546
FXUS63 KOAX 311959
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
259 PM CDT Thu Jul 31 2025

.KEY MESSAGES...

- Smoke has increased near the surface above what was expected,
  with an Air Quality Alert now in effect through 5 PM tomorrow
  for Moderate to Unhealthy air quality.

- Fog potential returns overnight for eastern Nebraska into Iowa
  as winds fall off overnight.

- The cooler conditions will linger into early next week,
  staying mostly in the 70s to near 80 degrees.

- Next chances for storms will be Saturday and Sunday (30-50%).

- Increasing chances for heat indices to warm to 100 degrees
  late next week.

&&

.DISCUSSION...
Issued at 257 PM CDT Thu Jul 31 2025

Today and Tomorrow:

Visible satellite imagery this afternoon shows the convective debris
from convection this morning that brought up to 5.5" inches to areas
near the Elkhorn and Platte River confluence. The leftover bank of
clouds and areas of mist continue to push further into Kansas
while stronger than expected subsidence arrives behind along
with clearing skies. The reason to mention subsidence is because
smoke from aloft has been able to reach the surface more
efficiently and lower the air quality into the Moderate to
Unhealthy categories. As a result we`ve issued an Air Quality
Alert at the request of NDEE in Nebraska for the lowered air
quality, with similar alerts being issued for the state of Iowa
this morning, that last through much of Friday. Otherwise,
temperatures are topping out in the upper 70s in the sunny areas
of northeastern Nebraska and Iowa while slightly cooler values
continue in the cloud cover a few degrees lower. We`ll have even
fewer reasons to have a repeat of the storms overnight, as
strong subsidence continues to hold over the areas that saw
rainfall last night, while an isolated shower or two could
persist out of a shortwave traversing the Dakotas. The overall
threat of heavy rain will be much less, with PWAT values being
only 1.18" according the 18z KOAX sounding. Dewpoints are much
lower this afternoon compared to last, but cooler temperatures
overnight could lead to some patchy fog formation, primarily in
areas that saw rainfall and into Iowa where subsidence is
strongest (though visibilities don`t look low enough yet to call
it dense fog).

For tomorrow, we`ll begin seeing the narrow ridge centered over the
Intermountain West begin to flatten out and bring increasingly zonal
flow in the mid/upper levels. Temperatures will continue to stay
cool, with highs expected to top out in the mid 70s alongside east-
southeasterly winds. Convection starting out over the High Plains
looks like it`ll try to push into the forecast area and bring
decaying winds of 40 mph at their strongest to northeast Nebraska
and shrinking rain chances overnight with no expected threat of
severe weather or flooding.

Saturday and Beyond:

Similarly cool temperatures are expected for Saturday and Sunday
with the dominant high pressure anchored over the eastern half of
the CONUS, while an increasingly broad disturbance in the mid/upper
levels traverses the northern Intermountain West. Shortwave activity
will bring widespread forcing for ascent to initiate convection
across the High Plains that will sweep towards eastern Nebraska and
Iowa each day during the late evenings into the early morning hours.
The lack of strong flow and timing of convection moving into the
area will make it very hard for any organized severe storms unless a
potent MCS is able to form to the west/northwest (which does not
appear to be likely at this time).

Starting for the upcoming work week, an oblong 500 mb high over the
northern Baja Gulf will begin to amplify and gradually increase its
influence over the forecast area while pushing the best forcing for
ascent to the north. Deterministic models do hint at the potential
for a "ridge riding" MCS to push south-southeast along the CAPE
gradient that could lay in the vicinity of eastern Nebraska/Iowa,
but we`ll have to wait for that signal to persist before calling any
severe shots. The extended forecast does appear to keep getting
hotter, with increasing potential for heat indices of 100 degrees
for the latter half of next week into the weekend, corroborated by
anomalously strong thermal ridges indicated by NAEFS and EPS
situational awareness table output.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1232 PM CDT Thu Jul 31 2025

Stubborn IFR to MVFR ceilings continue to slowly push southward,
with the northern edge just south of a line from KOLU to KOMA
that should arrive to KLNK by 19z. Largely easterly winds are
expected to stay in place at the moment with a few gusts in the
upper teens where full-fledged sunshine is overhead before winds
quiet down overnight and become increasingly southeasterly at
less than 5 kts overnight. Fog chances at the moment look low,
but leftover moisture could lead to increasing chances as the
forecast updates in the KOMA area for overnight/tomorrow
morning.

&&

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

&&

$$

DISCUSSION...Petersen
AVIATION...Petersen