809
FXUS63 KOAX 292323
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
623 PM CDT Sun Jun 29 2025

.KEY MESSAGES...

- A few isolated showers and storms are possible along a weak
  front left over in northeast Nebraska from the morning
  storms (30% chance).

- A stronger complex of storms is expected to move in from the
  west overnight, with strong winds and hail being the primary
  hazards alongside heavy rains after 2 AM.

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

- Chances are increasing for an active holiday weekend, as a
  frontal system arrives from the west Friday into the weekend.

&&

.DISCUSSION...
Issued at 357 PM CDT Sun Jun 29 2025

Today:

Water vapor imagery this afternoon depicts a messy patter that we
find ourselves in, with widespread debris from previous and current
convection while an arm of forcing associated with a mid/upper
shortwave trough starting to grow initial convection up the High
Plains. That morning convection that swept through eastern Nebraska
and southwest Iowa has complicated the forecast for today, tanking
temperatures and overturning the airmass in place, delaying robust
convection into the late evening/overnight hours. Taking a look at a
recent surface analysis, a surface low was placed over southeast
Colorado, with a surface boundary extending northeast from it across
northern Kansas, where it runs into the convectively turned over
airmass across eastern Kansas and Nebraska. A narrow corridor of
surface moisture extends along the northern side of the boundary
across much of south-central and into eastern Nebraska, with a
largely flat field of cumulus extending from northeast Kansas to
Grand Island. Across north-central Nebraska, an impinging cold front
has resulted in another narrow field of cumulus that stretches from
northwest Nebraska east-northeastward into southeast South Dakota.
As the forecast sits right now, we`re carrying a 20% chance that
convergence becomes strong enough along either of those boundaries
for an isolated shower or storm to form along them through the
evening hours. If one would form, it would likely struggle to
reach severe levels, though it could provide a nuisance for
those outside.

What is anticipated to be the main player for storm chances late
this evening into the overnight hours will come in the form of a
cluster of storms, swept off the High Plains by the incoming
front/shortwave, then likely riding the theta-e gradient draped
near the NE/KS border. There still is quite a bit of divergence
in CAM solutions for the location and orientation of that
gradient, with the latest runs of the CAMs suggesting that the
forecast area is in play for at least a portion of the MCS as it
moves eastward; especially the southern half. Taking a look at
ingredients that the MCS will be driving into, low-level wind
fields look rather flat, with shear values of less than 25 kts
to go along with steep mid/upper lapse rates with poor nocturnal
lapse rates at the surface taking away from overall CAPE
values. Sub-severe storms look most probable at this time for
the overnight hours, with a stronger section of the system
looking to track across northern Kansas, where potentially very
strong winds of 75 mph or more are possible. Our primary hazards
will be associated with marginally severe winds of up to 60
mph, and quarter-sized hail as the front edge of the cluster`s
updrafts pulse up before weakening. In addition, we could see
heavy rain rates create localized flooding if sufficient back-
building occurs (which is possible with the WNW orientation of
0-1 km shear vectors). This area has taken less water than
points to the northwest, making increased coverage of flooding
difficult.

Timing this out based on the latest convective model trends, we`ll
see clusters of storms across west-central Nebraska and western
Kansas by midnight, that push into the forecast area between 2-4 AM
before exiting the area 8-10 AM.

Monday Afternoon through Thursday:

Northwesterly winds will be left in place for the afternoon hours
Monday, as portions of the increasing pronounced shortwave trough
traveling through the area swing southward and bring low-end
(~10%) chances for a sprinkle/light rain during the afternoon
and evening hours. Highs will feel the cooler winds, with highs
expected to only top out in the low 80s, making a beautiful
start to the work week. From there, a cutoff low over the
California Coast is poised to amplify the ridging pattern over
the western half of the CONUS, helping to drive highs upwards
through the week. Low chances of precipitation are forecast,
with a decaying MCS being our only hope for seeing rain before
the end of the week.

Friday and Beyond:

The latest runs of the global deterministic models suggest that the
aforementioned cutoff low will begin sweeping up with the
mid/upper flow and help transition increased forcing for ascent
into the Central Great Plains for Friday afternoon and evening.
The position and timing of the front/forcing that comes with
this system will be of much interest for those wanting to enjoy
the holiday weekend, which is looking increasingly active.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 623 PM CDT Sun Jun 29 2025

VFR conditions this evening under mostly clear skies. Winds are
mainly out of the north or northeast. We have another chance for
storms overnight/Monday morning with uncertainty in timing and
location. Went ahead and put in our best idea for when storms
will impact the terminals, but this will need adjustment as we
see the storms actually develop and approach our area. Winds
will remain mostly out of the north through the remainder of the
TAF period, increasing again toward Monday afternoon with gusts
to 20-25 kt.

&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...McCoy