527
FXUS63 KLBF 231121
AFDLBF

Area Forecast Discussion
National Weather Service North Platte NE
621 AM CDT Thu May 23 2024

.KEY MESSAGES...

* An enhanced risk (risk level 3 of 5) of severe weather is possible
  this evening (Thursday evening) with large hail up to baseball
  size, severe winds up to 75 mph, and an isolated tornado as the
  primary threats.

* Active weather returns on Saturday and Sunday evenings, however,
  the severe potential remains low at this time.

* Drier weather with a gradual warming trend is expected for next
  week with highs returning to the upper 70s to low 80s by next
  Wednesday.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 356 AM CDT Thu May 23 2024

The main weather story in the short term will be the potential for
severe thunderstorms this evening and into the overnight. Dewpoints
will increase across the region through this afternoon providing
increased low level moisture across the region. Moderate instability
will also develop across north central and into central Nebraska by
the late afternoon. Ample instability will exist across the region
to support the development of supercells initially across portions
of north central Nebraska. As these storms track eastward, storms
will become more of a convective line, possibly even take on QLCS
characteristics. Current model guidance suggests lapse rates above 7
C/km along with significant CAPE (over 2000 J/kg). This combined
with large CAPE in the -10 to -30 degree C layer will support very
large hail (potentially up to baseball sized). This environment will
also create the potential for significant wind gusts up to 75 mph.
In addition to hail and strong winds, this environment will be
favorable for some brief tornadoes especially initially when low LCL
heights and near surface storm relative helicity remains above 200.
As this time, widespread flooding is not expected to be a concern,
although, some localized brief flash flooding could still occur
under some of the more intense thunderstorms falling on recently
saturated soil from earlier this week. Any impacts, though, should
be short lived as storms quickly push off to the east.

Showers and thunderstorms will move into eastern Nebraska by early
Friday morning (shortly after 06Z) bringing an end to the severe
potential to north central Nebraska. A drier day is expected for
Friday as surface high pressure builds into the Great Plains. A
cooler airmass will also move in behind the cold front and departing
system resulting in cooler than normal highs on Friday (normals in
the mid 70s). Highs are anticipated to only rise into the mid to
upper 60s, with a few locations south of I-80 potentially reaching
70 degrees.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 356 AM CDT Thu May 23 2024


Quiet conditions continue through Saturday morning as weak upper
level ridging slowly pushes off to the east. A series of
disturbances will then impact Nebraska through the remainder of the
weekend. At this time, severe weather risk remains low with
confidence remaining low on timing, track, and locations. Current
SPC guidance suggests that the strongest activity will remain off to
the east on Saturday night, however, this may change over the next
day or so. Those with outside plans in the evening this weekend
should stay weather aware and be prepared to make alternate plans.
Strong upper level ridging will return for the beginning of next
week bringing a return to dry weather to north central Nebraska.

For temperatures, cooler temperatures will begin the extended period
with highs only in the mid 60s to low 70s. These temperatures will
gradually increase as upper level ridging returns and warm air
advection pushes back into the region by early next week. Highs by
next Wednesday will rise back into the upper 70s to low 80s. Low
temperatures through mid-next week will remain well above freezing
keeping any frost concerns at bay.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 620 AM CDT Thu May 23 2024

Little change in reasoning as guidance remains consistent in
depicting VFR conditions at TAF sites through at least the
first part of the TAF period, but expect significant impacts to
aircraft operations gusty surface winds, potentially severe
thunderstorms late today/tonight, and low level wind shear for
an hour or two after issuance.

Significant low level wind shear will be present at issuance across
central and western Nebraska but expect it will wane over the
next 1 to 2 hours as the low level jet dissipates. Once diurnal
heating mixes the boundary layer this morning, surface winds
will become gusty with winds to 30kt or so expected into the
afternoon.

Guidance continues to advertise potential for 2 separate
triggers for convection, first with a dryline and then with a
cold front. Any storms with the dryline will have potential to
be discrete, individual cells with very large hail and strong
gusty winds. As the cold front overtakes the dryline and becomes
the dominant driver of convection, storms are expected to
develop into a linear complex that may produce very strong winds
and large hail as it moves from central into eastern Nebraska.
Storm initiation may occur west of Highway 83, though confidence
in exact timing and locations is not high. Will use 2 separate
periods for VCTS at KLBF and KVTN to indicate periods of best
potential for thunderstorms with the dryline followed by
thunderstorms along/ahead of the approaching cold front. All
convection with a return to VFR looks like a good bet by the end
of the valid period as convection pushes off to the east and
southeast. However winds behind the front tonight will become
quite gusty but confidence in amount of mixing is not high. Will
indicate northwesterly gusts near 30kt for KLBF and near 35kt
for KVTN thorugh the latter portion of the valid period with the
understanding that there is potential for gusts to overperform
behind the front.


&&

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

&&

$$

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