Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Austin/San Antonio Texas
1235 PM CDT Friday Jul 31 2015
Aviation discussion...for 18z taf package...
area of scattered clouds is moving into drier air out west and
clear skies are being observed upstream to the east. Some
beginning signs of cumulus development are also being seen in East
Texas and just northwest of kaus. This should not result in
category changes this afternoon. However...some isolated -tsra
should develop from kaus to ksat/kssf and may complicate some
approaches. Best shot at this development will be middle afternoon
through the early evening. Highlighted these times in the taf with
thunderstorms in the vicinity.
After Sundown...VFR will prevail.
Previous discussion... /issued 617 am CDT Friday Jul 31 2015/
not much change to the previous taf package. VFR conditions are
prevailing and will continue to do so for much if not all the day.
The only chance for restrictions will be from any possible
convection this afternoon. The best chances for storms will be
between 19z and 00z. Some of the storms could also produce gusty
winds in excess of 50 miles per hour...but chances are much too low for any
mention in the current taf package.
Previous discussion... /issued 355 am CDT Friday Jul 31 2015/
Short term (today through saturday)...
isolated showers and thunderstorms continue to redevelop over the
coastal prairies...confirming the area of middle-level moisture and
instability to spread west from East Texas into much of south
central Texas early today. GOES sounder dpi imagery at 07z suggests
that 2 inch precipitable water values have reached I-35 near aus although the
Storm Prediction Center mesoanalysis is more conservative. Hi-res model trends look to
suggest a period of weak stability this morning with only a few
showers forming...followed by scattered convection forming over
the coastal prairies and central Texas in the early afternoon. Trends
have also shifted the better rain chances southward to where
moisture depth is highest and the ridge influence is weaker.
Expect the intermittent cloud cover and convection to be good for
about a 2-3 degree drop in maximum temperatures along and east of I-35. Some
lingering clouds could hold temperatures up in a few spots tonight...but
will shade toward persistence on mins.
By Saturday...models trend drier. Much of the tropical moisture
is forecast to disperse...and there is a convergence zone over the
northwest Gulf that could further limit convection potential. Thus have
capped probability of precipitation at 20 percent and returned temperatures to the trends
from the past week.
Will continue to advertise the strong winds to 50 miles per hour today and
add Saturday...given NAM dcape values of 1200-1500 j/kg.
Long term (saturday night through thursday)...
the drying trend continues into Sunday with pop chances cropped
northward to include only a sliver of The Hill Country and
southern Edwards Plateau. The medium range trends show the upper
ridge building back east to reclaim stability over East Texas and western
la through middle-week and beyond. Temperatures have held off
reaching 100 at Sat Thursday but made for the first time of the
season at aus. There is a good chance the first 100 degree day of
the season comes Sunday or Monday...and possibly as early as
Saturday. Heat indices may again be a concern by middle-week when
onshore flow deepens.
Preliminary point temps/pops...
Austin Camp Mabry 77 100 76 101 76 / 10 10 - - 0
Austin Bergstrom international Airport 74 99 72 100 74 / 10 10 - - 0
New Braunfels Muni Airport 75 100 73 100 75 / 10 10 - - 0
Burnet Muni Airport 74 98 74 99 75 / 10 10 - - 0
del Rio International Airport 78 100 77 101 78 / 10 30 10 - 0
Georgetown Muni Airport 74 99 74 99 76 / 10 10 - - 0
Hondo Muni Airport 75 100 73 100 74 / 10 10 - - 0
San Marcos Muni Airport 75 99 73 101 75 / 10 10 - - 0
La Grange - Fayette regional 74 100 74 100 76 / 10 10 - - 0
San Antonio International Airport 77 99 76 100 76 / 10 10 - - 0
Stinson Muni Airport 77 100 75 101 76 / 10 10 - - 0
public service/data collection...Treadway