178
FXUS63 KOAX 200440
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1140 PM CDT Tue Aug 19 2025

.KEY MESSAGES...

- Fog is expected to begin overspreading the area by 2 AM
  overnight, with visibility expected to fall below 1 mile and
  the thickest fog being near Blair and points northeast.

- Near to slightly above average temperatures will continue
  through Thursday with highs generally in the upper 80s.

- Temperatures will drop below average this weekend, with highs
  in the 70s to low 80s through the weekend. Periodic rain
  chances begin Thursday night and continue through the weekend.

- A glimpse at fall is heading towards for the upcoming work
  week, with highs for portions of northeast Nebraska in the
  upper 60s to low 70s Monday.

&&

.DISCUSSION...
Issued at 307 PM CDT Tue Aug 19 2025

Today and Tomorrow:

Water vapor imagery this afternoon features broad ridging across
much of the central CONUS, with a few notable features
underneath of it including a shortwave/associated surface
system strung out from its center in the Great Lakes region
while a frontal boundary extends to the southwest through
Missouri. Looking locally, a ridge of high pressure is nosing in
form the northwest with a shallow field of cumulus gliding
along the northeasterly-to-southeasterly flow that rounds the
base of that surface ridge. A weak zone of convergence also
extends from the northern edge of ongoing convection in eastern
Kansas through central Nebraska, that could help clouds deepen
just enough to result in a few showers and storms that are not
expected to be severe due to the lack of shear and stronger
forcing for ascent. For most of eastern and Nebraska, expect a
warm summer day with very light winds and highs that top out in
the upper 80s to low 90s.

Winds should calm down once again this evening and the lingering
ridge of high pressure is expected to quickly kick start
efficient radiative cooling and result in fog development
overnight. Current dewpoints in the low-to-mid 70s should help
keep a high crossover temperature compared to the overnight
lows forecast to be in the upper 60s. As of now, models are
focusing on an area along a line from Blair northeastward
towards north-central Iowa for the lowest visibilities, but the
patchy fog will likely extend to the south and west as well but
at a lower intensity. Fog development should begin around 2 AM
and should dissipate by 9 AM. As for the rest of the day
tomorrow, similar temperatures are forecast with a deep, well-
mixed boundary layer that should amount to a few isolated
showers and storms that will struggle to amount to more than a
few gusts of up to 40 mph -- being limited in vertical
development by entraining dry air.

Thursday and Beyond:

Thursday will be day 3 of the continued warmth, with the main
mid/upper pattern starting to deamplify and flatten out. Similar
highs are forecast for the afternoon, with the next wrinkle in the
forecast being an approaching cold front that will begin pushing
into northeast Nebraska overnight through Friday. The front itself
is expected to be rather slow to move through the area, and will see
its best thermal environment be front-loaded during Thursday night
with some 700-500 mb lapse rates exceeding 7 C/km in northeast
Nebraska before losing CAPE going into Friday as more widespread
forcing for ascent continues and moves southward through the area.
As of right now, the SPC and the machine-learning guidance are not
terribly excited about the severe potential with these storm
chances, but they will still need to be monitored with active late
summer and early school year activities in full swing.

By Saturday, the main mid/upper pattern will swing southward a
seasonably potent jet streak through the heart of the Missouri
Valley, helping to cool down temperatures big time and remind us
that fall isn`t all that far off. Saturday is expected to be the
last day in the 80s for the current forecast period, with highs
falling into the mid-to-low 70s and even the 60s for some parts by
Monday alongside mostly dry conditions.

&&

.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...Petersen
AVIATION...Castillo