Scientific Forecaster Discussion
fxus64 kewx 280156
Area forecast discussion
National Weather Service Austin/San Antonio Texas
856 PM CDT Sat may 27 2017
isolated showers and thunderstorms developed under The Anvil of
thunderstorms over the serranias del burro and are moving to the east
along the Highway 90 corridor. Have added slight chance pops in this
area for tonight. Expect them to dissipate prior to reaching the San
Antonio area due to a strengthening capping inversion and have kept
pops out of there. Only other update is to reestablish nighttime
into morning temperature, dewpoint, and wind trends. Recent models
still show showers and thunderstorms along and behind the front later
on Sunday into Sunday night with a possibility of strong to severe
storms and locally heavy rains.
Previous discussion... /issued 609 PM CDT Sat may 27 2017/
Aviation discussion...for 00z taf period...
thunderstorms and rain west of kdrt this afternoon will flirt with terminal space
through the first few hours of the taf. Not expecting a direct impact
but an amendment may be needed if storms continue to develop farther
north and east. Otherwise, expecting cigs to develop tonight to bring
terminals down to IFR and MVFR. Added lines for each anticipated
category change throughout the morning but also expecting development
of thunderstorms and rain to begin reaching the taf sites towards the end of the taf
period. Did not include lines at this time due to uncertainty of
timing and direct impacts but wanted to include this possibility in
the discussion for later taf issuances.
Previous discussion... /issued 231 PM CDT Sat may 27 2017/
Short term (tonight through Sunday night)...
upper air analysis this morning showed nearly zonal flow over Texas with
a trough over the central rockies. At the surface, high pressure was
centered over the Gulf making the winds across our County Warning Area from the south
to southeast. The dryline was stretched from north to south across
Terrell County west of Val Verde and a frontal boundary was across
OK and the Panhandle. The upper trough will move away from The
Rockies into the Central Plains and turn the flow over Texas to the
south-southwest. Tonight the dryline will move slightly toward our
northwestern area and help develop convection over the Mexican
mountains. There is a chance some of these storms could cross into
Texas and we have included slight chance pops along the Rio Grande. The
frontal boundary will drop down to our northern border by Sunday
morning and then move through our County Warning Area during the day. Thunderstorms
will develop along the front Sunday and continue into the evening.
Model soundings show high cape and moderate vertical wind shear and
Storm Prediction Center has included most of our County Warning Area in a slight risk for severe
thunderstorms. The most likely threat will be damaging wind gusts
with a lower chance for large hail and a very low tornado threat.
There is also a chance for locally heavy rain from efficient, slow
moving storms. Storms should continue but weaken overnight into
Long term (monday through saturday)...
the upper flow will remain west-southwesterly into the coming week.
A series of short wave troughs will move through the pattern bringing
chances for showers and thunderstorms for much of the week.
Convection will be more likely during the afternoons and evenings
with daytime heating and decrease at night. Monday looks like it will
have the best chance with the surface front still near our southern
border. With front to our south precipitable water values will be reasonably low,
around 1.5 inches, so heavy rain is not likely. In addition there is
not strong signal for any severe storms, but it is still the end of
our climatologically most favored month for severe weather so we will
have to watch closely each day.
Preliminary point temps/pops...
Austin Camp Mabry 76 91 70 83 67 / 10 40 70 50 30
Austin Bergstrom Intl Airport 74 91 69 82 66 / 10 30 70 60 30
New Braunfels Muni Airport 74 91 70 81 66 / 10 30 70 50 30
Burnet Muni Airport 73 87 67 81 64 / 10 40 60 40 30
del Rio Intl Airport 75 92 71 84 68 / 20 30 70 50 40
Georgetown Muni Airport 74 89 67 82 65 / 10 40 70 50 30
Hondo Muni Airport 74 92 70 83 66 / 20 30 70 50 30
San Marcos Muni Airport 75 91 69 82 66 / 10 30 70 60 30
La Grange - Fayette regional 76 91 71 82 69 / 10 30 70 60 30
San Antonio Intl Airport 76 92 71 82 68 / 10 40 70 50 30
Stinson Muni Airport 76 92 72 82 69 / 10 30 70 60 30