-- Discussion containing changed information from previous version are highlighted. --
038
FXUS63 KLBF 161121
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
621 AM CDT Sun Jun 16 2024

.KEY MESSAGES...

- Isolated thunderstorms late today may produce large hail and
  damaging winds mainly along and south of I-80.

- Thunderstorms become more widespread tonight mainly along and
  north of I-80 with a primary threat for large hail and locally
  heavy rainfall, though there is potential for some isolated
  wind damage as well.

- Potential for another round of thunderstorms with large hail
  and damaging winds late Monday, primarily east of Hwy 61. An
  isolated tornado is also possible mainly near the Hwy 20
  corridor.

- The pattern remains active with daily chances for showers and
  strong to severe thunderstorms with locally heavy rainfall
  through next week.

- Very warm conditions persist south of Highway 2 for the next
  couple of days, but cooler temperatures will slowly push down
  from the north through the middle of next week.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 430 AM CDT Sun Jun 16 2024

Showers with a few rumbles of thunder associated with a weak
front are exiting the region to the east early this morning.
However the front will stall out just to our south, then build
back northward to near the I-80 corridor by late this afternoon
with a dry line extending down to the south as low pressure
starts to develop to the lee of the Rockies across Colorado.
Instability is expected to be considerable as CAPE values at or
above 3000J/kg pool along the boundary, along with equally
impressive 0-6 bulk shear values of 40 to 50kt. However Bufkit
model soundings continue to indicate the presence of a cap and
mesoscale guidance indicates the cap will be effective at
suppressing convective initiation. While confidence in defeating
the cap is not high, forcing along the triple point of the dry
line and frontal boundary may be strong enough to trigger a
couple of isolated cells across southwest Nebraska that will
grow upscale as they slide eastward along the frontal boundary
with potential to produce large hail and damaging winds. An
isolated tornado is also possible with any isolated cells that
manage to overcome the cap along the frontal boundary. Worth
restating that any severe threat late today is contingent on
enough forcing to overcome the cap, so this will be monitored
closely this afternoon.

As we transition to tonight the story starts to change as a low
level jet starts to develop and nose up into the region. Mid
level forcing will become quite robust with a good amount of
FGEN, deformation, and isentropic lift combined with elevated
instability advertised on Bufkit to be approaching 3500J/kg.
Expect thunderstorms will blossom after dark mainly north of
I-80 and grow upscale as they move east/northeastward. Guidance
is not overly consistent in depicting where these elevated storms
will track, but given the large hail potential of this environment
will be fine tuning the timing/location as later guidance
becomes available. Additionally, with precipitable water values
approaching the 90th percentile locally heavy rainfall and
potentially some flash flooding will be a concern especially
near and north of the Hwy 20 corridor. The severe threat will
start to wane in the wee hours of Monday morning as the most
vigorous storms push out of the area, though showers and
thunderstorms will linger past daybreak Monday especially along
and north of Hwy 2.

With the upper trof remaining upstream and continuing low
pressure to the lee of the Rockies, the convective environment
will remain robust. Instability will recharge as the low level
wind field amplifies considerably Monday afternoon with very
blustery conditions accompanying the arrival of mean CAPE values
at or above 3500J/kg by late in the afternoon while 0-6km shear
remains robust at 40 to 50kt. The dry line will offer assistance
to overcome the cap late in the day with potential to trigger
thunderstorms with large hail and damaging winds across the
southern panhandle and southwest Nebraska that may grow upscale
as they move east/northeast into Monday evening, and an
isolated tornado is also possible. Later Monday night as the
upper trof approaches from the northwest, a cold front will
start to push into the region and sweep the convection eastward
into Tuesday morning.

With the front across the region, temperatures today will range
from the middle 90s south of I-80 to the upper 70s further to
the north, followed by warmer readings Monday with upper 90s
south, upper 70s/lower 80s north. Lows will range from the
middle 50s northwest to upper 60s southeast.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 430 AM CDT Sun Jun 16 2024

Ensemble guidance continues to indicate a high amplitude
eastern ridge/western trof pattern through the early part of
next week, followed by a gradual flattening of the pattern with
a westward retrogression of the ridge. This will keep active
weather across the High Plains along with a good amount of
moisture as precipitable water values generally remain at or
above the 90th percentile. The cold front that moves through
Monday night will stall just to our east and eventually start to
build back into the region through midweek. This will act as a
focus for convective development with a good signal for
excessive rainfall in the EFI/SoT Tuesday night into Wednesday,
mainly from southwest Nebraska up through Ainsworth and
eastward. The signal for excessive rainfall becomes less
pronounced later in the week though diurnally biased rounds of
showers and thunderstorms with locally heavy rainfall can be
expected to persist into next weekend.

On the cool side of the front with fairly widespread clouds and
precipitation, temperatures Wednesday will be quite cool with
highs only in the middle 60s to around 70 degrees. This cool
down will only be temporary as readings head back well into the
80s as the upper ridge builds a bit westward into next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
-- Changed Discussion --
Issued at 620 AM CDT Sun Jun 16 2024

VFR conditions are expected to prevail through this evening
across western and north central Nebraska. By tonight,
increasing low stratus will lead to MVFR/IFR CIGs across
northern Nebraska, along with increasing showers and
thunderstorms. Timing and placement of thunderstorms still
remains somewhat uncertain, though future TS inclusion will
likely be needed at KVTN. Winds remain from the north this
morning before shifting easterly then southerly into this
evening, at around 10 to 20kts.
-- End Changed Discussion --

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...MBS
LONG TERM...MBS
AVIATION...Brown