Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 200525

Area Forecast Discussion
National Weather Service Topeka KS
1125 PM CST Thu Jan 19 2017

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Friday)
Issued at 330 PM CST Thu Jan 19 2017

A series of weak upper level troughs will traverse the outlook area
today and Friday. As of midday, the first trough axis was centered
across western Kansas. Forecast soundings suggest cloud depths
should continue to deepen as the trough approaches the area. These
increased cloud depths along with weak broad ascent should produce
drizzle across most of the area. As the trough axis pushes east the
near midnight, all drizzle should come to an end.

The combination of continued moisture advection overnight, current
dewpoint depressions < 4 F (and many spots at 100 percent RH),
and light winds overnight lends enough support to issue a dense
fog advisory for the entire area for tonight into Friday morning.
This solution is reflected in most of the high res and SREF
outputs. The stratus will help the fog linger well into the
morning on Friday before a warm front lifts north and helps to
scour out the fog by mid to late morning.

The second open wave will sweep across the CWA on Friday. For the
most part, this wave will mainly reinforce the low clouds across the
area. Although, Friday afternoon into the evening a few rain showers
are possible mainly north of Interstate-70 as the base of the trough
moves through.

.LONG TERM...(Friday night through Thursday)
Issued at 330 PM CST Thu Jan 19 2017

A relatively quiet pattern is forecast for the extended with only
token chances of precipitation through the seven day period. Above
normal temperatures are expected for much of the period as well.

A broad longwave upper level trough will be in place over the
central CONUS through Saturday before shifting east for Sunday.
Cyclogenesis will take place across central KS late in the day on
Friday with the 993 mb low lifting northeastward into west central
Iowa by 12Z Sat. Some rain may linger near the cyclone along the
occlusion early Friday evening before coming to an end. The near
surface flow remains zonal behind the passage of this boundary for
Saturday, which will allow highs to once again reach into the 50s--
well above the normal high of around 40 degrees for this time of

Models continue to trend southward with the second shortwave/closed
500 mb low that works around the base of the longwave trough late
Saturday into early Sunday. An increase in cloud cover appears to be
the only sensible impact and have removed the mention of POPs for
the CWA. Northwesterly flow behind this departing low will
moderate temperatures slightly for Sunday, but a surface ridge
axis will slide east Sunday night and allow warmer air to filter
back into the state for Monday. Models diverge on the track of the
next low pressure system on Tuesday as it ejects off the front
range and across the Central Plains, but both the EC and GFS take
the bulk of the forcing and precip north of the CWA.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1116 PM CST Thu Jan 19 2017

Visibilities and ceilings might bounce around tonight, but the
overall conditions will be IFR or lower. The tricky part of this
forecast will be when the fog and ceilings lift tomorrow. The
usually models want to keep IFR conditions into the afternoon,
while others try to improve by mid day. Towards the evening there
is a slight chance for showers, but coverage certainty and
probability remain low.


Dense Fog Advisory until 10 AM CST Friday for KSZ008>012-020>024-



SHORT TERM...Baerg/Skow
AVIATION...Sanders is the U.S. government's official web portal to all federal, state and local government web resources and services.