920
FXUS63 KOAX 171858
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
158 PM CDT Thu Sep 17 2026

.KEY MESSAGES...

- Mix of clouds and sun today with highs in the 70s to low 80s.
  Areas along and south of I-80 could see some spotty showers or
  storms this afternoon (20% chance).

- Storms redevelop across far northeast Nebraska late tonight
  into Friday morning (60-80%) and could bring some heavy rain.

- More storms redevelop Friday afternoon and evening (40-60%
  chance). There is a 5% chance that some could be severe.
  Additional storm chances persist for much of the weekend
  through Monday with cooler temperatures.

&&

.DISCUSSION...
Issued at 158 PM CDT Thu Sep 17 2026

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

18z SPC mesoanalysis shows H5 ridging remaining firmly in place
over much of the Southern Plains and southeast US. At the sfc,
high pressure is seen over the Dakotas and Minnesota, extending
southward into the Missouri River Valley. Should see some of the
pesky stratus clouds linger this afternoon as subsidence from
the high pushes downward and traps residual moisture. Spotty
showers and a few isolated storms may persist across our far
southern areas this afternoon (20% chance) as low level warm
advection remains in place. Highs today reach the mid to upper
70s.

Will see the sfc high pass to the north and east, while a sfc low
gets spun up in far eastern Colorado. The H8 baroclinic zone
lifts northeastward across most of the state, a LLJ will
overspread to the east over much of central into northern and
northeast Nebraska. Speed convergence along the jet nose, in
addition to an approaching H5 shortwave, should help force
parcels upward and tap into a narrow ribbon of MUCAPE of 500 to
1,000 j/kg, resulting in some showers and storms. Bulk shear of
around 30 kts could support a brief strong updraft capable of
some gusty winds or hail, but the more likely threat will be
heavy rainfall. PWATs remain high at 1.75 to 1.9 inches, while
warm cloud depths remain marginal just under 4,000 meters. Most
CAMs tend to keep the activity somewhat progressive which could
limit flooding potential, but still can`t rule out a few areas
seeing locally heavy rainfall underneath any storms. PoPs of 60
to 80% are forecast for primarily far northeast Nebraska along
the border with South Dakota after 03z, clearing by 11z. There
is some potential for fog development tonight, particularly in
northeast Nebraska near the Norfolk vicinity (20-30% chance per
12z HREF guidance). However, wind speeds will range from 5 to 10
mph overnight which could limit the threat.

The sfc low is progged to lift northeast, dragging the sfc warm front
through most of the forecast area by the daytime hours. This
should lead to another plume of instability overspreading the
warm sector, ranging from 2,000 to 3,500 j/kg by the late
afternoon. 0-6 km bulk shear remains rather weak at times,
around 20 to 25 kts seen from some hires CAMs and the various
parameterized models which could limit storm organization. Large
scale forcing for ascent still appears to lack around this
timeframe too as the H5 impulse won`t arrive until late Friday
night, but any remnant MCV from overnight convection could
provide some lift for storm development. BUFKIT soundings would
also suggest some element of low level capping around H8 that
could limit storm development in the late afternoon hours. If
storms can manage to form near and along the approaching sfc
front, the main severe threat would be damaging wind gusts or
even a brief tornado, but that will largely be dependent on if
we can be sfc based. By the evening hours, a 30-40 kt H8 LLJ
will ramp up across our southeastern areas which could fire off
additional elevated convection, some of which could have some
gusty winds or hail. PoPs at this time remain at 40 to 60%
Friday evening, particularly over far eastern Nebraska into
western Iowa.

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...

The sfc front will have moved off away from the area Saturday,
resulting in highs reaching the 70s to low 80s. More chances
for storms continue Saturday into Sunday as another mid level
impulse and remnant H8 advection persist. Expect PoPs of 50 to
70%, particularly along and south of Interstate 80 late Saturday
into Sunday morning. Rainy conditions continue into Sunday as
the closed H5 low now over the northern California coastal area
finally treks east into the Northern Plains, providing some lift
while low to mid level moisture transport remains pointed in
the area. Rain gradually ends by Monday afternoon as the mid
level wave moves away from the area and sfc high pressure builds
back in. Mostly dry conditions are progged for Tuesday, while
our next disturbance approaches for Wednesday and Thursday with
more PoPs of 20 to 40% areawide. Temperatures Sunday through at
least Wednesday will remain on the cooler side, with highs in
the 60s to near 70F. There is some signal for a warm up to the
upper 70s and low 80s late next week as H5 ridging makes its way
back toward the area.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1156 AM CDT Thu Sep 17 2026

Ceilings/Visibilities: A few brief periods of MVFR broken ceilings
will be possible across the next few hours as some low-level stratus
breaks apart. Though VFR ceilings (mainly between 5,000-10,000ft)
are forecast to return for a majority of the time between 21-5z
today, the low-level stratus hanging around as low as 1,000-3,000ft
may occasionally fill in enough to become the a MVFR ceiling. It is
uncertain how often this may occur or how scattered the cloud
coverage will become this afternoon/evening. What does seem certain
is the fact that at least MVFR ceilings will return after 4z with
IFR (possible even LIFR) ceilings likely after 6z for all sites.
Cloud bases may even drop to less than 500ft between 8-12z. VFR
ceilings would not be expected to return tomorrow morning until at
least 13z for KLNK or 16z for KOMA/KOFK. Though some light
reductions in visibility may be observed between 1-14z for
KOMA/KLNK, it is unlikely for visibilities to drop below 5 miles
outside of a brief window tonight. The better possibility for fog
formation will be concentrated closer to the KOFK area where
visibilities may drop to as low as 1 mile between 7-14z.

Precipitation Potential: Most of the period is expected to remain
dry, especially for KOMA & KLNK. Scattered storms are possible to
develop around 3-6z around KOFK with occasionally short bursts of
trailing showers and storms lasting as late as 10-13z. It is
uncertain how far south these storms will develop, though the best
window for KOMA would fall around 5-6z (30% chance). These storms
are not anticipated to become severe. A brief period of gusty
southwest winds up to around 30kts would be the primary hazard to
accompany any storm.

LLWS/Winds: Light winds are in the process of becoming easterly
today and southeasterly overnight tonight. Directions Friday morning
will later turn south. Speeds will gradually increase today and
tonight as pressure falls just east of the area. Speeds will for the
most part hover near 10kts today and tonight with gusts picking up
late tonight into Friday morning (as high as 20-25kt gusts). LLWS is
possible to break into the KOFK/KLNK area between 13-15z Friday
morning as the low-level jet peaks, though the latest shear profiles
appears to be more on the marginal side than certain for now (25-
35kts)

&&

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

&&

$$

DISCUSSION...Castillo
AVIATION...GID