Area Forecast Discussion
Issued by NWS Topeka, KS

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530
FXUS63 KTOP 121732
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1132 AM CST Fri Jan 12 2018

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 259 AM CST Fri Jan 12 2018

Continued cold air advection across northeast Kansas has brought
temperatures down into the single digits early this morning.  Winds
have continued to die down overnight although some occasional gusts
are still seen in east central Kansas.  By sunrise, lows will be
near zero degrees with wind chills will range from -7 to -14
degrees.

The main feature for today will be shortwave trough traversing
the central plains this afternoon into the evening. Cloud cover
will return with this feature keeping high temperatures today in
the teens and low 20s. Soundings indicate the best potential for
any snow will be in central and north central Kansas, with any
snow accumulations expected to be minor. Further east, a dry layer
near the surface looks to inhibit the potential for any real
snow, although a few flurries may be seen. This system moves
southeast of the area late tonight and any precipitation chances
will come to an end. Another cold night is in store with
temperatures falling mainly into the 5 to 10 degree range. Wind
chill values should range from around zero to 10 below.

.LONG TERM...(Saturday through Thursday)
Issued at 259 AM CST Fri Jan 12 2018

Northwest flow aloft is expected to persist across the central
plains through Monday. Models show the potential for a subtle
shortwave to move through the area late Saturday night and Sunday
morning. Forcing with this feature is not all that impressive and
there are some differences in the track of the wave between the
ECMWF/Canadian and the GFS/NAM. Overall any snow accumulations
with this system look to be minor since forcing is rather weak and
should be short lived due to the progressive nature of the
pattern. For now have favored a track that would keep
accumulations of less than an inch mainly across northeast KS
since that is similar to the prev forecast.

A better chance for accumulating snowfall appears to be Sunday
night and Monday morning as models dig a more substantial upper
low into the Midwest. This is expected to bring another strong
cold front through the area Sunday night with better organized
frontogenesis. There is some consensus for the column to saturate
as the front passes and a band of snow to develop. Overall models
are showing the potential for 1 to 2 inches. There are some minor
timing issues with the NAM being somewhat slower with the front.
But most guidance shows this similar idea so confidence in snow
chances are better than Saturday night.

After Monday, the forecast calls for dry weather. An upper level
ridge is progged to move over the plains mid week ahead of another
shortwave progged to move across the plains on Thursday.
Unfortunately there is no consensus in the track of this system
with model showing the wave anywhere from the Canadian boarder to
north TX. The GFS is the only solution that would bring the upper
wave close enough to the forecast area, and it appears to just
glance the area. So for now have opted to keep the forecast dry on
Thursday until there is better agreement among the various
solutions.

For temps, the cold weather looks to remain in place for the bulk
of the week with the cold front Sunday night ushering in another
arctic high pressure system. Highs Sunday could warm into the mid
and upper 30s as some warm air advection occurs ahead of the
front. Models show the latest arctic high weakening and moving
into the southeast U.S. by Thursday. This should allow for a
southerly and southwesterly low level flow to return and help
moderate temps by Thursday. Tuesday looks to be the coldest day
of next week as the center of the surface high pressure system
moves across the central plains.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1132 AM CST Fri Jan 12 2018

VFR conditions expected. Some increase and lowering in cloud
heights expected as a weak wave continues to weaken as it
approaches from the northwest, but heights should stay well above
VFR levels.

&&

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

$$

SHORT TERM...Heller
LONG TERM...Wolters
AVIATION...65



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