246
FXUS63 KOAX 102339
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
639 PM CDT Thu Jul 10 2025

.KEY MESSAGES...

- Strong to severe storms expected this evening, with greatest
  potential for northeast Nebraska & west-central Iowa. All
  hazards possible, with damaging winds and flash flooding as
  the biggest concerns.

- Severe storms remain possible on Friday afternoon and evening,
  too, but lower chance (level 1 out of 5 risk from SPC).
  Primary hazards damaging winds and hail.

- Temperatures cool slightly on Saturday before warming up
  Sunday through Tuesday. Active weather returns next week.

&&

.DISCUSSION...
Issued at 137 PM CDT Thu Jul 10 2025

A line of storms is slowly drifting northeast this morning,
which the Convective Allowing Models (CAMs) haven`t had the best
handle on. Satellite and the 500-mb RAP Analysis show two
distinct shortwaves approaching the area, one from the northwest
over central South Dakota and the second from the west over the
triple-point of Nebraska, Kansas, and Colorado. These two are
forecast to merge later today, merging a couple of convective
complexes into a line of storms which will move across our area.
The preceding environment is fairly juicy with CAPE forecast to
increase from 1500-3000 J/kg over the next few hours. Shear is
looking strong as well, with 30-40kts of 0-3km bulk shear which
will help organize storms into a strong line that should remain
balance heightening potential for damaging winds, especially
across northeast Nebraska. Low-level shear vectors will also
become more orthogonal to the line with time, which could lead
to some potential for brief tornadoes. One hindering factor
could be LCL heights which will be on the higher side. Areas
along and south of the Platte River should see cloud bases stay
above 2000-3000 ft which significantly lowers the tornado
potential. Areas in northeast Nebraska, though, will have lower
LCLs, which is why the better tornado potential (5% from SPC) is
highlighting this area.

Now for timing and evolution of storms. Since the line has
lifted north to near the state line, we expect discrete cells to
start to initiate in the Oneill, Knox County, Antelope County
region around 3-4 PM. At the same time, storms will start to
initiate in east-central Nebraska around Merrick, Nance, Boone,
and Platte counties associated with the southern shortwave.
These two areas of cells will merge, becoming a single complex
of storms by around 7 PM this evening, with a strong cold pool
forecast to develop behind the northern portion of the line. The
best chance for severe weather, again, will be across northeast
Nebraska, but potential for damaging winds and hail will be
possible across all of eastern Nebraska and southwest Iowa as
the line moves through. The line of storms will be approaching
Lincoln around 9-10 PM, and move into the Omaha metro around
10-11 PM. The severe threat should be wrapping up by around
midnight as the front line of storms moves east into central
Iowa.

Once the front line moves through, the concern shifts to heavy
rain and flooding as PWATs are in the 1.5-2 inch range, and we
see potential for a second surge of storms associated with a
third shortwave trek along a remnant boundary near the Platte
River. With this we likely will see some training storms over
areas already saturated from earlier rainfall. Overall, we`ll
likely see a broad swath of rain overnight of 1-1.5 inches, with
localized areas seeing 5+ inches. With significant potential
for flash flooding across the region along and north of the
Platte River, we went ahead and issued a Flash Flood Watch for
much of northeast Nebraska and west-central Iowa through 7 AM
tomorrow morning.

Showers should be exiting the area towards daybreak on Friday,
with rain chances dropping to around 20-30%, mainly for
southeast Nebraska and southwest Iowa for the rest of Friday
morning. Rain will clear first from northeast Nebraska with some
potential for fog development after midnight, hanging around
through mid-morning on Friday. The Storm Prediction Center has
shifted the Slight Risk that was over southeast Nebraska and
southwest Iowa for Friday afternoon east and out of our area,
but we still will have a marginal (level 1 out of 5) risk as
storms could redevelop along the remnant boundary Friday
afternoon. We also have the upper-level trough moving in Friday
evening, ramping up potential for additional showers and storms
across northeast Nebraska and west-central Iowa Friday evening.
With these systems, shear will be much weaker so the possibility
for storms to organize themselves and become severe is lower.
Despite the lower severe potential, saturated ground and
rivers/creeks running high will lead to another chance for flash
flooding Friday night.

Over the weekend, the pattern dries out giving us a break from
storms and allowing water to drain into our bigger rivers.
Depending on just how much rain we get over the next couple of
days, we could see main-stem rivers approach or rise over flood
stage. Weather-wise, temperatures should be cooler on Saturday
with highs in the low 80s. The upper-level ridge starts to push
back inland Sunday into early next week, bringing back warmer
temperatures starting Sunday and we`ll see the return of an
active northwesterly flow pattern next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 639 PM CDT Thu Jul 10 2025

Storms are moving across northeast Nebraska this evening as we
are developing a large complex of storms stretching back to
Grand Island. These storms will move southeast over the next 06
hours bringing storms to KOMA and KLNK with a burst of strong
winds expected as they arrive at the terminals. Showers and
storms will linger overnight leading to variable winds at times
from outflow out of nearby storms, but generally winds should
stay predominantly out of the east or southeast into Friday
morning. Showers should move out by 10Z or so, with winds
shifting to northerly during the day on Friday as a weak surface
low moves through. We could potentially see additional showers
and storms develop as this moves through, with a 30% chance of
rain through the morning, and a better chance (40-50%) of more
storms Friday afternoon. For now leaving these out of the TAFs
as timing and location of storms is still being determined.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flood Watch through Friday morning for NEZ012-015-017-018-
     031>034-042>045-050>053.
IA...Flood Watch through Friday morning for IAZ043-055-056-069.

&&

$$

DISCUSSION...McCoy
AVIATION...McCoy