514
FXUS64 KLUB 202300
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
600 PM CDT Fri Sep 20 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday)
Issued at 257 PM CDT Fri Sep 20 2024

The upper ridge near the Texas and Mexico border will slide into
southeast Texas by tomorrow as the upper low currently over southern
Cali swings towards the Four Corners. Continuous weak shower and
thunderstorm activity persists this afternoon across eastern New
Mexico with ample mid-level moisture in the southwesterly flow of
the approaching jet aloft. The main line of mid-level moisture and
precipitation is expected to remain to our west and north. There is
a very small potential for some of the precipitation activity to
clip the far southwest Texas Panhandle this evening, but with
dewpoints in the 40s and LCLs above 3000m, any precipitation is
likely to evaporate before reaching the surface. If a storm were to
push through the far northwest corner of the forecast area, the main
threat would be a strong wind gust or two. Tonight, high clouds will
continue across much of the area with the increasing mid-level
moisture ahead of the approaching trough axis. Temperatures will dip
into the 60s and lower 70s tonight.

Tomorrow, the 40-50 knot 500mb jet streak will fill into West Texas
as the bowling ball upper low approaches the Four Corners. The main
jet streak will remain just west of the forecast area across New
Mexico. Shower and thunderstorm activity is expected to continue
through the morning hours tomorrow west and north of the forecast
area. Surface ridging across the southeast CONUS will give way to
increased low-level GoM moisture with south-southeast winds.
Dewpoints will range in the lower to mid 60s by the afternoon hours
with temperatures warming into the 80s along the Caprock to mid 90s
off the Caprock. Breezy southerly surface winds will exist with
height falls as a surface low strengthens with the approaching
trough. Most of the models have the cold front nearing the far
southwest Texas Panhandle during the late afternoon hours tomorrow.
An axis of increased 700mb theta-e will setup across eastern New
Mexico and into the western portions of the South Plains, ahead of
the front and in the moist sector of the dryline. The aforementioned
area will be where instability is the greatest through the afternoon
hours with MLCAPE values nearing 1500-2000 J/kg and bulk shear of 50-
60 knots. Afternoon storms will develop across eastern New Mexico
and push east-northeast through the early evening hours with strong
to severe storms capable of producing large hail and damaging wind
gusts. Low-level shear profiles have decent backing winds near the
surface and surface-3km shear of around 20-30 knots, which could
support a tornado or two. Depending on where the cold front is
placed by the afternoon hours, if a storm or two latches to the
boundary then there could be an increased risk for tornadoes. PWATs
are near 1.5" to 1.75" and storms will be capable of heavy rainfall
with localized flooding. The bulk of the activity will persist into
tomorrow night and more details will be covered on this in the long
term discussion below.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 257 PM CDT Fri Sep 20 2024

Potential for severe storms and heavy rain will continue Saturday
night through early Sunday as large-scale forcing courtesy of a
broad mid/upper level jet streak increases as the potent upper
low approaches from the west. Synoptic and hi-res guidance remains
in good agreement depicting numerous showers and storms shifting
eastward into West Texas on Saturday evening as a cold front
slowly descends southward through the TX Panhandle. Strong forcing
for ascent overspreading steep midlevel lapse rates, impressive
deep-layer bulk shear magnitudes of 40-60kt, and robust low level
theta-e advection will continue to support an environment
favorable for severe storms into the evening over the far
southwestern TX Panhandle and western portions of the South
Plains. All severe hazards will be possible in this area, with a
low but non-zero tornado risk as mentioned above. The severe
weather threat is generally expected to decrease with eastward
extent and with time as instability wanes, with the primary hazard
shifting more towards heavy rain overnight as impressive northward
low-level moisture flux continues. Most models still keep the
axis of heaviest rainfall on Saturday night over the southwestern
TX Panhandle into northern portions of the South Plains where an
inch to perhaps several inches of rainfall are possible, but much
will depend on how far south the front progresses overnight.

Sunday will feature a continuation of active weather as the cold
front over the southern TX Panhandle advances further southward.
Additional thunderstorms are expected to develop and persist along
the front, with the lingering upper jet streak maintaining large-
scale lift through most of the day. The axis of rainfall on Sunday
currently looks to be smaller than on Saturday night with storms
concentrated along the front which may favor our southern and
eastern zones, but for now will maintain broad PoPs area-wide until
this becomes more clear-cut. Severe weather potential on Sunday
also looks limited due to a cooler and more stable airmass, but
robust focused ascent and a very moist airmass with PWATs in the
1.5-2.0" range will support a continued threat for heavy rain.

Monday will feature a return of dry conditions as surface ridging
builds into the region in the wake of the departing upper low. Many
locations on the Caprock will see lows in the 40s to lower 50s on
Monday morning, with below average temperatures continuing into the
afternoon. Rain chances return to the entire region on Tuesday as
most guidance depicts broad upper troughing deepening over the
central CONUS. Models diverge on the amplitude and positioning of
this troughing, but enough continuity is still present to maintain
high chance to likely PoPs Tuesday through Wednesday. Beyond this,
model spread supports keeping the blended forecast as-is with
temperatures warming back near normal and PoPs generally below
mentionable levels.

&&

.AVIATION...
(00Z TAFS)
Issued at 556 PM CDT Fri Sep 20 2024

The main impacts will be in the second half of this TAF period.
Low CIGS may move northward into the area after daybreak and may
affect KLBB before dissipating but chances are low of these CIGS
reaching the terminal. An approaching upper level storm system
will bring increasing chances of thunderstorms but are not
anticipated to affect KLBB and KPVW until close to and after 00Z
Saturday afternoon.

&&

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

$$

SHORT TERM...11
LONG TERM....30
AVIATION...01