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000
FXUS63 KTOP 112310
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
510 PM CST Wed Dec 11 2013

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Thursday)
Issued at 316 PM CST WED DEC 11 2013

Canadian high pressure centered over southeast Nebraska at 3 PM
will continue moving southeast overnight. Winds are already near
calm over north central KS and will remain that way through the
evening, before picking back up from the south later tonight. That
scenario will play out a little later in the east. With light
winds and clear skies, temperatures should fall to the lower
single digits in the northeast to around 10 across the
southwestern part of the forecast area. Would expect lows to occur
during the mid to late evening north central and around or just
after midnight in the east central and far northeast, then steady
out or very slowly rise as some mixing occurs with the southerly
winds developing behind the departing high.

On Thursday, mostly sunny skies and southerly winds will result in a
warmer afternoon, with highs in the lower 40s into the Minneapolis,
Abilene and Council Grove areas.  The coldest temperatures should be
along the far northeast KS border with Nebraska, with some remnant
snow cover, where maxima may only reach the mid 30s.

.LONG TERM...(Thursday Night through Wednesday)
Issued at 316 PM CST WED DEC 11 2013

There continues to be some uncertainty in precipitation chances and
types for Thursday night into Friday night periods. The upper low
near northern Baja ejects east into Central Plains Friday and Friday
night. Southerly flow ahead of this will bring in modified moisture,
though mid level trajectories remain veered. The overall setup is
not one that suggests a strong likelihood for drizzle, but some
guidance shows a small possibility as the low levels moisten, and
specific trends on very-near surface temperature and RH values will
need to be watched for possibly inclusion as the Thursday night and
Friday near. The last few runs of the NAM remain to be nearly free
of precipitation in the state, with quite dry mid levels and little
forcing, with the GFS and ECMWF bring much more pronounced area of
mid and upper level frontogenesis and deformation across northeast
Kansas, quickly saturating the column Friday. Temperature profiles
become the next challenge with just how strong the lift will be as
well as how moist the preceding airmass will be to produce
precipitation. Haven`t changed much of the previous forecast, with
at least some insolation to go with the near-surface theta-e
advection for warming low levels and mid levels still near to above
freezing for rain to dominate, though question on just how fast the
boundary layer modifies keeps the need for freezing rain to be
maintained. By late afternoon, temps aloft look to cool enough
behind the surface cold front and upper wave for a shift to snow
from northwest to southeast, encompassing the entire area by the
early morning hours. As with the earlier precip, amounts should be
quite low, with the worst case scenario seeming to be a narrow band
of moderate precipitation setting up and persisting for a few hours
with temperatures cooling enough for advisory-level amounts of
precip, likely snow in the late afternoon and evening. Cold air
advection could be enough for some light drizzle or flurries as well
Friday night if the mid levels don`t or don`t stay saturated.
Overall, will keep chances below likely levels give much uncertainty
on if and where accumulating precip would be.

Upper flow becomes more zonal again for much of next week.  This
should bring moderating temperatures and little chance for
precipitation. Can`t rule out a weak front passing around midweek,
but any such airmass passing through should be modified enough for
not much of a temp drop.

&&

.AVIATION...(For the 00Z TAFs through 00Z Thursday Evening)
Issued at 509 PM CST WED DEC 11 2013

For the 00z TAFs...VFR conditions are expected through the period as
surface high pressure shifts south of the area. With this passing
surface high, winds will be light and variable this evening and
gradually increase by Thursday morning out of the southwest. Skies
are expected to remain clear through the period.

&&

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

$$

SHORT TERM...Phillips
LONG TERM...65
AVIATION...Hennecke