Flash Flood Warning 25, NWS Lubbock, TX

Area Forecast Discussion
National Weather Service Lubbock TX
630 PM CDT Sat Jun 3 2023

...New AVIATION...

.SHORT TERM...
(This evening through Sunday)
Issued at 212 PM CDT Sat Jun 3 2023

A weak upper low will continue to undercut the larger scale omega
block over North America today. We will be on the subsidence side of
this low for this afternoon. We will see some better lift move
overhead this evening as convection attempts to move into the area
from the northwest. Weak low level convergence was noted along a
dryline near the Texas/New Mexico state line early this afternoon.
This will be just about the only forcing available for convective
chances this afternoon. Upslope flow into northeastern New Mexico on
the Raton Mesa will allow convection to develop in this area.
Steering flow will generally steer this convection to the southeast
towards the South Plains this evening and overnight. It is difficult
to say how far southeast this convection will persist through the
evening and overnight hours. Some CAM guidance runs have shown
storms plowing all the way into the Rolling Plains during the early
morning hours on Sunday. The steering flow will be fairly weak
leading to very little shear available for storms to take advantage
of. The low level jet will not be terribly strong feeding into the
expected ongoing convection in eastern New Mexico this evening with
east/southeast 850mb winds only on the order of 15kt or so. Despite
the weak low level jet, storms will be moving into a slightly better
thermodynamic environment the farther southeast they advect.
Therefore, there is some support for CAM guidance showing convection
through the nighttime hours marching to the southeast, likely with
strong forward propagation.

A fairly messy convective forecast is in store for tomorrow. Sunday
afternoon will again see very weak forcing overhead with a weakness
in the height fields undercutting the ridge. Low level flow will
remain out of the east resulting in broad upslope conditions similar
to a summer like pattern. Therefore, no particular area is favored
for convection with scattered storms just about anywhere will be
possible. However, afternoon convective chances may be dependent on
how much overnight convection occurs. An abundance of overnight
storms may squash afternoon chances on Sunday leaving little time
for any atmospheric recovery. Models that are showing recovery by
Sunday afternoon depict a deep but weak CAPE profile. Any severe
chances would likely be very isolated. With precipitable water
values continuing to be between 125 and 150 percent of normal,
isolated heavy rainfall will be a primary concern.

&&

.LONG TERM...
(Sunday night through next Friday)
Issued at 212 PM CDT Sat Jun 3 2023

Significant bifurcation of the upper air pattern is forecast heading
into the beginning of the work week. NWP guidance in considerable
agreement with an Omega Block centering over the CONUS where a
large, baroclinic low positioned west of the CWA on Monday with a
high-level/250 mb jet streak near 100 kt rounding its base. Heavy
thunderstorms should be ongoing late Sunday night into Monday
morning across the CWA, and flash flooding will be possible due to
the whopping 300-600 percent above normal rainfall that has occurred
across the Caprock and Rolling Plains over the last three weeks.
Forecast soundings indicate near-complete saturation of the columns
on Monday with tall, skinny CAPE profiles at around 1,000-1,500 J/kg
for non-diluted, most-unstable parcels. The saturated atmosphere
combined with weak cloud-layer shear similar to what was observed in
the middle of May should temper the magnitude of storms, though a
few STG-SVR-caliber storms cannot be ruled out. The strongest cores
and, therefore, the heaviest rain, should be focused on where
interactions with mesoscale boundaries occur; however, where these
features end up positioning remains nebulous at this time. Expect a
mild and wet/dreary day on Monday regardless.

The high-level jet streak rounding the base of the baroclinic low
over the California coast should begin to nose into northern Mexico
and the Desert Southwest on Tuesday, with 250 mb flow becoming
increasingly difluent atop the attenuating, mid-level ridge. The
gradual increase in large-scale forcing for ascent should result in
a line of convection forming across eastern New Mexico during the
day, thus keeping the CWA dry until the evening. NBM PoPs have been
cleaned up a bit to reflect this thinking with keeping the grids dry
through at least mid-day, though storms should gradually propagate
eastward towards the TX/NM state line by the late afternoon hours as
a weak shortwave perturbation rotates through the flattening ridge
with the South Plains having the best shot for another round of
heavy thunderstorms. Renewed chances for convection will follow
heading into Wed-Thu as mid/high-level flow gradually becomes zonal
from the collapsing Omega Block, allowing the baroclinic low to
emerge into the southern Great Basin/Desert Southwest by Thursday.

Global NWP guidance remains in agreement for this low to transition
into an open trough, which should unlock the more-amplified flow to
the west of the CWA and cause it to translate over the CWA by the
end of the week. This appears to be the next potential for organized
(severe) thunderstorms as cross-boundary shear vectors return in the
presence of the dryline. CIPS Experimental Analog-Based Severe
Probability Guidance has also picked up on this possibility as well,
and delineates low probabilities for severe-caliber storms across
West Texas towards the end of the forecast period. Therefore, the
blended/NBM PoPs have been accepted with this forecast cycle.

Sincavage

&&

.AVIATION...
(00Z TAFS)
Issued at 629 PM CDT Sat Jun 3 2023

VFR conditions are expected through the TAF period. There is a
slight chance of thunderstorms tonight if storms that form west
of LBB and PVW congeal into a line or broken line of storms and
move east but, confidence of this occurring is too low to mention
in TAF at this time.

&&

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

SHORT TERM...01
LONG TERM....09
AVIATION...17

Hazardous Weather Outlook...UPDATED
National Weather Service Lubbock TX
208 PM CDT Sat Jun 3 2023

TXZ021>044-041915-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
208 PM CDT Sat Jun 3 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 move into the South Plains region from
New Mexico this evening and tonight. Some storms could be strong to
severe and produce wind gusts up to 60 mph and hail up to the size
of quarters. Heavy rainfall will also be possible and could lead to
flash flooding.

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

There is a chance for strong to marginally severe thunderstorms with
heavy rainfall each day over the next week. Organized thunderstorms
will be possible by the latter part of the week and into early next
weekend.