Scientific Forecaster Discussion
fxus64 kewx 261548
Area forecast discussion
National Weather Service Austin/San Antonio Texas
1048 am CDT Mon Jun 26 2017
overall, the previous forecast is in good shape. Cumulus field on
satellite is becoming more agitated with isolated to scattered shower
development being noted on area radars late this morning. Cu field
looks best across the Edwards Plateau and Hill Country and this is
where surface moisture convergence is being maximized as a left over
boundary remains in northern Val Verde County from overnight storms.
These storms have also left an mesoscale convective vortex to the northwest of our County Warning Area that
is moving east-southeast. Will have to watch this feature closely as it could
serve as a focus for more numerous showers and storms later this
afternoon and evening mainly for the northern Hill Country and
Edwards Plateau. Should also see a decent coverage of activity in
the coastal plains this afternoon as the sea breeze boundary moves
into the region.
Previous discussion... /issued 648 am CDT Mon Jun 26 2017/
cigs vary from VFR to IFR this morning. We think they will settle at
MVFR across the region within the next hour or two. The should
rebound to VFR by around noon at all area airports. Showers and
thunderstorms are possible this afternoon and early evening. Most
likely time looks like between 18z and 22z in Austin and San Antonio.
Chances are lower at drt. Cigs should stay VFR overnight.
Previous discussion... /issued 405 am CDT Mon Jun 26 2017/
Short term (today through tuesday)...
a moist southeasterly lower level flow was across south central Texas
early this morning with precipitable waters little changed from this past weekend and
ranging from 1.5 inches Edwards Plateau to 2 inches east of I-35 to
the coastal plains. This is feeding a band of showers in a convergent
zone from the middle Texas coast into central Texas. Other showers
are trying to develop over the Edwards Plateau to Rio Grande plains.
Meanwhile, a linear mesoscale convective system is moving across the Permian Basin. Showers
will continue to develop this morning from the coastal plains into
central Texas in this flow, and over The Hill Country due to upslope
flow there. As heating destabilizes the airmass and with surface
boundary collisions, thunderstorms will also develop. After sunset
with loss of heating, showers and thunderstorms will tend to wane.
However, the mesoscale convective vortex or its remnant surface boundary generated by the
Permian Basin mesoscale convective system will likely be approaching the Edwards Plateau.
This should be enough to keep showers and thunderstorms going or
redeveloping over The Hill Country and Edwards Plateau this evening
into the overnight. Later tonight into morning, streamer showers are
expected again moving further inland from the coastal plains. Little
change in airmass is indicated on Tuesday with a similar pattern to
today. However, the MCV, possible mid level shear axis, may enhance
shower and thunderstorm development. The main threat in the short
term remains locally heavy rains that may cause some minor flooding.
Some minor stream flows or rises were noted from locally heavy rains
this weekend. Cannot rule out wind gusts to 30 mph with the stronger
storms. Temperatures continue below normal due to clouds and rain.
Long term (tuesday night through sunday)...
subtle changes take place mid to late week as the subtropical ridge
weakly builds into our area with a mid level shear axis along or just
off the Texas coast. The moist airmass shifts to the east with lower
pws, near 1 inch, moving into the Edwards and the 1.5 to 2 inch
range shifting to the I-35 corridor to coastal plains closer to the
mid level shear axis. Chances of showers and thunderstorms continue
for the central and eastern parts of south central Texas with most
activity during the early morning to evening hours and enhanced by
the seabreeze. Most models build the subtropical ridge a little more
over our area next weekend, effectively ending the rain chances.
However, the European model (ecmwf) show the shear axis moving west across southern
Texas maintaining at least slight rain chances. For now, the forecast
has followed the model consensus. A very slow warming trend develops
Wednesday and continues through Friday, then more stable
temperatures next weekend.
Preliminary point temps/pops...
Austin Camp Mabry 90 72 90 72 92 / 40 20 40 10 20
Austin Bergstrom Intl Airport 90 71 89 72 91 / 40 20 40 10 20
New Braunfels Muni Airport 89 71 90 71 91 / 40 20 40 10 30
Burnet Muni Airport 86 70 87 70 89 / 40 20 40 10 10
del Rio Intl Airport 92 73 92 73 94 / 30 30 30 10 10
Georgetown Muni Airport 88 71 88 71 90 / 40 20 40 10 20
Hondo Muni Airport 91 71 91 71 92 / 40 20 40 10 20
San Marcos Muni Airport 90 71 90 71 91 / 40 20 40 10 20
La Grange - Fayette regional 89 72 89 73 90 / 50 30 50 20 30
San Antonio Intl Airport 90 72 90 73 92 / 40 20 40 10 20
Stinson Muni Airport 90 73 91 73 92 / 40 20 40 10 20