-- Discussion containing changed information from previous version are highlighted. --
981
FXUS63 KLBF 042339
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
639 PM CDT Sat May 4 2024

.KEY MESSAGES...

- Strong to severe thunderstorm potential remains across eastern zones
  on Monday, however, greatest impacts lie outside the local
  forecast area.

- Strong winds are likely Sunday through Tuesday with gusts in
  the 40 to 50 mph range forecast.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 415 PM CDT Sat May 4 2024

Quiet conditions are prevalent across western and central Nebraska
in the wake of Friday night thunderstorms. Surface high pressure has
settled south into the area with light and variable winds across our
western zones and only modest northerly breezes across our east.
Diurnal cumulus clouds have nosed into far north central Nebraska
with the likelihood that this will dissipate with loss of daytime
heating this evening.

For tonight, surface high pressure will continue to settle south and
east into the middle Missouri Valley. Behind this, southerly flow
will return with modest moisture advection in its wake across the
majority of Nebraska. While not noteworthy in and of itself, this
slight increase in low-level moisture with the southerly flow should
help abate overnight frost concerns. Forecast lows should manage to
hold into the upper 30s to lower 40s east to west. As such, no frost
headlines are anticipated for Sunday morning. Winds will generally
be at or below 15 mph east of Highway 83. For areas to the west, a
strengthening low-level jet will promote stronger winds and the
milder temperatures. Can`t rule out gusts exceeding 30 mph west of
Highway 61 but overall the expectation is gusts exceeding 20 mph
west of Highway 83.

Sunday...strengthening southerly flow will promote stronger moisture
advection into the area. This will favor increasing cloud cover with
low stratus likely to envelope much of our western forecast area.
Lift through the saturated layer will be weak and elevated
instability nearly non-existent so no precipitation is expected from
this. This will lead to a fairly dreary day with afternoon highs
held in check as values struggle to climb out of the middle 60s.
Even with these "cooler" temperatures, values will actually be
seasonable for early May. Strong winds in the west early will
translate east with gusts likely climbing into the 40 to 50 mph
range for areas west of Highway 83 but more modest in the 30 to 40
mph range for areas east.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 415 PM CDT Sat May 4 2024

Attention quickly turns to an impending storm system expected to
bring a return to more active conditions across western and central
Nebraska.

Sunday night through Monday night...Deepening surface low along the
lee of the Rockies will promote increasing southerly flow along the
High Plains. Constricting pressure gradient across western Nebraska
will allow for strengthening southerly flow as strong 40+ mph gusts
to spread east into central Nebraska during the overnight. Strong
height falls and upper-level divergence will lead to rapid
cyclogenesis will lead to a sub 990 hPa surface low to track out of
northern Wyoming into far southwest Montana and the western Dakotas.
 A sharpening dryline will trail this feature south through the
southern Plains. Timing of this feature will determine locations
most susceptible for severe weather. With fairly early timing of
greatest upper-level dynamics and main h5 low shifting north of the
forecast area, the expectation is for the dryline to be progressive
and likely clear the area early. Though deterministic solutions vary
on placement around midday Monday by roughly 50 miles, confidence is
fairly high in seeing areas west of Highway 83 likely being behind
and within the invading dry airmass. This lends confidence to
lowering PoPs in these areas and have done so following latest SREF
probabilities and WPC QPF forecast. Meanwhile further east in the
warm sector, a few concerns arise regarding severe threat. Latest
SPC Day 3 highlights a Slight Risk east of Highway 83 with a
Marginal extending as far west as an Ogallala to Nenzel line.
This far north in the warm sector, stratus and ongoing rain and
general thunderstorms will hamper both low and mid-level lapse
rates thus limiting overall instability. Both NAM and GFS
guidance limit MLCAPE values to less than 1000 j/kg and even
MUCAPE values of around 1000 j/kg. This casts some doubts about
updraft strength with limited confidence in seeing surface based
storms. Meanwhile, shear will certainly not be lacking as the
area remains in close proximity to a deep h5 low with flow of
40-60 knots in the local area downstream of the highly amplified
negative tilt trough. Given the progressive nature of the
dryline, even if a strong or severe thunderstorm threat were to
develop, the window of concern would close quickly with the dry
air overspreading the area by late afternoon. This will be to
the tune of PWATs falling below a half inch. The QPF forecast
suggest a few areas may perhaps see a half inch while most
locations will likely remain at less than a tenth of an inch.
While setups like this tend to introduce favorable fire weather
conditions, recent rainfall and greenup in the area precludes
greater concern. Afternoon highs will range in the 60s and 70s
which will push humidity minimums below 30 percent for many in
areas with strong westerly winds in the 35 to 45 mph range.

Tuesday and beyond...temperatures for the extended drop off slightly
as the main trough stalls out across the northern Plains. While this
will maintain general westerly flow, regular frontal boundaries with
Canadian source air will keep temperatures near climatological
values. Strong winds continue into Tuesday and Wednesday with deep
low pressure north and shifting east by late Wednesday into
Thursday. Attendant frontal passages along with occasional
shortwaves will maintain low-end PoPs through the extended. For now,
confidence is highest in rain chances for Thursday and Friday where
the NBM paints the highest probabilities for seeing measureable
precipitation. That said, probabilities for widespread wetting rains
appear fairly limited with only the higher percentile values
suggesting this potential. Any precipitation should fall as rain
with lack of more significant colder air. The threat for widespread
frost or freeze events appears fairly limited as well, however,
localized needs cannot be ruled out.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
-- Changed Discussion --
Issued at 638 PM CDT Sat May 4 2024

Mostly quiet aviation conditions are expected over the next day. The
only concern will be some stronger winds across the region during
Sunday afternoon. South to southeast winds will gust up to 25 to 35
knots by late afternoon continuing through the rest of the TAF
period.
-- End Changed Discussion --

&&

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

&&

$$

SHORT TERM...NMJ
LONG TERM...NMJ
AVIATION...Kulik