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000
FXUS63 KLBF 141123
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
623 AM CDT Sun Apr 14 2024

.KEY MESSAGES...

-  Dangerous fire weather conditions are expected to develop
   behind a dryline Monday afternoon, with single digit relative
   humidity values and winds gusting in excess of 40 miles per
   hour.

-  Strong to severe storms are possible across much of western
   and north central Nebraska Monday evening into the overnight
   hours.

-  Showers and thunderstorms linger into Tuesday, with the
   greatest accumulations east of Highway 83. Strong northwest
   winds may gust in excess of 55 miles per hour Tuesday
   afternoon across much of the area.

-  Below average temperatures then persist late this week and
   into the weekend, with continued precipitation chances.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 410 AM CDT Sun Apr 14 2024

For today, another warm day is in store, with full sunshine expected
across the area. This will lead to ample diurnal mixing to tap into
very warm air aloft, and should promote widespread highs in the 80s
again. That said, temperatures look to be a few degrees cooler than
yesterday, with a weak backdoor cool front slowly pushing through
the area early this morning. Elevated to near-critical fire weather
conditions can be expected again this afternoon, though winds look
to remain weak again today and will temper the threat. Still,
relative humidity values in the teens to low 20s are expected across
the area this afternoon.

By tonight, an upper low (currently located over northern
California) will begin to eject eastward into the Rockies, with
increasing lee cyclogenesis across eastern Wyoming. This drags the
aforementioned backdoor cool front northeastward into the area
as a warm front. In response, flow begins to strengthen from the
southeast tonight and lead to increasing moisture advection.
Some breezy winds can be expected after midnight, with gusts of
20 to 25 miles per hour possible at times. This will also keep
lows more mild across the area, in the lower 50s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 410 AM CDT Sun Apr 14 2024

A high impact weather scenario then looks to evolve across western
and north central Nebraska Monday and Tuesday.

The aforementioned upper low will begin to slowly eject
eastward into the Plains Monday afternoon and evening, with an
associated surface low ejecting into northeast Colorado and
southwest Nebraska Monday afternoon. As this occurs, a northwest
to southeast oriented dryline will begin to lift northeastward
towards the HWY 61 corridor during the late afternoon hours.
Where precisely this boundary is positioned will have drastic
impacts on both fire and severe weather concerns, and this lends
to lowered confidence for now. Still, dangerous fire weather
conditions are expected to develop behind the dryline, and
further details on this threat can be found in the fire weather
section below.

Ahead of the dryline, increasing southeasterly flow should promote
good moisture advection into much of the Sandhills and central/north
central Nebraska, with dewpoints climbing into the 50s. A look at
area forecast sounding show that the depth of this moisture is
somewhat shallow, with mean mixing ration of only 8-10 g/kg and LCL
heights of ~1500-2500m. Still, with cold air beginning to stream in
aloft by late Monday evening, lapse rates steepen enough in the mid-
levels to increase MLCAPE to ~1000-2000 J/kg. Deep layer wind
profiles look ample to support organized updrafts, with deep
meridional flow aloft leading to elongated hodographs with height.
With a surface warm front lifting northward through the area during
the late afternoon, low-level flow remains backed and will lead to
good curvature in the lowest few kilometers of the hodograph as well
(especially as the low-level jet strengthens near/after sunset). The
environment looks to be supportive for initial discrete
supercell development across the area, though a few issues exist
with respect to this threat. The first is a capping inversion
aloft, noted near H7. Though not overly strong, this does look
to keep any convective initiation to a minimum through much of
the afternoon. The next issue is the timing of the upper level
wave, which does not look to arrive until late in the diurnal
cycle. That said, when it does arrive, the area looks to be
positioned in a favorable location, within the left exit region
of an H3 jet streak amid good diffluence aloft. The dryline
circulation should be more than deep enough to promote continued
erosion of the aforementioned cap, and any subtle forcing
mechanisms (or lack thereof) will likely be the difference
between diurnal cumulus and an arc of supercells across western
and central Nebraska. Trends will need to be monitored closely
as more subtle features begin to come into more clarity.

Should convection develop prior to sunset, all severe hazards would
be possible, within the aforementioned supportive background
environment. After dark, a cold front looks to overtake the dryline
as the surface low ejects across the area and could lead to more
widespread convective development. This looks to be a much messier
mode, with lots of interacting updrafts along the cold front. This
could temper the hail threat some, along with any damaging wind
threat as the boundary layer cools and storms may become elevated.

As the deep surface low begins to slowly push off to the east late
Tuesday morning, flow will quickly strengthen from the northwest
behind the surface cold front. Strong flow aloft looks to be
mechanically mixed to the surface amid increasing cold advection,
and could lead to winds gusting in excess of 55 miles per hour
Tuesday afternoon and evening. The greatest threat for now looks to
be across western Nebraska, though this threat may extend further
eastward into central/north central Nebraska with time. There is
lingering uncertainty with respect to timing (well after dark) with
eastward extent, though cold advections look strong enough to at
least promote some continued mechanical mixing overnight. The
exiting surface low will also lead to some wraparound precipitation
through the day Tuesday, with the greatest accumulations east of HWY
83. The system finally exits the area into Tuesday night, with
precip ending from west to east.

The lull in any precipitation looks to remain brief, as another
shortwave quickly enters the northern Plains behind the departing
Monday/Tuesday system. This looks to provide a quick shot of
moisture along a cold front pushing through the area Wednesday
night. Some snow could mix into the rain across western Nebraska,
largely diurnally driven as the column cools aloft. Flow aloft then
begins to transition northwesterly, with multiple shortwaves
anticipated to pass through the area. This will both lead to
continued shots for precipitation into this weekend and promote
temperatures remaining below average.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 617 AM CDT Sun Apr 14 2024

VFR is likely across wrn/ncntl Nebraska today and tonight. The
chance of MVFR or lower flight conditions during this time is
low, less than 20 percent.

A weak backdoor cold front will drift through the region this
morning. The front will begin lifting north tonight followed by
return moisture and stratus from the South (KS-OK). Any flight
concern from this feature is expected to remain across KS until
at least 12z Monday.

&&

.FIRE WEATHER...
Issued at 410 AM CDT Sun Apr 14 2024

Dangerous fire weather conditions are expected to develop across
portions of southwest Nebraska Monday afternoon behind a dryline. As
temperatures soar into the upper 80s to near 90 degrees, dewpoints
will quickly fall and single digit relative humidity values are
anticipated near the HWY 61 corridor south of I-80 Monday.
Strong south winds are also anticipated, sustained at 20 to 30
miles per hour and gusting as high as 45 miles per hour. Any
fire starts will likely spread rapidly and quickly become out of
control. Where exactly the dryline will be positioned Monday
afternoon remains somewhat low confidence, and further north and
east expansion in Red Flag headlines may be needed.

Of additional concern, a cold front will sweep through the area
Monday night, with winds quickly shifting from south to northwest in
its wake. Northwest winds will then strengthen into Tuesday morning
and the afternoon, with gusts in excess of 55 miles per hour
possible. Scattered showers and thunderstorms are possible Monday
night into Tuesday across the areas most likely to see Red Flag
conditions (far southwest Nebraska) though chances for wetting
moisture remain low confidence.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Monday morning through Monday evening
for NEZ210.

&&

$$

SHORT TERM...Brown
LONG TERM...Brown
AVIATION...CDC
FIRE WEATHER...Brown