998
FXUS64 KLUB 282325
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
625 PM CDT Fri Jun 28 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday)
Issued at 216 PM CDT Fri Jun 28 2024

The core of the upper level ridge remains over central TX early this
afternoon with a belt of stronger midlevel flow aloft associated
with a modest shortwave confined well to our north over SE CO and SW
KS. Relatively deep surface troughing has expanded over most of the
OK/TX Panhandles in response to this feature, resulting in breezy
southwest surface flow across most of our area. Strong diurnal
heating associated with this downslope flow should allow convective
temperatures to easily be reached across the South Plains region
which combined with a bit of residual midlevel moisture may allow an
isolated thundershower or two to develop through this evening. Given
the warm mid/upper level temperatures present, instability remains
quite low and no more than a few updrafts are expected to develop
and persist, but very high cloud bases will support a downburst
threat with any storms that do develop.

Surface winds will gradually back more south-southeasterly tonight,
with SE return flow continuing through most of the day Saturday
ahead of a cold front marching slowly southward over northern
portions of the TX Panhandle. Surface dewpoints will consequently
increase and are expected to remain above 60F off the Caprock
through Saturday afternoon. With ridging aloft still in place
overhead and highs in the upper 90s and low 100s, heat advisory
criteria is expected to be met once again over the eastern Rolling
Plains and far SE TX Panhandle on Saturday afternoon. The
aforementioned cold front will likely remain near or just south of
I-40 through the second half of the day on Saturday, but a relatively
moist boundary layer, subtle pre-frontal surface troughing, and a
weakness along the western edge of the upper ridge should all
combine to support the development of a few thunderstorms by late
Saturday afternoon over the SW TX Panhandle and NW portions of the
South Plains. Coverage of this activity will still be relatively
sparse, with much better storm chances confined to our north in
closer proximity to the front.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 216 PM CDT Fri Jun 28 2024

Isolated-to-widely-scattered thunderstorms may be ongoing across the
extreme southern Texas Panhandle and portions of the northwestern
South Plains on Saturday evening, with the best coverage forecast to
be across the extreme southwestern Texas Panhandle. At the beginning
of the period, the mid/upper-level pattern will feature a dampened,
subtropical ridge stretching over the entire State of Texas due to
an amplified shortwave trough digging into the Great Lakes region.
The CWA will be located on the western periphery of this 596 dam
ridge, with southwest-to-northeast-oriented steering flow becoming
established aloft by Saturday night. At the surface, a stalling cold
front should be located near the I-40 corridor as it moves beneath
the barotropic airmass, where moist, southeasterly flow will be
intact across the entire CWA after 30/00Z. Substantial adjustments
to PoPs have been made for the start of the period into Sunday, with
the chance PoP contour delineated across the extreme southwestern
Texas Panhandle while the slight chance contour was shifted farther
west and north compared to the blended initialization. These changes
were made due to the expectation for the stalled front to remain
north of the CWA; however, in the event a southward-surge of the
front occurs along the edge of the Mescalero Escarpment via
reinforcement from convective outflow, then chances for storms would
improve across the northwestern zones. The thinking is leaning
towards lower-bound PoPs/more-isolated coverage of storms compared
to areas north and west of the CWA. The primary storm mode will be
high-based, multi-cellular clusters with warm-cloud depths near 15
kft AGL, facilitating the potential for locally damaging wind gusts
and brief downpours on Saturday night into early Sunday morning.

Very warm temperatures are forecast heading into Sunday morning due
to near-neutral to slightly positive geopotential height tendencies
atop the return flow. Convective cloud/anvil debris should be
limited to the western South Plains and extreme southern TX PH due
to the southwesterly flow in the upper-levels with low temperatures
ranging from the lower 70s near the TX/NM state line to near 80
degrees along the 100th meridian, the latter adding to heat stress
on infrastructure and vegetation. Thunderstorm chances will be
confined to the extreme southern TX PH through late Sunday morning
with most of the convection occurring well to the north of the CWA,
though it is possible that residual outflows propagate southward
into the CWA. Such occurrence of this mesoscale phenom may result in
cooler temperatures than what is currently forecast across the
extreme southern TX PH. It is counterintuitive to forecast cooler
temperatures with slightly positive geopotential height tendencies;
however, the core of the subtropical ridge will shift over North
Texas by Sunday with easterly, mid-level flow advecting into the
Rolling Plains. Temperatures will still be hot but are forecast to
remain below 100 degrees across most of the CWA with the exception
of locales nearest the 100th meridian on Sunday.

Amplification of the subtropical ridge is forecast to occur by early
next week as it wobbles eastward across North Texas and into the
Mississippi Alluvial Plain. Hot, dry, and breezy conditions are
expected area-wide on Monday as surface troughing sharpens across
the High Plains in response to lee cyclogenesis associated with
another shortwave trough pivoting over the northern Rocky Mountains.
The deeply-mixed boundary and dewpoints in the middle-upper 50s will
keep heat indices in check; however, temperatures in excess of 100
degrees are forecast for portions of the Rolling Plains while
remaining in the middle-upper 90s across the Caprock. High
temperatures will also vary by a couple of degrees each afternoon as
broadly cyclonic flow eclipses the region, with Tuesday potentially
being the hottest day of the week as temperatures soar near or into
Heat Advisory criteria (i.e., heat index values or temperatures
between 105-109 degrees) across the Rolling Plains.

All suites of global NWP guidance are in agreement with the
subtropical ridge shifting farther east into the Deep South as the
aforementioned shortwave trough ejects over the northern Great
Plains. The CWA will be under the glancing influence of this trough
and also within the inflection point of the stout ridging to the
east. The position of these synoptic features will govern some
strengthening to the southwesterly flow aloft, with the CWA being
positioned within close proximity to the right entrance-region to
the 250 mb jet streak as it translates across the Great Plains.
Diurnally-driven, late-day thunderstorms continue to be forecast
each day Tuesday through Friday as broad troughing persists across
the northern U.S. due to an amplifying, mid/upper-level ridge over
the northeastern Pacific Ocean. The blended PoPs have been
maintained for this stage of the forecast period, with the best
potential for thunderstorms across portions of the Caprock as the
monsoonal fetch slowly shifts eastward towards the CWA.

Sincavage

&&

.AVIATION...
(00Z TAFS)
Issued at 621 PM CDT Fri Jun 28 2024

VFR conditions are expected to prevail at all three TAF sites
through the period. The south winds will back to the southeast by
early tomorrow afternoon with wind speeds generally around 5 to 15
knots. The potential for an isolated thunderstorm this evening has
lowered significantly with only a few to scattered high clouds
present. Check density altitude.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM CDT this evening for TXZ025-026-031-032-
037-038-042>044.

Heat Advisory from 1 PM to 8 PM CDT Saturday for TXZ026-032-038-
044.

&&

$$

SHORT TERM...30
LONG TERM....09
AVIATION...11