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000
FXUS64 KEWX 181721
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1221 PM CDT Thu Apr 18 2024

...New AVIATION...

.SHORT TERM...
(Today through Friday)
Issued at 320 AM CDT Thu Apr 18 2024

Stratus beneath the cap will continue to expand across south-central
Texas early this morning and lower. Some areas of fog and patchy
drizzle will be possible around daybreak along the escarpment. The
stratus should mix out around midday, and with high clouds
temporarily clearing off to the east a warmer, hazy, and partly
cloudy to mostly clear afternoon is expected.

At the surface, a dryline is forecast to advance east into Val
Verde and Edwards counties this afternoon. A cold front is also
forecast to drop south through central Texas and the Edwards Plateau
this afternoon, and into the Hill Country and southern Edwards
Plateau this evening where it overtakes the dryline. With strong
diabatic heating, forecast soundings indicate the cap eroding to our
north across central Texas and out along the dryline. Isolated
convective initiation is forecast after 3 PM north of the forecast
area, and perhaps along the dryline and higher terrain of Mexico.

Convective development to the north may increase in coverage through
the early evening hours as the front enters the northern Hill
Country and near the Austin metro area. Forecast soundings across
the northern and western forecast area late afternoon and evening
indicate steep, elevated lapse rates producing pockets of MLCAPE
values in excess of 3000 J/kg and coinciding with deep layer shear
values of 35-40 KT. This will be sufficient to produce a threat for
isolated severe storms producing large to possibly very large hail
and damaging downburst winds through the Hill Country, southern
Edwards Plateau, and Rio Grande early this evening. At question
farther southeast, toward San Antonio and east of I-35, will be
convective inhibition strengthening into the late evening hours.
There is spread in the HREF members on how organized and how far
south the convection make it before dissipating overnight.

How far south the cold front makes it tonight may be largely
influenced by difficult to resolve mesoscale convective processes.
Exact positioning of the cold front near or over the area will also
have a big impact on Friday`s temperatures as well as convective
chances and placement in the afternoon. Confidence in temperatures
and rain chance Friday across south-central Texas is currently low.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 320 AM CDT Thu Apr 18 2024

Friday evening will see a chance for some isolated to widely
scattered showers and thunderstorms across northern and western
portions of the CWA along a slow moving/stalled cold front as a weak
perturbation ejects eastward in the 500mb flow. As of now, CAMs are
favoring the SDB Mountains in Mexico and the Trans Pecos region of
west Texas for initial development mid-afternoon, with potential for
these storms to drift eastward through the evening. While not
currently outlooked by the SPC, these storms will have potential to
be strong to severe with hail and gusty winds.

The front will linger across the area Saturday and Saturday night as
a stronger shortwave ejects east across the region. The combination
of these two features should result in more widespread shower and
thunderstorm development by the late afternoon and evening hours,
with northern portions of the area likely seeing the greatest
coverage of activity. Widespread cloud cover and rain will limit
heating and instability for severe thunderstorms, though a few strong
storms still could not be ruled out. The greater concern though will
be the potential for heavy rainfall leading to areas of flash
flooding as PWATs are forecast to be 150-200% of normal. As a result,
WPC continues to have the Hill Country and northern portions of the
I-35 corridor and Coastal Plains in a level 2 out of 4 risk for
excessive rainfall. Exact rainfall totals are still in question and
will largely depend on where training convection sets up, but there
is some potential for multiple inches of rain across this level 2/4
risk area.

The front will eventually push south of the area Sunday morning
which will bring decreasing precipitation chances and cooler
temperatures, with many locations along and north of I-10 forecast
to remain in the 60s for Sunday afternoon. Temperatures will then
gradually recover through the beginning of next week with dry
conditions currently forecast until at least mid-week when forecast
confidence and model agreement decreases.

&&

.AVIATION...
(18Z TAFS)
Issued at 1220 PM CDT Thu Apr 18 2024

Many locations are still under MVFR ceilings early this afternoon,
although conditions should improve to VFR around 19-20Z.
Thunderstorms are likely to develop mid afternoon north of South
Central Texas, but have the potential to move into the Hill Country
and southern Edwards Plateau after 00Z. Confidence is still medium to
low on how far south these storms can make it, but a few models do
show showers or an isolated storm near the Austin area later tonight.
Have included a TEMPO for TSRA at AUS, but have no mention of storms
at other sites as confidence is too low to include. Low ceilings
begin to redevelop across the entire area after 07Z Friday, likely
lingering until a bit after 18Z.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              65  81  66  78 /  30  10  20  70
Austin Bergstrom Intl Airport  65  81  66  78 /  20  10  20  60
New Braunfels Muni Airport     67  83  66  80 /  20  10  20  60
Burnet Muni Airport            63  77  64  73 /  40  10  40  80
Del Rio Intl Airport           73  89  71  83 /  20  20  50  70
Georgetown Muni Airport        64  77  66  75 /  30  10  30  70
Hondo Muni Airport             67  84  66  81 /  30  10  30  70
San Marcos Muni Airport        65  82  66  79 /  20  10  20  60
La Grange - Fayette Regional   68  82  69  80 /  10  10  10  60
San Antonio Intl Airport       67  82  68  80 /  30  10  20  70
Stinson Muni Airport           69  84  69  82 /  20  10  20  60

&&

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

$$

Short-Term...76
Long-Term...Gale
Aviation...27