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

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000
FXUS63 KEAX 251120
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
520 AM CST Wed Feb 25 2015

.SHORT TERM...(Today through Friday)
Issued at 412 AM CST WED FEB 25 2015

Water vapor showing well anticipated shortwave trough dropping through
the northern Rockies this morning...with associated sfc reflection
now analyzed along the central Nebraska/South Dakota border. Out
ahead of the sfc low...latest sfc obs show a stationary boundary
extending east-southeast through southern Iowa into northern Illinois
and Indiana. With time today...main shortwave and sfc low will
continue tracking along this boundary before passing over the lower
Missouri Valley later tonight. As has been advertised in recent
days...region remains in the cross-hairs for accumulating snowfall
later tonight as system passes overhead. One would think that the
fcst would have been fairly easy this morning with us being so close
to event start time...but that could not be further from the truth as
latest 00z guidance has come in with a more northward track of the
main sfc low later tonight. With this being the case...our region stands
an excellent chance of warming quite a bit higher than previously
thought...which adds a fair amount of complexity to the going
forecast. Out ahead of the low...southwest downslope winds will
combine with modest warm air advection to allow temperatures to reach
the lower to middle 50s across west-central Missouri and eastern
Kansas to include the KC and STJ metros. To the east...a lingering
snowpack remains in place along and north of the Missouri River which
will likely result in a fairly impressive thermal gradient later this
afternoon. Meanwhile areas north of Route 36 also stand a decent
chance of warming up today as much of far northern Missouri also remains
snow free. In any event...warmer temps and the overall delay of the
system/s arrival by a few hours has resulted in changes to the fcst
to include snow total amounts.

As a result of the delayed arrival...latest models show precip
struggling to work into the area by 21z. With warmer temps in
place...precip will likely start out as rain across much of the
area...before cold air finally begins working into the region later
in the evening behind the main cold front. With limited winter precip
expected this afternoon...have elected to delay the winter weather
advisory start time until 21z this afternoon...and that may still be
a bit to early. In any event...models show main QPF max sliding
southeast over the area mainly between 00 and 06z tonight...with
precip gradually coming to an end from west to east during the early
morning hrs. Considering the amount of warming during the day...warm
ground temps should limit overall accumulations early on...before
precip rates increase heading into the early overnight hrs. In terms
of accumulations...expect maybe an inch in the greater KC area...with
even less across our eastern Kansas and our west-central Missouri
zones south of I-70. Further east where the heavier precip is
expected...have trimmed back on snowfall amounts slightly as fast
storm movement and delayed precip arrival time will likely lead to
slightly lower amounts. In general across the advisory area...expect
2-4" across most locations...however 3-5" will be possible north of
Kirksville before all is said and done. Cannot rule out a 6" report
up there but did not have enough confidence to even consider a
possible warning upgrade. As alluded to above...best accumulations
likely to occur after 00z...hence supporting the decision to slide
the advisory start time to the right.

Another factor to consider overnight will be the strong winds
with cold air advection following fropa. Current BUFKIT momentum
transfer tool output suggesting gusts in the mid to upper 30 kt range
later tonight. Combine this with any falling snow....blowing and
drifting will certainly be a possibility overnight.

Lingering light snow shwrs to come to an end by mid morning Thursday
as drier air and strong high pressure builds into the area. For the
remainder of the short term...focus will be on well below normal
temperatures as strong high pressure combines with fresh snow and clear
skies aloft. Have generally undercut guidance for temps both Thu and
Fri with Fri morning shaping up to be one of the coldest mornings of
the year /subzero at KCI?/. Any precip with this weekend/s system to
hold off until later on Saturday.

.LONG TERM...(Saturday through Tuesday)
Issued at 412 AM CST WED FEB 25 2015

Models continue to advertise an active weather pattern for much of
the extended range forecast. Two main features of interest that will
be the driving forces for sensible weather across our area will be:
1) An upper level trough across the central Rockies 2) A surface
front that will sink south through the forecast area and stall south
of the area.

On Saturday, an upper level trough will be sinking slow south across
the central Rockies. Further east, across the eastern half of the
CONUS, the upper flow will become quasi-zonal. Several shortwave
impulses will eject out from the upper level trough and into the
local area. Cold air will already be in place on Saturday and
precipitation should begin as snow...spreading from west to east
through the afternoon. Snow will continue through Saturday night.
Sunday, a cold front will sink south through the area reinforcing
the cold air and continue snow chances. However, as we get into
Sunday night we begin to lose ice crystals in the snow growth
zone...especially across the southern CWA...and snow may mix with or
change over to sleet.

Model solutions begin to diverge in the Monday to Tuesday timeframe.
On Monday, model differences revolve around how quickly the cold
front begins to lift back north towards the forecast area. Although,
precipitation continues to look likely on Monday, P-Type is more in
question with the front lifting back northward. Model soundings
indicate the potential for freezing rain to the south a wintry mix
across the central CWA with the northern CWA remaining snow. Tuesday
the main concern will be the upper level trough across the Rockies.
The GFS is faster moving it through the area on Tuesday bringing
another round of snow to the forecast area. The EC is about 24 hours
slower in moving the trough eastward into the local area. This
solution would bring a lull in precipitation on Tuesday with another
round of precipitation back in on Wednesday. Have maintained a
blended solution through this timeframe until forecast details can
be fine tuned.

&&

.AVIATION...(For the 12Z TAFS through 12Z Thursday Morning)
Issued at 520 AM CST WED FEB 25 2015

VFR conditions to continue much of the day with southwest winds
between 10-15 kts. By early evening...conditions will quickly
deteriorate to MVFR and eventually IFR and long anticipated storm
system moves overhead. Precip initially in the form of a RA/SN mix
will gradually change over to all SN as colder air filters into the
area. Terminals standing the best chance of seeing IFR VSBYs will be
STJ and MCI...with lower probabilities at remaining sites further south.
Precip will come to an end by 4z with low-end MVFR cigs remaining in
place through the duration of the fcst period. After fropa...winds
will quickly increase from the north by mid/late evening with north
winds gusting up to 35 kts overnight.

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...WINTER WEATHER ADVISORY from 3 PM this afternoon to 6 AM CST
     Thursday FOR MOZ002>008-014>017-023>025-032-033.

&&

$$

SHORT TERM...32
LONG TERM...73
AVIATION...32






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