889
FXUS63 KLBF 090024
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
724 PM CDT Tue Oct 8 2024

.KEY MESSAGES...

- Elevated to near critical fire weather conditions, mainly due to
very low humidity, through Thursday as above normal to near record
temperatures continue

- Haze, and potentially some smoke impacts, from Western US
wildfires through tomorrow

- A couple cool front passages to round out the week, resulting
  in below normal highs Sunday and Monday and the potential for
  a widespread freeze

&&

.SYNOPSIS...
Issued at 407 PM CDT Tue Oct 8 2024

The anomalous upper ridge holding over the Western US has broadened
over the Plains a bit more, with the axis lining up the High Plains.
The ridge is bounded by a deep low near the southern tip of the
Hudson Bay and an incoming trough for the Pacific Northwest. Upper
steering flow has also directed the atmospheric smoke from western
wildfires into the Sandhills. At the surface, a broad high remains
near the mid-Mississippi Valley, while a weak low near the Black
Hills stretches a trough southward through the Neb panhandle. These
features combined for another cloudless day with generally light
southerly flow and temperatures in the lower 80s.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 407 PM CDT Tue Oct 8 2024

This evening into tonight... A weak mid-level low and shortwave drop
south from the Dakotas, while the surface low and trough push into
the Sandhills. Despite the increased forcing associated with the
features, moisture content (in the low levels) remains very limited.
The surface trough will divide dew points in the 20s in the
panhandle from the lower 40s in central Neb. Also preceding the
trough will likely be a 25-30 kt low level jet. Forecast soundings
suggest a rather strong inversion holding through the night and
little if any of the jet being able to mix down. Used a blend of
NBM50 and Cons for speeds, which maintains ~5 kts at the surface.
Guidance suggests negligible to very weak warm air advection
overnight, roughly 1-2C rises at H85. With this in mind, nudged min
temp forecast up a degree or two, but kept values toward the lower
end of the NBM envelope to account for boundary layer decoupling and
very dry air. Forecast ranges from the mid 30s in the panhandle to
mid 40s central Neb.

Tomorrow... The upper ridge spreads eastward to cover the entire
Plains and part of the Midwest, although a subtle low will park over
northeast Nebraska. Little change in the surface pattern is expected
with the trough bisecting the Sandhills and the dominant high
centered near the Miss/Ohio R confluence. The day begins in
downsloping west winds before a gradual transition to northerly low
level flow takes place. Regardless, weak warm air advection
continues with much of the CWA achieving 20C at H85. The NBM
envelope spread is small (3-4F quartile range) for max temps,
centered around the mid 80s. These values also line up with the
milder MOS guidance (MET, ECS), but fall short of the aggressively
warm MAV. While clear skies and the dry airmass would support warmer
guidance, was hesitant to blend in 90s for highs given thicker haze
and the weaker nature of WAA. HRRR smoke also suggests increased
surface impacts, especially for the western CWA. Left forecast
values in the mid 80s for now. The vicinity of the surface trough
and the lack of strong low/mid level flow behind the low will keep
winds relatively light during the day. While widespread critically
low humidity values (<15%) are anticipated, especially near and west
of Hwy 83, the lack of gusty winds precludes any red flag headline.
After dark, near surface flow begins to return to southerly and
overall temp advection at H85 remains negligible. Min temps should
be similar to tonight, although humidity recovery will be more
limited. RH will struggle to reach 70% near and west of Hwy 61.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 407 PM CDT Tue Oct 8 2024

A shift in the synoptic pattern is in store for the end of the week,
including a breakdown in the large upper ridge and a deep digging
trough over the Great Lakes. Longer range guidance shows some
discrepancies in timing and placement of the western periphery of
the trough early next week, but indications point toward a greater
influence over Nebraska.

Overall, Thursday presents the greatest fire weather concerns as
critically low humidity remains over the western CWA and
southwesterly surface winds strengthen ahead of a cool front. While
some gusts to 25 mph are possible in the western Sandhills, the
threat of consistent or widespread red flag appears low. Will hold
off any headlines at the moment. Regardless, max temps will make a
push for 90F with the highest potential lies in the central Niobrara
Valley and far southwest. These values approach daily record highs.

A couple cool fronts then cross the forecast area, one being early
Friday and the next being later Saturday. Each passage will be
starved of moisture, but a change in temps and wind will be felt.
Highs will be knocked down into the 70s (still 5-10F above normal)
for Saturday, which will help keep humidity values above critical
levels despite 20-25 mph gusts. Guidance has trended much cooler
with the second front, now suggesting highs in the lower 60s for
Sunday and even 50s for Sunday. A widespread freeze, and possibly a
killing freeze, appear more likely to begin the week. NBM guidance
shows a 50-50 chance of a min temp of <28 at LBF and VTN.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 718 PM CDT Tue Oct 8 2024

VFR conditions will prevail across all of western and north
central Nebraska the next 24 hrs. A weak cold front will move
south across the area with winds shifting to the north-northeast
at 5-15 kts during the day Wednesday.

&&

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

&&

$$

SYNOPSIS...Snively
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...Taylor