Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 272342
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
642 PM CDT SAT AUG 27 2016
Satellite and radar are showing less and less chance that
convection will affect any of the TAF locations this evening.
There are still a few pop up SH/TS to the east and west of South
Central Texas but convection is not able to make it close. Chances
are too small to mention in the TAFs for the remainder of the
evening. May get some debris clouds overnight...with some SCT/BKN
low clouds by morning. Not totally sold on the idea of MVFR ceilings
based on the east and northeast flow in the lowest levels. We were
still able to manage some cigs this morning based on this
flow...so will mention in a tempo group for SAT/SSF. Question
tomorrow will once again be if and when convection will fire. MOS
guidances are fairly low on pop tomorrow and until PWs increase
significantly...will mention VCTS in the PM hours to handle the
isolated/scattered SH/TS that we are expecting.
.PREV DISCUSSION... /ISSUED 253 PM CDT SAT AUG 27 2016/
SHORT TERM (Tonight through Sunday Night)...
Over the course of the afternoon, isolated showers with occasional
lightning activity were developing and slowly moving westward.
Taking a look at the mesoscale environment...it appears RAP is
underdoing the low level instability and lapse rates over the
northern Hill Country and northwest towards Midland. 19Z
observations were showing temperatures already in the 90s just
north of the CWA border which is likely aiding in the added
convective potential over 60s dewpoints. Will have to watch for
some gusty wind potential and gust front generation fueling
development over the next several hours due to DCAPEs over 1000
j/kg as well as mid level dry air. PWATs across the CWA are in
the 1.5-1.8 inch range which is notably low relative to our
average over the last few weeks but the added convective potential
could still result in some brief heavy rainfall. Should see this
activity wane shortly after dark.
Coverage of QPF will increase across the CWA Sunday as the weak
gulf disturbance centers itself south of Galveston Bay. PoPs will
still favor the southeast quarter of the CWA but at least isolated
convection should occur to the Rio Grande Plains.
LONG TERM (Monday through Saturday)...
By Monday, the disturbance slowly rides the Texas coastline
southwest keeping PoP chances elevated across the CWA. PWATs will
have increased to around 2 inches as far west as the Rio Grande
thus increasing the potential for locally heavy rainfall. However,
this latest suite of model runs is overall keeping QPF output
rather low. Still maintain that some isolated spots...most likely
east of I-35...could see a couple inches of rain between now and
next Wednesday. But in general, the rainfall totals should stay
between a half inch to an inch over the next 5 days.
The upper low begins to lose continuity by midweek and with it the
loss of deep layer moisture over the region. The GFS depicts a
rather dry air mass filtering into South Texas by Friday morning
and riding up the Rio Grande Valley and Plains in central Texas by
next Saturday. This should serve to remove rain chances from the
forecast for next weekend. The main upper high begins to build as
well bringing highs back into the mid 90s by the end of the
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 73 88 73 89 74 / 20 40 30 50 30
Austin Bergstrom Intl Airport 72 88 73 89 73 / 20 40 30 50 30
New Braunfels Muni Airport 72 88 73 89 72 / 20 40 30 50 30
Burnet Muni Airport 71 87 72 88 71 / 20 30 30 40 30
Del Rio Intl Airport 74 93 74 91 73 / 10 20 20 40 30
Georgetown Muni Airport 72 88 73 88 73 / 20 30 30 40 20
Hondo Muni Airport 72 91 73 90 73 / - 30 20 50 30
San Marcos Muni Airport 71 88 72 88 72 / 20 40 30 50 30
La Grange - Fayette Regional 74 88 74 90 74 / 20 50 30 50 30
San Antonio Intl Airport 74 89 74 89 74 / 10 40 30 50 30
Stinson Muni Airport 74 91 75 90 75 / 10 40 30 50 30
Public Service/Data Collection...33