Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/27/23
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
757 PM CDT Wed Apr 26 2023
...New MESOSCALE UPDATE...
.TORNADO WATCH 170 IN EFFECT FOR BASTROP, BLANCO, HAYS, LEE, AND
TRAVIS COUNTIES UNTIL 1 AM CDT...
In coordination with the Storm Prediction Center, Tornado Watch 170
has been to the immediate southeast of the ongoing Tornado Watch 169.
Potential for isolated prefrontal supercell development continues
through the next couple of hours along and east of Interstate 35,
where a prefrontal trough continues to remain evident in surface
observations. Storms have struggled to deepen through early evening
in the absence of deeper forcing aloft, although an isolated storm
has managed to mature to severe levels over portions of Hays and
Travis Counties, prompting a Severe Thunderstorm Warning. Golf ball
sized hail has been reported near Dripping Springs with this storm.
Prefrontal development will eventually be overtaken by a line of
storms approaching from the north. We expect the main hazards to
begin to transition to damaging straight line winds/large hail as
this occurs, although isolated tornadoes will remain possible in and
close to the watch area through the first part of the overnight. Have
a way of receiving warnings over this portion of South-Central Texas
through the first part of tonight.
&&
.SHORT TERM...
(Tonight through Thursday night)
Issued at 130 PM CDT Wed Apr 26 2023
...Severe Thunderstorms possible from this afternoon through
tonight, with the best chances being along I-35 and in Hill
Country...
Synopsis/Mesoanalysis: Current surface observations show a low
pressure center located very near Abilene. A warm front extends east
out of this low, with a dryline weaving southwest through San Angelo
and western Val Verde County. A subtle prefrontal trough axis has
been observed over the last several hours further to the east of the
dryline, weaving south from Coryell County and paralleling
Interstate 35 in our area. Attempts at convective initiation have
been observed along and east of this feature over the last 45-60
minutes, with sporadic lightning flashes being noted in satellite
products. Updrafts have yet to mature, however, likely due remnants
of a capping inversion present in both the Austin and San Antonio
ACARS soundings. Continued surface heating will likely erode what
remains of this cap over the next couple of hours, pointing to at
least some potential of scattered thunderstorm development in
advance of the surface cold front passing through the region
tonight. Any prefrontal development will likely be supercellular in
nature, with all severe weather hazards possible. Additional storms
will move into the area along the advancing cold front tonight, with
peak potential being between 10 PM and 6 AM. Additional severe
weather -- predominantly damaging winds and isolated large hail --
will be possible in this activity, particularly over northern
portions of the area. Fair conditions will prevail through the
remainder of the short term period.
This Afternoon & Evening: We will be closely monitoring the
potential for prefrontal thunderstorm development through the first
portion of the evening hours. Confidence in this scenario has
increased through the morning hours, with several 12Z CAMs,
subsequent hourly runs of the HRRR, and the WoFS all depicting
isolated supercell development along and east of Interstate 35
between 4 and 9 PM. If this activity were to develop, large hail
exceeding 2 inches in diameter, damaging straight line winds, and
isolated tornadoes would all be possible. Have multiple ways of
receiving watch and warning information over the next several hours.
Seek safe/sturdy shelter immediately if caught driving or outside
when severe weather approaches.
Tonight: Additional storms will be possible from north to south
between 10 PM and 4 AM as a cold front moves through the region.
Additional strong to severe storms are possible, with damaging
straight line winds and large hail exceeding quarter size being the
most likely hazards. Severe potential will likely begin to wane
moving beyond the midnight hour as storms become progressively more
outflow dominant and begin to gust out. Activity should begin to
vacate to the Victoria Crossroads and Brush Country approaching
sunrise.
&&
.LONG TERM...
(Friday through Wednesday)
Issued at 130 PM CDT Wed Apr 26 2023
Friday the low level winds will be southerly to southeasterly
returning warm, moist air to the region. Another cold front will move
through the area Friday night. Models are in good agreement with
this system. They show a surge of PW with strong instability and
vertical wind shear. POPs have increased slightly from the previous
forecast. The ingredients also look to be there for strong to severe
thunderstorms with locally heavy rain. SPC has included most of our
CWA in a Slight Risk area for Day 3. Winds will be northerly again
Saturday bringing dry weather for the weekend. Temperatures will be
cooler with below normal with lows in the 40s and 50s and highs in
the 60s and 70s Saturday and 70s and 80s Sunday. Dry weather will
continue through the end of the period with temperatures warming a
few degrees.
&&
.AVIATION...
(00Z TAFS)
Issued at 646 PM CDT Wed Apr 26 2023
Isolated thunderstorms are expected in between San Antonio and Austin
early this evening. Chances for direct impacts to terminals with this
activity is low, but have VCTS mentioned in the TAFs as satellite
imagery indicates fairly widespread TCU across the area. Later this
evening into the overnight hours, a cold front will move from NW to
SE across south central TX, bringing more widespread showers and
thunderstorms, lower cigs (mostly MVFR, brief periods of IFR are
possible at AUS), and gusty winds. The current expectation is that
low cigs and rain chances will remain east of DRT, but we will
continue to monitor. The predominant wind direction behind the front
will be NNW, but variable and potentially strong wind gusts will be
possible in any thunderstorms as they move through. May have to add
TEMPO groups in the TAFs later for winds if confidence increases.
Conditions will improve through the remainder of the morning hours
tomorrow with diminishing winds.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 81 61 80 57 / 40 70 20 0
Austin Bergstrom Intl Airport 81 60 79 54 / 40 70 20 0
New Braunfels Muni Airport 83 62 82 57 / 30 60 20 0
Burnet Muni Airport 80 57 77 55 / 50 70 0 0
Del Rio Intl Airport 89 62 86 62 / 0 40 0 0
Georgetown Muni Airport 81 58 78 53 / 50 70 10 0
Hondo Muni Airport 85 61 84 57 / 10 60 20 0
San Marcos Muni Airport 81 61 80 55 / 30 70 20 0
La Grange - Fayette Regional 80 64 78 55 / 40 70 20 0
San Antonio Intl Airport 84 62 83 59 / 20 70 20 0
Stinson Muni Airport 85 64 85 59 / 20 60 20 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...Quigley
Mesoanalysis...Quigley
Long-Term...05
Aviation...Gale