359
FXUS63 KOAX 042027
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
327 PM CDT Fri Jul 4 2025

.KEY MESSAGES...

- Spotty storms are expected to move into northeast Nebraska
  this evening from the west beginning around 5-7 PM. A few may
  become strong to severe, with damaging winds (up to 60 mph)
  and locally heavy rainfall through 10 PM, though additional
  storm chances linger overnight.

- Storm chances return to southeast NE and southwest IA Saturday
  afternoon, with a 5-10% chance to bring quarter-sized hail and
  gusts to 60 mph.

- Daily storm chances persist Sunday overnight through the work
  week. Severe weather potential remains on the lower end,
  though repeated rounds of rainfall could introduce flooding
  concerns.

&&

.DISCUSSION...
Issued at 323 PM CDT Fri Jul 4 2025

Today and Tomorrow:

Water vapor imagery this afternoon depicts a peculiar mid/upper
pattern across the CONUS, with a deamplifying trough over the
western third of the CONUS over-top building ridging, a broad
shortwave entering the Central and Northern Plains, and ridging over
the eastern third of the CONUS. Drilling down to the surface
locally, we find ourselves on the eastern periphery of increased
cloud cover, deepening heights, and scattered showers and storms
associated with a poleward-oriented surface trough draped over the
Colorado/western Nebraska/Kansas area with convection. The increased
surface pressure gradient has allowed those southerly winds to gust
to 25-35 mph and take the edge off of the temperatures in the upper
80s to near 90 degrees, further aided by scattered to broken cloud
cover. Expect temperatures to climb a few more degrees, with heat
indices expected to top out around 95 degrees, making for a toasty
but manageable evening outside.

The main concern for the short-term forecast are shower and storm
chances moving eastward ahead of the aforementioned surface
troughing. While the 18z KOAX sounding depicts PWAT values of just
under 1.5", a ribbon of rich moisture is expected to move eastward
with those storm chance and break up the capping in place. Aided by
the mid/upper shortwave, a corridor of convective development is
expected to move into the forecast area by 5-7 PM, carrying
with it CAPE values in the 1500-2500 J/kg range and a crumpled
hodograph. Any severe chances associated with these storms will
be completely dependent on storms collapsing, with gusts of up
to 60 mph being possible (only a 5% chance) through 10 PM. Even
those wind chances will be knee-capped to a certain extent by
the increasingly moist airmass devoid of features like an
"inverted v" boundary layer or strong low-level flow, with both
of those increasing chances for localized areas of heavy rain.
After 10 PM, rain and storm chances are expected to continue
into the overnight hours, staying sub- severe and staying lower
in coverage into the mid-morning hours. By 10 AM tomorrow
morning, the area should be dry into the early afternoon when
storm chances return on the backside of the departing frontal
system.

By 4 PM tomorrow afternoon convective development in northwestern
Iowa more closely oriented with the main surface low is expected to
begin expanding into far eastern Nebraska and southwest Iowa,
bringing strong to severe storm chances back to the area through 9
PM. For this go around, the lower level sounding will feature
increased DCAPE, steeper lapse rates in the mid-levels, and a
similarly crumpled hodograph all pointing to increased damaging wind
chances and hail up to 1" in diameter. Once those storms exit
the area, we`ll enjoy a dry night with lows dipping into the 60s
and northwesterly winds.

Sunday and Beyond:

Sunday will start the upcoming week with a dry forecast as the
earlier system exits the area before the active pattern for the
upcoming week settles in. A cutoff low is expected to dip southward
from the main mid/upper flow and spin off the California Coast,
amplifying a narrow ridge with northwesterly/diffluent flow
dumping out into the mid-Mississippi Valley for much of the
week. Ensembles are keen on allowing the warmer west and
mid/upper ridge associated with it to keep temperatures warm
(upper 80s to low 90s) despite us being only on the eastern
periphery of it, and moving nearly daily rain and storm chances
in the form of shortwaves and High Plains convection into the
area. Details as to the timing and intensity of the convection
will continue to be hard to predict until we get closer, and we
could be heading into another poorly performing CAM week,
similar to the last.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1219 PM CDT Fri Jul 4 2025

A field of low clouds are increasing in coverage early this
afternoon and generally range from FL025-Fl040 and should last
through 02z. Main adjustments to the forecast have been slightly
lower wind gusts out of the south this afternoon, tightening
the windows for shower/storm chances this evening, and the
inclusion of lingering low clouds tomorrow morning. Showers and
storms will likely not be patchy at times rather than being non-
stop, so further cuts to the start/end time may be warranted as
we approach them.

&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...Petersen