Flash Flood Watch 1, NWS Lubbock, TX

Bailey County, TX, Briscoe County, TX, Castro County, TX, Childress County, TX, Cochran County, TX, Cottle County, TX, Crosby County, TX, Dickens County, TX, Floyd County, TX, Garza County, TX, Hale County, TX, Hall County, TX, Hockley County, TX, Kent County, TX, King County, TX, Lamb County, TX, Lubbock County, TX, Lynn County, TX, Motley County, TX, Parmer County, TX, Stonewall County, TX, Swisher County, TX, Terry County, TX, Yoakum County, TX

434 
WGUS64 KLUB 171908
FFALUB

Flood Watch
National Weather Service Lubbock TX
208 PM CDT Mon May 17 2021

TXZ021>044-172015-
/O.CAN.KLUB.FF.A.0001.210518T2200Z-210519T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-
Floyd-Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-
Yoakum-Terry-Lynn-Garza-Kent-Stonewall-
Including the cities of Turkey, Tulia, Guthrie, Denver City,
Silverton, Lubbock, Cee Vee, Plains, Muleshoe, Spur, Whiteface,
Dickens, Matador, Kirkland, Happy, Wolfforth, Quitaque, Lockney,
ODonnell, Slaton, New Home, Friona, Lake Alan Henry, Olton, Hale
Center, Dumont, Post, Memphis, Jayton, Sundown, Farwell,
Childress, Paducah, Littlefield, Wellman, Plainview, Dimmitt,
Aspermont, Meadow, Old Glory, Morton, Roaring Springs, Crosbyton,
Brownfield, Bovina, Floydada, Tahoka, Ralls, Levelland, Amherst,
and Hart
208 PM CDT Mon May 17 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for Portions of northwest and the Panhandle of 
Texas, including the following areas, in northwest Texas, Bailey, 
Childress, Cochran, Cottle, Crosby, Dickens, Floyd, Garza, Hale, 
Hockley, Kent, King, Lamb, Lubbock, Lynn, Motley, Stonewall, Terry 
and Yoakum. In the Panhandle of Texas, Briscoe, Castro, Hall, Parmer 
and Swisher. has been cancelled.

This watch will be replaced with a new Flash Flood Watch for this 
evening.

$$

McQueen

Area Forecast Discussion
National Weather Service Lubbock TX
1254 PM CDT Mon May 17 2021

.AVIATION...
There is a moderate risk for severe thunderstorms across the area
by late this afternoon and evening. Moist low level southeast
flow will be interacted upon by a strong, slowly approaching storm
system crossing the southern Rockies, expected to still be just
west of the area in 24 hours. Short-term forecast solutions
indicate an increasing risk for strong to severe thunderstorms
affecting the KLBB and KPVW airports by late this afternoon into
early this evening, and then KCDS by early to mid evening. After
moving this initial round of strong storm activity through the
area, there should be a break with VFR dominating. But another
round of storms is expected to develop late tonight and early
Tuesday. Keep note of RADAR trends today and be aware that storm
activity may differ significantly from departure conditions. Also
be aware that a few storms are expected to be capable of producing
tornadoes, very large hail up to or larger than the size of
baseballs, and downdraft wind gusts on the order of 70 to 80 mph.
This will also produce local LIFR conditions. RMcQueen

&&

.PREV DISCUSSION... /issued 637 AM CDT Mon May 17 2021/

AVIATION...
Showers and thunderstorms have shifted south and east of the
terminals early this morning, leaving cool and relatively moist
upslope flow in place. Low clouds have cleared at KLBB and KPVW,
but MVFR cigs are in place well south, west and north of the
terminals, and there is a decent bet that at least periods of
MVFR cigs develop on the Caprock later this morning. Given this,
we have carried a period of MVFR ceilings for KLBB and KPVW from
13Z to 18Z. Further east, KCDS will probably remain VFR this
morning. Intense thunderstorms will develop west of the terminals
this afternoon, then move east and could impact the terminals
through the evening hours. Another round of storms could
potentially form late tonight, after midnight, and affect the
terminals through early Tuesday morning. We have only addressed
the afternoon/evening convection in the TAFs ATTM, and will
address the later activity, if needed, with future issuances.

PREV DISCUSSION... /issued 327 AM CDT Mon May 17 2021/

SHORT TERM...
A Moderate Risk of severe weather covers much of the CWA today, with
an Enhanced Risk for the remainder of the CWA. Needless to say, we
expected another active afternoon, evening and overnight of severe
weather, including the risk for very large hail, damaging winds,
tornadoes and torrential rainfall. However, the details on how today
unfolds remain somewhat in flux due to ongoing convection early this
morning.

As of 07Z...a stout southerly LLJ continues to advect moist and
unstable air up and over the collective cool outflow occupying our
northeastern zones. This is keeping convection going/regenerating
across the southern Texas Panhandle, Rolling Plains and northeastern
South Plains. Where the best tap of instability is occurring, strong
to occasionally severe cells are being maintained, while training
cells are also resulting in areas of heavy rainfall. This
activity will likely persist through much of the rest of the
night, though it should gradually decrease in intensity and
coverage toward morning as the LLJ is progged to weaken and veer.

The big question mark to be answered is exactly what effect all of
the overnight convection will have on how the weather plays out this
afternoon. Currently the dryline is located in eastern New Mexico,
and we expect it won't move very far eastward later today as it is
reinforced by early morning outflow. In addition, a surface low will
deepen in east-central New Mexico today as an upper low traverses
the Four Corners. This will keep the low-level flow backed over
most/all of the FA through the day today. Where strong heating
develops, mostly likely in a wedge between the dryline and the
remnant outflow, a corridor of strong instability will form,
favoring our southern and western zones. Isolated to scattered
storms should explode in this corridor mid-late afternoon. The
magnitude of the instability (potentially approaching 4000 J/kg) and
around 40 knots of deep shear will support isolated supercells
capable of producing very large hail, damaging wind, torrential
rainfall and tornadoes as they propagate eastward. The greatest
tornado risk will exist along and immediately north of the residual
outflow/warm front where backed low-level flow will maximize storm
relative helicity. Currently, it appears this will be over the
southwest Texas Panhandle into the South Plains and Rolling Plains,
though this is subject to change and will have to be refined as the
day unfolds.

The convection may grow up into a MCS as it progresses eastward
through the evening hours, moving into western Oklahoma and/or
western North Texas. Behind this bout of intense convection,
additional thunderstorms should blossom late tonight (after
midnight) as large scale ascent in advance of the approaching upper
low spreads across West Texas. Strong instability feeding in from an
intensifying southerly LLJ will support another round of severe
thunderstorms, while training cells will pose an increased flash
flooding risk where this next MCS develops. If the early round of
convection produces a large cold pool it could shift the bulk of the
late-night activity south of our CWA, as some of the latest guidance
shows. However, there is a decent possibility this next round of
storms and heavy rain will affect the southern South Plains and the
Rolling Plains late tonight into Tuesday morning before shifting to
the east. If confidence grows in the scenario, a short-fused Flash
Flood Watch may be needed for parts of the CWA tonight. We'll let
the next shift evaluate this potential.

Regardless of details, very large hail, damaging winds, torrential
rainfall and a risk of tornadoes will exist this afternoon into this
evening and the weather should be watched closely through today and
tonight.

LONG TERM...
Long term starts Tuesday with the Pacific low pressure system
spinning just NW of the CWA. At the surface a trough will drop SE
through our southern counties forcing the dryline through the CWA
and into the far western Rolling Plains. All the while we will keep
a deep southeast surface flow pattern across the Rolling Plains
allowing for moisture to feed northwestward into the region. This
moisture and associated instability will provide areas east of I27
with a shot of showers and thunderstorms Tuesday afternoon/evening
with fair weather likely across the South Plains. It should be noted
that all of this activity will be dependent on how overworked or
under worked the environment is from today's activity.
Nonetheless we have left a mention of rain showers and
thunderstorms in the forecast for now.

Wednesday as the upper low dissipates and pulls north of the area
better storms chances shift north and east creating a "lull" in our
active weather until Friday. Each afternoon there could be
opportunities for limited thunder across the far eastern Rolling
Plains given the continued moisture advection and daytime heating.

For Friday through the weekend we are starting to see hints at a
return of active weather with the dryline setting up somewhere in NM.
Upper and surface troughing to our west and upper and surface high
pressure to our east will allow for a consistent SE surface flow off
the Gulf and into our area. Dewpoints as high as the 65F are
progged over our eastern zones Saturday and Sunday with some
instability and decent daytime heating. We have kept POPs and a
mention of thunder in the forecast Friday through Sunday, but
confidence in placement and severity of storms is not high at this
time given the inconsistencies between models on the dryline
placement.

&&

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

99/99/05

Hazardous Weather Outlook
National Weather Service Lubbock TX
1151 AM CDT Mon May 17 2021

TXZ021>044-181700-
Parmer-Castro-Swisher-Briscoe-Hall-Childress-Bailey-Lamb-Hale-Floyd-
Motley-Cottle-Cochran-Hockley-Lubbock-Crosby-Dickens-King-Yoakum-
Terry-Lynn-Garza-Kent-Stonewall-
1151 AM CDT Mon May 17 2021

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

.DAY ONE...This afternoon and tonight.

There is a moderate risk of severe thunderstorms for the South
Plains and Rolling Plains this afternoon into tonight, with an
enhanced risk of severe weather for the southern Texas Panhandle.

Isolated to scattered supercell thunderstorms are expected to
develop near a dryline across the southwest Texas Panhandle and
western and central South Plains this afternoon. These storms will
become more enhanced where the dryline intersects an east-west
boundary crossing the southern and central South Plains and southern
Rolling Plains. These storms will quickly become severe and be
capable of producing baseball size hail, wind gusts to 75 mph,
torrential rainfall and tornadoes. This activity will move eastward
through the evening, likely growing into a larger complex of
thunderstorms as it moves off the Caprock. A hail, wind and heavy
rain threat will continue with the complex of thunderstorm through
the evening as well as still a risk for a few tornadoes.

Another round of severe thunderstorms capable of generating golf
ball size hail, wind gusts to 65 mph and intense rainfall and flash
flooding may develop over the southern South Plains and the Rolling
Plains late tonight, after midnight, and persist into Tuesday
morning.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

More opportunities for thunderstorms will exist late Tuesday,
Wednesday and then again from Friday into next weekend. Some of
these storms could be strong to severe and produce heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be needed. Please relay any information
about severe weather to the NWS while following local, state, and CDC
guidelines.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LUBBOCK TX
845 AM CDT MON MAY 17 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0550 PM     HAIL             KIRKLAND                34.39N 100.07W
05/16/2021  E1.57 INCH       CHILDRESS          TX   CO-OP OBSERVER

            PING PONG SIZED HAIL. TIME ESTIMATED BASED ON RADAR AND
            ADJACENT REPORTS.

&&

EVENT NUMBER LUB2100297

RMCQUEEN