Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 212332
AFDTOP

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

...Update to aviation forecast discussion...

.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 00Z TAFs through 00Z Monday Evening)
Issued at 528 PM CST SUN DEC 21 2014

TOP should hold right at MVFR conditions for a few more hours
before IFR conditions impact all three terminals. Precipitation
should also get heavier overnight before decreasing mid morning
hours. Next sweep of energy moves through in the afternoon and
brings winds westerly and another band of precipitation, although
think cigs will be a bit higher in the MVFR category.

&&

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

$$

SHORT TERM...Gargan
LONG TERM...Sanders
AVIATION...67





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