Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 022334

Area Forecast Discussion
National Weather Service Omaha/Valley NE
534 PM CST Fri Dec 2 2016

.SHORT TERM...(tonight through Monday)
Issued at 234 PM CST Fri Dec 2 2016

Main forecast concern is the positively titled trough over the
intermountain west this afternoon. The south end of this trough is
expected to continue to dive into Mexico while the northern
portion should continue to progress eastward through the northern
and central Plains over the next 36 hours. Ahead of this trough we
will see high level clouds increase tonight, with the deck
lowering to mid clouds Saturday morning before deeper saturation
occurs on Saturday afternoon. The models are in general agreement
that broad isentropic upglide on the 285-295 K surfaces will
continue into Saturday night until the axis of the mid-level
trough passes. Precipitation type is an issue with initially a
cold airmass in place, but warmer air aloft moving in from the
south, as well as diurnal warming of the boundary layer. This will
likely result in a rain and snow mix across the southern 2/3rd of
the forecast area during the day on Saturday, with potentially a
more concentrated period of light snow on Saturday evening
associated with the strongest large-scale forcing for ascent before
the warmer air aloft shifts northeast into the CWA. Precipitation
may end on Saturday night as a little light rain/drizzle as we
lose the introduction of ice into the column. Snowfall amounts
would be light and mainly confined to grassy surfaces, but up to
or a bit more than a half inch seems reasonable over west-central
IA, with amounts for the OMA/LNK metro areas in the range of a
couple tenths.

This system exits to the east by Sunday morning with little in the
way of sensible weather expected for Sunday through Monday.

.LONG TERM...(Monday night through Friday)
Issued at 234 PM CST Fri Dec 2 2016

Longer range models continue to struggle with how to handle a
strong Pacific jet as it moves into the western US early next
week. It appears over the last several days that the EC has been
slowly moving toward a more GFS solution, and given the ensemble
support this appears more likely. This would generally just mean a
strong cold front by mid week with the coldest air of the season
descending into the Plains. We will continue to mention some
small chance pops associated with the incoming cold air, but
chances of a significant winter storms appear very small
currently. Once the cold air is in place by mid week we should see
well below normal temperatures through the end of the forecast


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 534 PM CST Fri Dec 2 2016

As of 23z, the western edge of MVFR ceilings stretched from KOFK
to near KOMA. Persistent westerly winds within the cloud-bearing
layer should allow for the eastward advection of these low clouds
with mainly an increase in mid to high-level moisture thereafter.
The low clouds and associated chance of precipitation will
increase at all TAF sites by Saturday afternoon as a short-wave
trough moves into the mid Missouri Valley.




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