It is broken into two segments; the first segment starts at
6 PM tonight for counties south of HWY 36 and the second segment
starts at 12 AM Thursday for counties along and north of HWY 36.
The advisory expires for everyone at 12 PM Thursday. Something
that should probably be monitored is trees and power lines,
because if we don`t see much melting today, the additional ice
accumulation could start causing problems.

Thursday afternoon, the precipitation should lighten up and change
over to all liquid as surface temperatures start warming above
freezing thanks to winds shifting to the south. Thursday night,
another shortwave trough will move over the area, increasing
precipitation chances again. Temperatures are expected to dip
below freezing overnight for at least the northwest half of the
forecast area, so a changeover to freezing drizzle since the
the 850 mb warm layer should still be in place. Some ice
accumulation is possible with this round as well.

A couple of more rounds of precipitation are expected Friday and
Saturday as the trough over the western U.S. finally moves east.
Starting Friday, temperatures will trend upward, meaning the
precipitation should be mainly rain, with the exception of some
wintry precipitation possible during the overnight hours when some
of the temperatures dip below freezing.

&&

.Aviation...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 536 AM CST WED FEB 21 2018

VFR conditions are expected for the majority of the TAF period
across the area. There are still some MVFR ceilings in central MO,
but those will start to lift within the next hour or so as the
cold front and precipitation continue pushing east. Winds will
veer to the east northeast today as the high pressure north of the
area moves east. Tonight, another round of wintry precipitation
will move into the area from the southwest. The precipitation will
start off as sleet/snow for areas north of the MO River, and
dominantly sleet for area south. As the night progresses, the
precipitation should change over to freezing rain from south to
north, reaching MCI at the end of the TAF period. Before the
precipitation changes over to freezing rain, there will be a
couple of hours or so of a freezing rain/sleet mix. The freezing
rain is expected to last through noon tomorrow and then should
change over to rain. MVFR ceilings will move in with the
precipitation with some indications we could eventually see IFR
ceilings. Finally, visibility will likely drop some as well with
the onset of precipitation.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...Winter Weather Advisory from 6 PM this evening to noon CST
     Thursday for KSZ025-057-060-103>105.

     Winter Weather Advisory from midnight tonight to noon CST
     Thursday for KSZ102.

MO...Winter Weather Advisory from 6 PM this evening to noon CST
     Thursday for MOZ028>033-037>040-043>046-053-054.

     Winter Weather Advisory from midnight tonight to noon CST
     Thursday for MOZ001>008-011>017-020>025.

&&

$$

Discussion...Grana
Aviation...Grana



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