361
FXUS63 KOAX 161902
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
202 PM CDT Wed Sep 16 2026

.KEY MESSAGES...

- Widely scattered showers and storms continue this afternoon,
  tapering off early this evening.

- More redevelopment of storms expected late tonight into
  Thursday morning, particularly along and south of I-80. Storms
  could have heavy rainfall which could worsen ongoing flooding
  in southwest Iowa.

- Chance for more storms on Friday, with a 5% chance that some
  could be strong to severe. Off and on rain chances persist
  into the weekend and early next week.

&&

.DISCUSSION...
Issued at 202 PM CDT Wed Sep 16 2026

.SHORT TERM /TODAY THROUGH THURSDAY NIGHT/...

17z RAP objective analysis depicts a strong 601 dam high in place
over most of the Southern Plains and southeastern CONUS, while a
potent longwave trof/cutoff low spins over the western coastal
areas. This places much of the Central and Northern Plains areas
into a southwesterly flow regime. East of the cutoff low, a few
shortwave trofs out in Wyoming and eastern Colorado have spun up sfc
lows in those respective areas, with boundaries extending
southeastward into northern Kansas.

The bulk of this morning`s showers and storms largely driven by low
level warm and moisture advection have finally pushed off into Iowa.
A few more showers could pop up this afternoon (20-40%) as the H8
baroclinic zone slowly approaches the Kansas/Nebraska border.
Otherwise, expect the low level stratus to remain in place through
the rest of the afternoon and evening hours. Have lowered today`s
highs several degrees from NBM guidance, with most seeing them reach
the mid 60s to low 70s.

Late this evening into early Thursday morning, the H8 baroclinic
zone will nudge slightly northward, and the attendant low level warm
and moisture advection should spark off a few more storms. While
some forecast BUFKIT soundings show elevated instability of 800-
1,100 j/kg, 0-6 km bulk shear is largely lacking so not really
expecting anything to become severe. However, still could see some
threat of heavy rainfall, particularly across our far southern areas
as warm cloud depths of 4,500 meters firmly remain in place, along
with PWATs well above the 90th percentile of OAX sounding
climatology. HREF guidance suggests about a 20 to 30% chance for
areas along and south of I-80 that could see an additional 1/2 inch
or more of precip. This could potentially worsen any ongoing flood
issues, particularly over southwest Iowa. Will continue to
monitor trends over the next few hours and see if a targeted
Flood Watch for flash flooding may be needed. PoPs increase
after 03z for areas along and south of I-80, peaking at 40 to
60% in far southeast Nebraska and southwest Iowa by early
Thursday morning.

In addition to rain chances, could also see some areas of fog
develop primarily along and west of a line from Norfolk to Fremont
to Shenandoah after 04z. While the light winds and residual moisture
will promote fog development, the earlier mentioned showers could
help visibilities not tank.

Showers gradually taper off by Thursday afternoon as a weak sfc high
tracks to our north. Temperatures warm to the 70s and low 80s. More
showers and storms develop (50-70% chance), this time in northeast
Nebraska, after 04z as a 40 kt LLJ points into the area.

.LONG TERM /FRIDAY THROUGH TUESDAY/...

Friday will see a stronger H5 shortwave eject from the Rockies
toward the western Dakotas. The sfc low will finally nudge to the
northeast, with the sfc warm front finally moving through the area.
Temperatures should then warm to the mid to upper 80s. Behind the
front, will see another unstable air mass of 1,500 to 2,000 j/kg of
instability, and with some deep layer shear of around 30-35 kts,
could see a few storms become severe in the evening. Forecast
soundings show high LCLs, which would likely imply some wind hazard.
PoPs remain at 50 to 70% for most of eastern Nebraska into southwest
Iowa.

By early Saturday morning, the main sfc low and cold front should
push off to our southeast. Could still see some more showers and
storms along the frontal feature early Saturday morning (50-70%
chance). Behind the front, most areas reach the low to mid 70s.

Sunday will see a more substantial H5 wave eject from Colorado
toward the area. The feature will help trigger or next round for
rainfall, particularly across the southern half of the forecast
area. Periodic chances for more rainfall continue through Tuesday as
we see more disturbances traverse the area, but chances remain
low at 15 to 30%.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1221 PM CDT Wed Sep 16 2026

At 17Z, IFR conditions have built into LNK/OMA, with low-end
MVFR at OFK. It is likely that these conditions will remain
steady for the next several hours, with the exception of a few
hours when -SHRA may again build in. There is some upstream sky
clearing, and a small chance for a briefly-cloud-free period
this afternoon, but more confident that all sites will maintain
ceilings at least through the next 18 hours. Also expect ceiling
heights to decrease with visibility also decreasing, especially
after dark. Fog then becomes likely at all sites, with some
potential for 1/4SM or less. Conditions gradually improve from
13-18Z.

&&

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

&&

$$

DISCUSSION...Castillo
AVIATION...Barjenbruch