604
FXUS64 KEWX 271836
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
136 PM CDT Thu Mar 27 2025

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Tonight through Friday night)
Issued at 134 PM CDT Thu Mar 27 2025

Key Messages:

- Flood Watch remains in effect across the coastal plains

- Additional locally heavy rainfall possible with the highest amounts
  focused across the coastal plains

A humid airmass remains across South-Central Texas with unusually
high precipitable water values ranging from 1.25 inches across our
north-northwestern most locations to 1.75 inches in our southeast
coastal plain counties. A thick warm cloud layer also is also in
place with thickness at or above 10,000 feet. There was a lull in
activity from overnight into much of this morning with mainly some
patchy to areas of light to moderate rain. Additional rounds and
generally a greater coverage of activity is expected later this
afternoon into midday Friday as the base of the trough approaches
and moves atop South-Central Texas with stronger upper level
forcing. However, the ongoing activity across the CRP and BRO CWAs
may disrupt the inflow and integrated water vapor transport (IVT)
into our region. Additionally, the instability levels across the
area remains quite modest with skinny CAPE profiles as cloud cover
will help to limit daytime heating across the region. This limited
instability keeps the severe weather risk reduced. Even with that
said, an isolated cell still could produce hail of up to 1 inch in
diameter or a wind gust near 60 mph. SPC continues to highlight a
portion of the region under a level 1 of 5 risk into and through
Friday. Once more, I want to reiterate, the locally heavy rainfall
component of the thunderstorm activity is the greater concern in
regards to this event.

The model guidance continues to generally struggle and vary on the
location of where the greatest footprint of rainfall falls across
South Texas. A general trend over the last several runs is for a
southerly shift of the footprint and this matches observational
trends so far. As a result, additional forecast rainfall amounts
across our region has lowered. The coastal plains remains the most
favored region in our area for rainfall where additional 1 to 3
inches are possible with localized higher amounts. Elsewhere, for
mainly along and to the west of the I-35 corridor, the rainfall
could range from as little as less than a quarter inch to 1 to 1.5
inches. A flood potential does linger with the greatest concerns
across the Flood Watch area in the coastal plains but the most
likely flood types given the precedent drought conditions will
remain mainly confined to urban and small stream flooding. The
heaviest rains so far in this event have resulted in brief small
rises on rivers. WPC maintains a level 1/2 of 4 risk of excessive
rainfall in portions of the region today and a level 1 of 4 risk
again for eastern portions of the region on Friday.

As the base of the trough swings across the region, the rain will
shut off from west to east gradually on Friday with most activity
shifting to the east of our CWA by the early evening hours. The
overnight could see some patchy fog develop with the saturated
grounds. Otherwise, its another warm and humid night with low
stratus.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 134 PM CDT Thu Mar 27 2025

Warmth returns this weekend as south winds push rain-cooled air out
of our area. Highs are likely to climb at least the 80s again, with
90s likely along the Rio Grande and possibly extending east to the I-
35 corridor. Moisture remains high with 70s dew points percolating
in the Coastal Plains, so morning cloudiness will be likely this
weekend. Some patchy fog is also possible Saturday morning for areas
with light south winds and wet soils, with the best chances of this
overlap over the southern Coastal Plains and in the southern Hill
Country.

A passing shortwave trough to our north will give the dryline a
decent push into our western counties Saturday afternoon. High LFCs
within the moist Gulf air are higher than the dryline circulation on
the latest guidance, which generally limits rain chances for most of
the region. A dry cold front then arrives late Saturday into early
Monday, which looks to only temporarily and briefly lower
temperatures by a few degrees. Temperatures Tuesday morning, the
"coldest" period in the post-frontal airmass, should only fall to
the low-50s at most over low-lying areas of the Hill Country. As is
typical for the springtime, a few isolated showers can`t be
completely ruled out when boundaries move into moist Gulf air, but
chances remain very low at this time.

Beginning Tuesday, southerly flow will return after the front washes
out, bringing back the higher temperatures and dew points. Models
diverge significantly after Tuesday regarding the evolution of the
jet stream over the western US, with the EPS showing a much more
amplified and slower trough developing over the western US compared
to a speedier less eventful shortwave on the GEFS. These scenarios
yield quite varied outcomes for our area for later in the week. Due
to large uncertainties, rain chances from this potential system have
been kept low for now, but could take the form of a line of frontal
showers if it does materialize.

&&

.AVIATION...
(18Z TAFS)
Issued at 1217 PM CDT Thu Mar 27 2025

Ceilings ranging from MVFR to IFR/LIFR levels and periods of light
to moderate rain will continue through the TAF period. Have also
added a PROB30 group from late afternoon through the evening hours
across the I-35 TAF sites for when guidance indicates increased
probability for a potential of thunderstorm activity. For KDRT,
thunderstorm potential trends later in the evening into the
overnight. There is a PROB30 group for that period at that site as
well. Within the precipitation, visibilities are expected to be
reduced into the 2 to 6 mile range as well. East-southeasterly and
south-southeasterly winds of around or below 10 knots should be
expected but directions at times could trend variable, especially
within any showers or thunderstorms. Confidence is lower than
average for placement and timing of any heavier rain showers or
thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              61  74  64  85 /  70  70  20  10
Austin Bergstrom Intl Airport  61  74  62  84 /  70  70  20  10
New Braunfels Muni Airport     62  76  63  86 /  70  70  10  10
Burnet Muni Airport            59  74  62  85 /  70  60  10   0
Del Rio Intl Airport           63  84  64  93 /  50  10   0   0
Georgetown Muni Airport        60  73  63  84 /  70  70  10  10
Hondo Muni Airport             61  77  62  85 /  70  50  10   0
San Marcos Muni Airport        61  74  63  84 /  70  70  20  10
La Grange - Fayette Regional   62  75  64  84 /  80  80  20  10
San Antonio Intl Airport       62  76  64  84 /  70  70  10  10
Stinson Muni Airport           63  76  64  85 /  70  70  10   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday afternoon for Atascosa-De Witt-Gonzales-
Karnes-Lavaca-Wilson.

&&

$$

Short-Term...Brady
Long-Term...Tran
Aviation...Brady