317
FXUS63 KOAX 170749
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
249 AM CDT Sun Aug 17 2025

.KEY MESSAGES...

- Hot conditions are expected again this afternoon, with highs
  in the low 90s and heat indices approaching 100 degrees.

- Isolated storms (20% chance) may develop across northeast
  Nebraska this afternoon and evening, followed by a more
  widespread thunderstorm complex overnight (40-60% chance).


- Heat will persist into Monday before gradually easing, with
  cooler temperatures and periodic storm chances through the
  rest of the week.

&&

.DISCUSSION...
Issued at 248 AM CDT Sun Aug 17 2025

Today and Tonight...

The syntopic-scale pattern this morning features a broad mid- to
upper-level ridge centered over the southern Plains/lower
Mississippi Valley. At the surface, a warm front is draped across
southeast SD and into southern MN. A shortwave disturbance entering
the Dakotas will bring subtle height falls through the day, but
continued southerly low-level flow and WAA will still drive
afternoon highs into the low 90s. Dewpoints in the low 70s will push
heat indicies into the 98-103 degree range. While some areas,
particularly along the Missouri River Valley, may approach Heat
Advisory criteria, headlines have been withheld for now given lower
confidence in afternoon cloud cover and convective development.
Regardless, another uncomfortable airmass will be in place this
afternoon.

Storm chances return later today into the overnight period, with two
rounds possible. The first develops this afternoon and evening as
strong destabilization yields an uncapped environment with 2500+ J/kg
of MLCAPE, especially for areas north of Interstate 80. However, weak
large scale forcing for ascent and bulk shear values generally under
20 kts will make organized severe storms difficult to achieve and
maintain. A few isolated storms or even a weak MCV may form, with
brief potential for hail and damaging winds before storms become
unbalanced and weaken. Given the low confidence in coverage, PoPs
remain limited to 15-30%, peaking across northeast NE.

The second and more robust scenario arrives overnight as the
approaching shortwave disturbance helps initiate an MCS over north-
central NE/south-central SD that tracks east-southeastward,
sustained by the nose of a strengthening nocturnal LLJ. The primary
hazard will be damaging wind gusts (60-70 mph), supported by a model
soundings exhibiting a stout dry layer and DCAPE values of 1000-1250
J/kg. Pockets of small hail (up to 1") may also occur. Locally heavy
rainfall will be a possibility with PWAT values of 1.75-2.00" and
warm cloud depths of 3-4 km favoring efficient rainfall processes.
Fortunately, the system appears progressive enough to mitigate any
widespread flooding concerns. SPC maintains a Marginal Risk (Level 1
of 5) for severe weather across much of the area, with PoPs peaking
at 40-60%.

Monday...

Lingering showers and cloud cover from the overnight MCS will likely
persist into Monday morning before gradually improving through the
day. The surface front previously positioned across southeast SD
will sag southward into eastern NE/western IA. Afternoon
temperatures will remain somewhat uncertain, hinging on the extent
of residual cloud cover and the front`s position. Locations south of
the boundary, where southerly low-level flow and ample sunshine
prevail, may climb into the low to mid 90s with heat indices
approaching 105 degrees. Areas north of the front or areas under
persistent cloud cover by peak daytime heating may only see highs in
the mid to upper 80s. A Heat Advisory could be warranted for
portions of the area, but given these uncertainties, no headlines
have been issued at this time.

Another round of storms will be possible late Monday afternoon into
the evening along the advancing boundary. Confidence in this
scenario remains lower, as the exact placement of any outflow
boundaries and lingering convective debris from the prior MCS will
heavily influence development. Any areas that manage to clear will
destabilize quickly, though large-scale forcing for ascent will
again be limited. SPC maintain a Marginal Risk (Level 1 of 5) for
severe weather across the area, with PoPs currently peaking at 15-
25%.

Tuesday and Beyond...

By Tuesday, the upper-level ridge will begin to retrograde toward
the Four Corners region, shifting the flow aloft to northwesterly.
This pattern change will usher in a more seasonable airmass, with
highs in the mid to upper 80s Tuesday and potentially the low 80s by
Wednesday and Thursday. Forecast confidence decreases during this
period, as the pattern shift could allow a stream of shortwave
disturbances to crest the ridge and slide into the area, bringing
periodic storm chances. Current long-range guidance suggests the
next disturbance could arrive Tuesday, with PoPs in the 15-30%
range. Wednesday and Thursday appear to offer the best window for
drier, cooler conditions before another disturbance approaches by
the start of the weekend. Though the finer details remain uncertain,
temperatures look to stay on the cooler side through next weekend.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1140 PM CDT Sat Aug 16 2025

Prevailing VFR conditions are forecast through this TAF period.
Latest model data continue to advertise the potential for
isolated thunderstorms development in the KOFK vicinity on
Sunday afternoon, with a comparably greater chance at all three
terminal locations toward the end of the forecast period. Will
refrain from a SHRA/TSRA mention until confidence increases in
the specific timing. Otherwise, LLWS develops overnight at KOFK
with south winds becoming gusty by 16-17z Sunday.

&&

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

&&

$$

DISCUSSION...Wood
AVIATION...Mead