000
FXUS63 KLBF 250531
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
1231 AM CDT Thu Apr 25 2024

.KEY MESSAGES...

- Isolated to scattered thunderstorms for the panhandle and
southwest Nebraska tonight into early tomorrow with a low severe
threat

- Greater severe threat with storms beginning tomorrow afternoon and
evening, continuing into the nighttime. Hail will be the main
concern, although strong winds and a brief tornado are also possible.

- Widespread rain showers Friday through Sunday with potential for
significant moisture totals of 1-2"

- Warmer and drier for first half of next week

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 418 PM CDT Wed Apr 24 2024

This evening and tonight... Two areas will be the focus for
thunderstorm potential. The first concerns ongoing convection along
the Laramie Range which may survive its journey through the Nebraska
panhandle this evening. Most short term high-res solutions suggest
this activity to dwindle as it approaches the Hwy 61 corridor, but
kept chc PoP. Severe threat appears limited as dew points hold near
40F and overall instability is weak. The second area will be toward
the southern reaches of the CWA as a warm front develops in Kansas
and a modest (~35kt) low level jet noses into the Sandhills. For
this setup, the most likely timeframe will be after 09z. Instability
appears to actually increase overnight as low level moisture
advection increases, but shear backs off compared to earlier in the
night despite the low level jet. With this activity likely being
elevated in nature, hail will be the main concern. Parameters
suggest it remaining sub-severe, however. Dry conditions and a
steady southerly breeze will be the most probable scenario for a
good chunk of the Sandhills or north central Nebraska. Used a
general blend for the min temp forecast and bumped up a degree or
two toward the upper end of the NBM envelope. Thinking the
combination of increasing cloud cover, likely in the form of a
stratus shield, and modest warm air advection will keep temps fairly
mild. Guidance suggests 24 hr temp changes at H5 ending at 12z of 3-
4C across the CWA. Forecast ranges from mid 40s panhandle to near
50F central.

Tomorrow into tomorrow night... Warm air advection slows, but
moisture advection keeps up throughout the day, partly shown by
surface dew points rising into the lower 50s. The main surface low
deepens across eastern Colorado and the attendant warm front
gradually lifts north across Kansas. Its northward progress will
play a huge role in severe potential for our forecast area. At this
time, guidance suggests it will bisect the GLD CWA by 00z, keeping
Nebraska in the cool sector. In fact, the NBM envelope falls almost
entirely in the 60s for highs for most of southwest into central
Nebraska. A bit more sunshine in the northern panhandle may push
locations toward 70F. The overrunning moisture and deep isentropic
upglide should maintain the stratus deck during the day, which will
hamper the best instability. While the greater low level forcing
lies south of the area, mid-level lapse rates may be very steep over
the Sandhills with some solutions showing 8-8.5 C/km. The strongest
deep layer (as well as low level) shear also stay south of I-80. The
vicinity of the surface low and front result in large helicity
values along the NE/KS line, and with modest moisture profile and
lower LCL`s, agree with heightened tornado potential. If the front
ends up drifting 50 miles farther north, think the tornado threat
increases quite a bit for our CWA. With the current info though,
hedging toward an isolated or scattered storm threat for
southwestern zones during daylight hours on the edge of the greater
severe potential. Toward dark, the redevelopment of the low level
jet and arrival of the upper low will greatly increase overall
forcing. While surface features may still be concentrated to the
south, abundant moisture and elevated features should fire off a
number of storms in the Sandhills. Modest MUCAPE values around 1000
j/kg and continued steep mid level lapse rates, along with bulk
shear up to 40 kts, will support some severe storms farther north.
Hail will be the main concern, although a few wind gusts may
approach severe limits. The PoP forecast reflects the conditional
storms in the south to begin the event and greater coverage and
confidence overnight in the north.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 418 PM CDT Wed Apr 24 2024

Friday through Sunday... The upper low hangs right on top of the
forecast area Friday, which will keep the rain potential going. Cool
and moist northwest low level flow will lessen the severe threat,
but a brief hail/wind concern exists for far north central Neb where
southerly H85 flow still exists at 21z. A second upper low is quick
on its heels, rounding the Four Corners on Saturday and reaching the
Sandhills early Sunday. The second system appears to have a classic
deformation band setup across the forecast area and be a winter
storm should this occur a month earlier. Thermal profiles suggest
rain, and moisture totals could be fairly impressive. When all is
said and done, widespread 1" amounts appear likely and some spots
could top 2" depending where the heavier storms roll through.
Temperature-wise, a steep gradient may set up across the area due to
the rain core and the transitioning low level flow. Highs will range
from 50s northwest to near 70F far southwest on Fri and Sat, then
40s and 60s for Sun.

Monday and beyond... Upper flow switches to quasi-zonal to start the
week as the low kicks out of the Plains. Surface high pressure also
gives way to a warm front pushing north through the Missouri Valley.
Additional precip chances appear limited, but temperatures moderate
quite a bit with highs in the 70s likely. The warmer end of the NBM
suggests 80s across the south toward midweek.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1226 AM CDT Thu Apr 25 2024

Active period begins early Thursday morning as light showers
track west to east along the Platte Valley, with little to no
impacts at LBF initially. Later, more widespread rain and
thunderstorms will develop near if not over the LBF terminal and
lift north and east. This will drop flight categories to MVFR,
largely due to lower CIGs though brief visibility restrictions
in heavy rain cannot be ruled out. This activity may linger
through sunrise before shifting north.

The bulk of the daytime Thursday is anticipated to be quiet
outside of breezy east winds under a low to mid level stratus
deck. Gusts this afternoon will approach 30 knots. Tonight, rain
and thunderstorms are again expected to move into western and
central Nebraska affecting many terminals. Confidence in timing
of this round of convection is medium at best, with guidance
split on arriving the activity into LBF prior to the end of the
period or just after. For now, will hedge on an earlier arrival
but later forecasts may have a noteworthy shift in timing.
Accompanying these thunderstorms will likely be IFR CIGs with
both HREF and SREF probabilities of < 1kft ceilings increasing
to roughly a 50/50 shot.

&&

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

&&

$$

SHORT TERM...Snively
LONG TERM...Snively
AVIATION...NMJ