395
FXUS63 KOAX 151928
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
228 PM CDT Tue Jul 15 2025

.KEY MESSAGES...

- There is a 50-90+% chance of storms mainly after 6 PM, with a
  15-40% chance of severe storms within 25 miles of any
  location; highest in northeast Nebraska. The primary threats
  are damaging winds and localized flooding. Isolated
  occurrences of marginally severe hail and/or a brief tornado
  are also possible.

- Additional rounds of storms are possible from Wednesday
  afternoon into early Thursday, and again Friday afternoon
  into the weekend. Severe weather will be possible at times,
  with the threat of flooding increasing with each successive
  round.

- Cooler on Thursday with highs in the lower to mid 70s, but we
  quickly warm back up with 80s Friday and mid 80s to lower 90s
  for the weekend into next week.

&&

.DISCUSSION...
Issued at 228 PM CDT Tue Jul 15 2025

...Late this afternoon through tonight...

Separate vorticity maxima observed in satellite data over
western SD and eastern WY/western NE as of early afternoon will
progress east through SD and NE tonight, ahead of another mid-
level disturbance moving through MT. At the surface, early-
afternoon mesoanalysis placed a surface front from central SD
into western NE. A cumulus-cloud field is beginning to develop
along the front in the vicinity of Valentine, with that general
location likely being the focus for intense thunderstorm
development later this afternoon.

Latest CAM data remain in reasonably good agreement in depicting
the upscale growth of initially more discrete thunderstorms
into a forward-propagating MCS, which moves into the northwest
part of our area after 6 or 7 PM, before eventually reaching
the Omaha and Lincoln areas between 11 PM and 1 AM. The CAMs all
suggest that the MCS will be intense as it moves into our area
this evening with the primary hazard being damaging wind gusts
of 60-75 mph. Isolated occurrences of marginally severe hail
and/or a brief tornado are also possible. However, the models
begin to differ on the intensity of the convective system into
the overnight hours as it approaches the MO River, largely due
to variations in the amount of instability across the warm
sector air mass. Recent runs of the HRRR indicate that the
southern portion of the MCS will remain the most intense, with
a corridor of damaging winds moving through southeast NE between
10 or 11 PM and 2 AM. That signal is supported by some of the
other 12z CAMs.

Given that the convective system will be progressive, there is
some uncertainty on heavy rainfall potential. Any flooding
threat will likely be dictated by the areal extent and
intensity of the trailing stratiform region, as well as any
regenerative storm development on the western flank of the MCS,
or atop the gust frontal surface.


...Wednesday and Wednesday night...

The MT short-wave trough mentioned above will progress through
the northern Plains, while at the surface, the convectively
augmented cool front will continue south through our area. The
models have backed off on precipitation potential along the
front on Wednesday afternoon, with better potential for showers
and thunderstorms within the post-frontal environment Wednesday
evening into Wednesday night. A nocturnal low-level jet will
strengthen at that time, enhancing lift and moisture flux atop
the frontal surface. The combination of MUCAPE of 1000-1500 J/kg
and 30-35 kt of effective bulk shear may support some storm
organization with the potential for isolated occurrences of hail
and wind approaching severe levels, mainly along and south of
I-80.

Highs on Wednesday will be notably cooler across northeast NE
into west-central IA with readings in the 70s. Temperatures will
be warmer along I-80 and points south with readings in the 80s.


...Thursday and Friday...

A cooler, Canadian air mass will overspread the entirety of the
area on Thursday, in tandem with surface high pressure building
through the area, with highs in the 70s. It appears most
locations will remain dry on Thursday and Thursday night, with
the forecast indicating 20-30% PoPs across portions of
southeast NE and southwest IA.

On Friday, another low-amplitude disturbance is projected to
move through the northern Plains, with a weak surface low
tracking along the SD-NE border. The eastward progression of the
surface low will encourage the northward advance of the front
previously positioned to the south back into our area. That
boundary may become the focus for shower and thunderstorm
development Friday afternoon into Friday night. Some severe
weather appears possible, as does heavy rainfall and potential
flooding.

It looks like we`ll see warmer temperatures on Friday with
highs in the 80s.


...This weekend...

A quasi-zonal, mid-level flow pattern will continue across the
north-central CONUS, with embedded disturbances rippling through
that regime. That coupled with the presence of a stationary
front in or the immediate south of the area will result in
continued shower and thunderstorm chances. The risks for severe
weather and flooding are expected to continue. Highs in the 80s
to low 90s are forecast.


...Early next week...

The 12z global models indicate the gradual strengthening of a
subtropical high across the southern and central U.S.,
especially during the latter half of the work week. That upper-
air pattern evolution will support a potentially drier stretch
of weather, along with progressively warmer temperatures. Highs
in the mid 80s to low 90s are forecast on Monday, with readings
warming into the upper 80s to mid 90s on Tuesday.


&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1159 AM CDT Tue Jul 15 2025

VFR conditions will prevail into this evening with FEW-SCT
clouds at FL050-060. This evening into tonight, a complex of
thunderstorms is expected to move southeast through the area,
affecting all three terminal locations. KOFK is mostly likely to
experience MVFR conditions and a brief period of strong wind
gusts. The MVFR conditions are expected to linger at KOFK into
Wednesday morning, with some potential for brief IFR conditions.

Winds will be from the south this afternoon at around 13-15 kt.
Gusts up to 22 kt are most probable at KOFK. Later this evening
into tonight, winds will switch to northwest with the movement
of the storms through the area.

&&

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

&&

$$

DISCUSSION...Mead
AVIATION...Mead