Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 092049

Area Forecast Discussion
National Weather Service Topeka KS
249 PM CST Mon Jan 9 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 151 PM CST Mon Jan 9 2017

Tonight, A weak upper level trough will move across the central
plains. Most models show the better residual moisture transport and
isentropic lift developing east of the CWA. However, there may be
enough ascent for a few sprinkles across the CWA late Tonight. It
wil be breezy as south winds will be 15 to 25 MPH with some higher
gusts through the night. The surface will gradually veer to the
southwest through the night. Overnight lows will drop into the mid to
upper 30s across the northern counties to lower 40s across the
southern half of the CWA.

Tuesday, A surface trough will move east across the CWA during the
morning hours and gradually shift winds from the southwest to the
west and eventually northwest during the afternoon hours. The upper
trough will move east into the MS river valley by late afternoon.
Highs will reach the lower to mid 50s south of I-70, with mid 40s
along the NE border.

.LONG TERM...(Tuesday night through Monday)
Issued at 151 PM CST Mon Jan 9 2017

Main concern remains evolution of the upper trough that will bring
the potential for significant and potentially damaging ice
accumulations to the area this weekend. To set the stage the first
of 2 cold fronts will sweep through the area Weds passing through
mainly dry with shallow lift/meager moisture so will keep conds
dry Weds/Thurs. The colder secondary surge will arrive later Thurs
into Fri but unfortunately the cold air will be shallow with
latest trends on operational ECMWF and GFS now suggesting that the
warm nose aloft will increase quickly by later Friday with 850mb
Temps of 0C across the far northwest (Cloud County) to around +5C
across the southeast (Anderson County) with sfc air temps in the
lower 20s. Overrunning is fcst to occur Fri night with one wave of
freezing rain and perhaps sleet expected through midday Sat.
Latest operational models then attempt to lift the upper low out
with a negative tilt later Sat night or Sun which would result in
another heavier period of freezing rain with most models
suggesting that air temps will remain in the 20s with NNE sfc flow until
midday Sunday at least. However confidence in this evolution of
the upper low lifting out remains modest given inconsistent
operational runs over the past 48 hours along with a mix of
ensemble runs.

Given that its only Monday the timing and location of the heaviest
ice accumulation may shift as the models continue to adjust the
track of the main upper system. In any event, the main message at
this point that we want to pass along is that significant ice
accumulations appear possible this weekend and impacts could be
considerable on trees/powerlines if the most recent runs are
accurate so stay alert of later forecasts.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1130 AM CST Mon Jan 9 2017

VFR conditions are expected through the period.  Have opted to
include LLWS in after 02Z at TOP/FOE where winds above the low level
inversion are strongest.  Models have backed off on lower
visibilities early morning due to winds still up to 10kts overnight.




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