818
FXUS63 KOAX 200742
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
242 AM CDT Wed Aug 20 2025

.KEY MESSAGES...

- Fog is developing this morning, with visibility expected to
  drop below one mile at times, particularly along and north of
  a Columbus-Omaha-Clarinda line.

- Temperatures will remain near to slightly above average today
  and Thursday, with highs generally in the upper 80s.

- A shift to cooler conditions arrives this weekend, with highs
  falling into the 70s to low 80s. Periodic rain chances begin
  Thursday night and continue through the weekend.

- Early next week will bring a taste of fall, with most areas
  only reaching the low 70s.

&&

.DISCUSSION...
Issued at 238 AM CDT Wed Aug 20 2025

Today and Tonight...

A broad mid- to upper-level ridge remains in place across much of
the west-central CONUS this morning. At the surface, high pressure
continues to extend over northeast NE into western IA, keeping winds
light and skies clear. The lack of cloud cover has allowed for
strong radiational cooling overnight, with calm winds and a shallow
near-surface saturated layer noted in model soundings, fog
development is once again underway. As of 2 AM, several sites
in northeast NE were already reporting visibility of 1-3 miles,
with further deterioration expected through the morning hours.
Visibility below 1 mile, including pockets of dense fog, will be
possible, especially along and north of a Columbus-Omaha-
Clarinda line. Conditions will be monitored closely in case a
Dense Fog Advisory becomes necessary. Fog should gradually lift
after sunrise, with visibility improving to 5 miles or greater
by around 9 AM.

This afternoon will turn warm and humid once again, with highs in
the upper 80s and dewpoints in the lower 70s creating a sticky and
uncomfortable airmass. A weak disturbance moving through the region
could trigger a few isolated showers or storms this afternoon and
evening (15% chance). Severe weather is not expected, but a brief
downpour and lightning strike cannot be ruled out.

Thursday and Friday...

Thursday and Friday will mark a transition in the current pattern as
a closed low tracks across Manitoba and Ontario into the Great Lakes
region, gradually dampening the ridge in place. Ahead of its
arrival, Thursday will have another foggy morning before a warm and
humid afternoon, with highs in the upper 80s to low 90s and elevated
heat indicies. A southwest-to-northeast oriented cold front will
advance into northeast NE late Thursday into early Friday, bringing
a return to precipitation chances. Current PoPs peak at 20-40%.
Severe weather potential remains limited at this time as the
steepest lapse rates and forcing for ascent appear displaced to our
north.

Friday`s temperatures will hinge on the position of the front, with
the upper 80s favored ahead of it and low 80s more likely in its
wake. Additional precipitation is expected to redevelop along the
boundary Friday evening (PoPs 30-40%). Modestly steep lapse rates,
enhanced instability, and improved bulk shear near boundary
could support strong to potentially severe storms during this
period. We will have to see how the details shake out as the
system approaches, though SPC has placed much of the area in a
Marginal Risk (Level 1 of 5) for severe weather.

Saturday and Beyond...

The post-frontal airmass will be felt on Saturday, with highs
topping out in the mid 70s to low 80s. Through the weekend and into
early next week, a closed low will remain anchored over the Great
Lakes region. A passing speed max will drive strong northwesterly
flow aloft into the region, supporting continued CAA and below-
normal temperatures. Highs in the 70s are expected Sunday through at
least Tuesday. Temperatures are running about 10 degrees below
seasonal average, with overnight lows dipping into the upper 40s to
mid 50s.

This pattern may also allow a few weak shortwave disturbance to
slide through, bringing occasional precipitation chances (occasional
15% PoPs), though conditions should trend more dry than wet overall.
The cooler regime looks to persist, with the CPC`s 8-10 day outlook
(valid August 25-29) highlighting a 70-90% probability of below
normal temperatures. The signal continues in the 8-14 day outlook
(valid August 27-September 2), showing a 50-70% probability of below-
normal temperatures across the area.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1140 PM CDT Tue Aug 19 2025

Main concerns for this issuance continue to be fog developing across
terminals, particularly after 09z as visibilities deteriorate
from MVFR to IFR. Potential exists for LIFR at KOFK after 12z
and have added a TEMPO group. Recent guidance has pushed
potential fog development to KLNK, where visibilities may drop
to MVFR after 12z. Visibilities should gradually improve after
14z to VFR at all terminals and continue for the remainder of
the TAF cycle.

Winds will remain light and variable at the start of the TAF
cycle, then become east northeasterly in the afternoon hours
but remain under 12 kts.

&&

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

&&

$$

DISCUSSION...Wood
AVIATION...Castillo