382
FXUS63 KLBF 011117
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
617 AM CDT Tue Sep 1 2026

.KEY MESSAGES...

- Following morning general thunderstorms, Tuesday afternoon
  and evening thunderstorms including the threat for severe will
  be possible with large to very large hail, damaging winds,
  and perhaps a tornado or two possible the main concerns.

- While most locations remain dry, an isolated thunderstorm or
  two will be possible in the afternoon and evening Wednesday
  for portions of west central Nebraska.

- A warmer, drier pattern sets up mid week through the weekend
  and into early next week. Highs remain above seasonal
  averages, with little to no precipitation expected.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 217 AM CDT Tue Sep 1 2026

Early this morning, rain and thunderstorm coverage was increasing
across western and southwestern Nebraska early this morning. This
was occuring in advance of an approaching mid-level disturbance.
Broad warm air advection and DCVA were the primary sources for lift.
Monday evening RAOB data from KLBF showed modest MUCAPE, at or
around 1500 j/kg. Early morning mesoanalysis shows little change to
this outside of a northward advection of some greater instability.
Mid-level flow was fairly strong, observed at 40 knots with this
RAOB sample and though some fluctuations are noted in short-term
guidance, a rebound in the early morning hours is expected with the
arrival of the h5 trough. This will maintain adequate deep-layer
shear for storm organization. The Storm Prediction center maintains
a Marginal Risk through 12z (7am CDT) and isolated severe wind gusts
and/or severe hail will be possible in the strongest storms.

Tuesday/Tuesday Night...a fairly active day for rain and
thunderstorms appears likely for western Nebraska. Aloft, the mid-
level wave will continue to lift north and east with a weak surface
low developing early in the day. This will form on the warm front
across northwest Kansas. To the east, southerly flow will strengthen
as the warm front begins to lift north. Earlier outlooks suggested a
closed low forming just off the surface but trends have been to make
the system more progressive with a lower amplitude. This has allowed
for a further northwest placement of the surface boundary. This
places the area deeper into the warm sector where ample diurnal
heating, with afternoon highs in the middle 80s to lower 90s,
beneath steep mid-level lapse rates will promote moderate to strong
instability of 1500-2500 j/kg MLCAPE. Given strongly veering wind
profiles and slightly backed surface flow into the boundary, deep
layer shear will be strongly supportive of organized convection.
Uncertainty remains regarding where storm initiation occurs with two
distinct camps: further north into south central South Dakota or
further south across the central Sandhills. The lingering difference
between these two solutions is placement of the frontal boundary in
the afternoon. The HRRR and RAP depict a northward push through the
day and a final placement closer to I-90 with the NAM lagging
considerably south as elevated convection early in the morning over
South Dakota reinforces the further south placement. The latter of
these outputs would prove to be favorable for severe weather locally
with the lingering boundary serving not only as a focus for
development but also perhaps a source for low-level vorticity which
could promote more supercell storm modes and perhaps a non-zero
tornado threat. HREF ensemble outlook favors the northern zone where
it paints the highest QPF probabilities. Even if the greater
coverage remains north, warm air advection in an unstable
environment could lead to more isolated development further south
with large to very large hail and damaging winds the main concerns,
especially with any supercell structures. The SPC has introduced a
Slight Risk (level 2 of 5) for north central Nebraska and agree
given the potential advertised by a few CAM solutions. Training of
storms along the surface boundary, should the further south scenario
play out, could lead to locally heavy rainfall as well with the
further south NAM12 solution depicting localized rainfall amounts of
up to 2". The going forecast resembles HREF output which allows most
if not all activity to depart the area by mid to late evening. This
will leave the bulk of the overnight hours dry with lows falling to
the upper 50s to lower 60s.

Wednesday/Wednesday Night...high pressure across the northern Plains
will nose into the area by early in the day. Within the
southwesterly flow aloft, the next disturbance will overspread the
Intermountain West. Lee troughing through the day will support
increasing southerly and southeasterly flow which will drive the
high pressure out of the area by midday. A dryline feature will set
up over the Panhandle and serve as the dividing line between richer
low-level moisture and increasingly dry air anchored to the higher
terrain. While the dryline appears likely to be fairly sharp,
convergence along the boundary will likely remain weak through the
day. Afternoon highs will reach the upper 80s to lower 90s. The lack
of greater forcing for ascent casts doubt on thunderstorm potential
for the afternoon and evening. Deep layer shear and moderate
instability would support a strong to severe threat but confidence
in development is too low to message any appreciable severe threat.
The SPC highlights low predictability with only a General Thunder
outlook (no severe). Will keep PoPs low but maintain a Slight Chance
mention (~15%) in our west. Further north and east later in the
evening, as a stronger low-level jet forms, do anticipate some
development to extend south into north central Nebraska. Though the
focus should remain over eastern South Dakota, believe enough
forcing exists to lead to at least widely scattered development. The
stronger winds off the surface will keep the boundary layer mixed
further east where lows will likely hold in the lower 70s with
general 60s expected elsewhere to the west.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 217 AM CDT Tue Sep 1 2026

Upper level ridging persists late week into next week. This will
continue to favor a warmer, drier pattern through the holiday
weekend into next week. Temperatures are expected to remain above
seasonal for early September. For reference, the first week of
September the average high drops from 85 to 83 degrees. However,
current forecast highs remain in the upper 80s to mid 90s, with
potential for upper 90s across southwest Nebraska. The cooler highs,
in the upper 80s to lower 90s, are generally expected to remain
across northern Nebraska and remain consistent with the 75th
percentile compared to climatology. So, while these highs are warmer
than usual, these are not too unusual. Further to the south, where
highs remain in the 90s, highs remain consistent with the 90th
percentile compared to local climatology, which is less usual. By
early next week, some uncertainty begins to build into the forecast,
though. GEFS spaghetti plots suggest most solutions still favor
upper level ridging to continue across the region, however, some of
the more progressive solutions begin to track an upper level trough
across the Northern Plains. If these solutions come to fruition,
then we could see the upper level ridge begin to break down early
week, potentially bringing slightly cooler highs, yet still
remaining above seasonal averages.

The upper level ridging is also expected to help limit precipitation
potential late week and through the holiday weekend. Ensemble
guidance continues to remain pessimistic on precipitation chances,
generally keep a less than 10 percent chance of exceeding one tenth
of an inch of precipitation through the weekend. However, ensembles
do still suggest around a 20 to 40 percent chance for light
rainfall, exceeding one hundredth of an inch. Deterministic guidance
suggests a few shortwaves tracking through the upper level flow,
though given the forecast positions, would expect this to keep
surface lows across the Dakotas. With this in mind, cannot
completely rule out some slight chances for very light
precipitation, but not expecting any wetting precipitation through
the weekend. For what it is worth, latest NBM guidance does keep
some slight chance PoPs, generally less than 20 percent, each
evening this weekend. However, based off the ensemble guidance,
would expect any precipitation that may occur will be very
light.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 616 AM CDT Tue Sep 1 2026

Rain showers are tracking across portions of the region this
morning, bringing localized low end VFR conditions. These showers
are expected to track out of the region in the next few hours, with
additional showers and thunderstorms redeveloping during the morning
and early afternoon hours. These storms may bring localized impacts
to ceiling and visibility, as well as gusty and erratic winds. At
this time, still expecting VFR conditions to prevail at KLBF and
KVTN. After this second round of thunderstorms, expecting light and
variable winds to prevail across the region. With the light winds
and recent moisture, there is is a possibility of patchy fog to
develop across the region. Confidence is low in how far fog may
spread at this time, so will continue to monitor today.

&&

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

&&

$$

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