507
FXUS63 KOAX 241111
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
611 AM CDT Mon Jun 24 2024

.KEY MESSAGES...

- Moderate to near Major flood stages are expected along the
  Missouri River from Blair to Rulo this week, rivaling stages
  that were last experienced in 2019.

- Flooding is ongoing along the Platte, Ponca Creek and Clear
  Creek. Flooding is expected to recede along the Ponca and
  Clear Creek later today.

- The hottest temperatures of the year so far are forecasted for
  today, with heat indicies from 106 to 111. The heat may extend
  into Tuesday afternoon across southeast Nebraska.

- Isolated to widely scattered thunderstorms will be possible
  Monday and Tuesday evenings. A Slight Risk for severe weather
  is present both days.

- More widespread chances for rain and thunderstorms return
  Wednesday night through Friday night.

&&

.DISCUSSION...
Issued at 222 AM CDT Mon Jun 24 2024

Short Term (Today and Tomorrow)

Scattered thunderstorm development is currently ongoing across
western Iowa as a weak mid-level disturbance slides across the area.
Weak instability (MLCAPE around 500 J/kg) should keep away any
chance of severe weather with these thunderstorms as they push off
to the east. Upper level ridging across the central CONUS will help
to bring some of the warmest temperatures so far this year across
the area. 850 mb temperatures will be in the mid to upper 20 degree
Celsius range today, bringing a boost to temperatures this
afternoon. High temperatures are expected in the 97 to 104 range.
Dewpoints in the low 70s will bring heat index values in the 106 to
111 range this afternoon. Given the elevated heat related concerns,
a Heat Advisory will go into effect from 1 PM to 8 PM today. Record
high temperatures will be within reach at Lincoln this afternoon
(current record high of 103 set in 1988).

Severe weather potential returns this evening as a weak cold front
pushes into the area. Scattered thunderstorm development is likely
in the late afternoon into the evening. MUCAPE of 2500-4000 J/kg
along with 25 to 35 kts of bulk shear should support a few high
based thunderstorms. A decent CAP is place should keep coverage
scattered to widely scattered. The relatively weak shear in place
should make it difficult for updrafts to remain organized for long.
Therefore, the primary hazards will be a brief period of hail and
strong wind gusts as storms quickly become outflow dominant. SPC has
much of the area in a slight risk (level 2 out of 5) for severe
weather this evening.

Much of the area will continue to experience above average
temperatures on Tuesday. However, a cold front orientated from the
northeast to the southwest will push to the southeast from South
Dakota through Tuesday. This will limit high temperatures near 90 by
the NE/SD border with highs increasing near 100 as you approach the
NE/KS border. With dewpoints still lingering around 70 degrees, heat
index values in the 100 to 105 range will be possible south of
Interstate 80. A Heat Advisory has been issued for our southern
counties on Tuesday afternoon (1 PM to 7 PM).

Another round of severe weather is possible late Tuesday afternoon
into the evening as scattered thunderstorm development is likely
along the aforementioned cold front. Plentiful instability will be
present ahead of the front (MLCAPE of 2500-4000 J/kg) with marginal
bulk shear (30-35 kts). A brief period of isolated storm development
is possible before upscale growth takes over. Primary hazards will
include strong winds and hail although a brief tornado can`t be
ruled out. SPC has placed a slight risk (level 2 out of 5) for
severe weather into eastern NE and western IA. Additional
flooding concerns remain low as the bulk of the QPF associated
with this event remains south of Interstate 80 with values
approaching 0.25" near the NE/MO border.

Long Term (Wednesday through Sunday)

Wednesday remains the only day this work week without precipitation
chances. Northwesterly flow returns to the area, bringing high
temperatures down into the 80s into Thursday. An upper level low
tracking across southern Alberta/Saskatchewan will push multiple
disturbances into the central and northern Plains towards the end of
the work week. A prolonged period of PoPs greater than 30 percent
enters the area Thursday afternoon and continues into the weekend.
The best chance for severe weather will be Friday afternoon/evening
as a cold front pushes through the area. CSU Machine Learning
highlights much of eastern NE/western IA for severe weather
potential on Friday. Flooding concerns will need to be monitored as
an extended period of rainfall is possible over an already sensitive
area. WPC has places a slight risk for excessive rainfall over
northeast NE and northwest IA on Thursday. Widespread PoPs of 30 to
50 percent continue into Saturday morning.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 604 AM CDT Mon Jun 24 2024

VFR conditions expected through the TAF period. Winds will be
out of the south today with wind shear this morning ending
around 15Z. A weak front moving through this evening could lead
to a few thunderstorms developing this evening between 23Z-03Z
which could impact the terminals. Chance of storms impacting
terminals stays down around 20-30 percent. Winds will weaken
again this evening and shift to southwesterly.

&&

.HYDROLOGY...
Issued at 105 PM CDT Sun Jun 23 2024

A number of forecast changes occurred for the Missouri, Platte
and Little Sioux Rivers during the morning round of updates.
Water flow from Missouri River tributaries down stream of Gavins
Point dam remain in major flood, with minor impacts beginning
along the Missouri River between Sioux City and Decatur. Minor
to moderate flooding is expected to occur along the Missouri
between today and next weekend, with a 5-25% chance of flood
levels reaching major stages downstream of Plattsmouth due to
additional water flow from the Platte River. The Platte
currently is flooding between Leshara and Ashland, with minor
flooding expected from Louisville to the confluence with the
Missouri tonight into early Monday. Minor to moderate flooding
is anticipated along the Little Sioux River Monday and Tuesday,
with historic crest levels being reached in northwest Iowa. Flooding
is abating along Ponca Creek to its confluence with the
Missouri in Knox County.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for NEZ011-012-015>018-030>034-042>045-050>053-
     065>068-078-088>093.
     Heat Advisory from 1 PM to 7 PM CDT Tuesday for NEZ068-088>093.
IA...Heat Advisory from 1 PM this afternoon to 8 PM CDT this
     evening for IAZ043-055-056-069-079-080-090-091.
     Heat Advisory from 1 PM to 7 PM CDT Tuesday for IAZ090-091.

&&

$$

DISCUSSION...Wood
AVIATION...McCoy
HYDROLOGY...Fortin