778
FXUS63 KLBF 110853
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
353 AM CDT Thu Jul 11 2024

.KEY MESSAGES...

-  Prolonged dangerous heat is expected for areas along and
   south of I-80 each afternoon Friday through Monday. An
   Excessive Heat Watch is in effect along and south of I-80 and
   along/east of HWY 61.

-  Further periods of dangerous heat are anticipated Saturday
   and Sunday across all of western and north central Nebraska.

-  Isolated to widely scattered thunderstorms are possible
   across western Nebraska this afternoon and evening and again
   tomorrow. Strong to severe storms will be possible both today
   and tomorrow generally west of HWY 83.

-  Increased fire weather concerns are possible into this
   weekend as well, with a combination of very hot and dry
   conditions. However, winds look to remain below 20 miles per
   hour each day this weekend.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 350 AM CDT Thu Jul 11 2024

Currently, temperatures have fallen into the upper 50s to 60s across
the area, under clear skies and light winds. Patchy fog has been
observed across portions of southwest into central and north central
Nebraska.

For today, expect broad warm advection to continue as southerly flow
strengthens this afternoon. This is in response to deepening surface
low pressure across eastern CO/WY. By late this afternoon, an
associated surface trough axis will slide east into far eastern WY
and the western Panhandle. It is along this surface trough that
isolated to widely scattered thunderstorm development is anticipated
this afternoon, as strong surface heating quickly erodes any
lingering convective inhibition. Flow aloft remains strong enough to
keep hodographs lengthened with height, and deep layer shear of 30
to 35kts is expected across western Nebraska today ahead of the
surface trough. Dewpoints in the low/middle 50s west of HWY 83
should support at least adequate MLCAPE (~750-1000J/kg) and a few
loosely organized thunderstorms are expected this afternoon and
evening across western Nebraska. The primary hazards look to be
strong outflow winds and dry lightning strikes, as forecast
soundings indicate robust inverted-v thermodynamic profiles. Any
threat for hail remains less certain, as temperatures remain very
warm aloft (H7 Ts ~14-15C). Storms should wane as they move eastward
into the Sandhills late this evening, amid a loss of diurnal heating
and encountering a more stable boundary layer.

Highs today range from the middle 80s in north central Nebraska to
the middle 90s along and west of HWY 61. Though the start of
dangerous heat looks to hold off one more day, heat index values
approaching the middle 90s across western Nebraska could still be
hazardous today to sensitive groups.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Issued at 350 AM CDT Thu Jul 11 2024

The primary concern in the long term is the arrival of much
advertised dangerous heat.

As we head into the weekend, heights aloft build above the 90th
percentile climo, as an anomalous upper ridge axis approaches
overhead. Broad warm advection will push temperatures aloft upwards
to near/exceeding the 90th percentile climo as well. The combination
of this will push temperatures into the upper 90s to low 100s, and
this looks to persist into early next week. The most prolonged heat
conditions look to exist along and south of I-80, where highs will
reach the low 100s by Friday. This will then stick around through
Monday, where areas of southwest Nebraska will remain pre-frontal as
a front begins to drop southward Monday afternoon. With the
threat for a multi-day period of prolonged dangerous heat (Heat
Index values near/exceeding 100F each day) looking increasingly
likely, have issued an Excessive Heat Watch for areas
along/south of I-80 and along/east of HWY 61. This is where
confidence is highest in dangerous conditions lingering for the
entire Friday through Monday period. Though we are nearing the
climatologically warmest part of the year, the persistence of
this heat for areas of southwest Nebraska is uncommon even for
mid/late July. In fact, when looking at the 149 period of record
for North Platte, a stretch of 4 consecutive days with highs of
100F+ has as recurrence interval of occurring just once every 8
years. Add in the dangerous heat centering over a weekend,
believe a prolonged heat headline is more appropriate across
southwest Nebraska.

For areas north of I-80, dangerous heat is still anticipated both
Saturday and Sunday, though confidence in this remaining prolonged
for more than just a couple of days remains low for now. Still, heat
headlines will likely be needed for the rest of western and north
central Nebraska Saturday and Sunday, as dangerous heat is looking
increasingly likely area wide. Sunday looks to be the warmest day by
far, with upper 90s in north central Nebraska (along with slightly
higher humidity) to temperatures nearing 105F in southwest Nebraska.
Those with outdoor plans this weekend should take necessary
precautions, as the threat for heat related illnesses will
significantly increase over the next few days.

Some relief will arrive on Tuesday behind the aforementioned
Monday frontal passage, though temperatures will remain in the
upper 80s to 90s. The greater relief looks to hold off until
Wednesday, when highs fall into the low to middle 80s.

Convection chances will also persist into Friday afternoon, as the
aforementioned surface trough remains positioned across the
Panhandle. Isolated to widely scattered thunderstorm development is
anticipated again along this boundary, with a renewed threat for
strong outflow winds and dry lightning amid similarly dry boundary
layer conditions across western Nebraska. Additional threats for
convection will return into early and the middle of next week,
though confidence in any severe weather threat remains low for now.
Will have to watch the progression of stronger westerlies aloft, as
the upper ridging breaks down early next week. Regardless, the
pattern looks to return to more active into next week, with a return
of more scattered to widespread thunderstorms.

The increasing heat and dry conditions could also lead to increased
fire weather concerns this weekend, especially across western
Nebraska where the driest conditions are anticipated. Fuel status
remains uncertain, but will have to monitor how things progress as
the dry and hot conditions continue. That said, winds look to
remain light both Saturday and Sunday when temperatures are
expected to be the warmest. Some dry lightning potential may
accompany thunderstorms both Thursday and Friday afternoon as
well. Will also have to monitor portions of southwest Nebraska
Monday, as ridge breakdown occurs and winds strengthen near and
behind the approaching surface front.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1215 AM CDT Thu Jul 11 2024

VFR should continue through the forecast period for western and
north central Nebraska terminals, although a couple concerns
exist. One is patchy fog development overnight into the early
morning hours, which should stay confined to eastern Nebraska,
but cannot rule out a brief visby reduction at LBF. Another is
isolated thunderstorm development in far western Nebraska during
the afternoon and evening, which should mainly be confined west
of LBF to VTN. Finally, south/southeast winds will be gusty
throughout the afternoon with speeds 20+ kts.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Excessive Heat Watch from Friday afternoon through Monday
evening for NEZ057>059-069>071.

&&

$$

SHORT TERM...Brown
LONG TERM...Brown
AVIATION...Snively