-- Discussion containing changed information from previous version are highlighted. --
170
FXUS63 KLBF 260557
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1257 AM CDT Wed Jun 26 2024

.KEY MESSAGES...

- Thunderstorms this evening near a warm front across northern
Nebraska with a threat of large hail and strong winds

- Near daily storm chances through the weekend, including potential
for a strong/severe storm tomorrow (west) and Thursday (everywhere)

- Varying temperatures the next several days, including warm
Wednesday, milder (north central) Thursday, and back to very hot by
Monday

&&

.SYNOPSIS...
Issued at 408 PM CDT Tue Jun 25 2024

Nebraska is squeezed between a bubble of high pressure over the Rio
Grande and an approaching upper trough in the Canadian Prairie
provinces, resulting in quasi-zonal flow aloft. Near the surface, a
low sits directly over the Sandhills with a warm front extending
east along the Hwy 20 corridor, a dryline stretching south near the
Hwy 83 corridor, and a cool front back toward the Colorado Rockies.
South of the front, highs in the mid/upper 90s accompanied nearly
cloudless skies. As of 20z, a cumulus field developed across north
central Neb from near VTN to ONL as backed northeasterly surface
winds intersect the front. Abundant moisture is available as shown
by dew points around 70F and PWAT of over 1" (at LBF) or 1.7" (at
OAX). Latest mesoanalysis from SPC/RAP and 19z RAOB from OAX
indicate ample instability along the front in the form of 4000 j/kg
MUCAPE and 30-40 kts of 0-6km shear.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 408 PM CDT Tue Jun 25 2024

This evening into tonight... The big question surrounds convective
initiation and evolution along the warm front in northern Nebraska.
CAMs guidance has differing scenarios, ranging from a couple rounds
of isolated storms that brush the CWA to widespread convection
across the northeast half. The environment is definitely capable of
organized storms and supercells, consisting of a severe hail and
wind threat. The 19z OAX RAOB shows a rather fat CAPE profile with
very steep mid level lapse rates (8.5+ c/km), but also abundant
DCAPE (1300+ j/kg). Also cannot rule out a tornado along/north of
the front where LCL`s dip and low level flow is sufficiently backed.
Despite these parameters, the cap appears to be holding in place and
will play a large role in the timing and overall coverage of thunder
in the northern Sandhills. For now, blanketed the Hwy 20 corridor
with chc PoP (~30%) through the evening. The most likely timeframe
of thunder activity will be 00-06z, centered around southeastward
progressing convection off the Black Hills and other initiation along
the front in Nebraska, although the latter may be concentrated
toward the northeast quadrant of the state. The tricky part of the
whole setup is the conditionality. Coverage may be very limited, but
whatever storm affects the region could very easily become severe.
Overnight, low level winds transition to north and eventually
northeast, helping to retain moisture. Lows should be fairly mild in
the lower/mid 60s.

Tomorrow and tomorrow night... The upper ridge expands northward
along the spine of the Rockies, ultimately broadening over the High
Plains. At the surface, high pressure builds in from the north with
southeasterly return flow beginning later in the afternoon. That
setup will influence the next round of convection. The most likely
scenario suggests deep upslope flow help kick off storms in CO/WY,
and the steering flow pushes the activity into the panhandle and
ultimately the Sandhills after dark. The initial wave may fizzle as
it reaches the Hwy 61 corridor in the evening, but a stout low level
jet and a mid-level wave rounding the large scale ridge should
provide the oomph to get new development across the Sandhills. As
for temps, predominant northerly low level flow will limit highs to
the lower/mid 80s across north central Neb, while fair skies and
quicker return to southerly flow should push temps to around 90F
again in the southwest.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 408 PM CDT Tue Jun 25 2024

Late week into the weekend, upper flow turns zonal once again over
Nebraska as the ridge flattens and a progressive trough swings
through the northern Plains and Upper Midwest. A brief buildup of a
ridge brings the heat to start next week. The combination of the
synoptic changes aloft and various surface boundaries and frontal
passages, temperatures will vary quite a bit both spatially and
temporally during this period. For instance on Thursday, more
consistent precip and clouds may hold north central Neb to the mid
70s while an H85 thermal ridge will push the panhandle into lower
90s. Friday, the heat dome is concentrated toward southwest Neb,
then some locations in the Sandhills may struggle to break 70F on
Saturday. Perhaps the greatest confidence in temps is regarding the
warmup next Monday where most spots should top 90F and the far
southwest has another chance to break 100F. On a related note to all
the thermal differences, precip chances will stick around through
the period, but vary wildly in coverage and overall potential.
Currently, the greatest potential exists Thursday evening, Friday
evening (south), and Sunday.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
-- Changed Discussion --
Issued at 1256 AM CDT Wed Jun 26 2024

Mostly quiet aviation conditions are expected over the next day.
Some isolated thunderstorms are possible during the evening across
portions of southwest Nebraska and the Sandhills, however,
confidence remains low if storms will impact either terminal. For
now, have kept thunderstorms out of the prevailing forecast, but
this may change in the next forecast cycle or two.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Snively
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...Kulik