456
FXUS63 KOAX 282024
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
324 PM CDT Fri Jun 28 2024

.KEY MESSAGES...

- Moderate flooding is ongoing or expected to begin along the
  Missouri River the next day or two. It`s forecast to last into
  next week for Omaha and points south.

- A few severe storms are possible this afternoon and evening
  with the potential for large hail, damaging winds, localized
  flash flooding, and perhaps a tornado or two.

- Quiet and cooler for the weekend, with highs in the mid 70s to
  lower 80s. Then warming back up and becoming more active for
  the holiday week.

&&

.DISCUSSION...
Issued at 255 PM CDT Fri Jun 28 2024

The current scenario at 3 PM Friday has a persistent area of
light rain showers, with elevated parcel inflow regions,
extending from Monona county back to Gage county. There have
been a few lightning strikes within this activity, but for the
most part they have been few and far between. However, the
southern tip of this area has shown recent signs of deeper
convective updrafts, and is likely beginning to interact with
near surface parcels. Mixed layer inhibition has decreased to
less than 25 J/kg while an axis of MLCAPE greater than 2000 J/kg
has developed amidst surface temperatures near 90 and dewpoints
in the middle to upper 70s in far southeast NE and southwest
IA. Effective shear is also in the 30-40 kt range in this area.
All of this suggests a window for strong to severe convective
development over the next 2-3 hours, seemingly focused south of
a line from Nebraska City to Red Oak, and points east. If storms
are able to surface base and organize, would anticipate a period
of large hail production as well as generally isolated wind
damage potential correlated with any stronger downbursts.

While there is a pre-frontal wind shift across the region, the
true cold front at 3 PM was analyzed near a line from near Onawa
back toward Fremont, and then down to around Seward, and is
making some southerly progress. With the light and/or westerly
flow in advance of the front, and northerly flow that isn`t
particularly strong behind the front, the boundary layer
convergence is present but not especially strong. This is
reflected in the shallow cumulus field in this area. But, as we
progress into the evening, some cool advection aloft and weak
height falls moving into the region may be sufficient to help
initiate new convection near the front in combination with the
weak boundary layer convergence. Inhibition is expected to
become weak or non-existing while CAPE will likely still be in
the 1500-2500 J/kg range and effective shear will be sufficient
for storm organization. Thus, we will need to continue
monitoring the front, especially in the 5-8 PM time frame for
new development as it could become severe with similar hail/wind
hazards to any afternoon activity. There is a non-zero tornado
potential, but it does look to be a very small potential, and
mainly tied to any intense updrafts that can develop near the
front and stretch existing vertical vorticity. After the front
and any associate storms push east, there is a likelihood for a
few storms to be moving east across central NE. However, these
storms will be entering an increasingly hostile environment with
eastward extent, and expect them to likely dissipate before
reaching the local forecast area.

Saturday and Sunday will be quite nice. There are a couple shots
at a light shower Saturday morning and mid day, but more likely
that we`ll see some cloud cover and virga rather than
measurable rainfall. Still something to keep in mind. High
temperatures both days will be in the 70s to lower 80s...with
Sunday morning lows probably dropping into the 50s.

Sunday night into Monday morning features a return of rain
chances and warm humid conditions as a new storm system enters
the Plains and brings a warm front back north. Sunday night
looks more rainy than stormy, probably seeing a widespread 0.25
to 1.00. There may be some potential for a bit more locally, but
not a major heavy rain threat at this time. As we go into
Monday, it appears somewhat likely that severe storm parameters
will again align with substantial CAPE and favorable hodographs
for supercells. There are many details to work out regarding
this period, but early indications are that all severe weather
hazards will be possible Monday afternoon and evening. This is
further amplified by the amount of atmospheric moisture
returning to the region on Monday night. Moisture convergence on
the LLJ appears favorable to produce some heavy rain, perhaps
2-3+ inches in some locations. A similar severe and heavy rain
setup could develop on Tuesday, but will depend on the details
of system timing from late Monday. The unsettled weather pattern
probably continues through the end of the week, but looks like
it may settle down into more of a dominant ridge pattern as we
get into next weekend.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1201 PM CDT Fri Jun 28 2024

TAF lines largely dominated by wind shifts and precip chances.
Current MVFR cigs at OMA should lift near 18Z to VFR. An area of
SHRA to the west will impact all sites over a 2 hour window of
time with tempo precip but continued VFR conditions. There is a
small chance for thunder during that time window but not
mentioned in the TAF at this time. Stronger TS development is
expected between 23-01Z, but currently believe it will be south
and east of OMA/LNK. Will need to watch this closely, but for
now have not included TS in the TAF.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION...Barjenbruch