Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 kewx 290556 
afdewx

Area forecast discussion
National Weather Service Austin/San Antonio Texas
1256 am CDT Wed Mar 29 2017

Update...
see below for 06z aviation update...

&&

Aviation...

San Antonio and Austin sites...
main aviation impacts will be the
line of thunderstorms that will reach Sat/ssf by around 630z and aus
by around 7z. Lightning, heavy rainfall lowering visibilities, and
strong winds up to 35-40 knots will be the primary aviation threats
from these storms. The storms should be clear of the San Antonio
sites by around 830z and aus by 9z. After this, visibilities and
ceilings should improve to VFR by around 11z to 13z at the I-35 sites
and remain there for the remainder of the forecast period. Winds
will shift from out of the southeast to out of the west as the line
of storms reach the terminals. Winds will calm following the passage
of the storms before picking up once more by mid-to-late Wednesday
morning, with gusts up to 15-20 knots.

Del Rio...
currently VFR at drt following the passage of the line of storms
earlier. VFR is expected to persist for the duration of the forecast
period. Winds will be out of the northwest, with winds gusting up to
20-25 knots beginning at 15z Wednesday morning and continuing for
the remainder of the forecast period.



&&

Previous discussion... /issued 1018 PM CDT Tue Mar 28 2017/

Update...
a Severe Thunderstorm Watch is in effect for areas along and west of
I-35 corridor through 4 am CDT.

Latest radar images showing a line of strong to severe storms
pushing across Val Verde County. The line will continue to fill as it
moves to the east and encounter favorable atmospheric conditions.
Hires models have a good handle on current radar trends and bring the
squall-line along the I-35 corridor around 3/4 am time frame. Main
weather threats tonight into the overnight hours will be damaging
winds and large hail. An isolated tornado is possible but the chances
of occurring are low. Heavy downpours associated with stronger
storms could lead to localized minor flooding across area roadways
and underpasses as well as poor drainage locations.

Previous discussion... /issued 636 PM CDT Tue Mar 28 2017/

Aviation...
isolated +tsra will pass just north of kdrt in the next hour and have
gone thunderstorms in the vicinity there. Otherwise, rain showers/thunderstorms and rain will develop over the lower
Pecos Valley into the Edwards Plateau later this evening and then
gradually form into a line by midnight and then move across the
remainder of south central Texas overnight into Wednesday morning to
midday. Have timing of 03z-05z at kdrt, and 08z-11z kaus/ksat/kssf.
VFR skies start the forecast, then MVFR cigs develop this evening.
Clouds lift to VFR after passage of the line of rain showers/tsra, then
become few-scattered a few hours later. S to southeast winds 10 to 20 kts with
gusts to 30 to 35 kts ahead of the line will become S to SW 5 to 15
kts with its passage, except west to northwest across the Rio Grande into the
Edwards Plateau. Wind gusts up to 50 kts are possible with any thunderstorms and rain.

Previous discussion... /issued 341 PM CDT Tue Mar 28 2017/

Short term (tonight through Wednesday night)...
for the next few hours, the main area of concern will remain out west
along the Rio Grande and southern Edwards Plateau. Currently, we are
beginning to see the low clouds erode across the Rio Grande plains.
Several hi-res models suggest development is possible along this
differential heating zone and this area will need to be monitored
carefully through this afternoon. For the early evening hours, the
Pacific cold front will overtake the dryline across west central
Texas, including the Edwards Plateau. As this occurs, convection
should quickly develop, then progress eastward into the Rio Grande
plains, southern Edwards Plateau and western Hill Country between 9
and 11 PM. For the overnight hours, this line will move eastward and
impact the remainder of The Hill Country and I-35 corridor between
midnight and 6 am. We continue to expect damaging winds and large
hail to be the main severe weather concern for tonight as this line
of storms moves through the area. However, we can't rule out an
isolated tornado as well. As the line shifts east of the I-35
corridor after 6 am, most models indicate a weakening trend as this
line of convection moves east of the strongest upper level lift.
However, we will still need to monitor this line of storms carefully
as it will be moving into favorable moisture and low-level wind
shear. Given the speed of this system, the risk for heavy rainfall
appears rather low at this time. Storm total amounts will likely be
lowest (1/4 inch or less) along the Rio Grande, with amounts
increasing to 1/2 - 1 inch for areas north of a Kerrville to Cuero
line. Some spots could pick up around 1.5 inches north of this line,
but these amounts should be isolated. Areas east of I-35 can expect a
low chance of rain Wednesday afternoon, with the remainder of the
area remaining dry.

Long term (thursday through tuesday)...
a relatively quiet weather pattern is in store Thursday and Friday
and this will lead to a dry forecast along with above normal
temperatures. The pattern is expected to once again become
increasingly active for the upcoming weekend into early next week as
another upper level storm system takes aim at the region. The medium
range models are starting to show a little better agreement with
regards to the mid-level flow pattern. This system should come across
Texas at a lower latitude and this should Bode well for a good chance
of rainfall and active weather across south central Texas, especially
Saturday night and Sunday. This upper system moves to our east by
late Monday, temporarily leaving a dry forecast into Tuesday.

&&

Preliminary point temps/pops...
Austin Camp Mabry 87 55 78 55 86 / 50 10 0 0 0
Austin Bergstrom Intl Airport 86 54 78 52 86 / 60 10 0 0 0
New Braunfels Muni Airport 86 53 79 53 87 / 50 10 0 0 0
Burnet Muni Airport 82 51 74 52 85 / 20 10 0 0 0
del Rio Intl Airport 85 54 82 56 93 / 0 0 0 0 0
Georgetown Muni Airport 85 52 76 52 85 / 50 10 0 0 0
Hondo Muni Airport 86 52 81 53 89 / 10 10 0 0 0
San Marcos Muni Airport 87 53 78 52 86 / 50 10 0 0 0
La Grange - Fayette regional 85 56 76 53 85 / 80 20 - 0 0
San Antonio Intl Airport 86 54 80 55 87 / 30 10 0 0 0
Stinson Muni Airport 86 54 80 55 88 / 30 10 0 0 0

&&

Ewx watches/warnings/advisories...
none.
&&

National Weather Service Glossary of Abbreviations