Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 162329

529 PM CST Tue Dec 16 2014

...Update to aviation forecast discussion...

.SHORT TERM...(This Evening through Wednesday)
Issued at 336 PM CST TUE DEC 16 2014

Much of the area getting a few hours of sunshine this afternoon as
thin low clouds slowly dissipate and surface ridging edges in from
the west. Changes to this were already appearing on southwestern
horizons however with high cloud coming in. Water vapor showing this
high cloud surging northeast ahead of a lead upper trough entering
the Baja region, dissipating somewhat as it reaches the upper ridge
axis over the Central and Southern High Plains.

Steady evolution of this lower and upper ridge to occur through
Wednesday afternoon. High cloud should thicken quickly this evening
as the upper ridge flattens, so despite the surface ridge across the
area, temps shouldnt fall too far, and went above MOS averages for
lows. Saturation of the mid steadily increases Wednesday with late
day forcing ramping up in southern and western areas as the upper
wave emerges into the Panhandle region. Have bumped up PoPs a bit,
with very light precip in still somewhat dry low levels possible.
Kept type as snow with only bits of the column just breaching
freezing and cooling late afternoon surface temps.

.LONG TERM...(Wednesday Night through Tuesday)
Issued at 336 PM CST TUE DEC 16 2014

Shortwave trough will continue to lift northeastward across the cwa
Wednesday night...but also weakening and encountering low level
drier air as it does. Drier air aloft in the dendritic growth zone
will advance eastward across the area overnight and will continue to
provide the potential for freezing drizzle as lows fall into the
middle to upper 20s. The stronger lift will occur during the late
evening and early morning hours...but will not be very sustained so
snowfall amounts of an inch a half to two inches will be
common...although a few locally higher amounts will be possible. The
areal coverage of the event however warrants increasing pops through
the likely range...but the northeast corner of the area will be last
to saturate. In the wake of the shortwave trough...weak lift in the
presence of cold sfc temps and a continued lack of ice aloft
warrants mentioning drizzle/freezing drizzle on into Thursday night.

The next shortwave trough which then advances eastward from southern
CA into TX will phase with a northern stream wave moving through the
northern Plains on Friday. This will veer the flow and likely keep
all but the southeast corner of the cwa dry. Will therefore trim a
rain/snow chance to slight south and east of I 35 then maintain a
dry forecast through the weekend as precip should remain well south
and east of the area. As the weekend progresses...the low level flow
will then back to the southwest and allow for warm air in the high
plains to advect eastward in advance of the next shortwave trough
moving into the northern plains. As a result the highs over the
weekend will commonly be in the 40s extending into Monday before a
cold front Monday night brings colder air and a chance for rain or
snow. Any lingering precip on Tuesday appears will be limited to the
southeast corner


.AVIATION...(For the 00Z TAFs through 00Z Wednesday Evening)
Issued at 526 PM CST TUE DEC 16 2014

VFR conditions should prevail through the period, although will
need to monitor deck around 2500ft agl for this evening. Guidance
suggests will be dry enough to keep it scattered out before
clearing and have phrased TAF cycle as such.




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