San Antonio, Texas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

012
FXUS64 KEWX 202328
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
628 PM CDT Tue May 20 2025

...New AVIATION...

.SHORT TERM...
(Tonight through Wednesday night)
Issued at 256 PM CDT Tue May 20 2025

Key Message:

- Low chance for isolated storms in the coastal plains this afternoon.

Early afternoon surface observations show dry air behind a cold
front continues to surge southward along the Rio Grande plains, with
dewpoint temperatures in the upper 20s to upper 30s. The drying and
warming in the low-levels is being aided by downslope, northwesterly
winds. This is offsetting any cooling behind the front, with current
temperatures in the mid 90s to 100 degrees over the mentioned area.
Farther east, the front is currently just south of Giddings to
Gonzales to just south of Pleasanton. The forecast remains dry and
hot behind the front, with perhaps a low chance for an isolated
shower or storm along and ahead of the front across the coastal
plains. Any activity will be tied closely to daytime heating, so
chances for rain will decrease after sunset.

Early this evening, the front will likely hang up across the coastal
plains, then begin to retreat northward as a warm front by late
evening. The return southeasterly flow behind the front will yield
warm overnight lows in the lower to mid 70s along the Rio Grande and
coastal plains, with mainly 60s elsewhere. A few spots in the Hill
Country may drop into the upper 50s. Return southerly flow on
Wednesday will lead to an increase in cloud cover, especially out
west along the Rio Grande. Highs will be in the 90s for most areas,
with perhaps near 100 along the Rio Grande if we see some afternoon
breaks in the clouds. We will also keep a low chance for some
afternoon convection in the forecast for the Rio Grande plains
mainly south of Eagle Pass given better moisture and daytime
heating. Wednesday night lows trend upward, with mid 60s to mid 70s
in the forecast.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 256 PM CDT Tue May 20 2025

Temperatures Thursday climb back to pre-frontal levels as southerly
flow continues, with upper 90s to around 100 for highs. A surge of
moisture Thursday morning will make the day feel noticeably warmer
with heat index values climbing into the 100 to 108 range mainly
along and east of the Balcones Escarpment and south of the Edwards
Plateau. A weak shortwave overlapping with a quasi-stationary
frontal boundary over North Texas brings a low chance (20 percent)
for isolated southward-moving showers and storms primarily over the
southern Edwards Plateau and Hill Country Thursday afternoon into
the evening. Storm coverage tends to overperform model expectations
in these setups with northwesterly flow aloft, so it will be worth
closely monitoring for trends in storm organization as convective
forcing approaches the area. Deep-layer bulk shear magnitudes look
modest (around 20 kt), so the kinematics favor multi-cellular and
subsevere activity rather than stronger storms at this time.

Friday and Saturday, a mid-level ridge axis with 588dm 500mb heights
slides across Texas, bringing quiet weather. High temperatures hold
steady, with a slightly drier Friday before moisture rebounds
Saturday. Peak heat indices continue to hold near and over 100 each
day for most of South Central Texas.

Southwesterly flow begins to redevelop in the mid-levels Sunday as
troughing activity intensifies over the western CONUS, bringing a
more favorable track for disturbances across our area. However, this
will also strengthen moisture advection over South Central Texas
during the day. This could drive heat index values into the 105 to
110 range for some areas, particularly in the Winter Garden region
and I-35 corridor. Some isolated shower and storm activity could
commence Sunday afternoon within the warm advective regime, but
better chances are associated with a front pushing south Monday.
Upper level flow will be better favored to push this front across
the region as a large trough swings across the Central Plains and
Midwest. Given the projected availability of deep layer moisture and
front-parallel shear vectors, locally heavy rains could be possible
along the front. Cooler temperatures, perhaps substantially so, are
forecast to spread across our region through the middle of the week
after the front passes.

&&

.AVIATION...
(00Z TAFS)
Issued at 624 PM CDT Tue May 20 2025

Some scattered mid and high level clouds are all we are expecting
through tonight. Winds should be mainly NE/N tonight, but should turn
SE after daybreak. There is a chance a pocket of MVFR cigs pool up
around DRT late Wednesday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              96  66  96  71 /   0   0   0   0
Austin Bergstrom Intl Airport  97  65  96  70 /   0   0   0   0
New Braunfels Muni Airport     99  67  96  71 /  10   0   0   0
Burnet Muni Airport            91  63  94  69 /   0   0   0   0
Del Rio Intl Airport           99  74  98  76 /   0   0  10  10
Georgetown Muni Airport        92  63  93  69 /   0   0   0   0
Hondo Muni Airport             99  70  96  72 /  10   0   0  10
San Marcos Muni Airport        99  65  97  71 /  10   0   0   0
La Grange - Fayette Regional   96  66  95  71 /  20   0   0   0
San Antonio Intl Airport       99  70  96  73 /  10   0   0  10
Stinson Muni Airport          102  71  98  75 /  10   0   0  10

&&

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

$$

Short-Term...Platt
Long-Term...Tran
Aviation...18