101
FXUS63 KLBF 172105
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
405 PM CDT Tue Sep 17 2024

.KEY MESSAGES...

- Strong to severe thunderstorms are expected to move into
  western Nebraska Nebraska this evening with the primary threat
  being damaging wind gusts of up to 80 mph..

- Strong southerly winds gusting up to 50 mph across much of the
  region will continue to create elevated to near critical fire
  weather conditions into this evening,mainly west of Hwy 83.

- Active weather looks to return this weekend into early next
  week as another trough within southwest flow aloft tracks
  across the area. At this time, precise details remain somewhat
  uncertain.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 248 PM CDT Tue Sep 17 2024

After nearly full sun into this afternoon, temperatures have reached
well into the 90s with a well mixed boundary layer getting high
momentum winds winds aloft to the surface with gusts of 35 to
45mph across central and western Nebraska. Given low humidity
and dry fuels west of Hwy 83 there will be enhanced to near
critical fire conditions into this evening.

A cold front approaching from the west is triggering thunderstorms
upstream over the higher terrain and this activity will
eventually come off the terrain and move thorugh the panhandle
and into the western sandhills early this evening. Dry air is
keeping instability limited to the west though mechanical lift
and modest lapse rates aloft will fuel initial development.
However the dry boundary layer with steep low level lapse rates
and widespread DCAPE values of 1400J/kg will aid downward
momentum transfer and create robust thunderstorm outflows.
There will be potential for significant winds in excess of 75mph
as the thunderstorms move in early this evening west of west of
Hwy 83, and especially out to Hwy 61. Greater instability to
the east will start to wane with loss of daytime heating as the
storms continue moving east to the Hwy 83 corridor later this
evening, though strops will maintain potential for winds in
excess of 60mph through Hwy 83 before diminishing as the
continue further east through the overnight hours.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 248 PM CDT Tue Sep 17 2024

While moderate uncertainty continues through the extended
period, the latest run of ensembles seems to be favoring the
initial closed low over the northern Rockies moving
northeastward into southern Canada through the end of the week,
while the second closed low takes a more southerly track through
southern CA and the Four Corners and moving across the Plains
this weekend. The result will be high confidence in temperatures
trending cooler with readings generally below normal this
weekend and into the first part of next week, though confidence
in precipitation is much lower. There is disagreement among
ensemble members with varying degrees of run-to-run consistency
as to how rapidly and how much the second low fills as it moves
into the Plains, as well as exactly how far south the system
will dig. This has direct implications for precipitation
potential this weekend with potential for a tight north/south
gradient between little precipitation north and significant
precipitation south, and this is evident with dispersion
increasing in QPF plumes through the weekend. Box and whisker
plots also show the uncertainty with a range of about 0.40
inches in the 25th percentile to 1.39 inches in the 75th
percentile at North Platte for 24 hour precipitation ending
Sunday morning, and these numbers become 0.10 and 0.84 at
Valentine. So after 2 dry days Wednesday and Thursday we will
see a steadily increasing potential for precipitation through
the weekend with the possibility for significant precipitation
mainly limited to locations from Imperial through North Platte
to O`Neill southward. Uncertainty continues into the first part
of next week with potential for unsettled conditions in
northwest flow aloft.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 1205 PM CDT Tue Sep 17 2024

Primary aviation concerns this period will be strong southerly
winds ahead of an approaching cold front, followed by potential
for severe storms this evening.

Expect winds will be increasing through this afternoon before
peaking at TAF sites just ahead of thunderstorm arrival,
generally in the 35 to 40kt range. Given strength of gusts at
the surface will omit LLWS from the TAFs as winds aloft are not
much stronger. Will use a 02Z-04Z window for timing arrival of
thunderstorms and potentially severe outflow winds with a quick
swing of direction to the west. Will reevaluate timing and peak
winds once radar trends become established. Will bring
conditions to MVFR with passage of the thunderstorms though a
brief period of IFR is possible, especially given potential for
blowing dust to accompany arrival of outflow winds. Favorable
flight conditions return by daybreak with VFR expected through
the latter portion of the valid period.

&&

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

&&

$$

SHORT TERM...MBS
LONG TERM...MBS
AVIATION...MBS