627
FXUS63 KLBF 051734
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1234 PM CDT Sat Jul 5 2025

.KEY MESSAGES...

- Thunderstorms are possible again this evening for areas west
  of Highway 83 with a Slight Risk (level 2 of 5) for severe
  weather across portions of the Sandhills.

- Additional severe weather is possible each day Sunday and
  Monday with a Slight Risk (level 2 of 5) for severe weather
  each day.

- Daily rain and thunderstorm chances continue through the
  upcoming week with probabilities of 30-40% each day Tuesday
  through Friday with highs in the 80s and low 90s.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 356 AM CDT Sat Jul 5 2025

Early this morning, scattered thunderstorms were developing ahead of
a passing surface trough and within an area of modest WAA. This
activity is not long for the local area and focus should quickly
shift east over the next few hours. Elsewhere, a decaying MCV across
the Sandhills was apparent over western Cherry County. This feature
was rapidly weakening and should allow for any rain to dissipate
over the next hour or two.

Saturday/Saturday Night...the shortwave responsible for rain and
thunderstorms Friday is progressing east this morning with northerly
low-level flow filling in behind. This should introduce some drier
air into western Nebraska. This will be reinforced by encroaching
high pressure extending south across the Northern Plains. Expecting
a mostly dry day across the forecast area today with only one
exception. As afternoon highs climb into the 80s, CAA off the
surface will allow low-level lapse rates to steepen. It appears that
convective temperatures will potentially be breached this afternoon,
effectively eroding any residual capping inversion. While forcing is
weak and nebulous, believe potential is good enough to introduce
Slight Chance (< 25%) PoPs across north central Nebraska. Shear is
rather weak at less than 20 knots, so any storms that form will be
unlikely to sustain themselves for long. SREF probabilities
highlight this area well and leaned on this and NAM output to paint
PoPs in the area. HREF probabilities appear highest to the east but
ensemble max QPF values suggest the area to watch extending as far
west as Highway 83 and as far south as Highway 30. In the evening,
winds will back to the east-southeast. This will promote moist
upslope flow across western Nebraska. This should be enough to allow
afternoon thunderstorms to develop off the mountains of eastern
Wyoming. Easterly h5 flow will steer activity through the Nebraska
Panhandle and into our western zones this evening. This is where
uncertainty increases. The local environment will be characterized
by 1000-1500 j/kg MLCAPE and deep layer shear of 30 to 40 knots.
This will be maximized during the afternoon but as evening settles
in, the loss of insolation will allow for boundary layer
stabilization. Further hampering this is decreasing lapse rates with
eastward extent. While a LLJ developing appears probable, focus will
be to the north and west of the area. This should aid storms across
western South Dakota but offer little support to maintaining storms
over western Nebraska. As a result, believe thunderstorm potential
locally is limited. Have capped PoPs to 25% or less for areas west
of Highway 83 as a result. SPC maintains the Slight Risk (level 2 of
5) over the northern Panhandle with a Marginal Risk (level 1) buffer
as far east as Highway 83. Believe this is adequate but should
trends continue, believe the Slight Risk can probably be removed
from the local forecast area. CAM guidance remains less than
enthused on thunderstorm potential with NAM Nest and HRRR output
killing off any storms that approach the Highway 61 corridor.
Overnight lows will hover in the 60s across the area.

Sunday/Sunday Night...uncertainty continues into Sunday with
previous day convection having large implications on Sunday threats.
Confidence remains fairly limited regarding precise placement of
greatest thunderstorm threats. That said, the background environment
will support thunderstorms and a threat for strong to severe so
advise persons to closely monitor later forecasts. Moderate LLJ will
continue to nose into western South Dakota. This will support a
continuation of rain and thunderstorms, perhaps strong to severe,
invof I-90. Deep moist/warm air advection into thunderstorms to the
north may promote development further south across the Sandhills.
Storms to the north may also dive southeast into the strengthening
LLJ. Earlier runs of the HRRR suggested this potential with multiple
supercell-like structures arriving into our northern zones around
midday. Output has recently trended away from this thinking but I
don`t believe this outcome can be completely ruled out yet. Outflow
from the cluster of storms will settle south into the area and stall
as a psuedo-warm front stretching across the Sandhills into central
Nebraska. South of this boundary, strong upslope moist flow should
allow for additional afternoon and evening thunderstorms over
western Nebraska. As storms move east, they are likely to encounter
a much richer low-level moisture environment. With afternoon highs
again climbing into the 80s beneath steep 7-9 C/km lapse rates,
strong instability will develop. Southeast low-level flow beneath
enhanced westerly flow as a shortwave trough tracks through will
promote strong deep-layer shear with 0-6km BWD values of 40-50
knots. Low-level shear will be fairly strong as well thanks to
another notable LLJ. Given the magnitude of shear aloft and expected
supercell structures, believe large to very large hail and damaging
wind gusts are the main concerns. Forecast soundings show little
curvature early on which would suggest splitting supercells but as
the LLJ strengthens, elongating hodographs with reasonable 3CAPE
values around 50-100 j/kg suggest a limited tornado potential as
well. Sounding analogs show expansive lists of very large exceeding
baseball size. Given distribution of instability largely above the
freezing level and strong mid-level shear, believe these analogs to
be reasonable. Storms may pose a damaging wind gust threat early on
but as cold pools merge, believe this threat will increase later in
the event. Strong theta-e advection across southwest Nebraska should
sustain convection and lead to a west-northwest to east-southeast
track to a mature system. The inherited model blend paints expansive
35-50% Sunday evening but believe these will be cleaned up with
later forecasts.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 356 AM CDT Sat Jul 5 2025

Active weather continues in the extended forecast. Upper ridging
across the Desert Southwest with strengthening, pushing heights aloft
to slight positive anomalies. A similar setup on Monday should lead
to expansive rain and thunderstorm potential across western
Nebraska. Latest SPC outlook highlights another Slight Risk (level 2
of 5) over much of the local forecast area. Southerly low-level flow
beneath enhanced westerly mid-level flow with afternoon highs
reaching seasonable norms should again promote an environment
supportive of organized convection. How early morning activity
across South Dakota and any residual outflow boundary affects the
setup remains to be seen but is something that will need
consideration.

Upper-ridging will continue to strengthen towards the middle of the
week. Northwesterly flow will settle in over the Central Plains as
the ridge axis remains between the Great Basin and Continental
Divide. Temperatures will climb as a result with NBM percentile
values showing gradual 2-4F climbs day-over-day from Monday through
Wednesday. The warmest days of the forecast appear likely to be
Wednesday or Thursday with highs reaching the middle to upper 90s.
For now, heat indices appear to remain below Advisory criteria (100F
or higher) so heat concerns are likely limited. Ridge breakdown
arrives for the latter half of the week as troughing arrives from the
Pacific Northwest. A cool front will dive south and lead to a
reasonable cooldown for Friday/Saturday with highs falling into the
lower 80s. Precipitation chances will join this cooldown and favor
Friday with the frontal boundary in the area. EPS ensemble
probabilities highlight much of the Missouri Valley with increased
QPF potential, notably ~40% of seeing > 0.50" for Friday, but GEFS
shows little support for this idea. Evolution of the parent trough
across the Northern Plains will be the wild card in the day 6-8 time
frame and until this becomes more clear, forecast confidence will
remain low.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1234 PM CDT Sat Jul 5 2025

VFR conditions are expected to prevail throughout the effective TAF
period across most of western and north central Nebraska. While some
low level cumulus is noted across portions of northern Nebraska this
afternoon, not expecting that this will result in impacts to
ceilings, as it should remain scattered throughout the day. This
evening, a chance of showers and thunderstorms is expected across
the Panhandle, however, should remain well west of area terminals.
Overnight, will likely see some more significant cloud cover ahead
of an advancing front, which may provide showers and storms late in
the TAF period, to just beyond the TAF period. Confidence in timing
is still low, so will omit precip mention from KVTN for now.

&&

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

&&

$$

SHORT TERM...NMJ
LONG TERM...NMJ
AVIATION...Richie