Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 071726
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1126 AM CST Sat Dec 7 2013
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 409 AM CST SAT DEC 7 2013
An upper level trough across OR and northern CA will dig southeast
into the four corners area Tonight.
A broad surface ridge will continue to build southward across
eastern KS this morning. Temperatures early this morning were in the
single digits across the CWA, with a 1 degree F reading at
Concordia at 200 AM.
As the upper trough across the western US digs southeast towards the
four corners region expect a gradual increase in high clouds this
afternoon. The cold surface ridge axis will gradually shift east of
the CWA late this afternoon. High temperatures will remain cold with
mid to upper teens expected across much of the CWA. Wind chill
indices will be lowest this morning with -10 to -15 across north
central KS and -5 to -10 degrees across the remainder of the CWA. As
temperatures warm into the teens the wind chill indices will
increase into the single digits.
Tonight, As the upper level trough digs southeast into the four
corners region, WAA/isentropic lift will increase from west to east
across the CWA. The isentropic lift at the 270K through the 290K
theta surfaces will increase and slowly saturate the lower levels of
the atmosphere. Eventually the sustained isentropic lift will cause
light snow to develop from west to east across the CWA from 4Z
through 8Z. The better WAA/isentropic lift will occur across the
northern counties of the CWA where an inch of snow may accumulate
during the early morning hours of Sunday. Snowfall will be much
lighter across the southern counties of the CWA where only a dusting
of snowfall may occur through the early morning hours of Sunday. The
I-70 corridor may see around a half of inch of snowfall by 12Z SUN.
Overnight lows will occur during the evening hours with temperatures
remaining steady or slowly rising during the early morning hours of
.LONG TERM...(Sunday through Friday)
Issued at 409 AM CST SAT DEC 7 2013
The stronger isentropic lift and deeper large scale ascent on Sunday
will occur through the morning hours then rapidly decrease through
the remainder of the day. This is primarily due to the shortwave
trough passing/exiting the cwa and the veering of the low level
flow with decreasing isentropic lift. Also a good deep dendritic
growth zone early in the day will decrease by late morning and
through the afternoon. Will maintain a slight chance pop for
lingering light snow across the northeast corner of the cwa Sunday
evening...otherwise will end snow chances beyond midnight with
drying and subsidence. Overall...total snowfall amounts across the
cwa for the event appear will range from slightly less than an
inch south and east of I 35 to 1-2 inches along the I 70 corridor
with the most...around 2 1/2 inches along the Highway 36 corridor.
With the passage of the shortwave trough...another reinforcing push
of arctic air will surge southward into the area. As a
result...following highs in the 20s on Sunday...should see lows
Monday morning from 2 above near Belleville to the lower teens far
southeast corner counties...with wind chill indices from zero
southeast counties to near -14 F around Belleville. This will set
the stage for highs on Monday primarily in the teens. The eastern
Pacific ridge aloft will break down through mid week as the axis of
the upper trough in central Canada shifts eastward. The combination
of these two changes in the upper pattern should result in a more
west to northwest flow aloft across the cwa through the end of the
work week with little chance for precipitation and a moderation in
temperatures as the llvl flow becomes more west to southwesterly
overall. Following morning lows Tuesday in the single digits and
teens...lows will moderate into the 20s by the end of the week.
Highs beyond Monday will generally be in the low to middle 30s...but
may reach the low 40s southern portions of the cwa by Friday.
.AVIATION...(For the 18Z TAFs through 18Z Sunday Afternoon)
Issued at 1123 AM CST SAT DEC 7 2013
VFR conditions should hold on through 06/07z before cloud deck
lowers to MFVR and light snow begins. Lowered deck further at
08/09z to low MVFR and will likely need to be IFR for at least a
few hours in the morning but will refine as period draws closer.
Kept low MVFR conditions through 18z although will likely be
tapering off toward the end of the period.