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

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FXUS64 KEWX 150239 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
939 PM CDT Thu Mar 14 2024

...New UPDATE...

.UPDATE...
Issued at 910 PM CDT Thu Mar 14 2024

Heads up:

OOZ hires models are coming in and showing isolated shower and
thunderstorm activity moving into the Rio Grande overnight. Forecast
sounding models suggest for the possibility of an isolated strong to
to severe storms moving across the southern part of the Rio Grande
moving to the northeast before day break. Forecast soundings show
large instability in place during that time period. Any storms that
develops within that environment could produce large hail as the
main weather threat. Also, localized heavy rain is possible with the
stronger storms and could lead to difficult driving conditions.

Will update the forecast later on and provide more details once all
the models are in.


&&

.SHORT TERM...
(Tonight through Friday night)
Issued at 227 PM CDT Thu Mar 14 2024

Key Messages...

*Confidence in storms developing this this afternoon and evening
across South-Central Texas remains low and conditional on the
capping inversion breaking.
*Higher confidence in some scattered strong to severe storms on
Friday; particularly in the afternoon and evening with the primary
threats being large hail and damaging wind gusts.
*Locally heavy rainfall will be possible on Friday and Saturday with
the potential for isolated flash flooding.

Discussion...

Low stratus continues to erode from west to east across the area,
lingering longest over the I-35 corridor and portions of the Coastal
Plains through mid to late afternoon. Light showers will also be
possible through late afternoon across the I-35 corridor and Hill
Country, confined under the capping inversion. Thinking is still
that the cap cannot erode enough today over South Central Texas and
strong to severe storms will form north and east of the area; that
said, if the cap does break they could become severe with large hail
and strong wind the main hazards.

A brief lull in any shower or storm activity is expected tonight
before a front moves closer to the area overnight, expected to reach
the northernmost portion of the CWA near daybreak. A disturbance in
the southwest flow aloft will also move over the area overnight
which will aid in the development of early morning showers and
thunderstorms. More widespread activity looks to move over the area
from the south sometime after midnight with several CAMs indicating
the greatest thunderstorm potential occurring in the far northern
portion of the CWA. Most likely these storms storms would form above
the boundary layer which means they could tap into the elevated
instability and shear and become severe. With steep lapse rates,
large hail would be the main threat with any morning convection.

Activity may once again lull late morning into the early afternoon
with the surface front continuing to very slowly progress southward.
Mid-afternoon storms may quickly become severe as they tap into the
plentiful instability combined with 40-50 knots bulk shear. The main
hazard would be large or very large hail and damaging straight line
winds. If a storm is able to root to the surface in the Coastal
Plains, an isolated tornado could be possible as well. No changes
with the SPC Day 2 outlook for severe weather have been made from
the previous outlook so a level 2 of 5 risk continues for locations
along and east of the I-35 corridor and a level 1 of 5 risk is noted
for the rest of the CWA. On top of the severe threat, heavy rain may
also be seen with storms tomorrow that could result in isolated
flash flooding. This is highlighted by WPC with a level 1-2 risk of
4 for excessive rain over South-Central Texas.

Storms should begin to drift south during the late evening, although
additional convection may begin out west during this time as another
disturbance in the flow aloft moves towards the area. These showers
and storms will gradually move east during the overnight hours with
precipitation chances continuing into Saturday.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 227 PM CDT Thu Mar 14 2024

An upper level low will spin over the southwestern US from Saturday
until Tuesday night. This will keep the flow over TX generally from
the southwest. A cold front will stall across South Texas Saturday.
The low level flow will keep a moist airmass in place. With the
boundary still in the vicinity, rain chances will continue Saturday
through daytime Sunday. PW is forecast above 1" and there could be
locally heavy rain during this period. Flash flooding is possible and
WPC has our area in a Marginal (1 of 4) to Slight (2 of 4) risk for
Excessive Rainfall. Monday chances for showers and thunderstorms will
shift to the west. Tuesday night the upper low will begin to open
and the trough will begin to lift into the central plains. As the
trough lifts to our north there will continue to be low chances for
showers and thunderstorms.

&&

.AVIATION...
(00Z TAFS)
Issued at 639 PM CDT Thu Mar 14 2024

The San Antonio metro area sites are currently reporting MVFR cigs
as of 2350z. There are some breaks in the clouds across the I-35
corridor based on latest visible images and decided to go with the
suggestion of some of the guidance: VFR cigs for a few hours. By
03z, cigs go back down to MVFR and even IFR before midnight tonight
and continuing into the overnight hours. Before dawn, there is low
confidence on showers and storms and even both cigs and vsybs
categories as models are having a hard time with a strong solution.
Some models bring vsbys to less than 1 mile with areas of dense fog.
Later on during the mid to late morning expect a wind shift from the
north and northeast as a cold front moves across the area. An upper
level disturbance is forecast to help with storm development mid to
late Friday afternoon likely affecting the all area terminals.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              68  77  60  69 /  40  80  30  80
Austin Bergstrom Intl Airport  68  79  61  70 /  40  70  30  80
New Braunfels Muni Airport     68  81  61  72 /  30  70  30  80
Burnet Muni Airport            64  72  57  66 /  60  80  30  80
Del Rio Intl Airport           68  87  63  76 /  30  40  70  80
Georgetown Muni Airport        66  75  58  68 /  60  80  30  70
Hondo Muni Airport             66  84  60  72 /  30  60  40  80
San Marcos Muni Airport        67  79  60  71 /  30  70  30  80
La Grange - Fayette Regional   70  80  64  72 /  30  70  30  70
San Antonio Intl Airport       68  81  62  71 /  30  60  40  80
Stinson Muni Airport           69  84  63  73 /  30  60  40  80

&&

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

$$

Short-Term...17
Long-Term...18
Aviation...17


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