Special Weather Statement, NWS Lubbock, TX

Area Forecast Discussion
National Weather Service Lubbock TX
634 AM CDT Fri May 28 2021

.AVIATION...
Low stratus is filling in quickly across the South Plains region,
with MVFR/IFR CIGs reported at KLBB and KPVW. Convection has
affected KCDS throughout the morning so far and another round of
sub-severe storms will affect KCDS within the next few hours.
CIGs may lift into MVFR/VFR this afternoon at all terminals,
though confidence remains low at this time.

Isolated to possibly scattered thunderstorms will be possible
this afternoon across the South Plains, potentially affecting
KLBB. Confidence has increased from the previous (06Z) forecast
assessment regarding this, and a prevailing VCTS mention has been
included in the KLBB TAF for this forecast package. Pilots can
expect strong downbursts up to 50 kt and hail up to two inches in
diameter surface to aloft in vicinity of storms, including a few
cumulonimbi with maximum tops to 50 kft. Any convection that
materializes will begin to wane in intensity and coverage near
sunset with IFR/MVFR CIGs redeveloping later tonight at all three
terminals.

Sincavage

&&

.MESOSCALE UPDATE...
Several complexes of thunderstorms have occurred so far this
morning across the extreme southern Texas Panhandle, with another
compact cluster propagating eastward at around 30 mph as it now
crosses the I-27 corridor in Swisher County. These clusters are
non-surface based/elevated and have been anchoring onto the
quasi-stationary front that has been reinforced by earlier
convective outflows evident on satellite imagery and recent West
Texas Mesonet data (i.e. Plainview gusting to near 30 kt from the
north).

As this complex moves east into the northeastern Rolling Plains,
it is expected to remain sub-severe given little change in the
mesoscale environment compared to earlier this morning where the
highest wind gust of 46 kt was reported at the KCDS ASOS, along
with a few other mid-30 kt range gusts measured by the West Texas
Mesonet. While storms have pulsated briefly to severe limits,
confirmed by a report of 1.25" diameter hail in Parmer County
(coincident on WSR-88D imagery with an ephemeral hail spike and
ZH values at 60-65 dBz collocated with ZDR values near 0 dB at
the time of the report), the potential for severe storms for the
remainder of the morning remains very low along the stalled front.

Sincavage

&&

.PREV DISCUSSION... /issued 209 AM CDT Fri May 28 2021/

SHORT TERM...
An arcing band of low stratus (likely fractus) associated with
convective outflow originating from south-central Oklahoma is
propagating westward across the Rolling Plains and southern Texas
Panhandle this early morning. Wind gusts abruptly increased at
several West Texas Mesonet sites following passage of this outflow
as it moves across the vicinity of the quasi-stationary front draped
across the region. Meanwhile, isolated showers and pulsating
thunderstorms were ongoing across the extreme southwestern Texas
Panhandle as of 0609Z, persisting through at least sunrise while
remaining well below severe limits. Low stratus will quickly
overspread the forecast area by the mid-morning hours owing to
modest, easterly upslope flow as the stalling front drifts
southwestward. The combination of an overcast sky and low-level,
upslope flow will greatly inhibit the degree of diabatic heating,
with temperatures peaking in the lower-middle 70s area-wide today.

Later this afternoon, a mid/upper-level ridge axis, now centered
over the Four Corners and Intermountain West regions and decreasing
in amplitude with southward extent, will progress over the CWA while
deep-layer flow remains westerly. While insolation will be limited,
the unidirectional, mid/upper-level westerlies will keep the EML
intact with approximately 2,500-3,500 J/kg MUCAPE surmounted by
lower 30 mb mean dewpoints around 58-61 deg F and a fairly large
separation of LCL-LFC. The enlarged area of upward-forced stable air
with ~20 kt of easterly low-level storm-relative inflow beneath
unidirectional flow aloft yields hodograph orientations favorable
for the development of isolated (possibly scattered), non-surface
based, classic supercells given anvil-level storm-relative winds
near 50 kt across the Texas/New Mexico state line.

Depending on how many storms form and become supercellular within
an environment conducive for storm-splits, destructive
interference will be possible along with efficient downshearing of
anvil debris, which will affect the longevity of both storm
organization and intensity. Nonetheless, storms will initially
have an attendant risk of producing large hail up to two inches in
diameter (i.e. around billiard ball size) across the western
South Plains before updrafts are entrained by dry air and sheared
apart while convective inhibition increases near sunset. The best
potential for a severe hail report or two should remain west and
southwest of the I-27 and Highway 87 corridors, and not everyone
will observe rain this afternoon and evening as the risk for
storms remains conditional.

Sincavage

LONG TERM...
An active pattern will continue through much of the forecast
period, albeit with a brief respite on Saturday as upper level
short wave ridging moves overhead. Upstream from the upper ridge
will be a closed low positioned over southern Arizona late in the
weekend, the bulk of the energy ejecting to the east-northeast
through Monday, but with a broad upper trough remaining over the
intermountain West southeastward to West Texas. This pattern will
likely be a wet one for the forecast area on Sunday and Monday as
the energy ejects from the upper low, bringing its own mid level
moisture and steepening mid level lapse rates. Surface
temperatures should remain on the cool side both days with highs
in the 70s, but dew points in the 60s should still result in some
periods of healthy instability while increasing and deepening
moisture will result in high PWAT with resulting potential for
heavy rain. Lingering cyclonic curvature over the forecast area
toward the base of the broader upper trough centered over the
Mississippi Valley will continue to bring chance for mainly
diurnally-driven thunderstorms through at least Wednesday.

&&

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

09

Hazardous Weather Outlook
National Weather Service Lubbock TX
1127 AM CDT Fri May 28 2021

TXZ021>044-291630-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
1127 AM CDT Fri May 28 2021

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

.DAY ONE...This afternoon and tonight.

Isolated to possibly scattered thunderstorms, some severe, will be
possible this afternoon and evening across the western and central
South Plains. Storms that do form will have the potential to produce
large hail up to two inches in diameter and wind gusts to 60 mph.
Also, heavy rain may lead to localized flooding.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorm chances Saturday afternoon and evening will be small
and confined to areas near the New Mexico state line. There is a
marginal risk that these storms could become severe. More widespread
showers and thunderstorms are expected Sunday and Monday and will
bring the potential for heavy rain and severe weather. Thunderstorm
chances will persist Tuesday and Wednesday and may again bring a risk
for severe weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed.

Special Weather Statement
National Weather Service Lubbock TX
742 AM CDT Fri May 28 2021

TXZ024-025-030-031-281315-
Floyd TX-Briscoe TX-Motley TX-Hall TX-
742 AM CDT Fri May 28 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN FLOYD...NORTHWESTERN
COTTLE...MOTLEY...SOUTHERN HALL AND SOUTHEASTERN BRISCOE COUNTIES
UNTIL 815 AM CDT...

At 741 AM CDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Flomot, or 10 miles northwest of Matador, moving
east at 40 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Matador, Turkey, Caprock Canyon State Park, Quitaque, Flomot, Valley
Schools and Northfield.

LAT...LON 3451 10048 3431 10051 3431 10052 3425 10052
      3395 10056 3401 10118 3450 10108
TIME...MOT...LOC 1241Z 266DEG 34KT 3413 10094

01

Special Weather Statement
National Weather Service Lubbock TX
813 AM CDT Fri May 28 2021

TXZ026-032-281345-
Childress TX-Cottle TX-
813 AM CDT Fri May 28 2021

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN CHILDRESS AND
NORTHEASTERN COTTLE COUNTIES UNTIL 845 AM CDT...

At 813 AM CDT, Doppler radar was tracking a strong thunderstorm 7
miles south of Childress, moving east at 15 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Childress and Kirkland.

LAT...LON 3423 10001 3424 10001 3424 10004 3427 10030
      3441 10030 3443 10000 3423 10000
TIME...MOT...LOC 1313Z 269DEG 12KT 3433 10021

01

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