Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 172117
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
317 PM CST Tue Dec 17 2013
.SHORT TERM...(This Evening through Wednesday)
Issued at 317 PM CST TUE DEC 17 2013
Surface high pressure center just west of the cwa has kept northwest
winds across the county warning area and limited highs to the upper
40s north to lower 50s south. With dry air and mostly clear skies in
place this evening...expect temperatures to fall off quickly as the
sfc high moves eastward across the area with light/calm winds and
excellent radiational cooling. As the sfc high then moves eastward
overnight...south winds develop west to east by midnight and slowly
increase through sunrise. As a result...expect lows tonight in the
upper 20s/low 30s to primarily occur by or shortly after midnight
with a slow rise through the low to middle 30s through sunrise. Gusty
south to southwest winds will aid warm air advection through much of the
day. Although afternoon high clouds will be on the increase...feel
enough mixing will occur to boost highs into the lower 60s most
areas except the far north near the Nebraska border.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 317 PM CST TUE DEC 17 2013
A nearly zonal upper flow starts off the forecast Wednesday night
transitioning to a southwest flow Thursday as the longwave trough
moves into the southwest U.S.. A northern stream wave moves across
the Northern Plains Thursday will bring a cold front south into
the Central Plains and through much of the CWA by 00Z Thursday.
Drizzle is possible ahead of the front on Thursday transitioning
to patchy freezing drizzle Thursday night as temperatures cool to
below freezing. Temperature profiles are warm enough for just rain
southeast of the Kansas Turnpike during the evening hours Thursday
Friday there is a break in the action before the potential winter
storm for the weekend. Models are trending a little further north
with the track of the upper trough ejecting northeast across the
Southern Plains. There still does exist some timing differences with
the GFS more progressive than the ECMWF with the negative tilt wave.
Placement of TROWAL and still in question, but given consensus will
increase precipitation chances Saturday and Saturday night.
Currently northeast and east central Kansas may see the heaviest
wintry precipitation. Thermal profiles Saturday and Saturday evening
differ between the models with the GEM and the GFS cooler at 850 MB
and more conducive to snow with the ECMWF the warmest by 00Z Sunday.
The consensus between the three still would yield rain and snow
south of I-70 Saturday with a transition to all snow Saturday
evening. If the ECMWF verifies Saturday night, as it has the highest
QPF, then there will be a potential for several inches of snow.
The system moves off to the east early Sunday and bringing an end to
the precipitation. A drier northwest to zonal flow will then follow
Good warming is still expected ahead of the front across east
central Kansas Thursday where temperatures may reach the upper 50s
to lower 60s. The cold air then moves in Thursday night sending
temperatures into the 20s with little recovery on Friday.
Temperatures rise into the lower 30s Saturday with highs Sunday
dropping back into the 20s. With potential snow cover on the ground
lows Monday morning will be in the single digits. Temperatures by
Tuesday begin to moderate.
.AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon)
Issued at 1143 AM CST TUE DEC 17 2013
Vfr conditions will continue with mainly few-sct high clouds
expected. Northwest winds will decrease through the late afternoon
as the sfc high moves across the area with light/calm winds aft 00z
before winds increase again from the south to southwest aft 04z.
Southwest winds will then increase further aft 15z with gusts near
20 kts thru the remainder of the fcst.