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000
FXUS63 KTOP 102328
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
528 PM CST Tue Dec 10 2013

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 223 PM CST TUE DEC 10 2013

Ample sunshine and a temporary warming trend into the upper 30s
has greatly reduced or eliminated the snowpack blanketing
northeast Kansas this afternoon. By sunset the only counties to
continue to have snow cover on the ground reside near the Kansas
and Nebraska border. Light southerly winds persist through the
early evening Tuesday before a passing shortwave trough to the
north surges another arctic cold front into the area. The
steepening pressure gradient directly behind the boundary should
increase northwest winds between 10 and 15 mph with gusts near 25
mph through the overnight period. Therefore guidance and trends
suspect the temperatures will not be as cool with low temps
dropping into the teens. Areas of snowpack across the far north
should fall further into the upper single digits. Short term
guidance is persistent with keeping the strongest forcing across
Nebraska into Iowa near the vorticity center. Sounding profiles
over north central and northeast areas show some lift in the
550-700 mb layer with an increase in mid level moisture. A decent
amount of dry air resides below this layer to evaporate any precip
before reaching the ground. Have added some increased mid level
clouds however along and behind the boundary.

Surface high pressure and accompanying cold air advection quickly
filters southward on Wednesday. Northerly winds remain gusty
through the mid morning for east central areas before weakening as
the ridge builds in. Leaned closer to the NAM mos guidance which
has performed fairly better than others the past few runs. High
pressure centered overhead holds the colder air in place with weak
mixing sustained up to 3 KFT. And with guidance trending slightly
cooler, have lowered highs a few degrees to the lower 20s for east
central to the upper teens towards the northeast and north central
areas.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 223 PM CST TUE DEC 10 2013

Warm air advection ramps up again overnight Wednesday night into
Thursday, and will likely see a repeat where temperatures are
cooler before midnight and then rise later. Still have lows in the
single digits to teens but again should rise toward morning. Highs
Thursday expected to mix into the 40s where the snow is clear with
30s elsewhere. The warm push continues from the south Thursday
night into Friday and will have warmer lows for a change with lows
in the 20s south to upper teens north and this may be too cool.
High temperatures more tricky as incoming shortwave begins to draw
the colder air southward by mid morning Friday. For now have highs
in upper 30s SE with right around freezing NW.

EC brings in what could be either light rain or freezing rain on
Friday morning, however GFS is dry and keeps precip farther south.
With low amplitude of the wave making details a bit tricky will
just stay the course with some lower pops in the morning. Also see
models trending toward taking brundt of the precip farther east
and south, however southeast half of the cwa still in line to get
some kind of precip with this wave. By afternoon, warmer air east
should keep precip as snow, with a mix farther NW. Cold air comes
in fast in the late afternoon / evening and may go back to a
rain/fzra/sleet mix in the east before enough cold air and
saturation come in after midnight for snow. Once again, these
smaller scale variables are likely to shift around as the storm
approaches, so stay tuned for updates. At this time accumulations
are not expected to be high but any ice accumulation could be
troublesome.

Cold air drops in from behind the wave for another cold day Saturday
with highs upper 20s to low 30s.  May see some trailing snow
flurries Saturday morning and afternoon.  Lows in the teens Saturday
night rise to highs in the 20s and 30s on Sunday as may get clipped
by another cold surge.  Variability returns for Mon/Tues as latest
EC drops another cold high into the plains with a large scale trof
over the Ohio valley. GFS is not nearly as defined with this trof
and is much more progressive. Have highs 30s Monday and 40s Tuesday
but these days may change if that cold air comes back in.

&&

.AVIATION...(For the 00Z TAFs through 00Z Wednesday Evening)
Issued at 527 PM CST TUE DEC 10 2013

For the 00z TAFs, VFR conditions are expected through the period. A
cold front will track southward over the area tonight. While no
precipitation is expected with this frontal passage, winds will
shift from the south to north-northwest overnight. Wind speeds will
increase some behind the front, upwards of 10-13kts by Wednesday
morning. Periodic scattered mid-level clouds can be expected through
the period.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Bowen
LONG TERM...67
AVIATION...Hennecke