San Antonio, Texas 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

422
FXUS64 KEWX 030019
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
719 PM CDT Wed Apr 2 2025

...New AVIATION...

.SHORT TERM...
(Tonight through Thursday night)
Issued at 240 PM CDT Wed Apr 2 2025

Key Messages:

- Low risk for an isolated strong to severe storm Wednesday and
Thursday.

- Unseasonably warm temperatures continue.

- Rain chances begin to increase Friday morning.

At 2 PM, a distinct dry line was currently extended northeast to
southwest along a line from Burnet to Boerne to Uvalde, demarcating
the boundary between a very moist Gulf airmass with dew points near
70F to the east and an arid airmass to the west with dew points
closer to 30F. Isolated to scattered light showers have been
intermittent over the northern I-35 corridor and northern Coastal
Plains this morning, but further development has been stunted by a
capping inversion aloft. Aircraft-sampled profiles in the vicinity
of Austin and San Antonio suggest a weak cap is in place, but with
meager convective inhibition. While cloud cover has prevented
significant destabilization, lifting could increase as the dry line
eases into the I-35 corridor. Rain chances are low (about 10 to 20
percent), but ample instability aloft could produce an isolated
strong to severe thunderstorm near the I-35 corridor should any
nascent updrafts break the cap.

Later this evening, a return to more southeasterly winds and loss of
daytime heating will force the dry line back west to around Val
Verde County overnight, allowing humid air and stratus to spread
across our area again. Overnight lows range from the mid-60s in
isolated spots in the Hill Country to the low-70s along and east of
the I-35 corridor. Low clouds should begin to gradually diminish in
the morning hours and be largely give way to cirrus-filled skies by
Thursday afternoon, though low clouds could be a little more
stubborn in our northeastern counties.

Thursday may behave quite similar to Wednesday, with the dry line
again making a push for the I-35 corridor late morning to early
afternoon. Capping will most likely keep rain chances low (with PoPs
around 10 to 15 percent), and mesoscale models across the board show
very little convective development or rain, if any. However, the
moist airmass east of the dry line will be quite conditionally
unstable with around 1500-2500 J/kg MLCAPE, and the cap is expected
to erode some during the afternoon with convective inhibition
becoming rather marginal (with HREF mean SBCINH below -20 J/kg in
some instances). A subtle line of confluent winds may also set up
over the Coastal Plains, setting up a corridor of locally higher
instability and ascent. Some models show very sporadic light, low-
topped showers along this feature from the late morning to late
afternoon. Given these parameters and 0-6 km wind shear values above
50 kt, any updraft that manages to break through the cap could
become strong to severe. Any activity of this caliber would be more
favored in the late afternoon to early evening over the northern
Hill Country to northern I-35 corridor. Highs Thursday afternoon are
expected to be in the upper 80s to low 90s for most, with highs in
the upper 90s to near 100 in the Rio Grande Plains. Some elevated
fire weather conditions are possible over the southern Edwards
Plateau and Rio Grande Plains with relative humidities mixing below
20 percent, but winds should remain light.

The pattern begins to change Thursday night as an upper level low
over the southwestern US begins to strengthen. This should lead to
the development of a surface trough and stationary front over West
Texas during the overnight hours. Rain chances will start to
increase mainly for the southern Edwards Plateau and Hill Country
early Friday morning closer to the front, though most of the action
will likely be later on in the long term forecast window.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 240 PM CDT Wed Apr 2 2025

Key Messages:

- Unseasonably warm Friday, turning unseasonably cool this weekend
  into early next week.

- Active pattern Friday night into Saturday morning with strong to
  severe storms possible.

Moist, southerly flow in the low-levels will be in place across most
of the region Friday morning. This will likely lead to plenty of
cloud cover along with a chance for showers and isolated
thunderstorms for the Hill Country and for areas generally along and
north of Highway 90. The leading edge of a cold front will gradually
move into the southern Edwards Plateau and Hill Country during the
afternoon hours as south-southwest flow aloft increases in advance of
an upper level low over the desert southwest. If we can manage to see
some clearing of skies, we could see some convection develop along
the leading edge of the cold front during the late afternoon.
However, the current suite of guidance is a little reluctant to show
much development during the daytime hours. However, this will change
beginning Friday evening continuing into early Saturday morning as
the upper level low advances eastward and the cold front continues to
drop southward through the region. The global models generally agree
in showing convection develop along the front across the southern
Edwards Plateau and expand convection into the Hill Country and I-35
late Friday evening through Saturday morning. Strong to severe storms
are possible with large hail, damaging winds being the main severe
weather concerns. In addition, we can`t rule out a tornado with
locally backed winds in the lower levels just ahead of the cold
front. Rain chances begin to decrease from west to east as Saturday
morning progresses with drier air moving in behind the front.

Additional improvement is expected Saturday afternoon behind the
Pacific cold front. We will keep a low chance for showers in the
forecast along the Highway 77 corridor in case the front slows down.
Farther to the northwest near the upper low and trough axis, we can`t
rule out some showers across portions of the southern Edwards Plateau
and Hill Country. Northwest winds will also be on the increase
Saturday behind the front, with breezy conditions beginning
immediately following frontal passage and continuing through most of
Sunday afternoon. We will need to monitor the Rio Grande plains,
southern Edwards Plateau and Hill Country for possible Wind Advisory
conditions (sustained 30-39 mph) Saturday afternoon into early Sunday
morning. Wind gusts to 50 mph over the mentioned areas are possible,
with gusts closer to 35-40 mph elsewhere. At this time, the strongest
winds are expected to occur Saturday afternoon into early Sunday
morning. Breezy conditions will continue Sunday, but wind speeds will
decrease around sunset as the pressure gradient eases and boundary
layer cooling cuts off mixing.

Temperatures will begin trending cooler behind the front on Saturday
with highs in the upper 60s in the Hill Country to the 80s generally
along and south of Highway 90. Lows Saturday night will dip into the
upper 30s in the Hill Country to mid and upper 40s along the Rio
Grande eastward into the coastal plains. The combination of gusty
north winds and cool overnight lows will drop wind chills into the
upper 20s to lower 30s over the Hill Country. When the winds finally
relax Sunday night into Monday morning, lows will drop into the mid
30s to lower 40s for most areas. We did opt to drop temperatures
below the NBM and would not be too surprised to see a few readings
near freezing in the Hill Country early Monday morning.

For the remainder of the forecast, a gradual warming trend is
expected along with dry weather.

&&

.AVIATION...
(00Z TAFS)
Issued at 703 PM CDT Wed Apr 2 2025

Tranquil evening expected as the cap didn`t allow for any dry-line
convection over the I-35 airspaces. The retreating dry-line will
likely reach DRT before sunrise, and a short period of MVFR cigs are
expected there. Spotty cigs around I-35 and the Coastal Prairies are
just above MVFR and could drop into MVFR in the next 2 to 4 hours. We
have ceilings in that category a bit later, so another look should be
taken as we get closer to 03Z. A similar daytime scenario should play
out Thursday, and there could be a few light sprinkles again over
I-35 in the morning. Winds shift to NW over DRT after daybreak but
return back to SE toward the end of the day. We`ll keep the winds
east of the dry-line over I-35, but show a more southerly direction
in the early afternoon when the dry-line is close. Isolated
convection could again show up near AUS, but as we saw today, there`s
no need to mention it until we see a break in the cap.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              71  89  72  88 /  10  20  30  60
Austin Bergstrom Intl Airport  71  89  72  89 /  10  20  30  50
New Braunfels Muni Airport     71  92  72  91 /  10  10  20  40
Burnet Muni Airport            69  88  68  85 /  10  20  40  70
Del Rio Intl Airport           70  95  72  94 /  10   0  30  10
Georgetown Muni Airport        71  87  70  87 /  10  20  40  70
Hondo Muni Airport             69  92  71  93 /  10   0  10  20
San Marcos Muni Airport        71  90  72  89 /  10  10  20  40
La Grange - Fayette Regional   73  86  74  89 /   0  20  20  30
San Antonio Intl Airport       72  91  73  91 /  10  10  20  30
Stinson Muni Airport           73  93  74  93 /  10  10  10  20

&&

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

$$

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