694
FXUS64 KLUB 282313
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
613 PM CDT Sun Apr 28 2024

...New AVIATION...

.SHORT TERM...
(This evening through Monday)
Issued at 217 PM CDT Sun Apr 28 2024

Quiet weather will persist tonight as the upper-level low slowly
shifts into the upper Midwest. A weak shortwave will slide across
the forecast area tonight although moisture associated with this
system will be shallow as dry air remains at the surface. This will
increase mid-level cloud cover across the far southern Texas
Panhandle into the northern South Plains and could lead to a few
virga showers which would cause gusty and erratic winds similar to
what happened last evening. We will be located on the subsident side
of the shortwave on Monday which will allow for mostly sunny skies.
A weak surface trough will slide east through the forecast area
during the day which will shift winds to the southwest behind it
while ahead of it winds will become southeasterly however wind
speeds will remain around 10-15 mph. This will help to bump
temperatures back above average into the mid 80s for most locations.
/WI

&&

.LONG TERM...
(Monday night through next Saturday)
Issued at 217 PM CDT Sun Apr 28 2024

The upper air pattern on Tuesday will feature a split in the belt of
high-level flow, with the CWA positioned beneath the bifurcation of
the 250 mb subtropical and polar jet streaks. Broadly cyclonic flow
in the mid-levels will continue to envelope the region along the
southern periphery of a larger-scale gyre located over the northern
Rocky Mountains, and into western and central Canada, where several
vorticity lobes and other smaller-scale perturbations will rotate
about the gyre. The primary shortwave trough is expected to eject
into the north-central Great Plains on Tuesday afternoon; however,
despite the dampened, deep-layer flow, the left-exit region of the
subtropical jet streak is forecast to emerge over the Big Bend
region and eclipse the CWA during the afternoon hours. Large-scale,
geostrophic deformation will also be maintained by the presence of
the broadly cyclonic flow over the central and southern Great
Plains. At the surface, lee cyclogenesis will be ongoing across
western Kansas in response to the ejecting shortwave trough over the
north-central Great Plains, with a sharp, well-defined dryline
extending south-southwestward into the CWA. Strong, mixed-layer
theta-e advection will be ongoing during the morning and into the
afternoon hours despite the attenuated 700-500 mb flow where an
elevated mixed layer (EML) will already exist in the morning hours.

Intense, diabatic surface heating is expected by mid-day with
temperatures breaching 90 degrees across the dry and moist sectors
as the dryline remains stalled near the vicinity of the edge of the
Caprock Escarpment. (LBB is forecast to reach 92 degrees, which is
shy of the record of 94 degrees set in 2013.) Already weak MLCINH
will erode quickly across the moist sector with superadiabatic lapse
rates developing west of the dryline, where an EML characterized by
MLCAPE values potentially in excess of 2,500 J/kg evolves across the
east and southeastern Rolling Plains amidst relatively straight
hodographs and weak, effective shear magnitudes of about 30 kt.
Prospects for supercells remain low owing to a number of reasons,
including: the position of the dryline, veered/parallel flow along
the dryline, and parcel residence time along the respective
circulation amidst a well-mixed (Inverted-V) boundary-layer profile
as MLCINH erodes from the intense heating. Slight chance PoPs have
been maintained across the east/southeastern Rolling Plains for late
Tuesday afternoon and evening as the thinking of a cell or two
forming remains intact, and would pose a threat for large hail as
the orientation of the deep-layer flow favors storm-splitting with
updrafts attain modest, mid-level rotation. The best window for
thunderstorm initiation will be as the dryline begins to translate
westward, resulting in an improvement of low-level confluence before
nocturnal stabilization occurs.

Return flow is forecast to intensify area-wide heading into
Wednesday morning as lee cyclogenesis of a 992-996 mb surface low
occurs near the Raton Mesa ahead of a positively-tilted shortwave
trough digging into the central Rocky Mountains. Breezy, southerly
winds will develop during this time as the translates towards the
Texas/New Mexico state line before propagating eastward once again
across the South Plains after sunrise, and perhaps stalling near the
I-27/HWY-87 corridors. Thunderstorm chances improve on Wednesday
with the potential for scattered convection to develop amidst a very
unstable moist sector as mid-level cooling from gradual geopotential
height falls bolsters strong instability with MLCAPE values >=3,000
J/kg developing by late afternoon. Marginal improvements to the
effective shear magnitudes to around 35 kt should occur as divergent
flow increases along the nose of the left-exit region of the 250 mb
jet streak that becomes more-cyclonic as the northern-stream trough
digs into the central Rocky Mountains. Severe thunderstorms will be
possible with supercell wind profiles expected via cross-boundary
shear vectors and relatively straight hodographs, which will once
again favor storm-splitting and potentially sustaining of mid-level
mesocyclones. The best storm chances remain in the Rolling Plains on
Wednesday, but the slight chance PoP extends as far as the HWY-385
corridor across the South Plains. The tail-end of mesoscale guidance
and area-averaged forecast soundings support this prognostication in
addition to the general synoptic-scale pattern. Heavy rainfall will
accompany severe-caliber storms, and this has been reflected in the
official forecast for Wednesday evening across the Rolling Plains.

Predictability of the upper air pattern towards the latter half of
the week becomes convoluted owing to significant discrepancies among
the global NWP guidance on the position and amplitude of the
shortwave trough as it ejects into the Great Plains. Differences
greater than 400 miles on where the base of the trough is located
exists among the deterministic suites, whereas the ensemble and
cluster indicate a lower-amplitude trough compared to the other
amplified solutions. Irrespective of these differences, continuity
remains with southwesterly flow remaining intact over the CWA as
broadly cyclonic flow persists at the very least. Due to the
limitations in the state of the synoptic-scale evolution otherwise,
the blended PoPs have maintained through Friday and into the
weekend, and future adjustments to PoPs may be necessary as NWP
guidance begins to converge in time. This will also dictate the
timing of when the cold front associated with the shortwave trough
moves through the CWA, which is currently late Thursday. Cooler,
though still warm, temperatures will follow as the cold front
eventually passes through the region with renewed chances for
thunderstorms possible area-wide through the end of the period.

Sincavage

&&

.AVIATION...
(00Z TAFS)
Issued at 613 PM CDT Sun Apr 28 2024

Continued VFR with light winds through Monday afternoon.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...58
LONG TERM....09
AVIATION...93