LINCOLN, NE Weather

Updated Aviation Forecast Discussion... 
.DISCUSSION... Issued at 312 PM CDT Sun Jul 12
2020  Overview: An upper level ridge is currently
centered over Arizona, while a long wave trough is
dominating the eastern third of the CONUS and
another trough axis has just come on shore in the
Pacific Northwest over the top of the ridge. On a
smaller scale, a short wave trough axis over the
Nebraska Sandhills was slowly shifting east this
afternoon with other shorter wavelength troughs
rotating around the ridge over the central
Rockies, and another slight enhancement over
northern Wyoming. An area of showers and storms
had developed in the warm advection regime along a
narrow axis of steep isentropic ascent and modest
elevated moisture over central NE. They produced
severe hail earlier in the day, but have waned in
intensity with eastward extent.  Through Tonight:
The showers and storms will continue to shift east
with the short wave forcing, but the trend of
decreasing coverage and intensity is likely to
continue over the next several hours as they
interact with a less favorable environment for
elevated convection survival. May see showers or
even a few lightning strikes into parts of Boone,
Antelope, or Knox counties, but doubt that it
would make it much farther east. However, as the
night wears on, the short wave and its focused LLJ
convergence and isentropic ascent may reinvigorate
enough to develop isolated to scattered
showers/storms mainly over northeast Nebraska.
Forecast soundings indicate periods of up to 1500
J/kg of elevated instability rooted around 8000 ft
AGL, which may be sufficient for a briefly-severe
hail storm if deep convection can develop and
persist. All of this is highly conditional though
as forcing is not particularly strong. At this
point, have only a 10-20 percent chance of storms
tonight.  Monday: Monday will be a bit warmer as
the trough over the northwest crosses the northern
Plains with warm advection locally. A cold front
will set up through north central NE into the
Dakotas and will act as a focus for convective
development by early evening. Expect moderate
instability near the frontal boundary but with
some warming temps aloft in eastern NE ahead of
the front. This may result in a fairly strong cap
for any storms that try to progress east off of
the frontal boundary. It appears most likely that
initiation will be northwest of the local forecast
area with clusters of storms eventually making
their way into northeast Nebraska. My main
question is if any of these clusters can develop
an organized cold pool deep enough to consistently
force parcels through the cap to the LFC for
eastward propagation. At this time, it appears
that it will be increasingly difficult to do so
with southeastward extent. So, while some cold
pools are able to over- perform this time of year,
the current focused severe risk northwest of a
Columbus to Wayne line seems to make a lot of
sense with a lower-end potential for an organized
forward propagating cluster to track slightly
farther south.  Tuesday: The big question on
Tuesday is how far south the cold front travels
early in the day. It appears likely that the front
will slow or stall somewhere near or south of here
on Tuesday. At that point, it becomes a matter of
timing of short wave impulses and the current
indication is that there will be a chance of
storms near/ahead of the front Tuesday afternoon
as a short wave tracks across the area...and then
perhaps a better chance near/north of the front
late Tuesday night as the next wave comes out and
enhances LLJ convergence into the boundary. 
Wednesday through Next Weekend: Storms may linger
early Wednesday but then looks to stay dry until
Thursday evening. Thereafter, we appear to be
firmly entrenched in a rather difficult forecast
pattern with a strong ridge to the south and
somewhat fast flow near and to the north with
frequent weak short wave trough passage. This
tends to spell continuation of our MCS pattern in
some form, where many days` forecasts are dictated
by the height of the LFC and the strength of the
cold pool in storms that initiate well north and
west of the local forecast area. With that said,
anticipate a warming trend as the ridge does build
over time, and also expect generally greater
precip chances with northward extent. Also see
potential for intermittent severe storms, but with
little confidence in timing those higher-end
chances. 

NWS OAX Office Area Forecast Discussion