Flash Flood Warning 9, NWS Austin/San Antonio, TX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
648 PM CDT Mon Jul 22 2024

...New AVIATION...

.SHORT TERM...
(Tonight through Tuesday night)
Issued at 155 PM CDT Mon Jul 22 2024

Key Messages
* There is a risk for locally heavy rainfall this afternoon and into
  tonight.
* Isolated pockets of a quick 1-4 inches of rainfall could lead to
  flooding.
* Be alert for flooding through the afternoon and tonight and never
  drive through a flood roadway.

Numerous showers and scattered storms are ongoing across the
southern Edwards Plateau, Hill Country, and northern I-35 corridor
as well as scattered showers and isolated storms across the Coastal
Plains. The actual weak cold front is still just north of the area,
becoming harder to identify, and much of the convection across the
northern CWA is being driven by surface outflow and upper level
forcing. New showers and storms should develop into the I-35
corridor and Rio Grande through the remainder of the afternoon and
well into the evening hours, driven by outflow from the north
working southeast into the instability axis and potentially the sea-
breeze converging inland.

We have seen some pockets of 1-3 inches of rainfall occur this
morning. This will continue to be the case as new activity develops
into the Rio Grande, I-35 corridor, and Coastal Plains. A few HREF
members have been indicating a stripe of heavier rainfall possible
late afternoon and evening stretching from just east of Austin,
southwest through San Antonio, and to near Eagle Pass. This may be
in the region where the outflow to the north and sea-breeze moving
inland merge.

The rain so far has been welcome in drought stricken areas of the
western Hill Country and southern Edwards Plateau, with only a few
Flood Advisories. However, we will have to watch rainfall rates and
storms mergers closely late this afternoon and into the evening for
areas to the east that aren't in drought conditions in addition to
the urban I-35 corridor, which will be more susceptible to a quicker
flood response with any heavy rainfall.

Beyond this evening forecast confidence in placement of showers and
storms becomes low. There is a signal in the HREF and some global
ensembles for the forcing for showers and storms overnight and into
Tuesday morning to focus across the Rio Grande and back into the
southern Edwards Plateau, then Tuesday afternoon and night near the
I-35 corridor and into the Coastal Plains. Again this is lower
confidence, and may ultimately be tied to mesoscale influences and
weak upper level forcing. A threat for isolated pockets of locally
heavy rainfall that could lead to flooding continues during this
time.

With the cloud cover and rain, much cooler temperatures are occurring
today across northern areas, with highs only 80s. High temperatures
Tuesday for most areas are forecast to be in the 80s.

&&

.LONG TERM...
(Wednesday through Monday)
Issued at 155 PM CDT Mon Jul 22 2024

The wet pattern continues into the extended/long term forecast. Each
day from Wednesday into the upcoming weekend, there are chances for
showers and storms. An upper level short wave axis is forecast to
linger across South Central Texas through Thursday before an upper
level cutoff low develops over the local area extending into the
northeast part of Texas. The shower and thunderstorm activity
depends where the short wave axis sits each day with models favoring
the I-35 corridor and the coastal plains. Can't rule out showers and
storms over the Hill Country and southern Edwards Plateau through
the period, however, the setup is for the heaviest rains to occur
along and east of the I-35 corridor and coastal plains. Each day in
the extended could end up with isolated spots with several inches of
rainfall as forecast precipitable water values are above 2 inches.
So, the forecast message is to stay weather aware as a wet pattern is
in place where some locations may experience minor flooding
especially across roadways, low lying and poor drainage areas.
Beside the welcome rain expected during the extended forecast period,
cooler temperatures are in store with highs in the 80s over most
places and low to mid 90s along the Rio Grande.

&&

.AVIATION...
(00Z TAFS)
Issued at 641 PM CDT Mon Jul 22 2024

There will be chances for showers and thunderstorms across the area
during the upcoming TAF period. Currently there are storms within
about 10nm of the Austin and San Antonio terminals. These will linger
for another couple of hours. After that timing will be difficult, but
any convection will bring erratic gusty winds and MVFR ceilings and
visibility. Outside of storms conditions will be VFR at all airports.
MVFR ceilings will develop in the Austin and San Antonio areas
overnight, but DRT will remain VFR. Chances for convection will
continue during the day Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              73  89  73  91 /  60  50  20  50
Austin Bergstrom Intl Airport  73  87  72  88 /  70  60  30  50
New Braunfels Muni Airport     74  88  73  89 /  80  70  30  60
Burnet Muni Airport            71  87  71  89 /  40  40  20  30
Del Rio Intl Airport           74  89  76  96 /  80  50  30  40
Georgetown Muni Airport        71  87  71  88 /  60  40  20  40
Hondo Muni Airport             73  86  72  90 /  80  40  20  50
San Marcos Muni Airport        72  87  72  88 /  80  60  30  50
La Grange - Fayette Regional   73  87  72  84 /  60  80  30  70
San Antonio Intl Airport       74  87  74  89 /  80  60  30  60
Stinson Muni Airport           75  89  75  90 /  80  60  30  60

&&

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

Short-Term...76
Long-Term...17
Aviation...05

Hazardous Weather Outlook
National Weather Service Austin/San Antonio TX
204 AM CDT Mon Jul 22 2024

TXZ171>173-183>194-202>209-217>225-228-230915-
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-
204 AM CDT Mon Jul 22 2024

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

.DAY ONE...Today And Tonight.

Scattered thunderstorms are forecast mainly over the northern
half of the area late morning into the evening which could
produce locally heavy rain and isolated flooding. Thunderstorms
may progress south and southeast through the afternoon and
evening.

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

Multiple rounds of scattered showers and thunderstorms are
expected through the work week. Any activity will be capable of
producing heavy rainfall which may lead to scattered flash
flooding.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

Special Weather Statement
National Weather Service Austin/San Antonio TX
648 PM CDT Mon Jul 22 2024

TXZ205-230015-
Bexar TX-
648 PM CDT Mon Jul 22 2024

...A strong thunderstorm will impact portions of northwestern Bexar
County through 715 PM CDT...

At 648 PM CDT, Doppler radar was tracking a strong thunderstorm near
Helotes, or 10 miles west of San Antonio Int Airport, moving
northeast at 15 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
San Antonio, Leon Valley, Helotes, Fair Oaks Ranch, Shavano Park,
Hollywood Park, Cross Mountain, Leon Springs, The Dominion,
Timberwood Park, Hill Country Village, Grey Forest, Fiesta Texas, and
Scenic Oaks.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 2963 9842 2949 9860 2963 9873 2974 9862
      2974 9860 2975 9860 2974 9858 2976 9855
TIME...MOT...LOC 2348Z 231DEG 11KT 2958 9863

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

MO