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Area forecast discussion 
National Weather Service Austin/San Antonio Texas
1238 am CDT Sat Aug 27 2016

Aviation...
VFR conditions will continue at all terminals for the next several
hours. MVFR cigs will develop around 09z in San Antonio and spread
to Austin by about 12z. Drt should remain VFR overnight and
through this period. Austin and San Antonio will rebound to VFR by
late morning. A chance for showers and thunderstorms will develop
during the afternoon and have included prob30 groups in the Austin
and San Antonio airports tafs to account for this. Don't think
convection will change flying category.

&&

Previous discussion... /issued 820 PM CDT Friday Aug 26 2016/

Update...
pops have been increased between Highway 281 and Interstate 35
north of San Antonio to account for two clusters of showers and
thunderstorms that will persist for the next 1-2 hours as they
ride a pair of outflow boundaries. The first area is a cluster of
storms in western Comal and Hays counties that has started to turn
more south-southwest as it rides a westward-moving outflow
boundary. These storms should begin to dissipate within the next
hour as they lose heating and the extra push from the outflow
boundary. The second area of storms is a more linear cluster that
is developing over western Williamson and central Burnet counties.
These storms have stronger outflows and will likely persist a bit
longer towards 10 PM as they also slide to the south-southwest. If
these storms organize into a more linear feature, they could push
more southeast into the western half of Travis County.

The main threats with these storms will be brief heavy downpours
up to 2 inches, gusty winds to 40 miles per hour, and up to dime
size hail. The Austin and San Antonio metros have been included
in 20-30 pops just in case storms briefly slide into these areas,
with the best chances in the western parts of Austin and north
portions of San Antonio. All storms should dissipate within the
next few hours to allow for a mild evening as temperatures
decrease from the 80s into the 70s.

Previous discussion... /issued 620 PM CDT Friday Aug 26 2016/

Update...
very isolated showers and thunderstorms will continue until sunset
before dissipating as a series of outflow boundaries continues to
briefly trigger convection. Instability will be high enough to
allow for brief thunderstorms as currently seen in eastern Blanco
County along and northeast of a line from Kerrville to San Antonio
to Pleasanton. Outflow boundary interactions will be most likely
to produce thunderstorms in western Travis, western Hays, eastern
blanco, and southern Burnet counties over the next few hours. All
convective activity over the area should dissipate around sunset
to allow for a mild evening in the low to mid 70s with increasing
cloud cover overnight.

Previous discussion... /issued 541 PM CDT Friday Aug 26 2016/

Aviation...
/00z tafs/
there are several outflow boundaries moving across the northern part
of south-central Texas late this afternoon. One of them already
moved over kaus with others projected to stay away from area
terminals. There is a slight chance for new showers and isolated
thunderstorms within the next few hours mainly across The Hill
Country. Area airports should remain dry with passing showers to
the north of ksat and kssf if they do develop later this evening.
Light and variable winds are expected to prevail through Saturday
morning. MVFR cigs are expected around dawn along Interstate 35
through 15z Saturday. VFR conditions will prevail for the rest of
the afternoon and evening.

Previous discussion... /issued 249 PM CDT Friday Aug 26 2016/

Short term (tonight through Saturday night)...
this afternoon isolated showers and storms were located across
Lavaca and Fayette counties across the eastern County Warning Area. Expansion
west toward the I-35 corridor and eastern Hill Country with these
isolated showers and storms may take place through the remainder
of the afternoon and into the evening, before dissipating late in
the evening. Also a few showers and storms will be possible
through the early evening across far western Val Verde County.
Should see isolated to widely scattered showers and storms
Saturday afternoon across the eastern cwa, I-35 corridor and Hill
Country.

Long term (sunday through friday)...an inverted mid and upper
level trough was located across the northwest Gulf of Mexico and
is forecast to close off Saturday night through Sunday somewhere
in the vicinity of the Upper Texas coast. The GFS and European model (ecmwf) move
the low southwest over the mid Texas coast on Monday. A spoke of
vorticity and pool of higher moisture is shown to wrap around the
low into the eastern half of the area on Sunday, leading to an
increase in coverage of showers and storms across the central and
eastern County Warning Area. Precipitable water values are forecast to increase to
around 2 to 2.25 inches along and east of I-35 Sunday. The GFS
indicates deep easterly flow develop on Monday as the low is
positioned just south of the area, with the higher pool of
moisture expanding farther western into the County Warning Area. Pockets of
locally heavy rainfall will be possible Sunday and Monday.
The mid and upper level low will weaken and continue west through
south Texas and Mexico Tuesday and Wednesday with a chance of
showers and thunderstorms continuing over the area. Drying is
forecast to gradually take place Thursday and Friday.

&&

Preliminary point temps/pops...
Austin Camp Mabry 89 74 89 74 87 / 40 10 50 30 50
Austin Bergstrom Intl Airport 89 73 89 73 87 / 40 20 50 30 50
New Braunfels Muni Airport 90 73 89 73 87 / 40 10 50 30 60
Burnet Muni Airport 89 72 88 72 86 / 40 10 40 30 50
del Rio Intl Airport 94 74 93 74 90 / 10 - 20 20 40
Georgetown Muni Airport 89 73 88 73 87 / 40 10 40 30 50
Hondo Muni Airport 92 73 90 73 88 / 20 - 40 30 50
San Marcos Muni Airport 89 72 89 73 87 / 40 20 50 30 60
La Grange - Fayette regional 89 75 89 75 88 / 50 20 50 30 60
San Antonio Intl Airport 91 74 89 74 87 / 30 10 50 30 60
Stinson Muni Airport 92 75 90 75 88 / 30 10 40 30 60

&&

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

$$

Mesoscale/aviation...05
synoptic/grids...04

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