Forecast Discussion
NWS Omaha/Valley, NE

972
FXUS63 KOAX 152335
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
635 PM CDT Fri May 15 2026

.KEY MESSAGES...

- Showers and storms likely this evening (60-80% chance).
  Storms may be severe with large hail and damaging winds.

- Additional rounds of strong to severe storms possible Saturday
  through Monday with large hail, damaging winds, tornadoes, and
  flash flooding all possible.

- Pattern quiets down Tuesday and beyond with highs in the 60s
  Tuesday and Wednesday, warming into the 70s later in the week.

&&

.DISCUSSION...
Issued at 1226 PM CDT Fri May 15 2026

Clear skies this morning with some scattered cu starting to
develop over south-central Nebraska. Water vapor satellite
imagery shows the deepening trough over the West Coast which
will lead to the development of our active pattern going into
the weekend. Over eastern Nebraska, RAP objective analysis shows
a front situated along the western extent of our area, from a
few miles east of Yankton south to around Hastings. This
boundary will continue to slowly move southeast, eventually
stalling from around Onawa, IA southwest to around Red Cloud,
NE. This corridor will be the focus for initial storm
development as the upper-level wave arrives this evening.

Temperatures are forecast to get very warm today, with highs in
the 90s. In northeast Nebraska, we will again expect humidity to
drop to 20 to 25 percent this afternoon leading to very high
fire danger. Fairly weak winds of 5 to 10 mph should limit Red
Flag conditions.

Through the afternoon we`ll start to see moisture pooling along
the surface front with an upper-level shortwave kicking off
storm development around 6-7pm this evening. We`re expecting
2000-2500 J/kg of SBCAPE to develop, combined with 0-6 km of
bulk-shear of 35 to 40 kt should favor supercell development
initially. Dry low-levels in the soundings indicate high-base
hailers initially evolving into a damaging wind threat as storms
converge into clusters or more into a line. The tornado threat
at this time is very low due to high LCLs along with little low-
level curvature in the hodograph, but SPC has bumped a good
portion of our west-central Iowa counties up into an Enhanced
Risk (level 3 of 5) for increased damaging wind and hail threat.


As previously mentioned, storms should initially develop along
the northeast to southwest frontal boundary which will stall
across our area this afternoon. The general consensus of the
CAMs suggest that these storms will congeal into clusters or a
line and move southeast through the evening, clearing out by
around midnight-2am. With increased confidence in placement of
these storms, have increased PoPs to around 60-80 percent this
evening in areas with the greatest chance of seeing storms.

Saturday will be another warm day, though a few degrees cooler
due to starting out the day with the post-frontal air mass in
place across our area. With the approach of our next upper-level
wave, we`ll see a warm front lift back north into our area
through the afternoon. CAM guidance is still not confident in
any convection developing along this front during the late
afternoon into the evening. The HRRR and RRFS, though, (both
notorious for over- convecting at times) give us at least an
idea of what it may look like if we get storms along this front.
3000-3500 J/kg of MLCAPE develop along and south of the warm
front with 40-50 kt of bulk shear. If storms develop, they`d
likely be severe developing into discrete supercells initially,
congealing into a east-west line with potential for large hail,
damaging winds, a tornado or two, and flash flooding. Over
western Nebraska an upper-level wave will kick off convection
during the afternoon, developing into a few different segments
of storm clusters that travel eastward across the state through
the evening. These segments grow into bowing segments tracking
eastward into our area by late evening with a damaging wind and
hail threat persisting through around 3-5am as they move across
our area.

Sunday`s severe potential may at least initially be greatly
impacted by any lingering showers, storms, and cloud cover from
the early morning system. As H5 troughing deepens over the
Intermountain West, we`ll see a strong low-level jet set up,
nosing into eastern Nebraska and western Iowa during the
afternoon. This will help to bring in more low-level moisture.
Surface winds could get fairly strong on Sunday, gusting 35 to
45 mph out of the south, enhancing low-level shear. Instability
of 3000-4000 J/kg combined with 40-45 kt of bulk shear should
support supercells as the cap erodes during the afternoon. With
greater low-level moisture and shear, all modes of severe
weather will be possible including large hail, damaging winds,
flash flooding, and tornadoes.

Monday will have a similar set-up as the H5 longwave trough
nudges eastward, closer to our area, with similar values of
instability and perhaps even more shear expected to develop. The
area of greatest threat on Monday will be a bit farther east
than Sunday, more directly across eastern Nebraska and western
Iowa.

The rest of the week next week looks quiet with cooler
temperatures moving in on Tuesday and Wednesday (highs in the
60s). Temperatures trend back upward later in the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 635 PM CDT Fri May 15 2026

Showers and thunderstorms are observed at the start of the TAF
cycle near and southeast of KOMA. More development is also
observed just southwest of KLNK. Have continued mentions at
KOMA and KLNK for -TSRA through TEMPO groups, with activity
ending after the 02 to 03z timeframe. Storms could be strong to
severe with large hail and damaging winds the primary threats.
Winds will remain gusty at KOFK and KOMA til late this evening,
becoming light under 12kts and from the north northeast. Expect
winds to increase after 16z at KOFK and KLNK with gusts from the
east southeast at 20 to 25kts. Chances for showers and storms
increase after 22z but remain at 15 to 30% at terminals.

&&

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

&&

$$

DISCUSSION...McCoy
AVIATION...Castillo

NWS OAX Office Area Forecast Discussion

Forecast Discussion
NWS Hastings, NE

267
FXUS63 KGID 152349
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
649 PM CDT Fri May 15 2026

.KEY MESSAGES...

- A few (potentially severe) storms will be possible late this
afternoon through early evening, mainly along the Hwy 81  corridor.
The main hazards will be hail up to the side of   ping pong balls
and thunderstorm wind gusts near 60 MPH.

- Generally greater coverage of strong to severe storms will  come
Saturday evening into the overnight and Sunday afternoon  and
evening. Baseball size hail and damaging thunderstorm wind  gusts up
to 75 MPH may be possible within the strongest  storms. A few
tornadoes will also be possible, esp. Sunday.

- The severe threat may continue into Monday as the large scale
storm system has trended slower. The greatest threat will  favor the
eastern half of the forecast area, but specific  timing and threat
remains uncertain.

- Near-critical to critical fire weather concerns may return for  a
southwest portion of the area Sunday given strong S winds   blowing
near 20-30 MPH and gusting as high as 35-45 MPH.

- Temperatures ahead of a cold frontal passage early next week  will
keep highs in the mid 80s and 90s (through Sunday) before
temporarily dropping down to the 60s to 70s by Tuesday. A steady
increase in highs will likely follow through the end of next week.

&&

.DISCUSSION...
Issued at 427 PM CDT Fri May 15 2026

This evening-overnight: No major changes in the latest thinking
regarding severe weather potential. Still appears the main
threat area will focus in the far E/SE portions of the forecast
area...along and ahead of a weak boundary. There`s not a lot of
temperature differences on either side, and winds are weak such
that convergence isn`t very strong either. Main differentiators
is moisture, with dew points in the mid 50s in places like
Hebron vs. lower 30s in the Tri-Cities. It got quite warm/hot
out there today, so areas that do have decent low level moisture
have moderate instability in the 1000-2000 J/kg range amidst
steep mid level lapse rates over 8 C/km. Wind shear is modest,
but sufficient, for organized deep convection with latest SPC
mesoA page indicating 30-40kt of effective deep layer shear,
decreasing with SW extent. Forecast soundings and sfc T/Td
spreads >30 degrees suggest inverted-V profiles/elevated bases
and wind gusts as the primary severe threat. The steep mid level
lapse rates and modest shear also support a severe hail threat,
particularly in the initial cores. Expect fairly quiet
conditions between midnight through early afternoon Saturday.

Saturday PM: The next round of potential severe weather will
come as early as late Saturday afternoon, but more likely during
the evening into early overnight hours. A deepening upper trough
over the W CONUS will begin to exert it`s influence by later in
the day in the form of modest height falls and difluent and
divergent upper level flow. Latest CAMs appear to be converging
on a general solution where today`s weak boundary stalls out,
then lifts northward as a warm front during the afternoon,
reaching central Nebraska by 00Z Sunday. Most likely area for
convective initiation will favor areas to our west along the
High Plains within a broad swath of Erly upslope flow and closer
to the arriving height falls. This activity will likely congeal
into one or two MCSs that roll E/NE during the late evening and
overnight, sustained by a strong LLJ increasing to 50-60kt by
03Z. Moderate to strong instability (MLCAPE as high as 2000-3000
J/kg), strong effective deep layer shear (40-50kt) - including
strong upper level storm-relative flow/venting - and very steep
low to mid level lapse rates all suggest potential for upper-
end type hail and damaging wind. In fact, wind-driven large hail
could be a concern. Will also need to watch the southern end of
an expected MCS or any embedded supercells, esp ones that
interact with the warm front, for a few tornadoes. This would be
most concerning in the 00-03Z time frame as LCLs lower and low
level SRH ramps up with the aforementioned LLJ.

The above scenario is the one that appears to be most probable
at this time (MCS rolling off the High Plains later in the day
with primarily a hail/wind threat), but isolated late afternoon
CI eastward into our area along the warm front is also
plausible...a la the 18Z HRRR. This scenario is highly
conditional due to some capping and weaker forcing, but
potentially high- impact, if it were to pan out. This scenario
would increase the high- end hail threat (up to around baseball
size) and also probably the tornado threat. Want to see more CAM
consistency before ramping up this messaging.

Sunday: appears any convection from Saturday night will have
shifted N/NE of the area by sunrise Sunday AM...setting the
stage for strong destabilization of a broadening warm sector. In
general, appears there will be most of the ingredients necessary
for a higher-end severe weather threat, including strong
tornadoes...but as always, the details matter and are still
murky this far out. With the lack of AM convection, don`t think
instability will be an issue, and the arrival time of stronger
upper level forcing appears to be well-timed towards the peak
heating hours. So even through mid level temps will be quite
warm (14C+) early in the day...some cooling/height falls
towards 00Z Mon along with strong destabilization should be
enough to support robust CI. Once storms form, should have
most/all of the ingredients in place for significant severe
weather...with the main uncertainty lying in the location of a
likely triple point (closer to Lexington or closer to Tri-
Cities) and QUALITY of boundary layer moisture. Some models
(e.g. 12Z EC) really mix the BL and lowers Tds into the
50s...whereas the NAM shields the BL a bit more and maintains
mid to upper 60s Tds through the late afternoon. RRFS is
somewhat in between. Thus...this casts some uncertainty on
mainly the tornado threat...at least early on in the convective
cycle. Threat could increase in time - even per the 12Z EC -
with gradual lowering of LCLs and increasing low level shear.
Not sure what convective mode would be by then, though. Still
plenty of time to hash out those details.

System as a whole has trended slower...which brings more of our
area into play for another round of significant severe weather
potential on Monday. This looks to be our last day (for at least
a few days) of severe weather threat as the upper trough finally
moves through Monday night. Haven`t looked into details of
Monday and beyond very much today since there`s plenty of
impactful weather in the short term.

One last thing...still monitoring the potential for a wedge of
critical fire weather conditions to punch into far W/SW zones
behind the dry line Sunday afternoon. Phillips down into Rooks
County would be most at risk, even if they see rain Saturday
night, as much of the fine (1hr) fuels are still susceptible to
large fire growth.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 645 PM CDT Fri May 15 2026

For KGRI/KEAR Airports:

VFR expected through the period. Have removed the PROB30 group
for tstms at GRI this eve as it appears the greatest risk will
remain off to the SE. Should be fairly quiet for the terminals
with just a few clouds and mainly light N to NE winds. Winds
will turn to the E on Saturday and incr slightly. Next chance
for storms looks to be at the very end of the valid period, so
only went with a PROB30 group at this time given uncertainty in
specific timing. Confidence: Medium.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.

&&

$$

DISCUSSION...Thies
AVIATION...Thies

NWS GID Office Area Forecast Discussion