Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 270120

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
820 PM CDT FRI AUG 26 2016

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.



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.


/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.


SHORT TERM (Tonight through Saturday Night)...
This afternoon isolated showers and storms were located across
Lavaca and Fayette counties across the eastern CWA. 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

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 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 CWA. 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 CWA. 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.


Austin Camp Mabry              92  73  89  74  89 /  30  30  40  10  50
Austin Bergstrom Intl Airport  90  72  89  73  89 /  30  20  40  20  50
New Braunfels Muni Airport     90  73  90  73  89 /  30  20  40  10  50
Burnet Muni Airport            90  72  89  72  88 /  30  40  40  10  40
Del Rio Intl Airport           93  74  94  74  93 /  10  10  10  -   20
Georgetown Muni Airport        90  73  89  73  88 /  30  40  40  10  40
Hondo Muni Airport             91  72  92  73  90 /  20  20  20  -   40
San Marcos Muni Airport        90  72  89  72  89 /  30  20  40  20  50
La Grange - Fayette Regional   91  74  89  75  89 /  40  20  50  20  50
San Antonio Intl Airport       91  74  91  74  89 /  20  30  30  10  50
Stinson Muni Airport           92  75  92  75  90 /  20  20  30  10  40




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