559
FXUS63 KOAX 050420
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
1120 PM CDT Thu Sep 4 2025

.KEY MESSAGES...

- A narrow axis of showers may develop in southeast Nebraska
  early this morning, mainly south of I-80 (20-30% chance). Dry
  conditions are then expected areawide by the afternoon.

- Cool and dry conditions continue through the weekend with a
  gradual warming trend expected next week.

- Shower and thunderstorm chances return Monday into Tuesday of
  next week (20-40% chance).

&&

.DISCUSSION...
Issued at 306 PM CDT Thu Sep 4 2025

.SHORT TERM.../TODAY THROUGH FRIDAY NIGHT/

A mix of clouds and sun is observed over much of the forecast area
this afternoon. 19z METARS show temperatures in the upper 60s to low
70s with southwesterly winds becoming gusty at times to around 25
mph over northeast Nebraska. Areas of smoke also continue to affect
Nebraska, although the worst concentrations appear to be just west
of our forecast area. Looking at our pattern aloft, 18z H5 RAP
objective analysis shows a strong shortwave trof ejecting from
southern Manitoba into the Dakotas. This feature has already
resulted in the formation of a 998 mb sfc low, with the resultant
cold front extending from near Huron, South Dakota southwestward
toward North Platte, Nebraska as of 1945z.

The cold front will eventually push east into OAX this afternoon and
evening, resulting in at least a low end threat for showers and
storms, primarily over far northeast Nebraska and western Iowa.
Model guidance depicts a narrow corridor of instability pooling just
ahead of the front late this afternoon and evening. BUFKIT soundings
reveal a skinny 400 to 800 J/kg CAPE profile rooted aloft. 0-6 km
bulk shear of 50 kts would seem to suggest that at least some strong
storm risk exists, but one of the main ingredients lacking here
appears to be forcing. While sfc convergence will be observed along
the front, the best large scale forcing/resultant Q-vector
convergence will be tied to the track of the H5 shortwave which
tracks over eastern South Dakota, Minnesota, and northern Iowa.

Taking a look at the latest CAMs, there is pretty good agreement
with showers and storms developing just to our northeast, and a few
storms may clip our far northern and northeastern borders with FSD
and DMX. If storms do manage to form, a few could have gusty winds
and small hail. The SPC currently has a marginal risk of severe
weather clipping far northeast Nebraska for this afternoon and
evening. Guidance also suggests a few spotty showers developing over
eastern Nebraska late this evening, but BUFKIT soundings suggest
that low level dry air below 10kft may limit rain reaching the
ground. Have decided to cut back PoPs to low end 15% chances
primarily along our shared borders with FSD and DMX through at least
02z.

Otherwise, for the rest of today, will see a mix of clouds and sun
as highs reach the mid 70s to low 80s in eastern Nebraska, and low
70s across western Iowa. Some smoke will linger too, but it will
push south and away from the forecast area by Friday morning once
the front makes its way through. Lows tonight will be in the mid 40s
across northeast Nebraska and western Iowa, and in the low to mid
50s across the rest of the area.

By early Friday morning, the majority of CAM guidance suggests a
line of scattered showers developing along and south of Interstate
80. This activity appears forced by lingering FGEN seen at H7 and
H8. BUFKIT soundings once again suggest that dry air may linger in
the lowest 10kft resulting in little to no precipitation reaching
the ground. Have only added low end 20 to 25% PoPs along and south
of Interstate 80 from 06z to about 15z Friday. PoPs will exit to the
south as the front finally pushes through.

Once the front pushes through, will see sfc high pressure settle in
across much of the Northern Plains resulting in quiet weather. High
temperatures for Friday will be cooler as strong CAA at H8 filters
in behind the front. Most will see highs in the low to mid 60s,
while upper 60s are expected near the Nebraska/Kansas border. Winds
will be from the northwest, with gusts up to 25 mph expected once
again in northeast Nebraska. Winds will subside by the evening
hours, and lows will be in the low to mid 40s.

.LONG TERM.../SATURDAY THROUGH WEDNESDAY/

By Saturday, the H5 shortwave trof will have fused together with a
531dam low located over eastern Ontario. This will result in a
longwave trof dominating much of the eastern CONUS this weekend
while to our west, H5 ridging begins to take shape. The sfc high
over the Northern and Central Plains will thus strengthen, resulting
in quiet conditions for much of the forecast area this weekend.
Highs Saturday and Sunday will be in the 60s to low 70s with light
winds resulting from the sfc high. Lows may dip into the upper 30s
across portions of northeast Nebraska and western Iowa late Saturday
night into Sunday morning!

Next week, will continue to see H5 heights rise as the ridge is
still progged to amplify over the western CONUS. 1000-500mb
thicknesses will be on the increase too, implying that temperatures
will be on a warming trend. Most locations will see a return to
temperatures in the mid 70s for Monday, to upper 70s and mid 80s by
Wednesday.

As the H5 ridge amplifies, will also see a few shortwaves ride the
ridge top. This results in the NBM extended having low end 15 to 20%
chances for showers and storms Monday. 30 to 45% chances arrive by
late Monday into Tuesday as a stronger shortwave riding the ridge
ejects east southeast into Nebraska. This is still several days out,
so expect to see further refinements and adjustments made to PoPs as
we get closer.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1120 PM CDT Thu Sep 4 2025

An axis of elevated VFR showers/sprinkles may develop near LNK
early this morning ~10-12Z, though the potential remains too
low to include in the TAFs with this update (20% chance), with
the expectation that it remains mainly south of I-80.

Wind gusts have mostly eased late this evening across the area
with NW to WNW winds prevailing in the wake of a cold front
around 10 kt through the overnight hours. Increasing gustiness
is expected by mid to late morning as daytime mixing allows
upper teen to lower 20 kt gusts to reach the surface through
much of the daytime hours paired with increasing VFR cumulus
coverage. Winds then ease toward sunset.

&&

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

&&

$$

DISCUSSION...Castillo
AVIATION...Petr