112
FXUS63 KOAX 300250
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
950 PM CDT Sat Jun 29 2024

.KEY MESSAGES...

- Seasonally pleasant weather through sunset on Sunday.

- Flooding continues on the Missouri River below Decatur through
  the coming week.

- Sunday through Tuesday will feature multiple rounds of
  thunderstorms. Severe thunderstorms are possible, particularly
  Monday afternoon through Tuesday evening, with very heavy rain
  possible during this time frame as well.

- Thunderstorms are possible on Independence Day, but overall
  confidence is low, and thunderstorm potential may change based
  on minor changes with speed of the storm system.

&&

.DISCUSSION...
Issued at 303 PM CDT Sat Jun 29 2024

The last two days of June, on a weekend nonetheless, are an
absolute delight in terms of weather. High pressure is building
into the region behind yesterday`s cold front with below normal
temperatures under mostly sunny skies. A northerly breeze has
been a bit gusty today, but we can expect decreased winds this
evening, and generally light winds through Sunday...just enough
to keep the seasonally pleasant air moving during the afternoon
hours. Overnight lows tonight will be in the 50s...with highs
Sunday in the 70s...and lows Sunday night in the lower 60s. For
some of us, windows-open weather has returned! While there may
be a passing sprinkle or light rain shower on Sunday, even
these will be light, and moving along at a good enough pace such
that they won`t linger long over any given location. After an
extremely busy April, May, and June, it is just nice to be able
to write this paragraph and look forward to enjoying a couple of
peaceful weather days across eastern Nebraska and western Iowa.

Now...on to the rest of the forecast for Sunday night through
the end of next week...

Sunday Night into Monday Morning:
Yesterday`s cold front has indeed pushed well south of the area,
but the extremely moist and warm airmass still exists south of
the front in Oklahoma and southern Kansas. As we move into late
Sunday, a longer wave trough will build on to the west coast and
northern Rockies with an upper ridge centered over Texarkana. An
intensifying upper level southwesterly jet will develop over
Wyoming with lee cyclogenesis over WY/MT. A lead short wave
trough will ride up and over the ridge on Sunday night, with
height falls extending across our region. These features will
help to pull the frontal boundary back north as a warm front,
with a good amount of heat and moisture riding northeast of the
front into the local area on the low level jet as early as
Sunday night. This will set up a favorable scenario for
widespread rain and thunderstorms associated with the short
wave trough passage. Currently expect elevated parcel MUCAPE
into the 1000-1500 J/kg range, but effective shear may struggle
to support much storm organization. Also, there will be good
moisture return with this system, but it also appears somewhat
progressive and scattered...so for now it appears that the
severe and hydro threats for Sunday night into Monday morning
are fairly low.

Late Monday into Monday Night:
Another subtle short wave trough focused a bit farther south
within the flow pattern will cross into the Plains by late on
Monday. Expect a surface low to develop over southwest NE and
another over northeast WY. These should be quite effective in
surging the frontal warm sector north into Nebraska and
eventually northeast into the NWS Omaha coverage area by late
afternoon into the evening. This will be a mobile warm sector,
at least initially, characterized by 1500+ J/kg of MLCAPE, but
most forecast soundings have a pretty stout cap in place.
Hodographs, particularly on the leading edge of the warm sector,
feature large cyclonic shear in the low levels. The main
question, it appears, is if that cap can be broken for surface
based thunderstorm development. If so, it would appear that
supercells would be the primary storm mode, with ample low level
shear available. For now, this is worth carefully monitoring,
especially west of a Falls City to Fremont to Neligh line.

As the evening progresses, see an increasing likelihood for
strong to severe elevated convection. Mid level lapse rates will
be steep, with a very impressive amount of moisture transport on
the LLJ focused into our region. Layer PWAT in the 2 to 2.4 inch
range along with a focused zone for moisture convergence and
ample instability points to the potential for very intense
rainfall rates on Monday night. And, while storms should be at
least somewhat progressive, any locations experiencing multiple
rounds of storms or periods of backbuilding will quickly see
flash flood potential increase given the intense rates. Some of
this heavier rain may also fall into already swollen or flooded
rivers, worsening existing flooding...but specific locations are
yet to be identified and at this time the main takeaway is that
the ingredients for very heavy rain will be present.

Tuesday into Tuesday Night:
The front sags back south and lays out across the region for
late Tuesday. Instability will likely be impressive south of the
front with mid 70s dewpoints and hot temperatures wherever
clouds break. Deep layer shear will again be quite strong,
although with less low-level turning than on Monday. The shear
vectors are also likely to be more parallel with the frontal
boundary than on Monday which tends to result in clusters or
more linear storm mode, although probably with embedded
supercells given the shear magnitude. Moisture content will
again be very high with impressive rainfall rates in the storms,
and with several hours of front-parallel flow, could easily
result in some higher-end rainfall totals once again, along with
the severe weather potential.

Rest of the Week:
Wednesday looks relatively quiet with the front south of our
area, but it lifts back north for Independence day as the
strongest of the short wave troughs crosses the northern
Plains. Depending on system timing, the 4th may be rather
stormy...with ingredients in place ahead of this storm system...
but hesitate to go all-in on this for now, as a slightly faster
system movement could make for a pretty clear evening.
Definitely a period worth paying close attention to the
forecast. Friday through the weekend, at least for now, look to
be largely dominated by high pressure, and relatively dry.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 950 PM CDT Sat Jun 29 2024

VFR conditions expected through the period with passing mid
level clouds Sunday. Light northeast winds overnight will become
southeasterly Sunday morning, with speeds on either side of 10
kts. A few pieces of guidance hint at shower and storm
development toward the very end of the period, but consensus
is to hold off until after 06Z and possibly even 12Z Monday.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION...CA