625
FXUS63 KOAX 150531
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1231 AM CDT Fri May 15 2026

.KEY MESSAGES...

- Chance for scattered showers and storms this afternoon and
  into the evening hours (40-60%). Storms may be severe with
  large hail and damaging winds.

- Warm temperatures expected today with highs in the low to mid
  90s.

- Periodic strong to severe storm chances continue for Saturday
  through Monday.

&&

.DISCUSSION...
Issued at 1231 AM CDT Fri May 15 2026

.SHORT TERM /TODAY THROUGH SATURDAY NIGHT/...

04z RAP objective sfc analysis shows a frontal boundary extending
from near Broken Bow to Neligh to just east of Sioux Falls, SD. To
our south, storms were able to fire along the nose of an H8 LLJ, but
these were largely confined into northeast KS. The best convergence
along the LLJ nose should point more towards Iowa/Missouri early
this morning, helping force elevated convection and keeping it away
from our forecast area. Temperatures remained in the low to mid 70s
for most of the forecast area with light winds.

The sfc boundary will push slowly to the southeast, eventually
stalling across portions of the forecast area by midday today.
Lingering H8 warm advection should help push high temperatures into
the low to mid 90s for most areas. While we`ll still see minimum RH
values in the upper teens to low 20% result in very high fire danger
over northeast Nebraska, the fairly weak winds of 5 to 10 mph should
limit Red Flag conditions.

As we head into the afternoon and evening hours, the H5 zonal flow
should allow a disturbance to track across portions of the Central
Plains. Moisture and instability will pool along and just ahead of
the frontal boundary, with around 1,500 to 2,000 j/kg of MLCAPE. Sfc
convergence along the front should result in the development of
showers and thunderstorms after 21z. Combined with the instability,
0-6 km bulk shear of 35 to 40 kts should favor supercell
development. Steep H7-H5 lapse rates of 8.5 deg C/km along with
long, straight hodographs should promote large hail with initial
convection, and over time upscale growth will lead to more of a
damaging wind threat. The tornado threat appears low at this time,
as forecast soundings show pretty high LCLs along with little
curvature in hodographs. With this forecast update, we remain under
a Slight (level 2 of 5) risk for severe thunderstorms.

Looking at recent 00z CAM guidance, a few differences are observed,
largely with the location of the front and where convection may
develop. The HRRR ignites convection slightly farther south and east
compared to other CAM members like the NAMNest, WRF ARW, and HiRes
ARW. Have added 15 to 20% PoPs after 21z over portions of northeast
Nebraska toward the Platte River, with chances increasing to 40 to
60% after 00z for areas southeast of a line from Tekamah to Seward.
PoPs eventually push east of the area after 07z. Lows Friday night
cool to the mid 50s to low 60s.

For Saturday, expect continued warmth with high temperatures in the
upper 80s to low 90s. With the boundary lingering in the area,
should once again see instability pool near and ahead of the feature
with 1,500 to 2,000 j/kg of MUCAPE and around 40 kts of bulk shear.
While latest CAM guidance doesn`t seem too interested in generating
afternoon convection, should storms develop, they`d likely become
severe with large hail and strong winds, and while a tornado threat
can`t completely be ruled out, LCLs appear rather high at 2 to 3 km
along with rather poor and little if any 0-1 km bulk shear. To our
west, a midlevel wave ejecting out of the Rockies should result in
sfc cyclogenesis, with convection progged to develop primarily over
portions of the western Panhandle near the vicinity of the sfc low
and into central Nebraska. 00z guidance indicates convection
eventually growing upscale into various bowing segments, tracking
along the baroclinic zone eastward into the forecast area by the
late evening hours into early Sunday morning. So, expect more of a
damaging wind potential with this convection. A Slight Risk (level 2
of 5) remains in place for much of eastern Nebraska into western
Iowa for Saturday. PoPs during the afternoon and early evening
remain at 25 to 30% for this forecast update, increasing to 50 to
70% areawide by the late evening hours.

.LONG TERM /SUNDAY THROUGH THURSDAY/...

The H5 pattern on Sunday will feature an amplifying longwave trof
over the western CONUS. Several shortwaves are seen ejecting from
the feature from eastern Colorado toward the Central and Northern
Plains areas. Sfc cyclogenesis ensues with the low progged to track
through the area. The H8 baroclinic zone should swing northward
through the area, allowing ample south/southwesterly flow to point
into the area for much of the day and evening. Expect to see a
strong 45 to 60 kt LLJ overspread the area behind the front, along
with instability of 3,000 to 4,000 j/kg. Forecast soundings appear
to show capping eroding in the afternoon, and when combined
with the strong bulk shear of 40 to 50 kts, should see severe
convection develop over the area with all hazards on the table.
In addition, some urban flash flood potential does exist. Should
see areas have efficient rainfall processes with warm cloud
depths approaching the 3,500 to 4,000 meter mark.

For Monday, should see a similar threat as the H5 longwave is
progged to track farther east into the Plains. Similar to Sunday,
should see similar values of instability along with strong deep
layer shear of 55 to 60 kts yielding a threat for severe convection.
For this update, the threat remains shifted slightly to the east.

Generally quiet conditions are expected for the remainder of the
extended with cooler temperatures.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1213 AM CDT Fri May 15 2026

VFR conditions are set to prevail through the at least the first
half of the TAF period, with a wind shift draped across the
local area, making overnight winds variable in direction at
times, but less than 10 kts. Winds out of the south-southeast
will become increasingly widespread towards the late
morning/early afternoon. Shower and storm chances are set to
develop in the area late afternoon/early evening Friday, with
those storms developing along a wind shift line that will be
near the KOMA/KLNK at 22z, with a 2 hour window or less being
likely for thunderstorms at those sites. The most likely time
has been placed in the TAF, and could shift an hour or two
based on the short-term trends leading up to that point.

&&

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

&&

$$

DISCUSSION...Castillo
AVIATION...Petersen

NWS OAX Office Area Forecast Discussion