Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 302321
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
621 PM CDT Sun Apr 30 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 314 PM CDT Sun Apr 30 2017

...Significant storm system to impact the region into Monday
morning...

Observational data indicate an intense, deep-layer cyclone over
south-central KS as of 19z with the center of this system forecast
to track just to the south and east of our forecast area tonight
into Monday. Increasing height falls ahead of the cyclone coupled
with pronounced low-level warm advection and isentropic upglide
have fostered widespread showers and a few thunderstorms across
the area today. Some sleet has recently been observed with the
embedded convective elements over Saunders County. Across the
higher terrain of our northwest CWA, a mixture of rain and snow
has been reported. This is especially the case where the highest
precipitation rates are occurring.

Near-term model guidance remains relatively consistent in suggesting
that the ongoing precipitation band oriented west-to-east across
the northern half of the CWA will pivot northwest, eventually
becoming aligned more north-to-south over our northwest counties
by this evening. Daytime heating, albeit quite weak, will likely
be sufficient to offset diabatic and adiabatic cooling effects
through the remainder of the afternoon with little snow
accumulation expected. However, by this evening into tonight, we
expect to see snow accumulate within the deformation precipitation
band which will gradually lift northeast through the northern
part of the forecast area tonight into Monday morning. Highest
accumulations of 2-5+ inches are expected across Knox, Antelope,
and Boone counties with 1-4 inches possible in adjacent Cedar,
Pierce, and Madison counties. Consequently, we have added these
latter three counties to the existing Winter Weather Advisory.
Elsewhere, light snow will likely mix with rain late tonight into
early Monday to generally along and north of I-80, though little
to no accumulation is expected.

Precipitation should gradually decrease in coverage and intensity
Monday morning with thinning clouds allowing temperatures to warm
into the 50s. Winds will remain rather strong and gusty from the
northwest. By Monday evening, a weak shortwave trough will
translate southeast into the area, bringing a slight chance of
light rain to our northern counties.

Tuesday night into Wednesday, a series of mid-level impulses will
contribute to the amplification of a shortwave trough over the
central CONUS. This upper-air pattern evolution will be
accompanied by a weak front that will move through the area,
along with increasing rain chances.

We will see a gradual warming trend with afternoon highs bouncing
back into the 60s on Tuesday and Wednesday.

.LONG TERM...(Wednesday night through Sunday)
Issued at 314 PM CDT Sun Apr 30 2017

The aforementioned central U.S. trough will advance east during
the latter part of the week with a mid-level ridge building east
into the Great Plains. This pattern will be supportive of
generally dry and warmer conditions.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 620 PM CDT Sun Apr 30 2017

Expect precipitation to continue into Monday morning. Rain will
mix with and change to snow at KOFK. Rain may become mixed with
some snow at KLNK and KOMA later tonight. IFR conditions should
become prevalent overnight, with some brief MVFR possible. TAFs
were shortened, but it should become VFR at KOFK by about 18Z, VFR
at KLNK by about 19Z and at KOMA by 21Z. Winds have dropped off
but should increase with north/northwest winds 20 to 30 knots and
gusty on Monday.


&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 9 AM CDT Monday for NEZ011-012-016-
     017-030-031.

IA...None.
&&

$$

SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Miller



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