Forecast Discussion
NWS Omaha/Valley, NE

897
FXUS63 KOAX 171026
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
526 AM CDT Sun May 17 2026

.KEY MESSAGES...

- The ongoing round of severe storms ending early Sunday
  morning. The rest of the morning hours will be cool and
  breezy, but become warm and muggy later Sunday

- Severe storms will develop again on Sunday afternoon. Very
  large hail, damaging downburst winds, and tornadoes will be
  possible. The greatest severe potential will be northwest of a
  Lincoln to Harlan line.

- A final round of severe storms develops on Monday afternoon.
  Very large hail, damaging downburst winds, and tornadoes are
  once again possible, particularly southeast of a Seward to
  Onawa line.

- Much cooler conditions are expected for the rest of the work
  week.

&&

.DISCUSSION...
Issued at 1141 PM CDT Sat May 16 2026

Overview:

A volatile severe weather setup will affect the local forecast area
through Monday, with multiple rounds of severe storms likely each
day, and significant severe weather at times, including very large
hail and tornadoes.

Early Sunday:

Widespread thunderstorms have been very efficient in eating up
instability late Saturday evening into early Sunday morning. This
will be capped off by a broad arc of surging severe thunderstorms
working along the Nebraska/Kansas state line. This bow echo will
push off to the east of the forecast area by around 3 AM, give
or take with a broad stable region overspreading the area and
pushing south into KS. Currently believe that the stable airmass
will spread 40 to 70 miles south of the KS/NE border. Normally
would suspect it would dive farther south, but the 0-3 km shear
vectors are favoring ENE gusting segments with this main bow,
and the overall flow pattern with an incoming strong short wave
with negative tilt and developing surface low will quickly draw
the unstable airmass back north. All this to say that the area
is set up for a pretty pleasant morning on Sunday after a rainy
Saturday night. But that will change over the course of the day.

Sunday afternoon into Sunday night:

The center of the upper trough axis will remain well to the west on
Sunday but an embedded lead short wave trough and attendant jet
streak will eject from eastern CO into eastern NE during the day. An
elongated trough of surface low pressure will extend from the main
surface low in southeast CO up through south central NE and into
southeast SD. Expect this to be a zone of persistent strong deep
moist convergence through the afternoon. Additionally, there is a
strong model signal for a narrow dryline surge into central NE and
central KS during the afternoon. East of this, in the warm sector,
middle to upper 60s dewpoints will surge back north during the day.
This will set up very strong instability with MLCAPE likely in the
3000-4000 J/kg range. It is worth noting that even amidst this
highly unstable environment, there is a slight weakness in the mid-
level winds, so forecast parameters such as the 0-6 km shear vector
are not particularly impressive. However, one look at hodographs
tells a story of ample cyclonic curvature in the lowest portions of
the hodograph with what is likely enough of a wind difference to
keep the updrafts relatively clean of downdrafts. Model guidance is
consistent in destabilizing sufficiently for initiation by 4 PM, and
would not be surprised if it`s slightly earlier. That initial
convective initiation will likely extend on a north-south line
from Knox County down through Boone County, and due south from
there. This is where things get especially interesting. The
strength of the forcing will play a significant role in whether
storm mode becomes linear or remains largely cellular. The deep
shear vectors, while not large in magnitude, are largely
perpendicular to the line, so as long as the forcing isn`t
overwhelming, convection is likely to remain cellular. The
significant speed and directional shear in the lowest levels,
impressive at initiation and increasing notably into the early
evening hours, point to the potential of quick organization into
a line of supercells with tornado, hail, and downburst
potential. Any longer-lived supercell features that can persist
into the intensifying environmental shear conditions will have a
chance to produce strong tornadoes. With that said, the storm
mode is not a simple forecast with this event, and will have
some dependency upon those mid-level winds, timing of convective
onset, and intensity of linear forcing.

Monday:

The primary trough and strongest jet streak eject across Nebraska on
Monday. Sunday`s convection looks to clear the area very early
Monday morning, and once again expect a robust early-day recharge of
moisture and instability north into Nebraska and Iowa. There are
question marks regarding just how far north and east this will
extend, but a majority of 00Z model guidance brings it well north,
perhaps extending as far as a Hebron to Wahoo to Onawa line by
early to mid afternoon. Warm sector instability will once again
be quite strong. Deep layer wind shear will be sufficient for
supercells storm mode to be dominant. Storm motion may take
these storms slightly more parallel to the initiating boundary
which may complicate storm mode, but most all signs point to a
broken line of supercells, potentially training over some areas,
with favorable hodographs for sustained supercells, very large
hail, downdrafts, and tornadoes. Also see potential for strong
tornadoes particularly in long-lived, more isolated supercells.
The question is not necessarily the available ingredients for
severe weather on Monday, but the locations in which they will
be present...how far north and west. And we may not know that
with great confidence until Monday morning.

After Monday:

Temperatures cool sharply with highs in the 50s and 60s at mid week
and even some potential for frost on a couple of mornings. Then
another slow warmup expected by the weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 520 AM CDT Sun May 17 2026

Largely VFR conditions are in place this morning, with a band
of thunderstorms extending from KOLU to KCBF, slowly moving
north while staying rather weak. Pockets of MVFR ceilings have
floated in and out of the area observations, but are too
isolated to put into the TAF with any confidence (would be at
FL012-025 if they did occur). Winds are out of the east-
northeast to southeast, with gusts to 20-25 kts expected to
become increasingly widespread through the morning, increasing
this afternoon to 30-35 kts.

The main concern of the TAF period will be associated with the
development of strong thunderstorms after 21z, starting first
near KOFK before expanding in a line and moving southeast toward
the KOMA and KLNK locations. The most up-to-date timing has been
amended into the TAFs, and storms look to be a bit more
progressive this time around, only affecting a terminal for 2
hours or less. Strong winds and hail are more likely and would
be of most interest to aviation, but tornadoes are also
possible.

&&

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

&&

$$

DISCUSSION...Barjenbruch
AVIATION...Petersen

NWS OAX Office Area Forecast Discussion

Forecast Discussion
NWS Hastings, NE

671
FXUS63 KGID 171152
AFDGID

Area Forecast Discussion
National Weather Service Hastings NE
652 AM CDT Sun May 17 2026

.KEY MESSAGES...

- Another evening of severe weather will be possible again
  today. Storms will be capable of producing large hail,
  damaging winds and even potentially a tornado.

- The best storm potential will be concentrated areas areas near
  and east of HWY-281 between 4-11PM.

- Critical fire weather conditions are expected to arise across
  a few southwest portions of the area. Gusty southerly winds as
  high as 35-40MPH will overlap with dry conditions (RH values
  as low as 10- 20%). A Red Flag Warning is in effect from 1-9PM
  for counties south of Harlan and Franklin counties.

- Severe weather is possible to return Monday evening for a few
  locations mainly southeast of the Tri-Cities.

- Highs, following the passage of a cold front Monday, will drop
  down to primarily the 60s for Tuesday/Wednesday/Thursday, the
  70s for Friday and the upper 70s to low 80s for Saturday.

&&

.UPDATE...
Issued at 351 AM CDT Sun May 17 2026


Today...

The active pattern continues on today as a negatively tilted upper-
level trough digs into the Central Plains. Height falls at the
surface, forced by CVA along the exit region of the trough, has led
to the strengthening of a surface cyclone centered over Western
Kansas/Nebraska this morning. This low should continue to take a
northeastward trajectory, lifting a warm front up and through the
area with a trailing dryline punching in behind. This dryline will
not only serve as a storm lifting mechanism, but as a demarcation of
the very dry airmass that is set to stir fire weather concerns for a
few southwest portions of the area. A Red Flag Warning will be in
effect from 1PM to 9PM as gusty southerly winds (gusting as high as
35-40MPH) mix with this very dry airmass (RH values as low as 10-
15%) for counties south of Harlan and Franklin counties. For more
information regarding the fire weather potential for the week,
please refer to the Fire Weather section below.

Ahead of this dryline, warm, moist and unstable air should seep back
into much of south central to southeast Nebraska, priming the
afternoon for yet another evening of severe weather. Given the highly
unstable environment (3,000-4,000J/km MUCAPE), sufficient shear (30-
45kts BWD) and ample moisture (mid to upper 50s dewpoints), any
storm that manages to fire this afternoon/evening will easily have
the potential to become severe. The main concerns would be damaging
thunderstorm wind gusts up to 70 MPH with large hail up to the size
of baseballs. An isolated tornado can also not be fully counted out,
though the linear forcing mechanism may favor a squall line
storm mode over discrete supercells.

The latest high resolution model guidance (HRRR & NAMNEST), both
highlight a line of storms zipping down the dryline as it crosses
through central Nebraska between 4-11PM. The main uncertainty that
has not been consistently handled across the model trends thus far
has been when and where these storms initially fire. The timing for
when storms develop and how far the dryline advances through the
day, will ultimately determine where the severe weather threat end
up. Generally speaking, the better potential for severe weather will
be concentrated to locations near and east of HWY-281. If storms,
however, snap earlier than the models currently suggest, a few severe
storms could manage to pop up just west of HWY-281.

Given the prime thunderstorm ingredients establishing across the
area, the SPC has included most of the area underneath an enhanced
severe weather outlook (level 3 of 5). In reality, the majority of
the action should take place across the eastern half of the area
(locations found ahead of the eastward advancing dryline.


Monday...

Severe weather concerns will once again be expected to return to a
southeast portion of the area Monday afternoon to evening. A cold
front powering through the area during the day, will drop highs from
the upper 80s and 90s Sunday down to the 50s and 60s for northeast
portions of the area and down to the 70s and 80s for the southeast
half of the area (locations where the front reaches later in the
day). The front will also be responsible for initiating a line of
severe storms between 3-5PM. The latest CAM guidance keeps the
convection bound to only a few of our far southeastern locations
(mainly to Mitchell, Jewell, Thayer and Fillmore counties.) The SPC
keeps only our southeast half under a severe weather outlook with
the highest risk (enhanced level 3 out of 5) southeast of a line
from Beloit, KS to Friend, NE.

&&

.DISCUSSION...
Issued at 327 PM CDT Sat May 16 2026

Short discussion here as we transition to severe weather ops.

Two main convective regimes for the short term:
1) isolated supercells along a retreating warm front over mainly
south central Nebraska late this afternoon and evening. All
modes of severe will be possible given potent combination of
instability and shear. Already seeing signs of this along I-80
corridor.

2) larger complex of storms is forecast to move in from the W
later this evening. This activity would have an organized with
threat with it, as well as potential for QLCS tornadoes. This is
concerning considering the late time of day and difficult to
spot them. Could also see some large hail, but would be a
secondary threat. Can`t rule out a few swaths of wind driven
hail. Isolated gusts up to 80 MPH will be possible in the
strongest cores. This batch favors south central Nebraska more
than Kansas, but KS zones by no means in the clear.

Severe threat should end by around 09Z.

Focus then turns to Sunday`s severe weather and fire weather
potential. Will all depend on where the dry line sets up, but
trends have been to shift this further E and bring more of the
dry surge and fire weather into play. Will need to seem how
things settle from today...but anywhere along and ahead of the
dry line could see significant severe weather, including intense
supercells with very large hail, damaging wind gusts, and
tornadoes. The greatest tornado threat looks to be along and
E/NE of the Hwy 81 corridor. Late afternoon and early evening is
the main time frame of concern for dry line storms. Another
batch of severe storms with mainly a large hail and wind threat
could move in from the NW along the primary cold front late
Sunday evening and into the overnight.

Fire weather discussion will be included below shortly.

Exactly how things unfold Sunday will determine frontal location
for Monday. As mentioned above, this is trending further E/SE
such that most of out area could be on the cool side of the
front by midday. In fact, far N/NW zones could struggle to get
out of the 50s while far S/SE zones push 90F. A strong spring
front, indeed, that is bound to spark off widespread severe
weather...just a question of if it`s here or just E/SE.

Not much time spent in the extended periods as it appears fairly
quiet.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 641 AM CDT Sun May 17 2026

For KGRI/KEAR Airports:

The MVFR ceiling to not become as widespread as originally
expected this morning. Instead bases have seemed to hover near
4-8kft. Broken to overcast skies will likely maintain through
most of the day (beyond a brief 17-22z period). Unless an
afternoon thunderstorm approaches the KEAR vicinity between
23-2z, MVFR ceiling are not expected to return for the rest of
the 12z TAF period.

Winds today will remain fairly stable through 19z. Southerly
winds picking up this morning will mainly blow between 15-25kts
today with gusts as high as 30-40kts. Between 19-0z, wind
directions will flip from a southerly to northerly direction
with the passing of a dryline. Winds are not expected to let up
after becoming northerly (15-20kts sustained with gusts as high
as 25-35kts). Wind speeds will not decelerate until closer to
6z.


&&

.FIRE WEATHER...
Issued at 351 AM CDT Sun May 17 2026

A deepening surface low across western Kansas and Nebraska today will
activate fairly gusty southerly winds. Wind speeds will pick up this
morning, blowing between 15-25MPH with gusts as high as 35-40MPH
possible through the evening. Highs peaking in the mid to upper 90s
across a few far southern Nebraska and north central Kansas areas,
with the dryline later dropping dewpoints from the 50s to 40s, will
quickly help dry conditions out. RH values as result will tank as
low as 10-20% across much of north central Nebraska and for the far
southern row of Nebraska counties.

Despite the moisture that was deposited from last night
thunderstorms, the dry afternoon punch will easily dry conditions
back down to critical concerns. A Red Flag Warning will be in effect
from 1-9PM for Harlan and Franklin counties in Nebraska and for
Phillips, Smith, Rooks and Osborne counties in Kansas. A few areas
of near-critical fire weather conditions may still be observed
across a few of our Kansas areas or far southern Nebraska areas
outside of the warning.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Red Flag Warning from 1 PM this afternoon to 9 PM CDT this
     evening for NEZ083-084.
KS...Red Flag Warning from 1 PM this afternoon to 9 PM CDT this
     evening for KSZ005-006-017-018.

&&

$$

UPDATE...Stump
DISCUSSION...Thies
AVIATION...Stump
FIRE WEATHER...Stump

NWS GID Office Area Forecast Discussion