Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 302116 CCA
AFDEWX

Area Forecast Discussion...CORRECTED
National Weather Service Austin/San Antonio TX
416 PM CDT Fri Apr 30 2021

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

Bottom Line Up Front

...Heavy Rains with Flash Flooding Potential through Saturday
Night...

...Flash Flood Watch is in Effect for areas east of a Vanderpool to
Hondo to Charlotte line through Saturday Evening...

...Rainfall Amounts of 2 to 5 Inches with Isolated 8 Inches
Possible...

...There is a Chance for Strong to Severe Thunderstorms through
Saturday Evening...

Scattered showers and isolated thunderstorms are affecting most of
the eastern half counties of South Central Texas as a surface low
pressure system pushes into the middle Texas coast. The surface low
is driving a warm front toward the Coastal Plains and into the I-35
corridor where most of the shower activity is occurring. Out west
across the Rio Grande, light to moderate rain is happening and
expected to persist through late tonight with the help of pulses of
energy ahead of the upper level system slowly moving over northern
Mexico.

We may have a short break early this evening before scattered to
numerous showers and thunderstorms develop and fill up most areas
from the south to north and from the southwest to the northeast
before or shortly after midnight tonight. HiRes models suggest a
heavy line of convection between Highway 281 and Interstate 35 and
another line of strong convective activity along the Rio Grande.

These lines of convection are expected to produce heavy rain
resulting in the potential for flash flooding. As the night progress,
the upper level low pressure system over Mexico will continue to
push to the east while adding more fuel to the storms already
affecting the area and offering new opportunity for storms to
develop. Any storm that develops has the potential to be strong to
marginally severe with main weather hazard being large hail and
damaging winds.

By Saturday morning, the upper level low is expected to enter the
Rio Grande and continue to push to the northeast and exiting our
area Saturday night into early Sunday. As the upper level
disturbance moves across the area, a broad surface low pressure
circulation is forecast to be in place for elongating the time of
the storms over our area. Rain chances come to an end from west to
east Saturday night into Sunday.

&&

.LONG TERM (Sunday through Friday)...

The upper level trough will be exiting stage east taking the showers
and thunderstorms with it early Sunday morning. Moisture decreases a
bit and with mixing, temperatures warm to above normal for Sunday. A
dryline moves east toward the I-35 corridor Monday allowing
temperatures to soar into the upper 80s and 90s most areas. Forecast
soundings show a weak capping inversion at time of peak heating that
may be able to be broken by the dryline and strong heating. Have
added slight chances of showers and thunderstorms for the eastern
Hill Country to the I-35 corridor late Monday afternoon. Forecast
soundings also show MUCAPEs of 2,000 to 3,000 J/kg along the dryline
indicating a potential for an isolated strong to severe storm. A cold
front and upper level trough move across our area Monday night into
Tuesday. Upward forcing by these features will generate isolated to
widely scattered showers and thunderstorms over our eastern areas
where moisture will be deepest. Convective parameters decrease Monday
night into Tuesday, however cannot rule out a strong storm or two.
Dry northwesterly flow aloft brings fair weather Wednesday through
next Friday. Temperatures will average within a degree or two of
normal for mid to late next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              66  73  64  86  69 /  90  90  70  10   0
Austin Bergstrom Intl Airport  65  73  63  86  68 /  90  90  70  10   0
New Braunfels Muni Airport     67  76  64  89  69 /  90  90  50  -    0
Burnet Muni Airport            64  71  61  85  68 /  90 100  60  10   0
Del Rio Intl Airport           64  77  61  95  66 /  90  80  10   0   0
Georgetown Muni Airport        65  73  63  85  68 /  90  90  70  10   0
Hondo Muni Airport             66  76  60  90  66 /  90  80  30  -    0
San Marcos Muni Airport        64  74  63  88  68 /  90  90  60  10   0
La Grange - Fayette Regional   68  76  66  87  71 /  90  90  70  10   0
San Antonio Intl Airport       67  74  64  88  69 /  90  90  50  -    0
Stinson Muni Airport           67  75  64  90  69 /  90  90  40  -    0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through Saturday evening for Atascosa-Bandera-
Bastrop-Bexar-Blanco-Caldwell-Comal-De Witt-Fayette-Gillespie-
Gonzales-Guadalupe-Hays-Karnes-Kendall-Kerr-Lavaca-Lee-Medina-
Travis-Wilson.

&&

$$

Short-Term/Aviation...17
Long-Term...04
Decision Support...Morris


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