183
FXUS63 KOAX 080007
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
Issued by National Weather Service St Louis MO
707 PM CDT Fri Jun 7 2024

.KEY MESSAGES...

- Severe thunderstorms will develop (95% chance) in northern
  Nebraska by mid to late afternoon, and move across parts of
  eastern Nebraska and southwest Iowa through late tonight.

- The strongest storms may produce areas of significant damaging
  wind and hail, flash flooding, and a lesser-but-non- zero
  chance for a tornado. The greatest potential for significant
  severe weather is southwest of a line from Oneill to Columbus
  to Syracuse to Nebraska City.

- There is another chance for showers or a storm late Saturday,
  and another low (20-30%) chance for storms on Monday night
  into Tuesday.

- The large scale weather pattern becomes increasingly
  favorable for a few rounds of strong to severe storms late
  next week into the weekend.

&&

.DISCUSSION...
Issued at 248 PM CDT Fri Jun 7 2024

Skies are partly cloudy this afternoon with a weak boundary
bisecting the northern and southern half of our area around the
Platte River. There is greater cloud cover north of the boundary
and winds are more easterly, while south of the boundary winds
are generally out of the south or southeast and skies are more
clear.

We`re watching an upper-level shortwave currently visible in
water vapor imagery over western South Dakota, approaching our
are. We`re already seeing storms out near Valentine associated
with this wave and expect additional development around and
ahead of these storms over the next few hours. CAPE values in
north-central Nebraska with these storms are estimated to be
around 2500+ J/kg with effective bulk shear around 50+ kt. Low-
level shear (0-1 km) is less impressive, only around 11-12 kt.
These environmental parameters indicate a significant hail and
wind threat initially with a lesser tornado threat. CAMs show
these storms continuing to develop and move along the stationary
boundary southeastward toward Ord, Grand Island, and possibly as
far east as Columbus. Trends have taken the strongest of the
storms farther west, hopefully taking them out of northeast
Nebraska completely. Southeast Nebraska isn`t looking as lucky
with the eastern extent of the corridor of strong storms moving
through Lincoln to Peru, NE.

As storms start to move into southeast Nebraska, they will tap
into an incredibly moist air mass with PWAT values possibly
approaching 1.9 inches, which would be a record for June 7th if
true. This will make these storms very efficient rain producers,
despite the speed of the storms, so they could very well put
down a very quick 1-2 inches of rainfall, and if they stall at
all, expect flash flooding to quickly become a concern. The
speed of this system is really our only saving grace here as far
as flash flooding potential.

The storms should be out of our area by 1-2 AM tonight, with
the cold front moving through actually a few hours later. We
could see some low clouds spread across the area Saturday
morning which will hang around until early afternoon. This will
keep temperatures cooler on Saturday with afternoon highs only
in the mid 70s across much of our area.

Another shortwave will bring low chances for storms to far
southeast Nebraska overnight Saturday night, but better chances
will be south of our area. Temperatures will stay mild on Sunday
and Monday with highs in the upper 70s to low 80s and mostly
sunny skies.

Our next widespread chance for showers and storms will be Monday
night as we see the breakdown of the upper-level ridge over the
Inter-Mountain West with a strong trough passing to our north.
The upper-air pattern flips toward the end of the week with a
high likelihood of a large-scale trough building into the
western CONUS and a series of short wave troughs ejecting into
the Plains. Boundary layer moisture will increase and this is a
favorable setup for increasing potential for rounds of severe
weather by next weekend into the following week. Most model
guidance keeps the heart of the jet stream north of the local
area, but embedded waves of enhanced mid/upper winds will drive
severe potential. There is plenty of time to watch this unfold,
but certainly appears to be a signal for an active weather
period.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 654 PM CDT Fri Jun 7 2024

The primary concern will at least initially be strong to severe
thunderstorms moving southeast out of central Nebraska into
south-central and southeast Nebraska this evening. Additional
thunderstorms extend along a warm front over southeast section
of Nebraska, where much of the convection will tend to track
through this evening. The strongest cells will include hail,
strong winds potentially over 60 mph, and visibility reductions
below 1SM with any direct impact. Any direct impact will be best
handled and timed out by later amendments/tempo groups, but much
of the support for higher impact convection skim along and
southwest of KLNK.

Thunderstorms move southeast and exit the region 05-07z. Light
and variable surface flow is expected through a majority of the
06z-12z timeframe. Guidance is leaning more pessimistic into IFR
cigs, but held with low end MVFR for now. Should trends
continue, IFR may be warranted along and just behind the cold
front in the 09z-15z window. Improvement is expected with VFR
returning from mid to late morning Saturday.

&&

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

&&

$$

DISCUSSION...
AVIATION...00