Severe Thunderstorm Warning 214, NWS Austin/San Antonio, TX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
425 PM CDT Fri Jul 31 2020

.UPDATE...
Did a quick update to up PoPs over our southwestern zones. Seeing
some moisture convergence along a line from Eagle Pass to Devine,
this coupled with daytime heating has led to some development over
the last hour or so. Overall storm motion with this activity is
fairly slow but rainfall rates have been generally 1-2 inches per
hour. Also retrended temps given the rain and cloud cover now
covering the northern portion on the CWA. This line of storms is
expected to slowly make it's way southward this evening.

&&

.PREV DISCUSSION... /ISSUED 258 PM CDT Fri Jul 31 2020/

SHORT TERM (Tonight through Saturday Night)...
A tricky short term forecast for today and tomorrow. An upper level
trough axis extending from the Midwest into South Central Texas has
generated a weak late July front that is expected to make it's way
across the region tonight. The placement of the front is difficult
to differentiate from the residual convective boundary left over
from yesterday's thunderstorm activity that occurred well north of
the CWA. Current thinking is the initial boundary that will move
through is the convective boundary from yesterday and a second push
will pass through late tonight being the actual front. This residual
convective boundary is currently infringing upon our northern tier
of counties and has generated a line of cells over Williamson County
as of 2:00pm.

Given sufficient heating this afternoon, moderate instability is in
place with 2000-2500 J/kg CAPE and steep low level lapse rates of
about 7 c/km. Surface dewpoints will be in the low 70s across much
of the region. So while there is sufficient instability and
moisture, the limiting factor will be a forcing mechanism. Namely,
enough surface convergence along the boundary as it pushes through.
Convective allowing models have a number of solutions on handling
convection over the next 24 hours but there seems to be two general
solutions. The first being, enough storms can get going this
afternoon and evening to become cold-pool dominated and sustain
themselves further into the overnight period. WRF, ARW, and NMM all
depict something similar to this solution. While the NAM Nest and
HRRR have isolated to scattered storms this afternoon into this
evening but dwindling with the loss of daytime heating.
Interestingly enough, the NAM Nest does have storms re-firing early
tomorrow morning, perhaps along the second push of the actual front.

SPC does have much of South Central Texas under a marginal risk for
severe storms with the main threats being strong winds and hail. A
weak late July front with a convective boundary ahead of it along
with NW flow aloft will make the next 24 hours a bit tricky to
forecast. Convective allowing models should converge on a solution
once storms, and to what extent, get going this afternoon and
evening.

What takes place tomorrow will heavily depend on how things go this
evening. Any residual boundary left over from tonights activity
could be a focus for initiation tomorrow with daytime heating. Highs
for Saturday afternoon will be in the mid to upper 90s for most
locations with areas along the Rio Grande approaching or exceeding
100 degrees.

LONG TERM (Sunday through Friday)...
A similar type of upper level pattern will still be around on Sunday
into early next week with upper ridging out west and troughing to
the NE. This will continue to give us good NW flow aloft. The
question is how much moisture will still be around and will any
smaller disturbances or remnant boundaries help to trigger
convection. Some models are pointing toward more development on
Sunday afternoon and have thus kept mention of chance pops during
that time. The wind will be fairly light Sunday and Monday which will
enhance the hot and humid weather. Monday will still see some
lingering pop mainly over the Hill Country, but any sort of
significant QPF will be absent. Looks like a pattern that will set up
some isolated to widely scattered convection for a few lucky folks.
By mid and late week, the upper ridge shifts east and puts a better
hold on Texas and should keep most convection at bay. That far out,
can't rule out some isolated storms especially seabreeze related
over the far SE, but confidence is not high enough right now for any
pop of significance. Temps will remain very warm...near 100 degrees
most days as he head into the beginning of August...historically our
warmest time of the year for South Central Texas.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              76  97  75  99  75 /  30  10  -   20  -
Austin Bergstrom Intl Airport  73  96  74  98  74 /  30  10  -   20  -
New Braunfels Muni Airport     75  96  74  98  74 /  30  10  -   20  -
Burnet Muni Airport            72  96  72  98  73 /  30  10  -   10  -
Del Rio Intl Airport           78 102  77 104  79 /  20  10  10  20  -
Georgetown Muni Airport        73  97  73 100  74 /  30  10  -   10  -
Hondo Muni Airport             76  98  75 102  75 /  30  20  10  20  -
San Marcos Muni Airport        74  96  74  98  74 /  30  10  -   20  -
La Grange - Fayette Regional   76  95  76  99  76 /  30  20  10  20  -
San Antonio Intl Airport       76  98  77 100  76 /  30  20  10  30  10
Stinson Muni Airport           77  97  77  99  76 /  30  20  10  20  -

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

Short-Term/Aviation...EWilliams
Long-Term...09

Hazardous Weather Outlook
National Weather Service Austin/San Antonio TX
1208 PM CDT Fri Jul 31 2020

TXZ171>173-183>194-202>209-217>225-228-011715-
Llano-Burnet-Williamson-Val Verde-Edwards-Real-Kerr-Bandera-
Gillespie-Kendall-Blanco-Hays-Travis-Bastrop-Lee-Kinney-Uvalde-
Medina-Bexar-Comal-Guadalupe-Caldwell-Fayette-Maverick-Zavala-
Frio-Atascosa-Wilson-Karnes-Gonzales-De Witt-Lavaca-Dimmit-
1208 PM CDT Fri Jul 31 2020

This Hazardous Weather Outlook is for South-Central Texas..

.DAY ONE...This Afternoon And Tonight.

There is a marginal risk of strong to severe storms along and
northern half of South Central Texas this afternoon and evening
mainly north of a line from Del Rio to San Antonio to Schulenburg.
Strong wind gusts are the main threats this afternoon along with
frequent lightning and locally heavy downpours.

Some of these strong storms may hold together and affect the
southern half of the region tonight and overnight, mainly south of
Interstate 10. Strong wind gusts, lightning, and locally heavy
downpours will be the primary threat.

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

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter reports may be needed later this afternoon and evening.

Special Weather Statement
National Weather Service Austin/San Antonio TX
250 PM CDT Fri Jul 31 2020

TXZ173-192>194-312015-
Bastrop TX-Williamson TX-Lee TX-Travis TX-
250 PM CDT Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WILLIAMSON...EAST
CENTRAL TRAVIS...NORTH CENTRAL BASTROP AND WEST CENTRAL LEE COUNTIES
UNTIL 315 PM CDT...

At 249 PM CDT, Doppler radar was tracking a strong thunderstorm over
Coupland, or near Elgin, moving south at 30 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Elgin, Coupland, Beyarsville, Rices Crossing and Blue.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3050 9752 3056 9732 3039 9715 3030 9744
TIME...MOT...LOC 1949Z 338DEG 27KT 3045 9739

Special Weather Statement
National Weather Service Austin/San Antonio TX
344 PM CDT Fri Jul 31 2020

TXZ173-188>194-206-312145-
Comal TX-Blanco TX-Gillespie TX-Bastrop TX-Williamson TX-Hays TX-
Kendall TX-Lee TX-Travis TX-
344 PM CDT Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN WILLIAMSON...HAYS...
TRAVIS...BLANCO...SOUTHEASTERN GILLESPIE...NORTHERN BASTROP...LEE...
NORTHERN KENDALL AND NORTH CENTRAL COMAL COUNTIES UNTIL 445 PM CDT...

At 344 PM CDT, Doppler radar was tracking a strong thunderstorm near
Austin Bergstrom Int Airport, moving southeast at 15 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Austin, Pflugerville, Kyle, Buda, Fredericksburg, Elgin, Bastrop,
Giddings, Dripping Springs, Wimberley, Blanco, Lexington, Tanglewood
Forest, Austin Bergstrom Int Airport, Lakeway, Manor, Bee Cave, West
Lake Hills, Hudson Bend and The Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3015 9681 3005 9763 3007 9766 3004 9769
      2989 9883 3030 9887 3049 9717 3046 9715
      3049 9709 3051 9693 3020 9674
TIME...MOT...LOC 2044Z 336DEG 12KT 3026 9768

Special Weather Statement
National Weather Service Austin/San Antonio TX
431 PM CDT Fri Jul 31 2020

TXZ190>193-206-208-312215-
Comal TX-Blanco TX-Caldwell TX-Bastrop TX-Hays TX-Travis TX-
431 PM CDT Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN CALDWELL...HAYS...
SOUTHEASTERN TRAVIS...SOUTH CENTRAL BLANCO...CENTRAL BASTROP AND
NORTHEASTERN COMAL COUNTIES UNTIL 515 PM CDT...

At 431 PM CDT, Doppler radar was tracking a strong thunderstorm over
Onion Creek, or over Buda, moving southeast at 15 mph.

Nickel size hail and wind gusts of 50 to 55 mph will be possible with
this storm.

Locations impacted include...
Austin, San Marcos, Kyle, Buda, Bastrop, Smithville, Dripping
Springs, Wimberley, Tanglewood Forest, Austin Bergstrom Int Airport,
Canyon Lake, Woodcreek, Uhland, Mustang Ridge, Niederwald, Bear
Creek, Camp Swift, Shady Hollow, Cedar Creek and Circle D-KC Estates.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3018 9832 3031 9729 3000 9715 2988 9829
TIME...MOT...LOC 2131Z 330DEG 13KT 3011 9782

Special Weather Statement
National Weather Service Austin/San Antonio TX
513 PM CDT Fri Jul 31 2020

TXZ191>193-206-208-312300-
Comal TX-Caldwell TX-Bastrop TX-Hays TX-Travis TX-
513 PM CDT Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN CALDWELL...HAYS...SOUTH
CENTRAL TRAVIS...SOUTHWESTERN BASTROP AND NORTHEASTERN COMAL COUNTIES
UNTIL 600 PM CDT...

At 512 PM CDT, Doppler radar was tracking a strong thunderstorm over
Kyle, moving southeast at 15 mph.

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

Locations impacted include...
San Marcos, Kyle, Buda, Lockhart, Wimberley, Canyon Lake Dam, Canyon
Lake, Woodcreek, Martindale, Uhland, Mustang Ridge, Niederwald,
Fischer, Cedar Creek, Onion Creek, Wyldwood, Mountain City, Hays,
Creedmoor and Rockne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 2983 9785 2985 9786 2985 9788 2982 9793
      2979 9833 3000 9834 3004 9830 3008 9828
      3014 9751 2987 9735
TIME...MOT...LOC 2212Z 334DEG 15KT 2996 9784

Special Weather Statement
National Weather Service Austin/San Antonio TX
534 PM CDT Fri Jul 31 2020

TXZ185>190-206-312315-
Comal TX-Blanco TX-Gillespie TX-Kerr TX-Real TX-Bandera TX-
Kendall TX-
534 PM CDT Fri Jul 31 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN BANDERA...KERR...
SOUTHWESTERN BLANCO...SOUTHWESTERN GILLESPIE...KENDALL...NORTHEASTERN
REAL AND NORTHWESTERN COMAL COUNTIES UNTIL 615 PM CDT...

At 534 PM CDT, Doppler radar was tracking a strong thunderstorm over
Ingram, or near Kerrville, moving south at 25 mph.

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

Locations impacted include...
Medina, Kerrville, Boerne, Comfort, Canyon Lake, Bulverde, Ingram,
Hunt, Walnut Grove, Guadalupe River State Park, Camp Verde, Kendalia,
Smithson Valley, Kerrville-Schreiner Park, Waltonia, Kerr Wildlife
Management Area, Sisterdale, Kreutzberg, Spring Branch and Welfare.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3005 9829 3000 9834 2978 9833 2979 9975
      3008 9977 3008 9976 3029 9976 3029 9975
TIME...MOT...LOC 2234Z 351DEG 20KT 3005 9925