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

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408
FXUS63 KEAX 140227
AFDEAX

AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
827 PM CST SAT FEB 13 2016

.UPDATE...
Issued at 825 PM CST SAT FEB 13 2016

Have made a significant adjustment to the winter weather advisory
by starting it later based on radar and short range model trends.
Regional radar loops shows the northwest-southeast band of snow from
northwest IA through northeast MO will miss the CWA overnight. the
southern edge may nick Schuyler county but no appreciable
accumulations expected. Inspection of the progged IRK sounding
reveals a desert-like sub-cloud region which will evaporate any snow
which falls out of the mid level deck. All that said still expecting
moderately strong isentropic ascent to top-down saturate this arid
zone late tonight resulting in light snow to develop across northern
MO with the best chance for accumulating snow over northeast MO.

Will also be watching for the development of freezing drizzle over
west central MO...mainly south of KC...during the pre-dawn hours.
Still looks like a small window for occurrence before the warm front
pushes through. Trend in HRRR reflectivity output has been to
decrease coverage and intensity as well as contain it more over the
southwestern counties. 00z NAM supports this.

&&

.DISCUSSION...
Issued at 327 PM CST SAT FEB 13 2016

Main forecast challenges deal with weather type and headlines. The
forecast area is really being split by wintry weather, both
spatially and temporally, with snowfall in our northeast and light
freezing drizzle in our south. The snowfall will likely start earlier
(late this evening) than the freezing drizzle, which may hold off
unto closer to sunrise. Strong isentropic ascent will eventually
saturate the lowest several thousand feet of the atmosphere in north
central to northeastern Missouri. Have delayed onset of snow several
hours based on forecast soundings,the large temperature/ dewpoint
depressions on surface observations and the relatively high cloud
bases. Forecast soundings for the Kirksville area saturate around
midnight or perhaps a little later. Have waited until then to
increase PoPs into the likely range. Snow amounts in our northeastern
zones are still expected to be in the 1" to as much as 3" range in
Schuyler County. After coordination with neighbors, have issued a
winter weather advisory for our extreme northeastern counties,
including the Kirksville area.

The other aspect of this wintry episode is the potential for
freezing drizzle in the southern half of the forecast area.
Confidence in this is quite a bit lower than with the snowfall in
the northeast. First, the lowest several thousand feet never really
saturate. Second, by the time saturation begins to lower, the warm
front lifts through, warms the surface above freezing and desaturates
the sounding aloft. So there really only looks like a marginal
potential for several hours when lift is maximized coincident with
the greatest amount of saturation. This seems to be around the 12Z
time frame +/- an hour or two. However, freezing drizzle can have a
major impact on travel as it can be deceptive in it`s ability to
slicken roads. So it`ll be important for people who have to travel
Sunday morning to understand that roads may be slick. But for now,
confidence just isn`t high enough to issue an advisory at this time.

Another clipper system will move through Monday night/ Tuesday
morning. Forecast soundings show the lowest several thousand feet to
be above freezing, even all the way into the northeastern portions of
the forecast area. So for snow, the wave should have little impact
with regards to wintry weather in the forecast area and we should see
just rain or perhaps a rain/snow mix in our northern zones.

The rest of the forecast looks quiet regarding precipitation. An
upper level ridge will spread east with low level flow out of the
south. This will help temperatures soar to well above normal levels
by Thursday into Friday. Highs may be in the 70s in parts of the
forecast area Thursday and potentially into Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 544 PM CST SAT FEB 13 2016

Widespread VFR ceilings around 5k ft agl across the region. A nw-se
oriented band of snow is developing from central IA and will stream
through northeast MO overnight with KIRK near the western edge of any
accumulating snow.

To the south expect to see MVFR ceilings form across west central MO
during the pre-dawn hours with areas of freezing drizzle developing.
May even see some sleet mixed in. The area of freezing drizzle should
expand towards central MO by late morning. Further north temperatures
will be cold enough for mainly snow across north central into
northeast MO.


&&

.EAX Watches/Warnings/Advisories...
KS...NONE.
MO...Winter Weather Advisory from 4 AM to 6 PM CST Sunday for MOZ008-
     017-025-033.

&&

$$

UPDATE...MJ
DISCUSSION...CDB
AVIATION...MJ



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