Flash Flood Warning 10, NWS Lubbock, TX

Area Forecast Discussion
National Weather Service Lubbock TX
637 PM CDT Sat May 27 2023

...New AVIATION...

.SHORT TERM...
(This evening through Sunday)
Issued at 228 PM CDT Sat May 27 2023

Yet another active round of weather is setting up over the region
today with a high likelihood for what would be our fourth
consecutive night that we see an MCS. The surface map as of 2 PM
featured cool and very moist ESE flow with an outflow boundary
draped roughly along Highway 70 from west of Clovis to just south of
Plainview, and at least two other outflows loitering in the southern
Rolling Plains. The former boundary is of greatest interest in the
near term as this is directed along the easterly upslope of central
NM where storm initiation is most favored. Any storms that interact
and track favorably along this boundary will have a heightened
potential for low-level mesos and a few tornadoes, particularly
given low LCLs and LFCs. Despite cool surface temps and unfavorable
low-level lapse rates, MLCAPEs are already pushing 1500 J/kg near
the NM border with negligible capping, and 0-6km bulk shear is
progged to improve to 35 knots in the coming hours. Additional
insolation in the coming hours should only improve prospects for
storms to intensify as they approach the TX/NM border.

Otherwise, the focus will shift to flooding through the night as
convection likely grows upscale into an MCS as it encounters an
amplifying southeasterly LLJ and Theta-E axis.

Background ascent is already evident this afternoon in the form of a
modest shortwave trough around 700mb with decent speed convergence.
This wave is driving a narrow N-S axis of storms into the Rolling
Plains this afternoon with a lull in its wake. Farther upstream,
water vapor imagery shows a better defined shortwave trough that
will serve to nudge weak upper riding out of the region tonight and
aid in driving our MCS east-southeast from the South Plains this
evening into the southern Rolling Plains after midnight. HREF mean
captures this scenario nicely with the potential for widespread 1"
rain amounts with locally 2-4". On top of already saturated soils
over the majority of the Caprock, this will fuel a greater flooding
risk as shown by WPC's moderate risk for excessive rainfall. Some
concern exists that our Panhandle counties may remain on the
cooler/more stable side of the aforementioned outflow boundary which
could curb rainfall amounts here, but considering the amount of
standing water still being reported over some roads particularly in
Castro and Swisher Counties, feel the threat for renewed flooding
concerns is credible. Rain chances taper on Sunday following the
MCS.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 228 PM CDT Sat May 27 2023

Monday will see any remaining precip begin to push off to the east
as upper amplifies and the axis moves over the South Plains. The
upper ridge will hinder precip chances for part of Monday into late
Wednesday which should allow for remaining surface water to soak
in/evaporate and allow mosquitoes to being their invasion. Despite
hindered rain chances, there is still a slight chance for showers
and thunderstorms Tuesday afternoon/evening as models depict a
weakness on the eastern side of the upper ridge. The Rolling Plains
would be favored the most with any rain chances. The upper low
currently just offshore of Washington and Oregon will push southward
and move inland across southern California by late Tuesday/early
Wednesday. Models disagree on whether the upper low will stay closed
(GFS) or transition to an open wave (ECMWF). The running consensus
had been to keep the low closed. Either solution would result in the
upper ridge being kicked eastward with the upper flow becoming more
diffluent over the FA. Models have the upper low/trough gaining a
negative tilt as it pushes eastward towards and settles near the
Four Corners resulting in increased chances for severe convection
during the afternoons and evenings Wednesday through Saturday. As
moisture will still be in abundance, heavy rainfall will continue to
be a possibility with any convection that develops.

&&

.AVIATION...
(00Z TAFS)
Issued at 636 PM CDT Sat May 27 2023

MVFR CIGs at LBB and PVW will likely persist this evening and
tonight ahead of approaching thunderstorms while CDS is expected
to remain VFR. Thunderstorms are expected to move east across the
area tonight and impact PVW and LBB as a line of storms or a
broken line of storms with strong erratic winds and possibly large
hail. There is a chance of thunderstorms at CDS late tonight and
early tomorrow morning but confidence is lower that the terminal
will be affected. MVFR and possibly IFR conditions will be
possible after the thunderstorm activity moves east of LBB and
PVW.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 5 AM CDT Sunday for TXZ021>024-027>030-033>036-
039>042.

&&

SHORT TERM...93
LONG TERM....51
AVIATION...17

Hazardous Weather Outlook...UPDATED
National Weather Service Lubbock TX
1227 PM CDT Sat May 27 2023

TXZ021>044-281730-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
1227 PM CDT Sat May 27 2023

This Hazardous Weather Outlook is for the South Plains, Rolling
Plains, and the far Southern Texas Panhandle.

.DAY ONE...This afternoon and tonight.

Thunderstorms are expected to develop in eastern New Mexico this
afternoon and move east into the South Plains and far southwest
Texas Panhandle by this evening. A few of these storms could produce
hail to quarter size and wind gusts to 60 mph. Additionally, any
storms that can interact favorably with an outflow boundary across
the northern South Plains could produce a few tornadoes.

Flooding will become the primary threat with storms tonight as they
expand in coverage and produce heavy rainfall over areas that have
already experienced flooding in recent days. A Flood Watch is in
effect for all of the South Plains and much of the far southern
Texas
Panhandle this evening and overnight.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Thunderstorms are expected to develop each afternoon and persist
into the evening and overnight hours on Sunday and Monday and
Wednesday through Friday. Some storms may be severe with large hail
and damaging winds. Heavy rainfall may also result in localized
flash flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is possible later today.