549
FXUS64 KEWX 200311
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1011 PM CDT Sat Apr 19 2025

...New UPDATE...

.UPDATE...
Issued at 1010 PM CDT Sat Apr 19 2025

Severe Thunderstorm Watch 147 has been left to expire and has been
replaced by Tornado Watch 151. The counties are the same, however
there is a potential for additional counties prior to the expiration
time of 10Z or 5 AM CDT. The greatest threats will be damaging winds
and large hail, however isolated tornadoes are possible due to the
airmass being in the warm sector. There are no changes in thought
from the afternoon discussion.

&&

.SHORT TERM...
(Tonight through Sunday night)
Issued at 253 PM CDT Sat Apr 19 2025

Key Messages:

- There is a Level 1 to 3 out of 5 risk for severe thunderstorms this
  afternoon through early Easter Morning for areas generally along and
  west of the I-35 Corridor.

Current radar trends show some scattered convection ongoing along
and just east of the I-35 corridor. This activity is not rooted in
the boundary layer, thus we are seeing fairly low 0.5 degree
reflectivity values on area radars, but are noting a decent amount
of cloud to ground lightning strikes.

For the remainder of the afternoon into the evening hours, the focus
for stronger convection will shift into the southern Edwards
Plateau, portions of the Rio Grande plains and western Hill Country.
The latest SPC mesoanalysis places an axis of higher CAPE in this
region, with storms already developing farther north into west
Texas. A Severe Thunderstorm Watch is in effect for Edwards,
Gillespie, Kerr, Llano and Val Verde counties until 10 PM. The hi-
res models generally agree in showing convection developing across
northern Edwards and Val Verde county where a level 3 of 5 risk for
severe storms is noted. We will also monitor for development over
the Serranias del Burro mountains west of Del Rio given strong
surface heating. Large to very large hail and damaging winds are the
main severe weather threats. As we head into the late evening and
overnight hours, a Pacific front and upper level shortwave will
likely result in a line of thunderstorms across the southern Edwards
Plateau and Hill Country. Models continue to show the strongest
convection will likely occur over the mentioned areas, with large
hail and damaging winds being the main severe weather concerns. This
line of convection is expected to move into the I-35 corridor around
sunrise Easter Sunday. A weakening trend is likely, but the I-35
corridor still remains in a level 1 of 5 risk for severe storms
Sunday morning. Most of the convection is expected to shift east of
the I-35 corridor Sunday afternoon as the frontal boundary slows
while approaching the coastal plains. We will keep a low chance for
showers and storms in the forecast through Sunday night in the
coastal plains with the front in this region.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 253 PM CDT Sat Apr 19 2025

Key Messages:

- Daily rain and thunderstorm chances middle to late next week.

- Above average warmth and increasingly humid conditions next week.

A lack of strong offshore flow in the wake of Sunday`s front favors
keeping the front draped over the Texas Coastal Plain on Monday.
This will support lingering chances for showers and isolated thunder
over the Coastal Plains along the stalling front. The rest of South
Central Texas will likely see mostly clear to partly cloudy skies as
a dry mountain airmass briefly settles over our area. Highs Monday
are forecast to be in the mid to upper 80s for most, with
temperatures above 90 for sunny locations along the Rio Grande.

This window of drier conditions will be short lived as pressure
falls over the Rockies causes a resurgence of southerly flow Monday
night onwards, causing the the front to regress northward and
reintroduce humid Gulf air across South Central Texas. This moist
airmass will help prime our area for daily chances for rain and
thunderstorms, in addition to maintaining warm daily high and low
temperatures. The maintenance of high PWATs (around the 90th
percentile of the climatological distribution) and adequate
conditional instability will also support the potential for locally
heavy rains and stronger organized thunderstorms. Given the
substantial depth of moisture up to about 700 mb, streamer showers
and drizzle are possible Tuesday morning as modest isentropic lift
and warm advection spread inland. As broad troughing and
southwesterly flow establishes over northern Mexico and the
southwestern CONUS, periods of more pronounced shower and storm
activity are possible with any passerby disturbance. Models are in
good consensus that a weak shortwave will amplify over West Texas
late Tuesday. That could result in a flare up of isolated to
scattered dry line showers which track eastward into our region,
persisting within the moist Gulf air late Tuesday into early
Wednesday.

Additional rounds of showers and storms are possible throughout the
second half of the week as broad troughing becomes slightly more
pronounced over the western US, providing more opportunities for
shortwaves to set off showers and storms in our area. Late Thursday
into early Friday could be another favored window for storm
development with hints of a stronger shortwave passing around that
time. Towards the weekend, divergence between the models increases,
but the general theme of southwesterly mid-level flow over our area
with troughing over the western US seems likely to be maintained
through at least the weekend.

While the pattern may slightly favor heavier rains western and
northern areas closer to the dry line and downstream of persistent
moisture advection, ensembles suggest decently widespread coverage
of rainfall totals across South Central Texas with relatively
uniform accumulations. Of course, the actual distribution will be
highly sensitive to the development and evolution of any organized
convective systems which deterministic guidance have been hinting at
for next week. There is medium to high confidence of widespread
totals of at least 1 inch of accumulated rainfall this weekend
through next week, with localized higher amounts above 2 inches
possible within the stronger storm tracks. Cloud cover and rains
will soften the warmth slightly throughout the week, but highs will
likely remain in the 80s with lows in the mid to upper 60s.

&&

.AVIATION...
(00Z TAFS)
Issued at 653 PM CDT Sat Apr 19 2025

Across most areas, including the I-35 sites, MVFR CIGs spread over
them on strong SE winds gusting up to 35 KTs this evening. Winds
gradually weaken toward Sunday morning and turn S to SW as a front
approaches, then a line of SHRA/TSRA move across the sites early to
mid morning with PROB30s from 11Z to 16Z. Skies rapidly become VFR
with light N winds, turning NE by evening.

Out west, including KDRT, VFR skies prevail. VFR CIGs are expected
with TEMPO SHRA/TSRA along the frontal passage from 04Z to 08Z.
Moderate SE winds with gusts to 25 KTs shift to breezy NW after
frontal passage, however, less gustiness is expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              65  82  58  86 /  40  70  10  10
Austin Bergstrom Intl Airport  65  81  55  87 /  30  70  10  10
New Braunfels Muni Airport     66  82  56  86 /  30  70  10  10
Burnet Muni Airport            61  80  52  85 /  70  60   0   0
Del Rio Intl Airport           62  86  59  91 /  80   0   0   0
Georgetown Muni Airport        63  81  52  87 /  50  70  10   0
Hondo Muni Airport             63  84  56  86 /  60  50   0   0
San Marcos Muni Airport        65  81  55  86 /  20  70  10  10
La Grange - Fayette Regional   70  82  61  84 /  10  60  40  20
San Antonio Intl Airport       65  82  59  86 /  40  60  10  10
Stinson Muni Airport           68  83  60  86 /  30  60  10  10

&&

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

$$

Short-Term...04
Long-Term...MMM
Aviation...04