Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 290931

331 AM CST Mon Dec 29 2014

.SHORT TERM...(Today and Tonight)
Issued at 322 AM CST MON DEC 29 2014

A weak shortwave trough over MT and UT will dig east-southeast into
CO through the base of a longer wave length upper trough extending
from the upper Midwest, southwest into the desert southwest. The H5
trough will fill as it moves east from CO into western KS. A surface
cold front extended from northwest KS, northeast into southeast NE
and IA at 9Z. This front was pushing southward  into the northern
counties of the CWA.

The strongest ascent and mid level frontogenetical forcing will be
located across western KS and extend east-southeast into central KS
this afternoon and Tonight. Forecast soundings show a fairly dry
layer of air from 900mb to 800mb across the CWA. As the mid level
ascent ahead of the H5 trough saturates the dendritic growth zone,
much of the ice crystals will sublimate before reaching the lower
levels of the atmosphere.  Most model forecast soundings show this
dry layer eventually saturating across the western half of the CWA,
thus light snow will develop earl this evening and continue through
the night. Accumulations will range from a dusting to less than one
inch across the southwest counties of the CWA. The eastern counties
of the CWA may only see flurries develop as the low-levels of the
atmosphere look dry.

Stronger CAA occurring across the northern plains due to a deeper
upper level trough digging southeast out of central Canada into the
northern Great lakes and Upper Midwest will cause a strong cold
front to push south across the CWA Today. Temperatures across north
central KS may only warm into the mid to upper 20s this morning and
slowly fall through the 20s during the afternoon hours. The
remainder of the CWA may warm into the mid to upper 30s ahead of the
front through the mid morning hours but temperatures will fall
through the 30s into the 20s this afternoon. North-northeast winds
will increase to 15 to 25 MPH with gusts to 30 to 35 MPH during the
afternoon making it feel even  colder as wind chills drop through
the 20s and into the teens through the afternoon hours.

The low-level CAA will continue across the central and southern
plains through Tuesday night. The light snow across the western CWA
should diminish to flurries late Tonight. North winds will continue
at 15 to 20 MPH with some higher gusts. Wind chill indices across
north central KS may drop to -17 to -15 degree range by 12Z TUE as
overnight lows drop into the single digits. At this time I will let
the next shift decide if a wind chill advisory will be needed for
north central KS for late Tonight through Noon on Tuesday. The
remainder of the CWA will see overnight lows from near 10 degrees to
the lower to mid teens. Wind chill indices across northeast KS will
range from -13 to -8 degrees and -5 to 0 degrees across east central

.LONG TERM...(Tuesday through Sunday)
Issued at 322 AM CST MON DEC 29 2014

Lift will continue to diminish across the southern county warning
area Tuesday morning with drier air moving into the entire area by
afternoon. Will therefore only carry a few flurries possible across
the southern cwa in the morning then dry all areas in the afternoon.
Bitterly cold windchills of 0 to -15 will be common...although the
-15 degree windchills will be limited to near the Nebraska no plans to go with an advisory at this time. Even
colder low temps expected Wednesday morning with the light winds and
less lows should range from 5 above in the far east
central to -2 near the Nebraska border. Again...some windchills
around -15 are expected...but should be confined to near the
Nebraska border only with indices of -9 to -13 elsewhere. Afternoon
high temps should recover back into the upper teens and lower 20s
with some sunshine.

Will then maintain a dry fcst on thru the day Thursday. As winds
become more west to southerly...temps should moderate back into the
30s for highs on Thursday. Will then continue to introduce a chance
for rain or snow south to north into Friday as the next West Coast
system digs into the desert southwest and then lifts out into the
central and southern Plains into the weekend. Models continue to
diverge on how far north it ejects out into the plains and how much
cold air will be associated with it as it does. The GFS is the
furthest north with the EC and GEM steadily further south. Any
precip in the cwa over the weekend should end across the far
southeast corner by Sunday morning. Highs on Friday and over the
weekend will generally be in the 30s.


.AVIATION...(For the 06Z TAFs through 06Z Monday Night)
Issued at 1128 PM CST SUN DEC 28 2014

For the 06z TAFs, VFR conditions are expected through the period. A
cold front will track southward over the region overnight with surface
high pressure advancing into the area behind the front. As a result,
expect light winds to gradually back from southeast to northeast
through the period with increasing wind speeds by the late afternoon
and evening hours. In fact, wind gusts may approach near 20kts by
the end of the period. There is the potential for some light snow to
develop near the TAF sites Monday evening as a shortwave advances
into western and central Kansas. As a result, anticipate an increase
in the mid-level cloud cover through the day with some low clouds
possibly developing by the early evening hours. Due to the
uncertainty in whether or not this light snow will actually develop
near the TAF sites, have not included a mention of it in the TAF at
this time but will need to continue to monitor this potential in
future updates.




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