397
FXUS64 KLUB 302325
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
625 PM CDT Sat Aug 30 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 621 PM CDT Sat Aug 30 2025

 - A Flood Watch is in effect for the entire forecast area from 4 PM
   CDT this afternoon through 10 AM CDT Sunday.

 - Thunderstorms, some severe, are expected from late this afternoon
   through early Sunday morning, posing a risk for flash flooding.

 - Storm chances are forecast to return by the middle of next week.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 1247 PM CDT Sat Aug 30 2025

In the mid/upper-levels, the subtropical ridge continues to
deamplify, as a well-defined shortwave trough that is currently
digging into the central Rocky Mountains ejects eastward into the
north-central Great Plains by this evening. The center of the
subtropical ridge continues to rotate over the TX Big Bend, and is
expected to position over central/east-central TX tonight. The
ejection of the shortwave troughing to the north and the eastward
progression of the subtropical ridge will cause the right-entrance
region of the 300-200 mb jet streak shift farther southward and over
the CWA. The 12Z objectively analyzed UA charts analyzed the 250 mb
jet streak at 55 kt on the WFO DDC RAOB, and 40-45 kt on the OUN and
FWD RAOBs. The 30/00Z RAOB from last evening from WFO AMA had also
observed 40 kt of west-northwesterly flow. High-level flow will
continue to become more-zonal over the next 12 hours due to the
ejecting shortwave trough farther north, resulting in a corridor of
intensifying divergence, especially as mid-level flow strengthens
over the southern High Plains. The MCS from earlier this morning has
since collapsed, with a well-defined, convectively-augmented
vorticity lobe apparent in water-vapor imagery over the CWA as of
this writing. This vorticity lobe will continue to become stretched
out via the zonal extension of the 250 mb jet streak, and there has
already been substantial clearing compared to what has been thought
in prior forecasts. It appears that rapid airmass recovery is
underway, with elevated boundary-layer cu bubbling across the far
southwestern TX PH and full insolation occurring over most of the
Caprock and Rolling Plains as anvil debris advects east. The
elevated cu field will eventually become surface-based, especially
as satellite trends indicate that the moistening is occurring along
a differential heating boundary, which was generated by the rainfall
gradient from last night.

At the surface, winds were veered to the west across the Caprock in
response to the wake low that developed behind the MCS, while winds
remain light and variable in the Rolling Plains. A surface trough
was located to the west of the NM state line, which connects to the
surface low rotating across the southern CO/KS border, with the cold
front arcing across southeast CO and moving southward. Prevailing
winds are expected to gradually restore to the southeast over the
next few hours in response to the leeward pressure falls generated
by the surface low to the north of the CWA. There was significant
convective overturning from the MCS last night, but the rapid
clearing will accelerate airmass recovery, which should be complete
by the mid-afternoon hours as temperatures warm into the middle 80s
area-wide. The most distinct outflow boundary was located along the
lee of the Caprock Escarpment, with another one across the southern
South Plains, which has since begun to erode and has some inkling
that it was associated with the MCV/wake low. These boundaries may
serve as foci for thunderstorm initiation this afternoon, despite
washing out/becoming invisible on satellite (an outflow circulation
can still exist even after the clouds dissipate).

The 12Z RAOB from WFO MAF, in addition to Blended TPW estimates and
mesoscale analysis data, indicate that PWATs remain anomalously high
and in exceedance of the 99th percentile. The 12Z MAF RAOB measured
a PWAT of 1.77", but was launched through convective debris, while
satellite estimates and mesoscale analysis show PWATs approaching an
impressive 2.00" in the Rolling Plains. These estimates are accurate
given the measurements by the 12Z RAOBs along the I-35 corridor that
are on the north side of the quasi-stationary front draped across
central and southern TX. Thunderstorm initiation is forecast to
occur by 21Z across portions of the CWA, with the highest confidence
in storms forming along the aforementioned differential heating
boundary draped across the far southern TX PH. 250 mb flow is
forecast to increase to near 40 kt over the entire CWA by tonight,
atop northwesterly flow in the mid-levels approaching 25 kt as a
vorticity lobe rounding the base of the shortwave trough rotates
over W TX.

Several rounds of storms are forecast across the CWA from this
afternoon through Sunday morning, with organized bands propagating
southeastward along the thickness gradient. Torrential rainfall will
accompany storms given the anomalously high PWATs; tall, skinny CAPE
near 2,000 J/kg; and an overall net increase in the magnitude of
deep-layer shear compared to yesterday. Downshear Corfidi vectors
will be slightly more elongated than last night due to the increase
in deep-layer shear/flow, which will offset the potential for a
slow, southward progression of any bands compared to what was
observed last night. However, repeated rounds of storms will
facilitate the potential for flash flooding, especially across the
central and southern areas on the Caprock where several locations
received 2-3", and nearly 4", of rainfall last night. A Flood Watch
is in effect from 21Z (4 PM CDT) this afternoon through 31/15Z (10
AM CDT) Sunday for the entire forecast area. Total QPF will vary
among locales, but swaths of 1-3" to locally 4" of rainfall will be
possible this afternoon through Sunday morning.

The Brazos River gauge four miles east-southeast of Lubbock rose
asymptotically from 6.39 ft at 12 AM CDT to 13.36 feet by 2:15 AM
CDT this past morning, or nearly 7.0 feet in two hours. While the
river level has since come down to 9.0 feet as of 12:22 PM CDT, the
environment this afternoon and tonight will be supportive of rapid
run-off, with the possibility of the river to rise sharply again
should the Lubbock area receive multiple rounds of intense rainfall
through Sunday morning. Those camping and/or doing recreational
activities near the river should monitor the behavior of the river
the rest of today and through Sunday morning, as playa lakes that
feed into it can prolong its flooding. A Flood Warning remains in
effect for the Brazos River in southeast Lubbock through 6 PM CDT.

Sincavage

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 1247 PM CDT Sat Aug 30 2025

Conditions will improve Sunday, as the cold front previously
mentioned in the short-term discussion moves through the CWA, with
brisk, northeasterly winds following the front. High temperatures
will be similar to today, with highs peaking in the lower-middle 80s
area-wide beneath a clearing sky. A few storms will be possible by
Sunday afternoon, primarily across the southwestern South Plains
where some cells propagating southward across eastern NM may clip
locales east of the state line. Otherwise, clouds will gradually
erode atop a stabilized airmass, with deep-layer flow becoming
increasingly confluent and extinguishing storm chances by Sunday
night. The subtropical ridge will continue to amplify over the Rocky
Mountains heading into early next week, with mid-level flow becoming
northerly, which should keep storm chances west of the NM state line
Monday and Tuesday. Storm chances are forecast to return by the
middle of next week, as global NWP guidance continues to indicate a
longwave trough digging into the Great Lakes region, which would
restore flow aloft to the northwest. A strong cold front may arrive
by late Wednesday or Thursday next week as the trough encompasses
most of the eastern U.S.

Sincavage

&&

.AVIATION...
(00Z TAFS)
Issued at 621 PM CDT Sat Aug 30 2025

VFR conditions are expected to continue through the evening.
However there remains the chance for late evening thunderstorms,
primarily at KPVW and KLBB which may allow for MVFR CIGS to
develop periodically. Thunderstorms may bring heavy rainfall which
may lead to reduced visibilities along with occasional gusty
winds. A brief lull is depicted by models before an additional
round develops and tracks through the terminals shortly after
midnight. Although confidence in this remains low at this time.
The biggest uncertainty is if storms will develop around daybreak
tomorrow at KCDS along any outflows to our north. Have opted for a
PROB30 at this time until we see better agreement.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Sunday morning for TXZ021>044.

&&

$$

SHORT TERM...09
LONG TERM....09
AVIATION...12