887
FXUS63 KOAX 152328
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
628 PM CDT Mon Jul 15 2024

.KEY MESSAGES...

- Dangerous heat continues this afternoon, with heat index
  readings of 100 to 110+ degrees.

- 20-40% chance of storms this afternoon and evening, with a 5
  to 15% chance of severe storms. Highest chances near and east
  of the Missouri River through 9 PM. Primary threats are
  damaging winds and hail.

- Additional strong to severe storms possible Tuesday afternoon
  and evening, especially in northeast Nebraska (30-50% chance
  of storms, 10-20% chance of severe storms). Questions remain
  on exact timing, but hail and damaging winds are the primary
  threats.

- An extended stretch of cooler-than-average temperatures will
  carry us into the weekend, with chances for widespread rain
  increasing into next week.

&&

.DISCUSSION...
Issued at 304 PM CDT Mon Jul 15 2024

Early afternoon analysis showed a surface trough pushing
southeast through roughly the Omaha and Lincoln areas as of 3
PM with a surface cold front lagging behind in northeast NE. As
the front continues to push southeast, expect some storm
development along it, especially as you go east into IA where
the primary shortwave energy will be tracking. Farther west and
in our forecast area, things are a little more uncertain, with
less influence from the aforementioned shortwave meaning we`ll
largely have to rely on daytime heating and the relatively weak
convergence along the front. In addition, model soundings do
reveal a cap that will need to be overcome, but latest RAP
soundings continue to indicate it largely erodes just as the
front pushes into the Omaha area. If this pans out, expect at
least one or two spotty storms along the front possibly
extending into eastern NE. And while most CAMs suggest
everything remains east, they tend to struggle in the more
weakly forced environments like we`ll see, so tend to think
something like the 15.12Z NAM 3km will be close to what we see.
If something does go, there will be plenty of instability to
work with, with HREF mean MUCAPE in the 4000 to 5000 J/kg range.
Combined with deep layer shear around 30-40 kts, there would be
potential for organized severe weather. The main threats would
be damaging winds and large hail with weak low level shear
limiting the tornado threat. That said, can`t completely rule
out a brief spinup tornado with a boundary in the area. So
bottom line, there`s about a 20-40% chance we see a storm or two
in our area, with a 5-15% chance of severe weather. Highest
chances will be within a county`s width of the Omaha metro and
points south and east in roughly the 4 PM to 9 PM window.

Heading into Tuesday, we`ll finally see relief from the heat as
the front will have pushed well to our south. Still expect
highs in the mid to upper 80s, but it won`t be anywhere near the
triple digit heat indices we saw in previous days. Latest short
term guidance has also trended up a tick in severe weather
potential for Tuesday afternoon/evening as another surface
boundary pushes south through the area. Ahead of the front,
guidance suggests a decent, but narrow plume of instability
extends into northeast NE with deep layer shear once again in
the 30-40 kt range in vicinity of the boundary. As a result,
guidance is in fairly good agreement of a line of storms
developing near the NE/SD border, pushing southeast through the
area, and gradually weakening as they run out of instability in
southeast NE. Still some spread on exact timing of the boundary
and just how far southeast the severe weather threat will
extend, but seems like a day where we`d have a hail threat as
storms develop and then transition into a damaging wind threat
as storms congeal into a line.

Beyond Tuesday, expect a rather nice work week under
northwesterly flow aloft as surface high pressure dominates.
Can`t completely rule out a few stray showers at times with some
hints at some weak shortwave energy rippling through the flow
at times, but we should largely be dry through at least Thursday
and possibly much of Friday. The next more widespread storm
chances look to arrive by Friday evening with guidance in pretty
good agreement a surface boundary and stronger shortwave trough
slide into the area as surface high pressure pushes east. These
chances also look to linger off and on through the weekend.
Otherwise, expect high temperatures in the upper 70s to mid 80s
and lows in the upper 50s to mid 60s. Enjoy!

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 625 PM CDT Mon Jul 15 2024

VFR conditions through the period with a northerly wind less
than 12 knots. There is a 20-30% chances for showers/storms at
KOFK 12-15z, but confidence is too low to mention in the actual
forecast at this time. Likewise for KLNK 14-21z. Will refine the
TAFs with later forecasts.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory until 8 PM CDT this evening for NEZ015-033-034-
     042>045-050-065-078-088.
     Excessive Heat Warning until 8 PM CDT this evening for
     NEZ051>053-066>068-089>093.
IA...Heat Advisory until 8 PM CDT this evening for IAZ043-055-056.
     Excessive Heat Warning until 8 PM CDT this evening for IAZ069-
     079-080-090-091.

&&

$$

DISCUSSION...CA
AVIATION...DeWald