Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 061131
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
531 AM CST Fri Dec 6 2013
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 355 AM CST FRI DEC 6 2013
An upper level trough will fill as it lifts northeast across the
southern and central plains into the Midwest Today. The stronger
frontogenetical forcing will remain south and southeast of the CWA
across southern MO and extend southwest into central OK.
Forecast soundings show a dry layer of air at 830mb, therefore even
if there is enough ascent ahead of the H5 trough for light snow to
develop at the dendritic growth zone most of the snow will sublimate
within the dry air layer before reaching the surface. There could be
some light snow showers or flurries across east central and
northeast Kansas this morning.
At the surface the cold arctic ridge will continue to build
southward across eastern KS tonight. Skies should clear from west to
east across the CWA this afternoon.
Afternoon highs will remain cold with most areas only reaching the
mid to upper teens. North winds will gradually diminish through the
late afternoon hours. Wind chill indices across north central Kansas
this morning may dip to the -8 and -12 degree range with -3 to -8
degrees across the remainder of the CWA. Wind chill indices will
increase into the singe digits this afternoon.
Tonight, light winds and clear skies should allow radiative cooling
to drop lows to zero or 3 below across the western CWA with 0 to 5
above across the eastern counties of the CWA. Winds should be light
enough late tonight to keep wind chill indices only a few degrees
cooler than overnight lows.
.LONG TERM...(Saturday through Thursday)
Issued at 355 AM CST FRI DEC 6 2013
The axis of the cold surface high pressure will be centered across
the eastern portions of the county warning area to start the day
keeping cold east to northeast winds across much of the area.
Despite a sunny start to the day...the winds will limit the degree
of warming as clouds then increase through the afternoon. Bottom
line...this combination will may way for a very cold day with highs
only ranging from 16 degrees north to near 20 far south. Morning
wind chills will be in the -9 to -12 F degree range.
Initially Sunday evening...very dry air will be in place across the
entire cwa but the combination of warm air/moisture advection will
begin to saturate the low to mid levels by midnight with a chance
for light snow over the western 2/3 of the cwa...although any snow
amounts would be very light. After midnight through
sunrise...frontogenetical forcing increases dramatically with the
approach of the first of 2 shortwave troughs. The strongest and
longest combination of lift and some instability will reside over
the northwest portions of the cwa late Saturday night and into early
Sunday where will keep likely pops late in the night and through the
day Sunday with high end chance pops further southeastward where
forcing will not be as strong or sustained. A second shortwave
trough will move into the area Sunday afternoon and early evening
with more snow chances...although higher again across the north cwa.
Have ended snow chances beyond midnight Sunday night with drying and
subsidence. There is some concern that the strongest and most pronounced
period of forcing will be initially utilized to saturate the column
and what effects this could have on total snowfall amounts. In
general...models have trended back slightly with qpf generated with
these very progressive waves. As a result...have lowered snow totals
slightly for the entire event...ranging from a little over an inch
in the far southeast corner to nearly 3 inches in the far northwest
corner of the cwa near Belleville.
With the passage of these waves will come another reinforcing shot
of arctic air. Therefore after highs on Sunday in the 20s...highs on
Monday will only reach the mid to upper teens. Lows Monday night in
the single digits will be the coldest night next week as the flow
aloft begins to back more to the west northwest. Will keep the
remainder of the week dry as well. Highs should moderate into the
upper 20s and lower 30s by Wednesday before rising above freezing
all areas Thursday with readings in the middle to upper 30s.
.AVIATION...(For the 12Z TAFs through 12Z Saturday Morning)
Issued at 524 AM CST FRI DEC 6 2013
Vfr conditions will continue through the forecast as mid level AC
deck scatters aft 22Z. Sustained north winds 11-13 kts will
decrease to blo 8 kts by 00Z/07.