272
FXUS63 KLBF 300855
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
355 AM CDT Tue Apr 30 2024

.KEY MESSAGES...

-  Elevated to near-critical fire weather conditions are
   expected to develop across western Nebraska into the
   panhandle this afternoon though greenup is well underway.

- There is potential for strong to severe thunderstorms late
  this afternoon for portions of Nebraska mainly along and
  east of Highway 281.

- There is potential for strong to severe thunderstorms again
  Wednesday evening into early Wednesday night mainly from Grant
  through North Platte to Broken Bow and southward.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 353 AM CDT Tue Apr 30 2024

A vigorous short wave will drive a surface low across the High
Plains and push a cold front through Nebraska today. The front has
good mid level deformation and FGEN forcing but deep moisture is
lacking. Anticipate there may be a few sprinkles from some mid level
moisture early this morning with the better chances for
showers/thunderstorms more closely associated with the frontal
passage and mostly confined to along/north of Hwy 2 closer to the
better moisture. The best potential for string to severe
thunderstorms will accompany a plume of moisture surging up from the
Gulf this afternoon, but this will be mainly across eastern Nebraska
later this afternoon as the front is exiting the region. There
may be a window for convective initiation to occur near Hwy 281
with a marginal severe threat but the main threat area is
expected to reside off to our east.

Winds behind the front will veer to the northwest and become quite
gusty with probabilistic guidance showing up to an 80 percent
chance for gusts in excess of 35 mph west of Hwy 83 and
particularly in a corridor down the North Platte river valley
from Oshkosh to North Platte. The lack of moisture combined with
some downsloping will generate very dry conditions with a much
better than even chance for minimum relative humidity values
below 20 percent from the southern panhandle into southwest
Nebraska this afternoon. This will create elevated to near
critical fire weather conditions for any patchy/areas of
lingering old growth cured fuels, though green up and our recent
cool/damp conditions will help mitigate fire concerns.

A progressive upper level pattern with a closed low/trof moving into
the northern Rockies will keep our weather active through midweek.
So after a brief break of dry conditions Tuesday evening into
early Tuesday night, isentropic lift associated with a surface
low developing over eastern Colorado will start to push some
showers northward into Nebraska toward daybreak Wednesday
morning, and by Wednesday afternoon showers and some thunder
will have overspread the majority of the area. As the low starts
to eject eastward late Wednesday into Wednesday night it will
combine with a plume of deep moisture moving up from the south
and significant mid level forcing to bring thunderstorms with
locally heavy rainfall to portions of southwest and central
Nebraska, mainly from Imperial through North Platte to O`Neill.
Will be monitoring locations along and east of Hwy 183 closely
for potential flooding from excessive rainfall on soils that
remain wet from recent heavy rainfall from Hwy 183 eastward.
Additionally, modest elevated instability with steep mid/upper
level lapse rates will be able to generate some robust storms
with a marginal severe threat primarily for hail early Wednesday
night mainly from Imperial through North PLatte to Broken Bow
and southward. Will be monitoring the potential for severe
weather and hydro concerns closely over the next several data
cycles for any chances that may impact threat levels across
central and western Nebraska. Showers and thunderstorms will be
pushing off to the east later Wednesday night.

Highs today will range from only around 60 degrees across northwest
Nebraska where the cold front will pass earlier in the day, to the
middle 70s across south central Nebraska where the frontal passage
will be later. Post frontal highs tomorrow will be cooler with
readings topping out generally in the 60s. Overnight lows will
generally be in  the upper 30s to lower 40s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 400 PM CDT Mon Apr 29 2024

The threat for strong to severe storms persists into Wednesday, as
yet another shortwave is progged to cross into the Plains by late
Wednesday evening. At the surface, the aforementioned cold
front will quickly stall across central Kansas, with lee
cyclogenesis beginning across southeastern CO. This places our
area in post frontal broad east-southeasterly upslope flow. The
easterly flow will pull the moisture that was ushered out
behind tomorrow`s cold front right back into the area, with
dewpoints increasing through the afternoon. The exact degree of
moisture recovery remains somewhat uncertain, and this will
determine the areal coverage of any severe weather threat.
Portions of central and north central Nebraska look to have the
best shot at higher dewpoints/greater instability, in closer
proximity to the surface warm front in central Kansas.
Hodographs look more than adequate to support severe weather
across much of the area as well, with ample curvature in the
lowest few kilometers and increasing speed shear aloft.
Synoptically, this does resemble a regime that is favorable for
severe weather across western Nebraska as well, with convection
initiating across the Front Range of Colorado in the broad
upslope and pushing northeastward into the area. Should discrete
storms sustain themselves into western and southwest Nebraska,
a threat for large hail and damaging winds would be possible,
again driven by the degree of instability with northeastward
extent.

The pattern remains active into the latter part of the workweek and
into early this weekend, as multiple shortwaves look to push through
the area in the quasi-zonal flow aloft. Nearly daily shower and
thunderstorm chances exist through Saturday across much of the area.
The degree of any severe weather threat will be driven by surface
features each day, though mid/upper level flow does look strong
enough to warrant at least some concern for severe weather.
Mesoscale features will need to be watched closely, and additional
threats for severe weather may exist as we wrap up the workweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1245 AM CDT Tue Apr 30 2024

VFR conditions are expected to prevail across western and north
central Nebraska through tomorrow night. The primary aviation
concerns over the next 24 hours are mostly wind related. Tonight, a
strong low level jet brings LLWS concerns to both terminals and the
surrounding areas. Before 09Z, LLWS concerns may be observed across
all of western and north central Nebraska, but expect that LLWS
concerns after 09Z will be primarily along and east of Highway 83,
including both KLBF and KVTN. A frontal passage will bring numerous
wind shifts tomorrow afternoon and evening, with winds eventually
becoming strong northwesterly winds with strong gusts. Forecast
soundings show potential for strong mixing, so gusts may end up
being stronger than currently forecast. Due to the amount of wind
shifts expected throughout the period, decided to focus more on the
near term, and will attempt to catch the later wind shifts (after
01Z) in the follow on forecasts.

&&

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

&&

$$

SHORT TERM...MBS
LONG TERM...Brown
AVIATION...Richie