Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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342
FXUS63 KOAX 202342
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
542 PM CST Tue Feb 20 2018

.SHORT TERM...(Tonight through Friday)
Issued at 327 PM CST Tue Feb 20 2018

WV imagery was showing the upstream longwave trof has nudged a bit
to the east since yesterday and currently extends from about central
Canada to Baja. However, models are in pretty good agreement large
scale pattern will become stagnant with the upper trof moving little
the next several days. Meanwhile natural color imagery was clearly
showing demarcation of snow cover across the region...with snow
generally northwest of a line from northeast NE to east-central CO.

Onset of precip and dominate type on Wednesday evening is the main
issue to contend with. Models are in good agreement showing precip
development over KS late afternoon Wed within region of 300K
moisture advection/upglide. Precip in the form of light snow then
expands across the CWA during the overnight hours with increase of
mid layer ageostrophic lift. Thursday morning, precip type becomes
problematic as MaxT aloft push just above freezing. And with BUFKIT
showing feeder-seeder process waning along with boundary layer temps
below freezing, dominate precip type will likely be freezing drizzle
by late morning and continuing through the afternoon. Light freezing
drizzle appears to still be possible Thursday evening. At this
point, expect snow totals to range from about one or so inches south
of I-80 corridor, with up to an inch the rest of the CWA. Ice
accumulations, around a tenth of an inch extreme southeast
NE/extreme southwest IA, with less that a tenth elsewhere.

.LONG TERM...(Friday night through Tuesday)
Issued at 327 PM CST Tue Feb 20 2018

Next round of possible snow accumulation comes on Saturday when the
GFS/ECM prog a vigorous vort max crossing into the central Plains.
Otherwise, dry conditions will prevail Sunday through Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 540 PM CST Tue Feb 20 2018

A short period of MVFR cigs near FL025 will affect KOMA and KLNK
through 02Z. Then VFR conditions with clearing skies are forecast.
Gusty northwest winds 15 to 25kt will also diminish to less than
12kt by 06Z, then become east or northeast Wednesday afternoon.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

$$

SHORT TERM...DEE
LONG TERM...DEE
AVIATION...Dergan



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