310
FXUS63 KOAX 290822
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
322 AM CDT Sun Jun 29 2025

.KEY MESSAGES...

- Morning thunderstorms will move across much of the area with
  periods of gusty winds and heavy rain, but the overall severe
  weather threat is low this morning.

- By this afternoon, scattered strong to severe thunderstorm
  development is likely along a weak front left over from the
  morning storms. It`s hard to know exactly where this favored
  area for storms will be, but there is a 40-50% chance for
  thunderstorms across much of the area this afternoon and
  evening.

- Much of Monday and Tuesday will be dry, with temperatures
  heating back up by late in the week.

&&

.DISCUSSION...
Issued at 256 AM CDT Sun Jun 29 2025

At 3 AM Sunday morning, much of the landscape across northern
Nebraska, South Dakota, and northwest Iowa featured clusters of
convective storms. A 30-40 kt low level jet was feeding into
southern Nebraska while an upper trough axis was centered over
eastern Montana and a surface trough extended from northeast
Colorado into southeast SD. Objective analysis indicates an axis
of higher quality sub-850-hPa moisture extending from north
central into southeast Nebraska...and into northeast KS. Mid
level lapse rates across the region are pretty impressive,
lending to rather substantial MUCAPE 3000 J/kg or greater. In
analyzing model forecast soundings as well as the radar
representation of the cold pool persistently ahead of the deep
convection, it is clear that the most unstable parcels are at
least somewhat capped, but still able to freely convective given
a deep enough cold pool. Despite having a seemingly good grasp
of the pre-convective environment, models are having a
challenging time in nailing down this forecast, as is often the
case in borderline events driven by a shallow, difficult-to-
resolve cold pool.

The current thought is that the most likely scenario is for the
ongoing , largely non-severe bow echo will continue to propagate
southeast, and will probably travel across much of the forecast
area as the soundings indicate it should actually be easier to
lift MU parcels to the LFC with southward extent into greater
moisture quality. The limiting factor is that the LLJ is likely
to decrease in magnitude and veer a bit over the next few hours
so there is yet a chance the the cold pool becomes to shallow to
lift parcels to the LFC without the added LLJ convergence.
Additional scattered storms may develop along the LLJ
convergence region in the better moisture over southeast NE into
southwest IA in the next few hours, similar to what is ongoing
in northeast KS. Throughout all of this convection this morning,
the overall severe threat appears pretty limited. Instability is
sufficient but wind profiles just struggle to support severe
storms in this environment...and any that become severe would
probably be isolated severe events amidst broader sub-severe
conditions.

Morning storms will greatly influence the late day forecast.
Wherever the outflow boundary sets up and stalls, it will cook
quite a bit with significant instability developing in the
pooling moisture. If the morning storms push that outflow well
south, then the local area sets up for a quieter afternoon. But
if the outflow holds up, or mixes out before initiation, then
expect some rather intense updrafts to develop this afternoon.
Effective shear will again be limited, but could be sufficient
for storm organization on the north side of the outflow
boundary, which would make for a severe weather threat in this
zone if it plays out this way. Could also see some heavy rain
rates and flash flood potential wherever storms struggle to move
off the boundary.

This afternoon`s storms will influence overnight storm potential
as the upper trough moves through. If the atmosphere has
stabilized, it`ll be a quiet night. But otherwise could see a
fair amount of storm activity with a low end severe and flash
flood potential. After that, look to have a couple of dry days
through Tuesday followed by a building ridge and hotter
temperatures by late in the week, and additional storm chances
for next weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1143 PM CDT Sat Jun 28 2025

A line of storms is approaching northeast Nebraska tonight,
likely to primarily track eastward. This will likely clip KOFK
around 09Z with a burst of wind on the leading edge, and causing
a wind shift to northwesterly. Latest guidance keeps storm
activity north of KOMA and KLNK through Sunday morning with the
outflow boundary gradually dropping south leading to a wind
shift to northerly Sunday afternoon. We`ll watch this boundary
as it sinks south this afternoon for potential storm
development, but right now confidence is only around 20% that
we`ll see storms Sunday afternoon and evening along this
boundary. If weather stays quiet as guidance suggests right now,
expect VFR conditions through the remainder of the TAF period.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION...McCoy