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

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FXUS63 KEAX 251012

412 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 the western zones 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 these areas also remain snow free. In any event...warmer
temps and the overall delay by a few hours of when precip will start
across our region has resulted in changes to the fcst to include snow

As a result of the delayed arrival time...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 west-central
Missouri zones. Further east with the heaviest precip is expected to
fall...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 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. 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 06Z TAFS through 06Z Wednesday Night)
Issued at 1120 PM CST TUE FEB 24 2015

Latest model guidance suggests that precip chances will arrive a bit
later than previous TAF issuance. Precip looks to move in tomorrow
afternoon and depending on the arrival of the system, precip will
likely begin as rain before changing over to snow. There may be a
brief period of a rain/snow mix or wintry precip mix before the
changeover to all snow occurs. Timing on precip will likely change as
this system develops, but current forecast indicates changeover to occur
between a 23Z-01Z time frame. MVFR cigs will be possible as the
precip moves into the region.


MO...WINTER WEATHER ADVISORY from 3 PM this afternoon to 6 AM CST
     Thursday FOR MOZ002>008-014>017-023>025-032-033.



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