Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 211743

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1243 PM CDT Wed Mar 21 2018

.SHORT TERM...(Today through Friday)
Issued at 301 AM CDT Wed Mar 21 2018

Water vapor imagery as of 08z depicted a coupled of weak mid-level
perturbations within the general area: one over our CWA and the
other traversing the Dakotas. Both features will shift east today
in deference to a longer-wavelength ridge which will amplify over
the Rockies. In the low levels, a surface ridge axis from the ND-
MN Red-River Valley to mid-MO Valley will build east while a lee
trough deepens along the Front Range. This will result in light
and variable winds gradually becoming south or southeast by
afternoon. IR satellite data indicate patchy stratus over our
eastern NE counties with more widespread cloudiness across
southwest IA. Model guidance suggests a gradual clearing trend
today from southwest to northeast across the area. Highs will
range from the lower to mid 50s at locations that will experience
more sun to upper 40s in west-central IA.

Tonight, the development of a nocturnal low-level jet will focus a
zone of warm advection and isentropic upglide over far eastern NE
into western IA with isolated to widely scattered showers possible
toward daybreak Thursday.

On Thursday into Thursday night, the aforementioned mid-level
ridge to our west will build into the Great Plains while a surface
low deepens over eastern WY. While low-level winds will remain
light and from the east or southeast, clouds should decrease
through the day allowing temperatures to warm into the mid 50s to
mid 60s.

On Friday, a progressive short-wave trough will move into the
central High Plains by afternoon and through the mid-MO Valley
Friday night. In response, a surface low will consolidate over
western KS prior to tracking into northwest MO by Saturday
morning. Strengthening southerly winds ahead of the cyclone will
draw and warmer and more moist air mass into the region with
showers developing within the associated warm-advection regime on
Friday. Highest precipitation chances will exist across our
northern counties, decreasing with southward extent toward the KS
border. Highs will be dictated by the cloud/precipitation
distribution with generally cooler readings in the north and
warmer afternoon temperatures in the south.

.LONG TERM...(Friday night through Tuesday)
Issued at 301 AM CDT Wed Mar 21 2018

By Friday evening, the co-location of steep mid-level lapse rates,
a moistening low-level air mass, and deep-layer forcing for
ascent immediately ahead of the synoptic cyclone will yield a
weakly unstable environment with scattered non-severe storms
possible across southeast NE and southwest IA. Precipitation
chances should decrease from west to east across the area on
Saturday with the passage of the weather system to the east.

By Sunday into Sunday night, we will see an increase in
precipitation chances within a zone of warm advection associated
with a short-wave trough lifting through the northern High Plains.
On Monday into Tuesday, 00z medium-range guidance indicates that
an upper low will cutoff over the southwestern U.S. with an
associated surface front slowly sagging south through the central
Plains. This setup will favor continued precipitation chances with
some light snow possible across the northern half of our area
Monday night.

High temperatures through the extended range should generally be
in the 40s and 50s.


.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1238 PM CDT Wed Mar 21 2018

VFR conditions are likely through the TAF period with a very small
chance for visibility restrictions to develop late tonight but
have currently kept VFR TAFs due to the low potential for fog.




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