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000
FXUS63 KOAX 141058
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
558 AM CDT Sun Apr 14 2024

.KEY MESSAGES...

- Well above average temperatures across the region today and
  tomorrow with highs in the mid to upper 80s (highest temps
  expected in southeast Nebraska and far southwest Iowa).

- Strong storm system will bring the potential (15-25% chance)
  for severe weather Monday night into Tuesday. Isolated
  instances of flash flooding will also be possible.

- Cold front will bring below average temperatures by the end of
  the work week, with highs in the low to mid 50s.

&&

.DISCUSSION...
Issued at 230 AM CDT Sun Apr 14 2024

     Today and Tonight...

Upper level ridging and an associated surface high pressure will
continue to bring dry conditions and well above average
temperatures to the region this afternoon. High temperatures are
expected to be in the mid to upper 80s, with a few low 90s
possible, especially in far southeast Nebraska.

     Tomorrow through Tuesday Night...

An incoming storm system will bring several chances for rain and
thunderstorms across the region tomorrow evening into Tuesday
night. A few of these storms may be strong to severe,
particularly Monday night and Tuesday afternoon.

An upper-level trough currently positioned over the Pacific
coast is expected to eject out into the Great Plains tomorrow
night. Ahead of this disturbance, strong surface cyclogenesis is
expected to develop a surface low in the central High Plains
tomorrow afternoon. GEFS and ECMWF Ens still have some spread on
the exact track of the surface low, but are generally in
consensus with the low tracking through southern Nebraska late
tomorrow night into Tuesday, and in eastern Nebraska/western
Iowa by tomorrow evening. Ahead of this low pressure, south-
southeasterly winds will transport moisture from further south
into the region, bringing dew points into the upper 50s and low
60s. This will result in MUCAPE ranging from 1000-2000 J/kg
tomorrow and Tuesday afternoon/evening. Along the north side of
this airmass, a warm front will extend from south-central South
Dakota into south-central Iowa.

Despite some instability and forcing for ascent associated with
PVA and height falls overspreading the central Plains, there
are several details that provide uncertainty to this forecast
and may ultimately limit storm coverage and strength,
particularly tomorrow evening and night. Forecast soundings
resolve an EML over the region associated with south-
southwesterly mid-level flow off the Rockies. This will help
reinforce the capping inversion at the top of the boundary
layer, even during peak diurnal heating tomorrow. Tomorrow
evening, model guidance also suggests the jet max will still be
rounding the base of the trough in New Mexico/west Texas, keeping
the most favorable shear well to the southwest of the area.
There is some signal for a weak short wave to propagate across
the Plains ahead of the main upper-level feature, but will
likely not be strong enough to produce widespread convection.
With that being said, the most likely scenario from tomorrow
evening into the early overnight hours will be for a chance
(25-35%) of isolated shower/thunderstorms to develop along the
warm front (which will likely stretch from northeast Nebraska
into southwest Iowa). Any convection that is able to develop
despite the capping inversion will likely be unorganized at
first due to the weak shear that is expected across the area,
but may strengthen if it persists through the night with the
approach of the main disturbance from the west.

Further southwest, strong to potentially severe thunderstorms
are expected to develop along a dryline in the southern Plains.
After midnight tomorrow night, these storms are expected to
approach the area from the southwest. By the time these storms
arrive, a more favorable dynamic environment will be in place,
with short range model guidance suggesting bulk shear ranging
from 20-35 knots as the associated upper-level disturbance
shifts into the central High Plains. Nighttime thermodynamics
will offset this somewhat with radiative cooling of the
nocturnal boundary layer limiting the potential for strong
surface based convection. Nonetheless, scattered thunderstorms
(70-90% chance of rain) should become widespread by Tuesday
morning, with a few strong to severe storms possible (15-25%
chance). Hail will be the biggest threat Monday night,
especially with relatively low freezing levels near 3 km.
However a severe wind gust cannot be ruled out. There is also
some uncertainty with regards to how fast this storm system will
move out into the Plains and how early convection will initiate
along the dry line in the High Plains. If storms are able to
develop into the region earlier than model consensus, a tornado
or two cannot be ruled out.

Scattered thunderstorms are expected to remain across the region
Tuesday as the surface low traverses the region. Diurnal
heating Tuesday afternoon will bring another chance for a round
of strong to severe thunderstorms (70-90% chance of rain, 15-25%
chance of severe storms), especially east of the Missouri
River. Though temperatures will be cooler on Tuesday, steeper
lapse rates will help keep some instability in the region to
sustain stronger updrafts. All modes of severe weather will be
possible, though large hail appears to be the greatest threat at
this time. The tornado threat will be slightly higher Tuesday
afternoon than it will be tomorrow night due to enhanced
surface vorticity associated with the surface low pressure that
will track across the region.

Tuesday night, a cold front will push through the region from
northwest to southeast with scattered showers lingering into
early Wednesday morning (40-60% chance of rain).

     Wednesday through Saturday...

Much cooler temperatures are expected by the middle of the work
week, with highs in the 60s on Wednesday. Another cold front
will move through the region Thursday afternoon bringing
temperatures down even more, with highs Thursday through the end
of the forecast period in the 50s. Ahead of the Thursday cold
front, scattered showers (30-50% chance of rain) are expected
to develop out west and move east across the region Thursday
morning into the early afternoon hours.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 557 AM CDT Sun Apr 14 2024

VFR conditions will persist through the period. Winds are
shifting to the north this morning and will gust to 20 kt
through midday. Expect winds to continue to shift towards
northeasterly this afternoon, then easterly toward the end of
the TAF period.

&&

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

&&

$$

DISCUSSION...Darrah
AVIATION...McCoy