833
FXUS63 KLBF 040901
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
401 AM CDT Mon Aug 4 2025

.KEY MESSAGES...

- A Slight Risk (level 2 of 5) of severe weather is in place for much
  of western and central Nebraska with scattered severe
  thunderstorms possible this afternoon and evening.

- Isolated severe thunderstorms are possible again Tuesday
  afternoon and evening mainly for the Sandhills into north
  central Nebraska.

- Temperatures climb to well above normal values for the latter
  half of the week with forecast highs in the triple digits and
  heat indices approaching Heat Advisory criteria (100F) for
  portions of central Nebraska.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 401 AM CDT Mon Aug 4 2025

This morning, remnant rain and embedded thunderstorms from Sunday
afternoon has cleared the area to the east leaving dry conditions in
its wake. A surface boundary has settled east near an Ainsworth to
Imperial line. To the east, southerly flow was helping usher
moisture into the area allowing expansive low-level stratus and fog
to develop. Can`t rule out some patchy fog working into central
Nebraska and the eastern Sandhills but current expectations are for
visibility restrictions to fall short of reaching Dense Fog Advisory
criteria (< 1/4SM). Will continue to monitor closely.

Later this afternoon/early evening...a highly conditional severe
weather setup is likely for much of the region today. The Storm
Prediction Center (SPC) has opted to introduce a Slight Risk (level
2) severe weather outlook for the area. Given the uncertainty but
magnitude of severe weather potential, am in agreement with this
decision. Shortwave ridging will nose in from the southwest leading
to expansive mid-level height rises. At the same time, troughing
will move onshore the Pacific Northwest and lift north and east into
the northern Rockies. In response to this, a deepening low pressure
will form over central Wyoming. Low-level flow will increase across
the High Plains as a result with strengthening southerly flow. This
flow will promote warming temperatures and modest moisture
advection. As a result, dew points will climb into the middle to
upper 60s with afternoon highs ranging in the upper 70s over central
Nebraska to upper 80s across the Panhandle. Capping does not appear
likely to fully erode and with the lack of greater synoptic forcing,
believe storm coverage will be fairly limited. That said, the
southeasterly moist flow should interact with terrain enhancement
around the Pine Ridge and the Black Hills to yield at least isolated
to widely scattered thunderstorms. The background environment is
more than supportive for severe thunderstorms...beneath a strong EML
with mid-level lapse rates around 8C/km, moderate instability will
develop with forecast soundings depicting 2500-3500 j/kg MLCAPE.
Beneath a belt of enhanced h5 northwesterly flow, surface
southeasterly flow will enhance deep-layer shear with magnitudes of
40-50 knots 0-6km BWD. Based on HREF probabilities, believe storms
will likely initiate around 4-6pm CDT and quickly become
supercellular given ample instability and shear. The greatest
uncertainty is should storms actual initiate. Upstream RAOBs from
Sunday evening show ample low-level moisture and anomalous
precipitable water values. Given steady advection of this richer
moisture, believe storms should initiate with the assistance of
orographic lift. Supercells capable of large to very large (2"+
diameter) and damaging wind gusts will be possible. Believe a very
limited tornado threat exists but will likely favor the evening
hours as a strong LLJ develops and hodographs rapidly enlarge while
LCLs decrease. NAM forecast sounding analogs highlight copious
significant hail events lending credibility to the threat. Heavy
rainfall with rain rates exceeding 1"/hour will also be possible
leading to a localized flooding concern as Bunkers right storm
motions appears likely to remain below 20 mph.

Late tonight...the strong LLJ developing tonight will help usher in
rich theta-e air into any southeast moving thunderstorm. Given the
fetch of unstable air and merging of cold pools that support upscale
growth, believe a southeast diving complex should maintain itself
beyond Midnight into early Tuesday morning. This is advertised well
with the 18z and 00z extended runs of the HRRR. The NAM Nest
highlights a similar outcome but is quicker to carry thunderstorms
out of the area. Believe this all suggests a fairly longer duration
severe weather threat persisting into the overnight hours. Did opt
to boost PoPs across our southwest zones as a result but for now
have kept things limited to Slight Chance (< 25%) for now. Event
total rainfall will likely total 1.0-1.5" in the heavier locations.
Given the expected cloud cover and precipitation, believe Monday
night lows will remain on the mild side with values only reaching
the middle 60s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Issued at 401 AM CDT Mon Aug 4 2025

Tuesday...another conditional threat for strong to severe
thunderstorms will set up across western Nebraska. As the low
pressure system lifts north and east out of central Wyoming, a warm
front will lift up through the area. High temperatures will quickly
climb into middle 80s to middle 90s east to west. Similar to Monday,
beneath strong capping and the lack of any appreciable forcing
questions remain on whether storms can develop. A sharp dryline will
settle into far western Nebraska with strong instability to the east
across a broad warm sector. Forecast sounding ahead of this dryline
show very strong capping and though the dryline circulation may be
deep, MLCIN values nearing -100 j/kg should effectively quell any
and all potential attempts at initiation. Further north in closer
proximity to the departing low-pressure, scattered convection should
initiate along the warm front in South Dakota. Though the majority
of this should remain north of the local area, will maintain the low-
end PoPs inherited by the NBM into the Sandhills. Strong instability
of 3500-4500 j/kg MLCAPE and 0-6km BWD would again support
supercells as hodographs show long/straight shear profiles. Strong
theta-e advection off the surface should once again support
sustained convection well into the evening and overnight hours and
so have kept PoPs through daybreak on Wednesday as a result.

Wednesday and beyond...Precipitation chances should wane for the
late half of the week as ridging aloft appears to peak across the
Desert Southwest. This will bolster geopotential heights to the 90th
percentile or higher at h5 and h7. Similarly, h7 temperatures will
climb to around the 99th percentile across portions of Nebraska by
late Wednesday, all according to NAEFS guidance. ECMWF Extreme
Forecast Index (EFI) continues to highlight localized positive
anomalies of 0.5-0.7 with non-zero Shift of Tails each day Wednesday
through Friday. The going forecast calls for daytime highs in the
low 90s east to low 100s west and southwest. Specific values at
LBF/VTN exceed the 90th percentile in their respective climatology`s
and climb to within a few degrees of record values. This expected
heat in addition to low-level mugginess will promote heat indices
nearing Heat Advisory criteria (100F+). Should the current forecast
hold, heat headlines will be necessary for portions of the local
area Thursday and Friday. Will forego issuing anything at this time
until confidence increases. Day-to-day precipitation chances appear
quite limited, particularly as temperatures off the surface maximize
and capping strengthens as a result. Have kept low-end PoPs from the
NBM solution but EPS/GEFS show fairly good agreement in a lengthy
window of little to no QPF Wednesday through Friday. As ridge
breakdown begins this weekend, a frontal boundary will slide south
into western Nebraska. The result will be cooler temperatures
arriving by Sunday with increased rain and thunderstorm potential
continuing into early next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1227 AM CDT Mon Aug 4 2025

VFR conditions will continue to prevail across western and north
central Nebraska for the next few hours. Prior to sunrise, stratus
redevelops over southwest and south central Nebraska, which may
introduce IFR ceilings across portions of the region. Will continue
to include KLBF in the IFR ceilings. This will be closely watched
over the next several hours, and amendments may be needed if timing
and extent change. By mid morning, a quick return to VFR conditions
is expected, remaining VFR throughout the day. Another round of
showers and thunderstorms is expected in the late afternoon to early
evening. For now, think that impacts to the terminals will be later
in the evening, however timing will continue to be refined over the
next forecast cycles.

&&

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

&&

$$

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