098
FXUS63 KOAX 250859
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
359 AM CDT Tue Jun 25 2024

.KEY MESSAGES...

- Flooding is expected to continue along the Missouri River this
  week. See the Hydrology section for more details.

- Hot temperatures are expected to continue tomorrow, with a
  heat advisory in effect for heat indices as high as 106
  degrees.

- Scattered strong to severe thunderstorms will be possible
  (40-60 percent chance) this afternoon and evening with primary
  threats being large hail and damaging winds. A low tornado
  threat exists as well.

- Scattered thunderstorms will return to the region Thursday
  night into Friday. Some locations may see up to an inch of
  additional rain heading into next weekend. A few storms may be
  strong to severe.

&&

.DISCUSSION...
Issued at 356 AM CDT Tue Jun 25 2024

Isolated to widely scattered storms surround our area but we`ve
remained dry so far this morning. We could see the showers in north-
central Nebraska spread eastward this morning leading to isolated
storm chances in northeast Nebraska through 7 AM. More than likely,
though, nothing will develop enough for accumulating rainfall to
reach the ground. Temperatures stay very warm this morning, in the
low-to-mid 80s as of 2:30 AM.
Humidity is helping to keep temperatures up, which may keep morning
lows up in the mid 70s across most of our area.

Today will be another hot one, but a weak, stalled cold front across
the northern half of our area will help keep temperatures and
humidity lower across northeast Nebraska, while southeast
Nebraska and southwest Iowa see heat indices get back up to 100
to 106 this afternoon. This boundary will act as a focus as a
shortwave moving across the boundary will trigger storm
development late this afternoon/early this evening. There is
quite a bit of uncertainty in where this weak boundary will be
by this evening, with some CAMs lifting it north focusing storm
development along the Nebraska/South Dakota border, while others
drop the boundary south to the Kansas border by 00Z, which
would focus storm potential across southeast Nebraska and
southwest Iowa. Half the CAMs keep storms east of our area
completely. The National Blend of Models keeps storm chances
down around 30 to 40 percent this afternoon, likely due to this
spread in the models. In any case, instability across the region
will be plenty sufficient with SBCAPE values around 3500-5000
J/kg. Shear will be maximized along this boundary which will
likely see isolated supercells develop along it initially. Lack
of any cap will likely lead to the development of convective
clusters fairly quickly off of outflow boundaries from the
initial storms. Primary threats with these initial storms will
be damaging winds, large hail up to baseball-size, as well as a
low tornado threat. As the convective clusters get established,
expect a cold-pool to develop transitioning these storms into
more linear clusters with bowing segments with more of a
damaging wind threat. The bigger MCS does look like it should
come together east of our area, impacting more of central Iowa
down into northeast Missouri and western Illinois. We are mainly
concerned with the potential across our area which covers the
early stages of this system`s development. Any storms that do
develop across our area should move off to the south or east by
midnight tonight, and our severe threat will be over.

Wednesday - Friday:

Wednesday will be milder and very pleasant with dry, northerly flow
across our area. Highs will only be in the mid 80s with humidity
dropping to around 40 percent during the afternoon.
We`ll see the return of the low-level jet Wednesday night shifting
flow back to southerly out ahead of our next shortwave which will
likely bring more numerous showers and storms to our area during the
day on Thursday into Thursday night. Colorado State Machine Learning
Algorithm highlights potential for severe weather Thursday evening -
night across our area, so this is definitely a period to watch. A
moderately strong cold front and strong low-level jet ahead of it
definitely looks like the potential is there. Low shower and storm
chances linger into Friday, though right now models show the better
axis of moisture dropping south of our area with the cold front late
Thursday/early Friday. Temperatures on Friday will depend on timing
of the frontal boundary and if it drops completely south of our
area, but right now we see temperatures get back up into the 90s
across southeast Nebraska and southwest Iowa and stay down in the
mid 80s to the north.

Saturday - Monday:

Confidence in forecast details drops off over the weekend, though
the general pattern shows a dampening of the upper-level ridge as a
broad surface high drops south out of Canada down into the Northern
Plains. This appears likely to bring temperatures down, with
ensembles putting the forecast highs in the upper 70s to low 80s
Saturday and Sunday. Depending on how far south this surface high
gets, we could stay mostly dry over the weekend, but we keep low
precip chances as some models do show the potential for an overnight
MCS Saturday night with showers lingering into Sunday. While we
remain cooler, the upper-level ridge builds back up to our west over
the weekend and will bring back hotter weather and storm chances
going into early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1129 PM CDT Mon Jun 24 2024

VFR conditions through the period. There could be LLWS at KOMA
through about 09z with winds at 1500 feet from the southwest at
40 knots. Any convection across north central NE will fall apart
before reaching any TAF sites this morning. And while there will
be chances for thunderstorms after 00z, but way too far out to
predict with any certainty with this forecast cycle.

&&

.HYDROLOGY...
Issued at 356 AM CDT Tue Jun 25 2024

River flooding remains expected along the Missouri River, with
crests expected Wednesday - Friday night. We`re concerned about
the potential for backwater flooding near the area where the
Platte flows into the Missouri as well as in other areas where
creeks and streams flow into the Missouri. Backwater flooding
could lead to problems around highway 75 north of Plattsmouth.
We`ll also want to watch the following gauges for potential
backwater issues: Papillion Creek at harlan Lewis Road near La
Platte and Offutt Ditch (Bellevue Drain) near Offutt AFB. We`re
not sure when these issues may start, but the best chance will
probably be around the Missouri River Crest at Omaha Wednesday
night into Thursday. No additional updates likely until the next
forecasts for the Missouri are released later this morning.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory from 1 PM this afternoon to 7 PM CDT this
     evening for NEZ051>053-066>068-088>093.
IA...Heat Advisory from 1 PM this afternoon to 7 PM CDT this
     evening for IAZ069-079-080-090-091.

&&

$$

DISCUSSION...McCoy
AVIATION...DeWald