Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 162340

Area Forecast Discussion
National Weather Service Topeka KS
540 PM CST Tue Jan 16 2018

...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Wednesday)
Issued at 200 PM CST Tue Jan 16 2018

Quiet weather is forecast for tonight and tomorrow with a warming
trend beginning on Wednesday.

Surface high pressure centered over the Central Plains was
exerting its influence on the region this afternoon, allowing for
clearing skies but continued weak CAA. A few patches of low
stratus could be found pushing southward along the eastern flank
of the ridge over Iowa, Missouri, and far eastern portions of
Nebraska and Kansas. These thin clouds have been on the decline
through the morning and this trend is expected to continue through
the afternoon. Lows tonight look to fall to around or slightly
below zero as the high passes overhead. The combination of light
winds and fresh snow pack may modulate temperatures lower than
forecast early in the night, but with southerly flow beginning to
build after 06Z, temperatures should stabilize for the remainder
of the night. Wednesday features the beginning of our late week
warm-up with increasing S/SW return flow and H850 temps rising
above 0 C by sunset. Surface temps will likely remain in the upper
20s to around 30 given the influence of the widespread snow pack.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 200 PM CST Tue Jan 16 2018

Continued warm weather is forecast for the end of the week with
the next notable weather system arriving late in the weekend.

A large upper tropospheric omega block centered over the Rockies
this afternoon breaks down tonight and tomorrow, placing the
region in split flow for the remainder of the week. Broad SW flow
will be established at the onset of the period Wednesday night and
allow continued WAA through Saturday, with H850 temps reaching +6
C midday Thursday and +12 C midday Friday. There is some concern
that any residual snowpack on Thursday may result in lower
temperatures, but with snow depths across the region generally
around 1-2 inches with locally higher pockets, it was felt that
these temperature modulations would be localized. Winds look to
increase by Friday given the 15 mb pressure gradient over the
state ahead of our weekend system.

An H300 trough digs southward over California early Saturday and
ejects into the Four Corners region by 06Z Sunday, possibly
transitioning to a cutoff low as it lifts over the Central Plains
late on Sunday. Medium range solutions are in good agreement on
the general evolution of the upper level wave with some expected
timing discrepancies. At the surface, lee cyclogenesis takes place
along the Front Range late Saturday with increasing baroclinicity
along a warm front arching eastward into Kansas. The deepening
996 mb surface cyclone looks to lift through NE Kansas by late in
the day Sunday with the dry slot punching up through the eastern
CWA and the trailing deformation snow band affecting primarily
north central Kansas. Snow looks to be the biggest impact from
this system with temperatures in the dry slot too warm for FZDZ.
CAA behind this system early next week looks to be limited given
the zonal flow pattern developing in its wake.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 539 PM CST Tue Jan 16 2018

VFR conditions are expected through the TAF period. Winds will
shift to the southwest and increase to 5-10 kts after 15Z
Wednesday morning.




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