Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 212107
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
307 PM CST Sun Dec 21 2014

.SHORT TERM...(This Evening through Monday)
Issued at 300 PM CST SUN DEC 21 2014

A longer wave-length upper level trough across the plains will
amplify as a short wave trough over MT digs southeast into NE.
Residual moisture was advecting northward across eastern KS. The
resulting isentropic lift will cause patchy drizzle, areas of light
fog and isolated showers this evening. As the H5 trough digs
southeast into NE, stronger ascent will cause more widespread rain
to develop across the CWA late tonight into early Tuesday morning.
Due to limited moisture, QPF will generally be less than 0.15".

The upper trough will evolve into a closed upper low over NE on
Monday. The best rain chances will occur during the morning hours
ahead of a weak surface cold front. Drier air at 700mb will advect
across the CWA bringing an end to the rain showers through the
afternoon hours. Skies will be mostly cloudy, though skies may clear
during the afternoon hours across the southwest counties of the CWA.
Highs will range from the mid 40s across the northwest counties to
the lower 50s across the southern counties.

.LONG TERM...(Monday Night through Sunday)
Issued at 300 PM CST SUN DEC 21 2014

Tomorrow night the main upper level low will be centered just
northeast of the forecast area. Several pieces of energy will rotate
around the main low and pass over eastern KS. The models strengthen
this energy as it phases with energy lifting through the base of
the main trough. The models vary on the interaction of this
phasing and therefore the strength of the upper low as it passes
overhead. The 12z NAM was the strongest and generates the most lift
across the area during the day Tuesday into Thursday night. The
lift is still relatively weak and does not appear to amount to
much accumulation. At the moment there is barely any lift to
generate ice in the cloud and surface temperatures may warm well
above freezing therefore mentioned rain and or snow in the
forecast. This is especially true during the daytime hours on
Tuesday. That system quickly moves off to the east Wednesday
morning as northwest flow develops behind the departing trough.
Another weak system aloft is forecast to pass north of the area
Thursday night and looks to bring a slight chance for snow to
north central KS. Although the models have been rather
inconsistent with handling this system. The remainder of the
period appears dry.

&&

.AVIATION...(For the 18Z TAFs through 18Z Monday Afternoon)
Issued at 1125 AM CST SUN DEC 21 2014

The main challenges for the TAF period will continue to be the
CIG/VIS categories. IFR is expected to persist during the first
half of the period. Winds will be fairly steady but there is
potential for some gusts into the mid 20 mph range as we see some
directional changes come into play. Some uncertainty remains with
light areas of drizzle along with potential for light rain. But
for now, just keeping mention of drizzle. Lower confidence with
the actual CIG/VIS remains with these areas as well, but generally
improving conditions can be expected near the end of the TAF period.


&&

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

$$

SHORT TERM...Gargan
LONG TERM...Sanders
AVIATION...Drake





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