520
FXUS63 KOAX 181113
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
613 AM CDT Mon Aug 18 2025

.KEY MESSAGES...

- An ongoing thunderstorm complex will continue to push
  southeast across the area this morning. The primary hazards
  will be damaging wind gusts (60-70 mph) and locally heavy
  rainfall.

- Above average temperatures are expected again today with
  afternoon highs in the upper 80s to low 90s and heat indicies
  approaching 100- 103 degrees.

- Additional thunderstorms are expected (40% chance) in the
  evening and overnight period, with a few strong to severe
  storms possible.

&&

.DISCUSSION...
Issued at 127 AM CDT Mon Aug 18 2025

Today and Tonight...

Water vapor imagery early this morning displays a mid- to upper-
level ridge centered over the southern Plains with a broad/messy
shortwave trough pushing across the NE/SD border. This features has
spun up a loosely organized MCS near the central NE-SD border late
Sunday evening. As of 1 AM, the system is pushing east-southeast
into northeast NE. While instability remains potent (2500+ J/kg of
MLCAPE), forcing for ascent and bulk shear (<25 kts) remain on the
weaker end. A nocturnal LLJ is ramping up to help maintain the
storms, though it will also be on the weaker side (25-30 kts) and
unfavorably veering away from the complex. These factors considered,
radar and satellite imagery of the ongoing convection reveal cold
pools surging ahead of much of the convection, which is reasonable
given the unbalanced environment. The LLJ has also fired some widely
scattered elevated thunderstorms ahead of the main complex. Severe
potential with these storms are low, though frequent cloud to ground
lightning and a good rain showers remain probable. The slow moving
motion of these storms could bring hydrological trouble, though the
updrafts have been collapsing quickly.

The MCS is expected to continue to push east-southeast across
eastern NE and southwest IA through the morning. While wind gusts as
of 1 AM have been mainly under 45 mph, CAM guidance is hinting at
accelerating the system in the next few hours, bringing a brief
period of enhanced winds. This signal matches up well with some
enhanced convection in north-central NE accelerating and catching up
with the outflow boundary. Therefore,the primary hazards this
morning will be damaging wind gusts (60-70 mph) with pockets of
small hail possible (up to 1"). Given PWAT values of 1.60-2.00" and
a warm cloud depth of 3-4 km, the system looks to be efficient at
producing rainfall. Locally heavy rainfall concerns will need to be
monitored, but the system appears to be progressive enough to avoid
any widespread flooding concerns. The system is expected to
gradually weaken by the time it reaches the Interstate 80 corridor
(likely in the 4-6 AM timeframe), though pockets of gusty winds will
continue. SPC maintains a Slight Risk (Level 2 of 5) for severe
weather across for areas north of Interstate 80.

Convection is expected to clear by the mid to late morning with
cloud cover gradually improving behind it. Southerly low-level flow
will shift to northerly/northeasterly through the afternoon and
evening as a weak cold front pushes south across the area. This will
damped the stream of warm air that has been pulling to the area for
the past few days. Highs remain in the upper 80s to low 90s,
dependent on residual cloud cover and the location of the cold
front. Resultant heat indices are expected to peak at 98 to 103
degrees, just shy of Heat Advisory criteria. Have opted against a
Heat Advisory for the time being given the lower confidence in high
temperatures.

Storm chances return later today. A few isolated to scattered storms
will be possible, primarily in southeast NE and southwest IA during
the afternoon and evening hours as strong destabilization occurs
around the sagging cold front, and potentially any remaining outflow
boundaries from the mornings MCS. While afternoon destabilization
will likely be strong, the lack of any large scale forcing for
ascent will leave any storms that do develop to struggle. If a storm
is able to establish itself (10-15% chance), a brief period of
damaging wind gusts or hail will be possible.

The better potential for storms (PoPs 40%) will again be overnight
as a shortwave disturbance and associated vorticity maxima pivot
into the area. CAM guidance is in decent agreement on initiating an
MCS in central Nebraska that pushes east-southeast into the area
overnight, though its track will likely depend on how morning and
afternoon convection plays out. CAM guidance so far this morning
tracks the MCS along a remnant outflow boundary draped across
southeast NE into extreme southeast IA, though the location of this
boundary may wiggle north of south. Damaging wind gusts (60-70 mph)
and locally heavy rainfall will be the primary concern with this
system. SPC maintains a marginal risk (level 1 of 5) for severe
weather across the area with a slight risk (level 2 of 5) introduced
just to our west, with PoPs peaking at 30%.

Tuesday and Beyond...

By mid week, the aforementioned mid- to upper-level ridge over the
southern Plains will continue to retrograde towards the Four Corners
region, bringing northwesterly to northerly flow aloft. This trend
will drop temperatures back near seasonable norms, with Tuesday
highs in the upper 80s/low 90s and Wednesday and Thursday highs in
the low to mid 80s. Wednesday and Thursday still look to be the best
chance at dry, mild weather, though any weak disturbance sliding by
could change those odds.

By the end of the work week and start of the weekend, a potent
shortwave disturbance will help to dampen the ridge in place and
bring additional precipitation chances. An associated cold front
passing through and enhanced CAA will bring high temperatures for
the weekend in the low 80s and potentially even the 70s for some
locations.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 558 AM CDT Mon Aug 18 2025

A weakening complex of showers and thunderstorms will continue
to move through eastern Nebraska and into western Iowa this
morning. An isolated lightning strike may be possible at KOMA
and KLNK, though primarily showers are expected. While brief
periods of MVFR ceilings may be possible with storms this
morning, primarily VFR conditions are forecast to prevail.
Winds will generally be out of the southeast today, becoming
variable behind the passage of a weak cold front this evening.
Showers and storms could redevelop along a boundary this
evening, however a better chance for storms (30 to 40 percent)
will arrive late tonight into Tuesday morning.

&&

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

&&

$$

DISCUSSION...Wood
AVIATION...KG