736
FXUS64 KEWX 040217 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
917 PM CDT Thu Jul 3 2025

...New UPDATE...

.UPDATE...
Issued at 855 PM CDT Thu Jul 3 2025

Updated the Flood Watch to include Bexar, Kendall, Gillespie, and
Llano Counties. The Flood Watch is in effect through 7 AM Friday.

Abundant tropical moisture continues to be pulled across the local
area this evening and stays through the overnight hours. A low level
jet is forecast to increase through the period and helps with the
development of new cells which are expected to be heavy rain
producers with precipitable water values ranging from 2 to 2.5
inches. Rainfall amounts of 1 to 3 inches with isolated 5 to 7 inches
are possible across the Flood Watch area.

&&

.SHORT TERM...
(Tonight through Friday night)
Issued at 138 PM CDT Thu Jul 3 2025

Scattered shower activity has been ongoing across South-Central
Texas throughout the late morning and early afternoon, with a
gradual increase in coverage. A substantial plume of deep tropical
moisture continues to stream north across South-Central Texas,
characterized by unseasonably moist precipitable water values as
high as about 2.4 inches. The 12Z Del Rio upper-air sounding this
morning observed a PW of 2.31 inches, which is near daily record
high values. The axis of a negatively tilted mid-level trough most
readily apparent on 700mb analyses is beginning to move poleward
towards the Edwards Plateau, leading to rounds of shower activity
throughout South-Central Texas into tomorrow as the advancing trough
prompts the ascent of moist air. A mesoscale convective vortex over
the Big Bend area has also enhanced moisture advection into our
region.

Observed and simulated vertical profiles show an environment
presently conducive to heavy rain, supporting 1 to 2 inch per hour
rain rates. Given the broad region of rising air and lack of
dominant surface boundaries, shower activity looks to remain widely
distributed across South-Central Texas with sufficient instability
for isolated to widely scattered thunderstorms. Strong gusts of 40
to 50 mph are also possible as the heavy rain rates drag down cooler
air aloft. Cold pools expanding under weak deep-layer flow may
become a focusing mechanism for concentrating a few clusters of
showers and storms as depicted on some of the high-resolution
mesoscale guidance, and the heaviest rain totals may be associated
with these slow-moving clusters. Models remain in disagreement over
the placement of the heaviest rain totals, though the greatest
rainfall potential this afternoon into tonight is over the Highway
90 corridor, southern Edwards Plateau and Hill Country. Rainfall
totals of 1 to 3 inches appear likely, but locally higher amounts
upwards of 5 to 7 inches could materialize if slow-moving storms
begin to cluster. Given the heavy rainfall potential, some flooding
is possible. A Flood Watch is now in effect through 7 AM Friday
morning for the southern Edwards Plateau and western Hill Country,
where the intersection of higher forecast rainfall amounts and
rainfall from the past few days is most evident. While the greatest
concentration of modeled precipitation is in the aforementioned
areas, the highest rain amounts could shift depending on where
storms aggregate, and expansion towards the I-35 corridor is
possible later this evening into the overnight as the trough moves
gradually east.

Coverage of showers and storms should begin to decrease Friday as
the axis of the trough swings out of our area. However, the
environment continues to support isolated showers favoring mostly
the southern Edwards Plateau and Hill Country as the moist tropical
airmass remains in place. Additional shower development could also
occur along convergent flow through the Coastal Plains towards the I-
35 corridor. Cloud cover and rain-cooled air will support
temperatures near to below average for this time of year. Highs in
the 80s to low 90s are expected with lows in the mid 70s.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 138 PM CDT Thu Jul 3 2025

The core of the shortwave trough triggering today`s rains should be
clear of our area this weekend. However, the combination of an
overlapping trough over the North Central US and a retrograding
upper-level low in the Gulf will prevent the subtropical ridge from
rebuilding over our area. Thus, the unseasonably moist airmass will
stick around our area for this weekend, though northeast flow from
the Gulf system will gradually bring in drier continental air on
Sunday. Forcing doesn`t look very strong, but the moist air, daytime
heating, and residual troughiness could support isolated afternoon
showers and some thunder over the weekend. Within the moist tropical
air, the strongest storms could produce locally heavy rain rates.
The best rain chances, about 20 to 35 percent, would be over the I-
35 corridor and Hill Country Saturday afternoon, shifting west to
the southern Edwards Plateau Sunday afternoon as the residual
tropical air begins to be squeezed westward.

Temperatures are expected to return to more seasonably warmer levels
as rain chances decrease under sunnier skies. Subtropical ridging
and subsidence looks to become better established across the region
next week, though ensemble medium-range guidance places the core of
the ridge decently far enough to our west over the Desert Southwest
and Four Corners region. Subsidence should limit rain chances,
though there looks to be enough weakness in the ridging to permit
low chances for isolated seabreeze rains in the afternoon for the
Coastal Plains into midweek.

&&

.AVIATION...
(00Z TAFS)
Issued at 640 PM CDT Thu Jul 3 2025

Concerns for SHRA/TSRA continue this evening and based on radar
data, have placed TEMPO groups in the forecast for all I-35 TAF
sites from 00Z-03Z and will continue monitoring Hi-res model guidance
and amend as needed. Continued mention of VCSH until 05Z for KSSF
and KSAT and 07Z for KAUS as models continue to highlight SHRA/TSRA
possibilities. Gusty outflow winds, frequent lightning and
heavy rainfall will be the main concerns with TSRA. Have left out
PROB30 for most sites as confidence is just not high enough to
include at this time due to sporadic developing nature of these
storms. Low cloud development will lead to TEMPO IFR conditions at
SAT and SSF Thursday morning with prevailing IFR at DRT. Regarding
DRT have added in PROB30 for 03Z-06Z based off incoming model data
and trends. VFR conditions are expected to resume by friday afternoon
for all TAF sites and last through the remainder of the forecast
period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              75  91  75  92 /  30  30  10  30
Austin Bergstrom Intl Airport  76  89  75  90 /  30  30  10  30
New Braunfels Muni Airport     75  91  74  90 /  30  30  20  30
Burnet Muni Airport            74  87  73  89 /  50  40  10  30
Del Rio Intl Airport           75  91  76  95 /  50  40   0  10
Georgetown Muni Airport        75  87  74  89 /  40  30  10  30
Hondo Muni Airport             75  87  73  87 /  40  30  10  30
San Marcos Muni Airport        75  90  74  90 /  20  30  20  30
La Grange - Fayette Regional   76  90  76  92 /  10  20  20  30
San Antonio Intl Airport       76  89  75  89 /  40  30  10  30
Stinson Muni Airport           76  91  76  91 /  40  30  10  30

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flood Watch until 7 AM CDT Friday for Bandera-Bexar-Edwards-
Gillespie-Kendall-Kerr-Kinney-Llano-Medina-Real-Uvalde-Val Verde.

&&

$$

Short-Term...17
Long-Term...17
Aviation...CJM