Tornado Warning 18, NWS Omaha, NE

Area Forecast Discussion
National Weather Service Omaha/Valley NE
637 PM CDT Sun May 17 2026

.KEY MESSAGES...

- Sunday and Monday will be days to watch very closely if you
  live within the Omaha area of forecast responsibility.
  Multiple rounds of severe thunderstorms are expected bringing
  the potential for large hail, damaging winds, tornadoes and
  flash flooding.

&&

.DISCUSSION...
Issued at 142 PM CDT Sun May 17 2026

This afternoon, an elongated sfc low will be in place from SE
Colorado/SW Kansas up into the Dakotas. A dryline is set up toward
the KS/CO border and a warm front is located across central
Nebraska. Temps are currently in the 80s in the warm sector with
dewpoints in the mid-60s. SBCAPE values of 3500+ J/kg, MLCAPE values
of 3000+ J/kg and DCAPE values of 1200+ J/kg are expected. Expect
good instability through the afternoon/evening and fairly steep
lapse rates, particularly down into central and eastern Nebraska.

Portions of northeastern Nebraska in particular are showing
potential for an environment favorable for strong updrafts and
potentially some longer lived supercells. Any storms that are able
to get going and become sustained in that favorable environment
would have the best chance of developing a tornado, with some
potential to be strong. Storms are expected to develop into a line,
posing a damaging wind threat along with hail and tornadoes
possible.

Heading into Monday, a broad trough extends from the PACNW up into
eastern Nebraska/western Iowa. Another system moves in through the
day, bringing additional chances for strong to severe storms,
particularly for areas along and south of Interstate 80. There still
remain some questions as to how far north the warm front and system
get. The environment is expected to be primed with strong
instability and deep layer shear conducive for supercell development
and maintenance. With this type of set up, large hail and damaging
winds are to be expected in addition to the possibility for a few
strong and potentially long-lived tornadoes. Flash flooding will be
possible, particularly in areas that have also received a few inches
of rain over the last 48 hours.

Expect cooler temperatures for much of the week as a cold front
pushes into the region Monday. Tuesday and Wednesday bring relief
from the recent storms.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 637 PM CDT Sun May 17 2026

A line of severe thunderstorms is observed at this hour from
near KOFK to KJYR to KHJH. These storms have a history of
producing large hail, damaging winds, and tornadoes. The line
will continue progressing eastward this evening, eventually
turning into more of a damaging wind threat as it approaches
KOMA and KLNK. Have continued mentions of -TSRA at terminals
this evening, refining timing at KOMA with the line expected to
arrive by 01z per latest model guidance. Expect frequent updates
and amendments. Background winds will switch to the west
northwest once the line moves through, and remaining at 12 kts
or less after 06z. Ceilings will deteriorate to MVFR and IFR at
terminals tonight behind the line of storms and persist through
much of the TAF cycle. After 20z, will see more redevelopment of
showers and thunderstorms, with chances over 50% late in the
TAF period. These storms will once again become strong to severe
with all hazards possible.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch through Tuesday morning for NEZ065-066-068-078-
     088>093.
IA...None.

&&

DISCUSSION...ANW
AVIATION...Castillo

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
151 PM CDT Sun May 17 2026

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-181900-
Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-Page-
Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison-Stanton-
Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler-Saunders-Douglas-
Sarpy-Seward-Lancaster-Cass-Otoe-Saline-Jefferson-Gage-Johnson-
Nemaha-Pawnee-Richardson-
151 PM CDT Sun May 17 2026

This Hazardous Weather Outlook is for southwest Iowa, west central
Iowa, east central Nebraska, northeast Nebraska and southeast
Nebraska.

.DAY ONE...This afternoon and tonight.

Strong to severe thunderstorms are expected to develop after 4 PM,
initially across northeast Nebraska before spreading south and east.
Large hail (2+ inches), damaging wind gusts, and a few tornadoes
(possibly strong) are the expected hazards. Heavy rain due to
several storms moving over the same area may result in some concerns
for flash flooding. A Tornado Watch has been issued for the northern
portion of the outlook area through 10 PM.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Additional strong to severe storms are forecast for Monday
afternoon, with an increased threat for large hail (2-4+ inches) and
strong tornadoes. Additional chances for heavy rainfall on top of
what has already fallen since Friday night will result in a potential
for flash flooding, particularly for portions of southeastern
Nebraska. Chances to see severe storm activity is maximized over
southeast Nebraska.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed. Any reports of hail, strong winds,
tornadoes, flooding or damage are greatly appreciated today and
Monday.

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