938
FXUS63 KOAX 231128
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
628 AM CDT Thu May 23 2024

.KEY MESSAGES...

- A line of strong to severe thunderstorms is expected to move
  through Thursday evening into early Friday (80-90% chance).
  Damaging winds will be the primary threat, but additional
  localized flooding, large hail, and tornadoes will be possible.

- Rivers will remain elevated over the next day or 2, with some
  minor flooding continuing, especially along portions of the
  Missouri River.

- Additional storm chances through Memorial Day weekend,
  especially Saturday evening and Sunday. Severe weather could
  be possible at times, but confidence in exact timing and
  location is low.

&&

.DISCUSSION...
Issued at 142 AM CDT Thu May 23 2024

Short Term (Today through Friday)

The day will start with mostly clear skies as a few low and mid
clouds pass through the area. High temperatures are expected to
reach into the low 80s this afternoon. A few river flooding concerns
remain in the area from previous excessive rainfall, primarily along
the Missouri River. Meanwhile, a shortwave trough traversing the
Northern Rockies is expected to spin up a surface low over western
South Dakota with an associated cold front draped to the south-
southwest. The low will move northeast towards central
Minnesota through the day, dragging the cold front across
Nebraska. This feature will be the primary source for our severe
weather threat this evening into the overnight hours.

Ahead of the front, strong moisture advection is expected to bring
dewpoints in the upper 50s/low 60s into central and eastern
Nebraska. This feature incorporated with steep mid-level lapse rates
will bring a corridor of 2250-3000 J/kg of MLCAPE into southeast
Nebraska. This area is coupled with bulk shear values of 35-45 kts
and an increasingly strong low-level jet into the evening.
Convection initiation is expected in the Sandhills during the early
evening with a few initial supercells before upscale growth
brings a QLCS structure pushing east. The QLCS is expected to
push through the area in the 9 PM to 3 AM timeframe. The primary
hazard will be damaging straight line winds and hail.
Impressive low-level dynamics (30-40 kts of 0-1 km shear)
brings the possibility of a few tornadoes spinning up along the
line.

These factors considers, the Storm Prediction Center has upgraded
portions of southeast Nebraska to an enhanced risk (level 3 out of
5) for severe weather. Given the quick-moving nature of this system,
rainfall totals look to stay in the 0.25-1.00" range. Recently
saturated areas could see minor flooding as a result. Cloud cover
should slowly push out of the area on Friday, bringing dry
conditions and high temperatures into the upper 60s and low 70s.

Long Range (Saturday through Wednesday)

The Memorial Holiday weekend will see high temperatures primarily in
the low 70s. Those with outdoor plans should keep an eye on the
weather as a few showers and storm chances will push through the
area. Saturday looks to stay dry into the late afternoon before an
upper level trough pushes into the region. Storm chances will be
possible Saturday night into Sunday. While the primary severe
weather threat is to our southeast, a few strong to severe
storms may not be ruled out at this point. Trailing rain and
storm chances will continue into much of Sunday (PoPs 40-60%).
An additional shortwave disturbance traversing the northern
Plains could bring additional chances for showers and storms on
Monday. In this extended time frame, the ECMWF is much quicker
to move the upper level trough out of the region than most GEFS
members. The details of this system will have to be ironed out
as it approaches to determine our chances for dry conditions on
Monday. Ridging is expected to build into the Plains during the
mid work week, bringing Tuesday and Wednesday highs into the
upper 70s and low 80s.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 628 AM CDT Thu May 23 2024

VFR conditions will hold through the daytime hours today. A line
of strong storms will move through between 05-09Z tonight
bringing strong winds and MVFR/IFR conditions at least briefly
as the line moves into the terminal. Storms should linger for
1-2 hours before exiting with a return to VFR conditions and
wind shift to northwesterly behind the storms.


&&

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

&&

$$

DISCUSSION...Wood
AVIATION...McCoy