902
FXUS63 KLBF 151755
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1255 PM CDT Sun Sep 15 2024

.KEY MESSAGES...

- Although widespread severe weather is not anticipated,
  isolated to widely scattered strong to severe storms are
  possible this evening for areas generally west of Highway 61.

- Confidence continues to increase on the potential for gusty
  winds (30+ mph) Monday and Tuesday ahead of a potent system
  pushing inland across the western US.

- A cold front will bring an increased threat for precipitation
  Tuesday night into Wednesday, with a secondary threat for
  precipitation late week into the weekend.

- High confidence (>90%) in above normal temperatures through
  the week before trending cooler into the weekend.

&&

.SYNOPSIS...
Issued at 338 AM CDT Sun Sep 15 2024

Recent GOES-16 WV imagery and RAP 500-mb analysis showed the
remnants of tropical system Francine across the Tennessee Valley
and Deep South. Just to the north of this feature, an upper-level
high pressure system continues to hold strong over the Great Lakes
region with a ridge extending northward into the eastern portions of
the Hudson Bay. A potent upper-level low was centered off the coast
of British Columbia with a trough extending southward along the
Pacific Northwest. All of these features combined has resulted in
southwesterly flow aloft across western and north central Nebraska.
A weak shortwave traversed across portions of the region overnight,
generating widely scattered showers and thunderstorms across north
central Nebraska. Outside of this activity, a relatively quiet night
has set up across the area with 3 AM CT temperatures ranging from
62 degrees at Imperial to 67 degrees at North Platte.

&&

.SHORT TERM /THROUGH MONDAY NIGHT/...
Issued at 338 AM CDT Sun Sep 15 2024

Today and Tonight... Dry and breezy conditions are expected through
a bulk of the day across western and north central Nebraska. Surface
high pressure will continue to hold strong across the eastern half
of the US with the surface trough of low pressure deepening across
eastern Wyoming into eastern Colorado. Southeasterly flow ahead of
the surface trough will amplify with a tightened surface pressure
gradient (SPG) between the two surface features. As a result,
southeasterly winds will become rather breezy today with widespread
gusts of 25 to 30 mph. High temperatures will remain in the above
normal range from the upper-80s to low-90s. As we head into this
evening, a shortwave trough is forecast to move northeastward
through the central Rockies. The low-level flow will allow for
increased moisture advection across the area with afternoon dew
points rising into the upper-50s to mid-60s. This combined with
daytime heating will support a corridor of moderate instability
(MLCAPE up to 2,000 J/kg) ahead of the disturbance. Isolated to
scattered thunderstorm initiation is expected by this evening across
the higher terrain of Colorado and Wyoming, tracking northeastward
into portions western Nebraska through midnight CT. Though 0-6km
shear remains moderate(25 to 30 kts), steep mid-level lapse rates
(approaching 8.5 C/km) will create an environment supportive of a
few strong to severe storms capable of producing damaging winds and
large hail for areas west of Highway 61. Anticipate this activity to
diminish through the early tonight period as it moves further
northeast/eastward. Unfortunately, not much in the way of wetting
moisture is anticipated with this activity with most locations
remaining dry versus seeing any meaningful precipitation.
Otherwise, generally quiet conditions will ensue through the
overnight period with low temperatures falling into the
upper-50s to mid-60s. The low-level jet (LLJ) will amplify
through the overnight period resulting in continued breezy wind
gusts up to 30 mph.

Monday and Monday Night...The previously mentioned LLJ and
increased mid- level warm air advection (WAA) may be enough to
trigger early morning elevated showers and thunderstorms for
areas east of Highway 183. Outside of this, dry conditions are
expected to continue across western and north central Nebraska
on Monday. The western US upper-level trough will move inland
across California, with amplified southerly low-level flow.
This will set the stage for a windy day on Monday with current
guidance suggesting widespread gusts up to 35 mph with locally
higher gusts up to 40 mph. While not an anomalous event,
especially for Nebraska, these gusty winds have continued to be
highlighted by the Extreme Forecast Index (EFI) such that the
SoT (Shift of Tails) is greater than 0. Daytime temperatures
will remain in the above normal range from the mid-80s to
low-90s across western and north central Nebraska. Though
conditions remain hot, dry, and windy, low level moisture will
be prevalent across the area, limiting fire weather concerns
through midweek. Another shortwave ejecting northeastward across
the central Rockies combined with increased mid-level WAA and a
strengthening LLJ will present another opportunity for elevated
shower and thunderstorm development overnight Monday for areas
east of Highway 83. The LLJ will result in continued gusty winds
up to 35 mph through the overnight period into Tuesday.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Issued at 338 AM CDT Sun Sep 15 2024

Tuesday and Wednesday...The strong upper-level trough will track
northeastward into the Great Basin on Tuesday with continued
amplified low-level flow. As such, strong southeasterly winds will
persist on Tuesday with widespread gusts up to 35 mph and locally
higher gusts up to 40 mph possible. By Tuesday night, a strong
upper-level shortwave will lift into the northern Rockies,
forcing a frontal boundary through the area leading to an
increased threat for showers and thunderstorms. When looking at
precipitation totals, NBM Probabilities indicate a 40 to 60%
chance for 24 hour (12Z Tue through 12Z Wed) 0.25"+ liquid
equivalent precipitation across all of western and north central
Nebraska. Fortunately we will get another shot at widespread
meaningful precipitation as we head into the latter end of the
week into the weekend. This frontal boundary will also bring an
end to the gusty winds for Wednesday as the low-level flow
relaxes.

Thursday and beyond...The upper-level trough of low pressure will
remain across the western CONUS through the end of the week.
Additional frontal boundaries advance through western and north
central Nebraska through the weekend resulting in unsettled
conditions continuing and a trend towards cooler temperatures,
falling into the 70s by Saturday.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1249 PM CDT Sun Sep 15 2024

VFR conditions will prevail across western and north central
Nebraska the next 24 hrs. Isolated thunderstorms will be
possible this evening across portions of western Nebraska,
mainly the Panhandle into the western Sandhills. Otherwise
low-level wind shear is expected to develop across the area
after midnight tonight and persist until sunrise Monday morning.

&&

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

&&

$$

SYNOPSIS...Viken
SHORT TERM...Viken
LONG TERM...Viken
AVIATION...Taylor