765 
FXUS63 KTOP 170551
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1151 PM CST Wed Dec 16 2020

...Update to aviation forecast discussion...

.DISCUSSION...
Issued at 343 PM CST Wed Dec 16 2020

Clouds have been slow to push eastward this afternoon as the 
forecast area remains within a surface ridge under northwest upper 
flow. This has kept cool conditions with most locations still in the 
low to mid 30s, a few degrees warmer in north central KS where more 
insolation has taken place. Upstream water vapor imagery at 21Z 
shows upper level ridging making its way into the southwestern CONUS 
ahead of a more amplified trough in the eastern Pacific. This upper 
ridge will slide east across the Rockies tonight, allowing skies to 
eventually clear across the eastern part of the CWA this evening 
with morning lows in the low 20s. As a result of the clear skies and 
light winds providing radiational cooling, some patchy freezing fog 
may develop especially in low-lying areas, which is supported by 
forecast soundings.

WAA increases during the day Thursday and into the nighttime hours 
as the ridge axis passes over the area, bringing daytime highs into 
the 40s for most, possibly reaching 50 in east central KS with 
plenty of sunshine. Low-level winds strengthen Thursday night into 
Friday morning as the aforementioned trough amplifies while 
translating across the western US. In response, lee troughing 
deepens leading to a tightening pressure gradient over eastern KS on 
Friday, which could result in some gusty southerly winds. As these 
continue to usher in warmer air, highs are forecast in the upper 40s 
to low 50s. The surface trough and attendant frontal boundary are 
progged to pass west to east from the late afternoon through evening 
time frame, with the upper trough not far behind overnight. Forecast 
soundings in CNK and EMP show a brief period of saturation during 
the overnight hours, though still not overly impressive, and there 
remains enough variation between models on moisture content. For 
this reason, have opted for low PoPs with only a chance of 
sprinkles/flurries at this time.

After the Friday night/early Saturday morning system, no other 
precip chances are noted as upper troughing passes well north, 
leaving us in mainly zonal flow into early next week. Temperatures 
may be a bit cooler on Saturday in comparison to Friday, but then 
they rebound with highs in the 50s Sunday through Tuesday and lows 
in the 20s and 30s.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1149 PM CST Wed Dec 16 2020

MVFR stratus has cleared the terminals. Patchy fog has developed
across the area with MVFR VSBY at MHK. Expect MVFR VSBY to develop
at the Topeka sites within the next 1-2 hours. Any fog formation
should scatter by 14Z with VFR conditions thereafter. 

&&

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

$$

DISCUSSION...Picha
AVIATION...Baerg