Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Austin/San Antonio Texas
1151 PM CDT Sat Sep 20 2014
Discussion...update for 06z aviation below.
Aviation...isolated rain showers will remain possible along the Rio
Grande overnight...and have accounted for this in drt taf. MVFR
ceilings still expected to develop overnight at all taf sites...
becoming IFR at Sat/ssf 10z-14z. Could also be MVFR visibilities
in br at aus around sunrise. VFR conditions re-developing 15z-17z
across the County Warning Area. Less coverage in rain showers on Sunday across central
and eastern County Warning Area...with deeper moisture axis residing across the
western County Warning Area and Mexico.
Previous discussion... /issued 924 PM CDT Sat Sep 20 2014/
to account for decreasing convection.
convection is on the decrease this evening and rainfall rates are
lower than previously anticipated. Have lowered probability of precipitation for the after
midnight period and taken out any heavy rain. Have also increased
cloud cover overnight. Expect mostly cloudy skies will continue.
Other minor changes to hourly grids to account for observational
Previous discussion... /issued 258 PM CDT Sat Sep 20 2014/
Short term (today through sunday)...
the airmass across south central Texas remains quite moist. Last
night there were signs of drying as the kdrt radiosonde observation sampled a precipitable water
of 1.81 inches but that quickly climbed back up to 2.12 inches
this morning. Weak lift can be seen on water vapor imagery west of
the area...and this is where the bulk of the heavy rain has been
this morning and afternoon. We expect the scattered convection to
continue through the late afternoon hours with the bulk of the
showers and storms decreasing in coverage and intensity after
sunset with the loss of daytime heating. Will keep probability of precipitation in the
forecast after 00z to account for any activity lingering this
evening. The higher probability of precipitation will be across the western counties where
the best lift is associated.
Tomorrow...850 flow is expected to become more easterly as the 850
High Breaks down across the southeastern Continental U.S. And replaced by
increasing heights to our northwest. Models are showing quick
drying of the airmass with precipitable water values tomorrow afternoon dropping
to near 1.5 inches for all areas except the western counties.
Will keep probability of precipitation in the forecast tomorrow for areas mainly west of
Highway 281 and will not need to mention locally heavy rainfall
Long term (sunday night through friday)...
the focus of the forecast will then shift to a strong trough
dropping into the northeastern Continental U.S. Sunday and Sunday night. This
feature will send a weak front into the area Monday afternoon.
Upper level support with this front will be quite poor and the
thermal gradient is not expected to be strong. Will carry slight
chance probability of precipitation for the northern counties on Monday afternoon and for
the southeastern zones Tuesday. With associated cloud cover and
weak cold air advection...highs Tuesday through Thursday should be
in the 80s for much of the forecast area...except for the southern
zones. Enough moisture should linger across the south for low rain
chances Wednesday and Thursday. Temperatures will slowly increase
once again Friday.
Preliminary point temps/pops...
Austin Camp Mabry 87 72 90 72 91 / 30 10 10 - 20
Austin Bergstrom international Airport 87 69 90 70 91 / 30 10 10 - 20
New Braunfels Muni Airport 88 71 92 71 93 / 30 10 10 - 20
Burnet Muni Airport 86 70 89 71 90 / 30 10 10 - 20
del Rio International Airport 90 75 88 74 88 / 40 40 30 20 10
Georgetown Muni Airport 88 71 90 72 90 / 30 10 - - 20
Hondo Muni Airport 91 72 93 71 94 / 40 30 20 10 10
San Marcos Muni Airport 86 71 89 71 91 / 30 10 10 - 20
La Grange - Fayette regional 88 72 92 72 92 / 30 10 - - 20
San Antonio International Airport 90 74 92 73 93 / 30 20 10 10 20
Stinson Muni Airport 89 74 93 73 94 / 30 20 10 10 10