Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/29/20
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
926 PM CDT Tue Apr 28 2020
.UPDATE...
In terms of grid updates have only made minor updates to shift
precipitation for South Central Texas until after midnight. This fits
in line with the most recent runs of the HRRR and other high
resolution models. It looks like the best window for precipitation
will be between 5 and 8 am. These recent runs of the HRRR also show
the western flank of the squall line weakening slightly with the main
bowing portion with the greatest severe wind risk focusing more in
Houston`s area and possibly getting into our eastern counties like
Lee and Fayette. If the recent HRRR runs and the 18z Texas Tech WRF
verify the 30% PoP for Bexar County is too high and San Antonio may
once again totally miss out on any precipitation.
One probable reason for the storms weakening as they approach South
Central Texas by Wednesday morning is the continued presence of a
capping inversion still evident on evening aircraft soundings out of
the AUS and SAT airports. While the advancing front should overcome
that cap it may play a role in limiting some of the thunderstorm
activity. Trends will certainly be monitored through the night, but
as of now it looks like the greatest threat will be concentrated east
of I-35 and possibly east of our area. SPC does have Severe Watch 154
across our northern border with the Fort Worth and Houston until 4
am. As stated earlier in the discussion storms should be approaching
our northern border around then and any need for a watch at that
point will be coordinated between SPC and EWX pending the radar and
model trends early Wednesday AM.
&&
.PREV DISCUSSION... /ISSUED 651 PM CDT Tue Apr 28 2020/
AVIATION...
VFR conditions persist this afternoon across all of South Central
Texas. Storms across Mexico are producing some cirrus blow off
around K5T9 (Eagle Pass) but this is all south of Del Rio. VFR skies
should continue through much of the night ahead of a front which will
arrive early Wednesday morning.
Precipitation chances will be greatest at AUS and so prevailing
thunder has been included from 08z to 11z Wednesday AM. When the
front arrives winds will switch around to the north and begin around
12 knots, but quickly pick up through the day Wednesday and be gusty
at times up to 25 knots. The front will arrive around 11z at SAT/SSF.
Models show much of the precipitation to the east and north of the
San Antonio terminals so have only kept VCTS in for those areas. DRT
should remain dry through the period with the front and north winds
arriving around 09z. Ceilings could briefly drop to MVFR with the
precipitation along the front, but VFR skies return by 15z across the
I-35 corridor.
PREV DISCUSSION... /ISSUED 219 PM CDT Tue Apr 28 2020/
SHORT TERM (Tonight through Wednesday Night)...
A cold front will move down through North Texas tonight bringing
showers and thunderstorms into the eastern half of South Central
Texas. The front will be moving into a moist, conditionally unstable
airmass. Dewpoint temperatures will be in the middle 60s to lower
70s. Forecast soundings show very high CAPE, but a stout cap.
Convection should be ongoing as the front arrives and this cap may
not matter. SPC has included a small portion of Burnet, Williamson,
and Lee Counties in the Enhanced risk area with the Slight risk down
to a Fredericksburg to New Braunfels to Hallettsville line and the
Marginal risk from Kerrville to San Antonio to Kenedy. They expect a
line of storms to be moving into our CWA late tonight and that
damaging wind gusts will be the most likely threat with large hail
also possible. The tornado threat is very low, but not zero. Models
have slowed things down and the short term models are showing a line
of storms moving into our northeastern counties sometime after
midnight and moving through San Antonio by around 6 am and out our
CWA by mid-morning. Convection should end quickly behind the front
as drier air moves in. Winds will become breezy from the north
during the afternoon. Winds will weaken during the evening as the
pressure gradient relaxes. Clear skies, light winds, and cold
advection will lead to low temperatures Thursday being below normal.
LONG TERM (Thursday through Tuesday)...
After a dry and pleasant Thursday, conditions get warmer and more
humid with southeasterly winds. Temperatures will reach into the 90s
on Friday with most areas near the triple digits by Sunday. Overnight
temps will be warm as well, with lows in the 70s. The combination of
heat and moisture will produce heat indices of up to 104 to our west
along the Rio Grande Plains, and 100 to 102 in our metro areas of San
Antonio and Austin. This trend continues into midweek next week.
Another upper disturbance approaches by Wednesday, but with typical
Day 7 model inconsistency, the forecast remains dry, and is likely to
change over the next few days.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 69 82 55 84 59 / 50 10 0 0 0
Austin Bergstrom Intl Airport 68 81 51 84 57 / 50 20 0 0 0
New Braunfels Muni Airport 67 83 53 84 56 / 40 20 0 0 0
Burnet Muni Airport 66 79 52 83 57 / 50 - 0 0 0
Del Rio Intl Airport 69 87 59 91 63 / 0 - 0 0 0
Georgetown Muni Airport 66 79 53 83 58 / 60 10 0 0 0
Hondo Muni Airport 69 86 54 89 57 / 20 - 0 0 0
San Marcos Muni Airport 67 82 53 84 56 / 50 20 0 0 0
La Grange - Fayette Regional 69 81 54 84 57 / 60 40 0 0 0
San Antonio Intl Airport 69 84 55 86 58 / 30 10 0 0 0
Stinson Muni Airport 69 86 56 87 58 / 30 10 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Treadway
Long-Term...BMW