Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 09/26/23
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
916 PM CDT Mon Sep 25 2023
...New UPDATE...
.UPDATE...
Issued at 916 PM CDT Mon Sep 25 2023
Widely scattered showers and isolated thunderstorms continued near
the Coastal Plains this evening. HRRR appears to the best model this
evening and will generally follow keeping low POPs that area until
Midnight. Otherwise, have removed POPs, although cannot rule out very
isolated showers and perhaps a thunderstorm elsewhere. Re-established
trend to the sensible weather grids.
&&
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 126 PM CDT Mon Sep 25 2023
Synopsis/Mesoanalysis: A highly variable surface pattern is evident
in regional surface observations early this afternoon. Influenced
heavily by both overnight and early morning convection, last night`s
front was analyzed along an approximate Del Rio - Uvalde - Seguin -
Austin line as of 1:00 PM. The Uvalde - Del Rio segment is
attempting to return northward as a warm front, though its forward
progress has been hindered by morning showers, storms, and cloud
cover over the southern Edwards Plateau. The north-south oriented
portion of the boundary running from Seguin to Austin serves as a
rough demarcation between a modestly cooler/drier air mass over Hill
Country, and a hot/muggy regime further east. This has led to the
establishment of an effective warm sector along & east of Interstate
35, where deeper cumulus agitation has been noted over the last
couple hours. Said cumulus have struggled to mature into convection
through 1:00 PM, which is a likely consequence of residual CIN
apparent in both San Antonio and Austin ACARS soundings. Said
stability is further confirmed in visible satellite imagery, which
depicts pockets of gravity waves/bores over portions of the Coastal
Plains at the current hour. This stable layer should erode given
continued daytime heating, with at least scattered convection
becoming possible along/east of I-35 and over the Coastal Plains by
mid afternoon. Additional showers and storms are possible over the
southern Edwards Plateau and Rio Grande through mid-evening, where
the western portion of the front will continue to attempt to advance
north. A few storms could become strong/severe with large hail and
damaging winds being the primary concerns. Locally heavy rainfall is
also possible. Storms should taper near and after midnight. Remnants
of the front will support additional isolated storm potential on
Tuesday, with areas over the Coastal Plains and Rio Grande being
favored. Severe weather is not currently expected in any of the
Tuesday activity.
This Afternoon & Evening: Scattered showers and storms remain
possible over the southern Edwards Plateau, Rio Grande, and
locations along/east of Interstate 35. Given weaker shear in place
across the area, organized severe weather potential is a touch lower
in today`s storms relative to yesterday. Nevertheless, CAPE values
are expected to climb into the 2000-3000+ J/kg range leading up to
storm development, which will likely support at least some hail
potential in the strongest storms that develop. Efficient mixing
will drive steep lapse rates within the boundary layer, which will
result in scattered damaging wind potential as well. We thus can`t
rule out a few strong to severe storms through this evening across
the area. The Storm Prediction Center continues to carry a marginal
(level 1/5) risk for severe weather over the majority of South-
Central Texas given this potential. Minor flooding is also possible
in any heavy downpours, particularly over the southern Edwards
Plateau, where 2-3 inches of rain have already fallen today. The
Weather Prediction Center thus continues a marginal (level 1/4) risk
of excessive rainfall over the southern Edwards Plateau, San Antonio
metro, and Coastal Plains through this evening. Apart from the
shower/storm potential, a few locations across primarily the Coastal
Plains and Rio Grande could see elevated heat indices in the 105-107
range. Practice proper heat safety if spending prolonged periods of
time outdoors in these locations through the rest of this afternoon.
Tomorrow: Anticipate modestly cooler high temperatures areawide with
a post-frontal regime firmly entrenched. Most locations should top
out in the low-mid 90s. Isolated storms will be possible along
remaining wind shifts during the afternoon hours over primarily the
Coastal Plains and Rio Grande. Severe weather is not currently
anticipated.
&&
.LONG TERM...
(Wednesday through Monday)
Issued at 126 PM CDT Mon Sep 25 2023
Any sort of convective activity over locations outside of the Coastal
Plains is unlikely beyond Wednesday afternoon. Weak northwesterly
flow aloft will result in some slight chance PoPs Wednesday
afternoon, which will be primarily driven by daytime heating, but
some weak synoptic support could result in some stronger storms with
gusty winds and small hail.
Thursday through Friday look to be mainly dry, as 500mb ridging
returns, however, not quite as strong. Temperatures will remain above
normal, but more manageable, at least compared to the torture we
endured this Summer. Lower to middle 90s will be common, with some
spots of the Hill Country actually staying below 90 degrees each
afternoon. The Coastal Plains have the best shot at any sort of
precip, with chances for seabreeze showers/isolated thunderstorms
each afternoon Thursday-Friday.
This weekend will perhaps be the start of our next shot at more
widespread precip chances, but how the overall pattern evolves beyond
Saturday is still in question. Both the GEFS and ECM ensembles
indicate southwest flow aloft as long wave troughing develops over
the western CONUS. This will result in a more active jet stream
pattern for South-Central Texas. Meanwhile, the deterministic GFS has
been fairly consistent the last few days in depicting a cutoff low
developing just outside of this forecast, next Monday-Tuesday. This
low could result in increased chances for heavy rainfall, and the WPC
Week 2 Hazards outlook does indicate a slight risk for heavy
precipitation over the Hill Country October 3rd-6th. At this time,
we will take it with a grain of salt, but know that the overall
pattern might finally be tilting more in our favor as we move into
the month of October.
&&
.AVIATION...
(00Z TAFS)
Issued at 639 PM CDT Mon Sep 25 2023
Widely SCT SHRA/ISOLD TSRA are occurring east of I-35 and over the
Edwards Plateau. Have VCSH/VCTS mention at all TAF sites for this
evening. Chances of SHRA/TSRA return Tuesday, however, too low to
mention, at this time. VFR flying conditions prevail tonight through
Tuesday evening. There could be brief lower CIGs/VSBYs in SHRA/TSRA
and a possibility of MVFR CIGs overnight into early morning, however,
chances are too low to mention, at this time. With a chaotic surface
pressure pattern, generally light at 6 KTs or less and VRBL winds
are expected tonight, except briefly gusty near SHRA/TSRA. Winds
increase a little Tuesday, though remain under 10 KTs with NE at the
I-35 sites and E at KDRT.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 72 93 69 95 / 10 10 10 10
Austin Bergstrom Intl Airport 72 92 69 94 / 10 10 10 20
New Braunfels Muni Airport 72 94 70 96 / 10 20 10 20
Burnet Muni Airport 71 92 69 93 / 10 0 0 10
Del Rio Intl Airport 74 94 73 96 / 10 20 10 20
Georgetown Muni Airport 72 92 68 92 / 10 10 0 10
Hondo Muni Airport 71 93 68 94 / 10 20 10 20
San Marcos Muni Airport 70 93 68 94 / 10 10 10 20
La Grange - Fayette Regional 73 91 70 92 / 10 20 10 30
San Antonio Intl Airport 73 93 72 94 / 10 20 10 20
Stinson Muni Airport 75 94 73 95 / 10 20 10 20
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...04
Long-Term...Gale
Aviation...04