809
FXUS63 KOAX 202306
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
606 PM CDT Thu Aug 20 2026

.KEY MESSAGES...

- There is a low chance (15-30%) of thunderstorms across
  northeast Nebraska this evening thru 10PM. Severe weather,
  including large hail and damaging winds will be possible with
  the strongest thunderstorms.

- Highs fluctuate between the upper 70s and 80s with periodic
  thunderstorm chances through the remainder of the forecast
  period. Severe weather may continue to be possible with
  thunderstorms.

&&

.DISCUSSION...
Issued at 222 PM CDT Thu Aug 20 2026

Quiet weather as of 1pm today with temperatures in the upper 70s
to low 80s. A fairly broad cu field has developed across much of
eastern Nebraska, indicative of relatively steep surface lapse
rates capped by the strong inversion around 5000ft. Looking at
the broader upper-level pattern we have broad ridging over the
Rockies with a deep trough over the Mississippi River Valley.
This puts us in our fairly active northwesterly flow regime.

For this evening we`re watching a cold front approach from the
western Dakotas that will move into northeast Nebraska this
evening. Ahead of this front we`ll see moisture pooling and
steepening lapse rates generating around 2500 J/kg of CAPE just
ahead of the frontal boundary. This combined with increasing
0-6km bulk shear could lead to a few organized storms starting
to develop around 4-5 PM. Limiting factor will be moisture as
the front stalls just to our north and west, weakening through
the evening. With this we`ll have a window from around 4pm to
10pm of a conditional threat for strong to severe storms over
northeast Nebraska. If we can get anything to develop, it has a
good chance of becoming severe with primary threats being
damaging winds to 75 mph and large hail up to 2 inches in
diameter. Anything that develops should dissipate by 10pm as
temperatures aloft warm and the environment becomes more
stable.

Overnight we could see some patchy shallow fog develop, but
significant dry air in the lower levels should significantly
limit extent, more likely in low-lying areas particularly near
water. We`ll be watching for more storms developing over our
western counties starting around 6-7 AM as the next shortwave
interacts with a theta-e gradient stretching from Central NE
southeast toward Gage County. As this shortwave clears around
noon we should see scattered storms wane and mostly clear to the
southeast; however, a few hi-res models including the HRRR keep
a few scattered showers and storms through the afternoon. CAPE
only increases into the afternoon with daytime heating, but we
will be lacking much of a trigger. Any storms that develop could
become strong to severe through the afternoon with 50 to 60 kt
of 0-6km bulk shear with hazards mainly being damaging winds and
large hail again. Low-level shear will be much weaker, but
can`t completely rule out a tornado threat.

A third shortwave will trigger a better chance for strong to
severe storms Friday evening through around midnight. Storms
initiate as discrete storms just west of Boone County, likely
organizing into a cluster of storms and a bowing line riding
this same theta-e gradient into southeast Nebraska.

Northwest flow will continue to bring shortwaves through leading
to periodic chances for showers and storms through the weekend
into Monday. The ridge to our west builds eastward into next
week, weakening and deamplifying as it does. A strong jet
streak passing over the top of the ridge will keep this unstable
flow regime into next week likely with more periodic chances for
showers and storms. Temperatures stay on the milder side for
August with highs generally in the low-to-mid 80s and overnight
lows in the low-to-mid 60s.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 600 PM CDT Thu Aug 20 2026

VFR conditions prevail this evening. Winds are light from the
south to southwest across the area. A few thunderstorms have
developed over portions of northeast Nebraska and southeastern
South Dakota. These thunderstorms are not expected to approach
any TAF sites in the area. Patchy, shallow fog may develop
early Friday morning, especially in low-lying areas. Confidence
remains low on the amount of fog coverage and aviation impacts.
Trends will be monitored if visibility impacts from fog appear
more likely. Winds will become light and variable before
gradually shifting towards the northwest Friday morning as a
weak front slowly pushes into the region. Afternoon
thunderstorms are forecast across the region, but exact details
are unclear at this time.

&&

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

&&

$$

DISCUSSION...McCoy
AVIATION...Chehak