Severe Thunderstorm Warning 421, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
608 PM CDT Mon Sep 14 2026

.KEY MESSAGES...

- There is a conditional threat for severe weather through this
  evening and overnight with potential for damaging winds, large
  hail, tornadoes, and heavy rain/flooding.

- A Flood Watch is in effect through Tuesday morning. If
  additional storms Tuesday evening look like they'll impact the
  same areas, the watch may need to be extended.

- A wet pattern continues through the week with daily shower and
  storm chances. While the threat for hail, damaging winds, and
  tornadoes will diminish, repeated rounds of rain may lead to
  an increasing flooding threat.

&&

.DISCUSSION...
Issued at 211 PM CDT Mon Sep 14 2026

A somewhat conditional severe weather threat remains in the
forecast for later this afternoon into this evening and
overnight with the big questions being how unstable we can get
and how many surface-based storms we can get. Early afternoon
analysis showed a warm front stretching from north-central KS,
east-southeast into northeast KS and western MO. This will surge
northward into southeast NE through this afternoon while a
stream of shortwave energy starts pushing through leading to
storm development. 18Z KOAX sounding did show a very stout cap,
though obviously was well north of the boundary. In addition,
satellite showed quite a bit of cloud cover across the area
aside from some decent clearing across far southeast NE where
temperatures had climbed into the mid 80s with dewpoints
approaching 70. And you don't have to go very far south and west
to see upper 80s and lower 90s. So while much of the area
remains capped now, the unstable airmass is on the way, though
questions remain as to how far north it'll get.

As for model guidance, there's very good agreement in
developing a southwest to northeast line of thunderstorms. SPC
objective mesoanalysis shows sufficient effective layer shear to
yield some supercell structures, but with the line going up
quickly, think it could become somewhat of a messy storm mode as
we go into the evening. As storms first develop, all severe
weather hazards would be possible, including tornadoes and even
a strong tornado, owing to large, looping low level hodographs.
However, threats should transition to mostly damaging winds and
heavy rain/flooding with guidance suggesting potential for
training thunderstorms. In addition, guidance shows 1.75-2" of
precipitable water with warm cloud depths exceeding 4 km. Low
level moisture transport will also ramp up this evening and
overnight and point toward the NE/KS border, where 3+ inches of
rain fell in some locations last night/this morning. While short
term guidance doesn't produce much precip in those areas, there
remains the possibility that an outflow boundary surges
southeast out of the line of initial convection owing to line-
parallel 0-3 km shear. This could provide a focus for storm
development near the NE/KS border as the aforementioned moisture
transport ramps up. Therefore, ended up issuing a Flood Watch
for much of southeast NE and southwest IA, pairing areas where
training thunderstorms are most likely with areas that will
require less rain to see flooding.

The remainder of the week is looking relatively wet with pretty
much daily shower and storm chances. The surface boundary will
push just south of the area by Tuesday morning, but rain chances
will persist, especially near and south of I-80, as additional
shortwave energy passes through. While the damaging wind, hail,
and tornado threat should remain to our south with the higher
instability, we will see a heavy rain/flooding threat with
potential for training showers and storms, though still some
questions as to how far north those will extend. In addition,
NAEFS precipitable water values look to be in the 1.75-2 inch
range, good for the 99th+ percentile of climatology for this
time of year, so anything that does develop will be a pretty
efficient rain producer. Should it look like heavier precip will
end up in our area, may need to extend part or all of the Flood
Watch.

A steady stream of shortwave energy will continue Wednesday
into Thursday while the surface boundary slowly meanders back
north, eventually reaching SD by Friday. At least on and off
showers and storms will be possible through that period, with
potential for repeated rounds of rain to lead to flooding
concerns. Friday is generally favored to be a drying period,
though still looking at 20- 30 percent chance of rain in the
afternoon with a few various ensemble members a little slower
with the northward advancement of the front. However, any dry
period looks to be short-lived as a cold front pushes in from
the northwest for the weekend and gives us continued 30-50%
chances of rain. Machine learning severe weather guidance keeps
severe weather potential below (under 5%) through this active
period, though again, potential heavy rain and flooding will
remain a concern with each successive round.

Otherwise, temperatures may be a bit of a roller coaster
through the week and will hinge on precipitation on a given day.
Currently, upper 60s and 70s are favored Tuesday and Wednesday
before the front moves back north and marks a return to the 80s
Thursday and Friday. Behind the weekend cold front, expect to be
back down in the 70s to lower 80s. But again, lots of moving
parts, so confidence in exact temperatures on a given day is
relatively low.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 555 PM CDT Mon Sep 14 2026

A line of strong to severe storms is beginning to take shape
from just north of Fairbury, NE to Mapleton, IA. Expect the
strongest storms to impact KOMA and KLNK between 00-03Z, and
generally remain just to the south of the KOFK area. Scattered
showers and storms will likely redevelop behind the main line
through the overnight hours and into early Tuesday morning.
Showers and storms should move south of the TAF sites by around
18Z. Winds will be out of the south initially, and turn to the
north behind the main line of storms.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch through Tuesday afternoon for NEZ052-053-066>068-
     089>093.
IA...Flood Watch through Tuesday afternoon for IAZ069-079-080-090-
     091.

&&

DISCUSSION...CA
AVIATION...KG

Preliminary Local Storm Report
National Weather Service Omaha/Valley NE
622 PM CDT Mon Sep 14 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0609 PM     Tstm Wnd Dmg     2 ENE Davey             40.99N 96.64W
09/14/2026                   Lancaster          NE   Public

            3 to 6 inch diameter branches down. Time
            estimated from radar.

&&

CA

Preliminary Local Storm Report
National Weather Service Omaha/Valley NE
633 PM CDT Mon Sep 14 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0627 PM     Tstm Wnd Gst     4 N Memphis             41.15N 96.44W
09/14/2026  M57 MPH          Saunders           NE   Mesonet

&&

CA

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