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000
FXUS63 KTOP 312331
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
531 PM CST Sat Jan 31 2015

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Sunday)
Issued at 234 PM CST SAT JAN 31 2015

First decent storm system of the new year is well under way across
northeast Kansas as areas of precipitation continue to spread
northeastward across Kansas this afternoon. Main upper trough is
currently observed across the four corners region while a secondary
strong wave was quickly pushing southeast towards the central
plains. This kicker wave will help deepen the upper trough as it
spreads eastward tonight and tomorrow. Current trends this afternoon
show light to occasionally moderate rain for areas south of
Interstate 70. Thicker cloud cover and lighter winds overcoming the
warm air advection have cooled temps a few degrees during the day,
allowing the rain to mix with snow in the Topeka/Manhattan areas,
while near the Nebraska border mostly snow up to 2 inches is
reported in Marshall county, to a light dusting for most locations.
Rainfall totals have been pretty close to radar estimates, if not a
bit higher, ranging from a quarter to near an inch across portions
of Dickinson and Riley counties.

During the early evening, temperatures deviate little if not cool
slightly so would expect the rain/snow mix to continue for much of
the CWA through midnight. Light accumulations on grassy areas and
elevated surfaces are possible especially across northern areas where
more snowfall has been observed. Otherwise snowfall should melt upon
impact. Q vector convergence enhances with the passing upper trough
after midnight tonight, enhancing precipitation bands. Latest few
runs of short term guidance has trended a bit slower with the upper
trough and attendant surface low which is progged to track directly
over the CWA. This change will delay the onset of much colder air to
arrive by a few hours. Thus exact changeover to all snow is still
somewhat uncertain as temps will hover in the lower and middle 30s
for much of the evening. Will maintain a rain and snow mix until the
cold front arrives from the northwest with a quick shift to all snow
by 12Z Sunday morning. As system phases and lifts eastward, light
snow lingers into Sunday afternoon across far east central and
northeast areas. I would anticipate the snowfall to be heaviest
between 9 PM and 6 AM across the northern tier of counties where the
colder air and higher snow ratios coincide with highest QPF from a
quarter to half of an inch during this period. Snow ratios on
profilers along and behind the front average from 15 to 20 to 1
which could quickly accumulate 2 to 4 inches from Brown to
Washington counties. Therefore have issued a Winter Weather Advisory
for the northern tier of counties near the Nebraska border.
Elsewhere for the CWA, a light dusting to an inch most of which
should melt by Sunday afternoon. Secondary concern is the strong
northwest winds Sunday morning and afternoon as speeds sustain from
20 to 25 mph with gusts up to 35 mph. These should remain below
criteria levels, however will continue to monitor. Strong cold
advection from the north will fall temps through the day into the
teens by late afternoon. Wind chills may reach the single digits for
northern areas.

.LONG TERM...(Sunday Night through Saturday)
Issued at 234 PM CST SAT JAN 31 2015

Some light snow could linger into early evening Sunday night
across the far eastern counties, but ended early enough in the
period that have left out for now. Temperatures continue to drop
as center of the cold high pressure settles over Eastern Kansas
toward sunrise Monday. Expecting single digit lows. Warm advection
slowly returns Monday with highs around 30, and holding overnight
lows up in the 20s. Tuesday temperatures are a challenge as next
cold front is forecast to move in late in the afternoon to the
northern counties. Ahead of the front is a pool of warmer air
aloft and am carrying forecast highs up near 50. Will need to cool
if the front moves in quicker but think will still see a warmer
start to the day. Lows then drop into the teens to low 20s as the
front comes through. Some chance for light snow with the front
Tuesday night through Wednesday. Thursdays forecast is cold and
dry with lows in the teens and highs in the 20s.

Temperatures should return to mild for Friday through the weekend
with the western ridge slowly breaking down and the general storm
track remaining across the Northern Plains. Highs rise to the 40s
and 50s with lows in the upper teens to 20s.

&&

.AVIATION...(For the 00Z TAFs through 00Z Sunday Evening)
Issued at 531 PM CST SAT JAN 31 2015

IFR to LIFR conditions are expected through most of the period.
Cigs will remain IFR/LIFR and vsbys will vary from MVFR to IFR.
Forecast soundings show a change over to snow after 10Z. Winds
will increase to around 20kts with gusts to 30kts after 16Z
Sunday.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY until 6 PM CST Sunday FOR KSZ008>012.

&&

$$

SHORT TERM...Bowen
LONG TERM...67
AVIATION...53