182
FXUS64 KLUB 221129
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
629 AM CDT Tue Apr 22 2025

...New AVIATION...

.KEY MESSAGES...

 - Scattered thunderstorms are expected across much of the
   forecast area this afternoon through late this evening, with
   some storms likely becoming severe.

 - Daily chances for thunderstorms, some severe, will exist
   through the rest of the week as an unsettled weather pattern
   persists across the region.

&&

.SHORT TERM...
(Today and tonight)
Issued at 320 AM CDT Tue Apr 22 2025

Flow aloft has backed to a more west-southwesterly direction early
this morning ahead of a low-amplitude upper level shortwave trough
analyzed on water vapor imagery just off the SoCal coast at 07z.
This feature appears a bit weaker than previously progged, with the
southerly component of the flow aloft over West Texas set to also be
relatively weak as a result. At the surface, SSE flow has resulted
in a gradual increase in low level moisture, but this will continue
to be a relatively slow process over the next several hours, with
upstream observations showing >50F dewpoints still confined to the
TX Hill Country at 07z. Model consensus still brings these 50+
degree dewpoints into our region by mid-morning today, but given the
slow northward progression this moisture is likely to be more
shallow than previously expected which will have some negative
impact on convective potential later today.

Clear skies this morning will allow for a fairly rapid warm-up with
temperatures expected to reach into the 80s by early this afternoon.
Models remain in good agreement that little, if any, capping
inversion will exist today which will in turn allow for relatively
deep diurnal mixing up to or just above 700mb. Hi-res models are
consequently fairly aggressive in mixing out the shallow low level
moisture present, with the dryline likely to be more diffuse and
positioned further east than previously forecast as a result.
Although we still expect scattered thunderstorm development just to
the west of the I-27 corridor this afternoon, this initial activity
is likely to be more high-based with a larger threat for damaging
wind gusts and large hail with the overall tornado threat looking
quite low today. MLCAPE up to about 1500 J/kg and bulk shear
magnitudes near 30 kt should allow a few storms today to become
severe, with wind gusts up to 70 mph and hail up to golf ball size
the primary hazards. Given the only very modest large scale forcing
from the weak upper level shortwave disturbance, and weak WSW flow
aloft, there is less confidence in how this initial thunderstorm
activity evolves later in the day. Models have almost unanimously
trended more sparse in regards to storm coverage this evening into
tonight, with a much lower chance of a heavy rain producing MCS
overnight than previously expected. This seems reasonable given the
weaker forcing and less robust low level moisture, and have
therefore capped PoPs in the chance category today through tonight.
Given the uncertainty in how the event evolves, have also left PoPs
quite broad spatially, with more targeted refinements likely to be
made once it becomes clearer how the initial convection this
afternoon evolves this evening. In general though, expect initial
storms to position near and west of I-27, gradually shifting
eastward and off the Caprock this evening with PoPs decreasing from
west to east tonight.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 320 AM CDT Tue Apr 22 2025

A stormy week ahead remains the main theme of the extended forecast
package, as an unsettled weather pattern develops. Southwest flow
aloft will remain persistent overhead, as an upper level shortwave
trough translates through the Intermountain West, ahead of an upper
level trough that is expected to move onshore the PacNW Friday. A
series of perturbations tracking through the southwest flow aloft
each afternoon will bring daily chances for showers and
thunderstorms to the FA each afternoon through rest of the week and
into the weekend.

Ongoing overnight convection from Tuesday`s system, if any, will
quickly diminish while shifting east out of the area by Wednesday
morning. In the wake of this, low-level stratus is expected to
linger across much of the region through mid-morning, possibly
into the early afternoon for areas off the Caprock. Additionally,
remnant outflow boundaries from overnight convection may also
linger across the FA which in combination with any stubborn clouds
may delay boundary layer recovery during the morning hours. As
skies begin to clear, southwest surface winds will help boost
temperatures and promote diurnal heating across the FA. With
boundary layer mixing deepening through the afternoon, leading to
the erosion of the weak capping inversion depicted on forecast
soundings. Given daytime highs are forecasted in the upper 70s to
lower 80s, convective temperatures look to be attainable with
forecast temperatures set in the mid 70s. Similar to todays set
up, the dryline will be positioned across the TX/NM state line
with dewpoints in the 50s and 60s east of the boundary, which will
serve as the focus point for convective initiation as a ripple in
the flow aloft moves through. MLCAPE values up to 2500 J/kg,
steep mid-level lapse rates around 8 C/km , and effective bulk
shear magnitudes of 30 knots will favor thunderstorms capable of
producing large hail and damaging wind gusts. Overall confidence
in the timing and coverage of storms remains low, being dependent
on boundary layer recovery in the morning and early afternoon
hours. Storms that develop will track from west to east through
the FA where they have the potential to linger overnight once
again as the LLJ ramps up with MUCAPE values around 2000 J/kg.
The synoptic pattern will continue, with a similar set up to
Wednesday expected on Thursday with the dryline positioned out
west, dewpoints progged in the 50s and 60s, in addition to MLCAPE
values of 1500 to 2000 J/kg will promote thunderstorm development
during the afternoon. However this will all be dependent on how
fast the environment is able to recover from previous day and
overnight convection.

Friday will see a shortwave ridge move over the FA, as the upper
level trough moves into the PacNW region, this may allow for a brief
lull in precipitation with NBM looking to pick up on this indication
with PoPs not as high compared to previous runs. Additionally,
ensembles hint at the trough translating through the Great Lakes
region swinging a front through the area. Although deterministic
models have backed off on this, with the front washing out to our
north before reaching the FA. Which has led to NBM high temperatures
Friday and Saturday being much warmer as well compared to previous
runs. Diffluent flow will thereafter return as the ridge exits to the
east, with moist southerly flow prevailing at the surface. Which
will lead to the continuation of thunderstorm chances Saturday
through early next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 621 AM CDT Tue Apr 22 2025

Initially light southerly winds will increase and become breezy by
mid-morning, then remain breezy through the rest of today. Iso-Sct
TSRA are expected to develop to the west of LBB/PVW after about
21z, then slowly shift eastward through the rest of the afternoon
and evening. Thunder will be possible at all TAF sites by this
evening, but exactly how convection evolves and the spatial
coverage of TS remain uncertain, so will cover all terminals with
a PROB30 for the time being until confidence in specifics
improves. Expect strong/erratic wind gusts in the vicinity of any
convection. Outside of TS, VFR is expected to prevail until
chances of MVFR CIGs increase towards the end of this TAF period.

&&

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

$$

SHORT TERM...30
LONG TERM....12
AVIATION...30