Special Weather Statement, NWS Austin/San Antonio, TX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
221 PM CDT Thu Apr 15 2021

.SHORT TERM (Tonight through Friday Night)...

WYSIWYG would be the one word forecast for the next 36 hours, with
little practical change in conditions for most locations until
Friday evening.

In greater detail, the stalled front/boundary over the southern part
of our area will stay in place tonight, then slowly shift northward
tomorrow, re-introducing southerly, low-level flow progressively
northward during the day. Meanwhile, a cold front will continue
southward across North Texas, reaching the north edge of our CWA by
sunset Friday evening. For those playing along at home, the increase
in temperature/moisture gradients over our area result in
frontogenesis, and not surprisingly, a source of lift for
convection. Not coincidentally, another shortwave trough will
approach the area from the west tomorrow, pass overhead during the
day, and move east of the area tomorrow night. This trough will also
serve as a source of lift, especially over the Rio Grande Plains late
tonight and Friday morning. Last, but not least, the Low Level Jet
will reach it's diurnal peak late tonight and wane by late Friday
morning, also providing a source of lift/moist air feed for
convection.

Putting this all together for sensible weather, a few thunderstorms
may continue on the coastal plains this evening. Some of these
storms may be severe with large hail and damaging wind. Cloudy skies
with patchy fog and drizzle will occur for most places overnight. On
the Rio Grande Plains, expect scattered showers and a few
thunderstorms to develop as the shortwave trough approaches. These
storms will progress across the rest of the area during the day on
Friday, and a few storms may become severe in the northern Hill
Country, metro Austin, and coastal plains to the east of Austin.
Since these storms will not be surface-based, the most likely severe
threat will be large hail. The cold front will then sweep through
the area Friday evening and overnight, ending rain chances and
ushering in cooler and drier air.

&&

.LONG TERM (Saturday through Thursday)...

The period starts out under western flow aloft, which will quickly
be followed by a much cooler pattern for the weekend, as colder air
filters in behind a cold front Saturday morning. In fact, the GEFS
and ECM Ensembles both depict area high temperatures some 15-20
degrees below normal for mid to late April. That would put almost the
entire CWA in the upper 50s and lower 60s for highs, with the
exception being our far southern zones which should manage to climb
into the upper 60s. There is a slight chance for some remnant
showers behind the departing front on Saturday, so have kept some
20-30% PoPs in play for our southern zones, but honestly, not all
that impressive with the setup late Saturday, so chances may need to
be trimmed further in future forecast packages.

By Monday, another piece of energy quickly dives south over
southwestern New Mexico, bringing with it a chance for some rain
showers across mainly Val Verde county. Moisture will be harder to
come by, so chances look rather slim. Will keep 20-30% PoPs in play
for western Val Verde county, with the remainder of the CWA likely
staying dry.

Models are in agreement that yet another unseasonably strong cold
front for mid to late April will arrive sometime late Tuesday into
early Wednesday am. Going thinking is that this will be a dry frontal
passage. Beyond that, the active pattern continues with yet another
longwave trough digging southward over the Four Corners region by
late week, bringing showers and storms back into the picture.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              64  81  53  64  50 /  70  80  20  10  -
Austin Bergstrom Intl Airport  64  81  53  65  48 /  60  70  20  10  -
New Braunfels Muni Airport     66  83  55  67  50 /  50  50  20  20  -
Burnet Muni Airport            62  79  50  62  47 /  60  60  10  -   -
Del Rio Intl Airport           68  91  57  67  52 /  40  10  10  20  10
Georgetown Muni Airport        63  79  50  63  47 /  70  70  20  -   -
Hondo Muni Airport             66  87  55  67  50 /  40  30  10  20  10
San Marcos Muni Airport        64  82  53  65  49 /  50  60  20  20  -
La Grange - Fayette Regional   67  79  55  67  51 /  50  80  20  20  -
San Antonio Intl Airport       66  83  56  65  52 /  50  40  20  20  10
Stinson Muni Airport           67  85  57  66  52 /  40  30  20  20  10

&&

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

Short-Term/Aviation...Zeitler
Long-Term...Morris
Decision Support...KCW

Hazardous Weather Outlook
National Weather Service Austin/San Antonio TX
330 AM CDT Thu Apr 15 2021

TXZ171>173-183>194-202>209-217>225-228-160830-
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-
330 AM CDT Thu Apr 15 2021

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

.DAY ONE...Today And Tonight.

A few strong to severe thunderstorms are possible across much of
South Central Texas today into early this evening. The greatest
threat area is along and northwest of a Del Rio to San Antonio to
Austin line. The main threat will be large hail, although damaging
winds are also possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated strong thunderstorms are possible across our Central
Texas counties on Friday with hail and gusty winds possible.

Elevated fire weather conditions are possible across Val Verde and
western parts of Edwards and Kinney counties Friday afternoon due
to low humidities and breezy winds.

No hazardous weather is expected Saturday through Wednesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
353 PM CDT THU APR 15 2021

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

0352 PM     HAIL             BERTRAM                 30.75N 98.05W
04/15/2021  M2.75 INCH       BURNET             TX   PUBLIC

&&

HAMPSHIRE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
406 PM CDT THU APR 15 2021

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

0405 PM     HAIL             1 ESE LEANDER           30.56N 97.84W
04/15/2021  E2.00 INCH       WILLIAMSON         TX   TRAINED SPOTTER

            2 INCH HAIL AT THE INTERSECTION OF 183 AND
            CRYSTAL FALLS PKWY.

&&

HAMPSHIRE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
407 PM CDT THU APR 15 2021

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

0402 PM     HAIL             4 ESE LIBERTY HILL      30.65N 97.85W
04/15/2021  E1.50 INCH       WILLIAMSON         TX   PUBLIC

&&

HAMPSHIRE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
410 PM CDT THU APR 15 2021

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

0408 PM     HAIL             5 NE LEANDER            30.62N 97.81W
04/15/2021  E1.50 INCH       WILLIAMSON         TX   EMERGENCY MNGR

            PING PONG SIZE HAIL AT LAKE SIDE DRIVE AND
            LAKE SIDE COVE.

&&

HAMPSHIRE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
411 PM CDT THU APR 15 2021

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

0411 PM     HAIL             1 NNE LEANDER           30.58N 97.85W
04/15/2021  E2.00 INCH       WILLIAMSON         TX   PUBLIC

&&

HAMPSHIRE

Special Weather Statement
National Weather Service Austin/San Antonio TX
411 PM CDT Thu Apr 15 2021

TXZ173-152200-
Williamson TX-
411 PM CDT Thu Apr 15 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN WILLIAMSON COUNTY
UNTIL 500 PM CDT...

At 411 PM CDT, Doppler radar was tracking a strong thunderstorm near
Jarrell, or 10 miles northwest of Granger, moving east at 40 mph.

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

Locations impacted include...
Georgetown, Taylor, Granger, Serenada, Bartlett, Jarrell, Thrall,
Weir, Georgetown Dam, Sun City, Granger Dam, Theon, Laneport, Hoxie,
Waterloo, Hare, Walburg, Schwertner, Jonah and Noack.

A Severe Thunderstorm Watch remains in effect until 500 PM CDT for
south central Texas.

LAT...LON 3087 9762 3074 9727 3047 9716 3067 9775
      3087 9765
TIME...MOT...LOC 2111Z 283DEG 36KT 3083 9756

KCW