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362
FXUS63 KOAX 162328
AFDOAX

Area Forecast Discussion
National Weather Service Omaha/Valley NE
628 PM CDT Sun Jun 16 2024

.KEY MESSAGES...

- Hot temperatures expected today with afternoon highs in the
  middle 90s and afternoon heat index values of 98 to 103.

- Storm chances remains in the forecast tonight through Monday for
  northeast Nebraska. Severe storms will be possible, along
  with locally heavy rainfall.

- Hot temperatures continue Monday with highs in the lower 90s
  and afternoon heat index values of 95 to 98.

- Strong and possibly severe thunderstorms are expected Tuesday
  into Wednesday, along with locally heavy and possible flooding
  rains. Rain chances continue every day Thursday through Saturday.

&&

.DISCUSSION...
Issued at 251 PM CDT Sun Jun 16 2024

Short Term (Today and Tomorrow)

Temperatures today have reached their highest yet this year for much
of the area. Heat index values are expected to peak in the 98 to
103 range this afternoon. Breezy southerly winds will help to
bring some relief yet plenty of sunshine this afternoon will
bring elevated heat concerns. Severe weather potential returns
this evening with a slight risk (level 2 out of 5) from the SPC
in our northwestern counties. A surface low located in northeast
SD is draping a trailing cold front oriented from the north to
the southwest across northeast NE. This front will be the source
of convective initiation this evening, likely in the 7 to 10 PM
timeframe. CAM guidance continues to show a varying solution in
coverage this evening with the highest confidence in convection
north of Interstate 80.

Plentiful moistures and afternoon destabilization is expected to
bring a corridor of 2500 to 4000 J/kg of MUCAPE into eastern NE.
Modest 0-6 km bulk shear (approx. 30 kts) will be aided by a 45-55
kt LLJ this evening to produce elevated convection before upscale
growth takes over. Steep mid level lapse rates will bring the
potential for large hail with any of the stronger updrafts. Damaging
winds will be an additional concern along with the potential for a
brief tornado or two.

The front will slowly push to the southeast overnight before slowing
retreating northward as a warm front Monday morning. This will bring
a prolonged period of potential storms and rainfall. A Flood
Watch will go into effect for portions of northeast NE this
evening and persist into early Monday. Yesterdays heavy rainfall
(3 to 5 inches) in this area has led to saturated soils. The
area is also reflected by an enhanced swatch of QPF and
increased confidence in the potential for convection this
evening. Localized flash flooding concerns will be of interest
this evening if additional rainfall is received. WPC has much of
this area in a slight risk (level 2 out of 4) for excessive
rainfall. A marginal risk (level 1 out of 5) for severe weather
will also continue for areas north of Interstate 80 into Monday
morning before PoPs begin to recede during the early afternoon.
Highs will likely stay in the upper 80s/low 90s Monday with
strong southerly winds (gusts up to 35 mph) through much of the
afternoon. Heat index values top out in the 95 to 98 range while
a major HeatRisk (level 3 out of 4) category is present for
areas lacking the cloud cover and precipitation.

Long Term (Tuesday through Saturday)

High temperatures will take a small step down on Tuesday with the
upper 80s and low 90s expected. Tuesday afternoon and evening will
bring another chance for strong to severe storms. A cold front
draping across much of the northern and central Plains will be
oriented from northeast NE down through south central NE before
pushing southeast later in the day. Convection is expected to
develop along the front during the late afternoon. A linear
storm mode is likely across much of the area with damaging
winds and some hail the primary hazards. The front is expected
to stall in southeast NE and southwest IA, bringing an extended
period of overnight rainfall. WPC has placed much of the CWA in
a slight risk (level 2 out of 4) for excessive rainfall on
Tuesday. PoPs remain in the 60 to 90 percent range for much of
this period. Localized flash flooding concerns will be present
for this event as multiple rounds of rainfall are met with PWAT
values of 1.5 to 2" across much of the area.

Rainfall will continue into Wednesday before the aforementioned
front transitions into a warm front and begins its push to the
northwest. Thunderstorms along with a potential risk for severe
weather will be present along this front Wednesday evening with the
exact location yet to be ironed out. On the bright side, high
temperatures will dip down into the 70s for much of the area on
Wednesday. A marginal risk (level 1 out of 4) for excessive rainfall
is present on Wednesday while PoPs remain in the 50 to 80 percent
range.

PoPs begin to taper off Wednesday into Thursday (20 to 30 percent)
as the front makes its way into SD. In return, high temperatures
will work their way back into the 80s and low 90s. More
uncertainty enters the forecast by the end of the work week with
additional rainfall and convection chances remaining nearby.
Long range guidance keeps the front in the NE/SD vicinity with
some GEFS ensemble members pushing the front back into northeast
NE with daily chances of convection. As of now, the best
chances for convection remain north of Interstate 80, yet there
are still details to iron out as it approaches. High
temperatures will also depend on the placement of this front
with 90s expected to the south of it and slightly reduced
temperatures behind the front.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
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Issued at 613 PM CDT Sun Jun 16 2024

Isolated thunderstorms are expected to develop and track
northeast across northeast Nebraska (KOFK). As such, have put in
a TEMPO group to highlight the timeframe that is most likely to
see lightning at the KOFK terminal. There is a low but non-zero
chance of storms further south towards the I-80 corridor (KLNK
and KOMA), however probabilities are too low to include in TAFs
at this time. Tonight between 06Z and 12Z, LLWS is expected to
be in place across southeast Nebraska and western Iowa (KLNK and
KOMA). Shear magnitudes will range from 35 to 40 knots in the
lowest 2 kft. Otherwise, gusty southerly winds will develop and
prevail at all TAF sites tomorrow after 12Z, with the strongest
winds between 17Z and the end of the TAF period. Wind gusts up
to 30 knots will be possible.
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&&

.OAX WATCHES/WARNINGS/ADVISORIES...
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NE...Flood Watch through Monday morning for NEZ015-017-018-031>033.
IA...None.
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&&

$$

DISCUSSION...Wood
AVIATION...Darrah