631
FXUS64 KEWX 200520
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1220 AM CDT Thu Jun 20 2024

...New AVIATION...

.UPDATE...
Issued at 1026 PM CDT Wed Jun 19 2024

The tornado Watch over Atascosa, Dewitt, and Karnes counties has
been cancelled as the greatest threat for brief isolated tornadoes
will remain concentrated across South to Deep South Texas through
the overnight hours. Adjusted grids as well, including PoPs, to
match latest radar and observational trends. There was some decent
rainfall that had fallen across portions of our northeastern most
counties this evening that had been forecast to see some lower
amounts from this event. Some locations received 1 to 3 inches of
rain with a few localized higher amounts. However, this band has
weakened and producing less efficient rainfall rates. Otherwise,
rainfall has been greatest east of I-35 and south of I-10 as
forecast.

&&

.SHORT TERM...
(Tonight through Thursday night)
Issued at 224 PM CDT Wed Jun 19 2024

Key Messages:

*Moderate to locally heavy rainfall will continue into early
Thursday.

*Confidence in the highest rainfall totals is seen across the far
southern portions of the area where the Flood Watch remains.

*Rain amounts have trended down overall.

*Isolated tornado threat remains across our southeastern-most
counties into this evening.

Discussion:

Rain bands from what is now the first named storm of the season,
Alberto, are moving in over South Central Texas with some embedded
thunderstorms. So far, rainfall rates have been tame, but as heavier
showers move into the region, especially south of I-10, any embedded
thunderstorms could contain rainfall rates of 1-2"/hour. There is
still a low end threat for flooding and flash flooding, and the
Flood Watch remains in effect for our southern tier of counties
through midday Thursday.

Overall, rainfall totals are expected to remain between 1-3 inches
over the southern CWA, with between 0.5-2" for the remainder of the
area. The 12Z sounding out of CRP showed PWATs in excess of 2.5"
along with a nearly saturated profile all the way up to 100mb. Long,
skinny profiles, along with modest CAPE and high moisture
environments can produce significant tropical rainfall. Despite
lowered amounts, this is still a beneficial event, as it will act to
keep temperatures down during what is usually one of the hottest and
most humid months of the year and it should help limit short term
drought impacts as we add some moisture to area soils without
widespread severe weather. Speaking of severe weather, there is a
Marginal Risk (Level 1 of 5) for tornadoes over the Coastal Plains,
but the primary concern continues to be locally heavy rainfall and
the low end chance for flooding.

The heavier rain threat should end from east to west by sunrise
Thursday, but there is still a threat for widely scattered showers
and storms to develop Thursday afternoon. The primary threat would
be locally heavy rainfall, but widespread flooding and flash
flooding are not expected at this time beyond 18Z Thursday.
Temperatures will remain some 5-15 degrees below normal for late
June as well, so the first official day of Summer will certainly not
feel like it across South Central Texas.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 224 PM CDT Wed Jun 19 2024

As the remnants of Alberto dissipate over Mexico there will still be
a deep, moist airmass over South Central Texas. Chances for showers
and thunderstorms will continue Friday with the best chances along
and south of I-10/Hwy 90. The low level flow over the weekend and
early next week will be from the southeast. This will keep a warm,
moist airmass in place. A weak upper ridge will allow for isolated
convection driven by daytime heating each day Saturday through
Wednesday over the Coastal Plains. Some days the storms will spread
toward the west and north. Chances will mostly be slight and most
places will remain dry through the period. Temperatures will slowly
warm through the long term to back above normal by the middle of next
week.

&&

.AVIATION...
(06Z TAFS)
Issued at 1220 AM CDT Thu Jun 20 2024

Rain is moving west across South Central Texas with some heavier
bands forming behind the main cluster of showers. Prevailing rain
showers should end at I-35 sites around 08Z with only some VCSH
expected to linger near SAT/SSF through 10Z. DRT will likely see -RA
through this morning. The lull in activity is short lived as
scattered showers and thunderstorms are expected to redevelop across
the area this afternoon. Ceilings will generally be VFR/MVFR, with
IFR ceilings possible for the Hill Country, Rio Grande Plains, and
southern I-35 corridor near 10Z. Gradual improvement will be seen in
the morning although MVFR conditions may linger into the afternoon
for many locations. Gusty northeasterly wind will persist today with
gusts from 20-25 knots shifting from the east after 00Z Friday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              90  75  93  74 /  30  10  10   0
Austin Bergstrom Intl Airport  90  74  91  72 /  30  10  20   0
New Braunfels Muni Airport     88  74  91  72 /  50  10  30   0
Burnet Muni Airport            88  74  90  72 /  30  10  10   0
Del Rio Intl Airport           90  77  93  77 /  60  60  50  20
Georgetown Muni Airport        89  73  90  72 /  30  10  10   0
Hondo Muni Airport             88  74  89  73 /  50  20  30  10
San Marcos Muni Airport        89  72  90  71 /  40  10  20   0
La Grange - Fayette Regional   90  74  90  73 /  30   0  30   0
San Antonio Intl Airport       89  75  90  74 /  50  10  30  10
Stinson Muni Airport           89  76  91  75 /  50  10  30   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this afternoon for Atascosa-De Witt-Dimmit-Frio-
Gonzales-Karnes-Lavaca-Maverick-Wilson-Zavala.

&&

$$

Short-Term...Brady
Long-Term...05
Aviation...27