Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Austin/San Antonio Texas
255 PM CDT sun Jul 24 2016
Short term (today through monday)...
the heat will hang around for one more afternoon before a major
change in the weather comes late Monday. Heat index values this
afternoon are already up to 104 - 106 in spots across the I-35
corridor and the coastal plains. Due to increasing moisture an
isolated shower or storm is possible late this evening along the
sea breeze, but high resolution models keep that activity to a
On Monday the ridge of high pressure weakens and pushes eastward.
This will open the door for two westward moving upper level
disturbances. Both right now can be seen on water vapor, one over
the lower Mississippi Valley, and the other over South Florida.
Models show the first disturbance kicking off a complex of storms
over northeast Texas late tomorrow. This will move southwestward.
The combination of increased moisture, the outflow boundary from
the complex of storms, and daytime heating will lead to isolated
showers and thunderstorms late tomorrow into the evening hours.
The best chances for storms will be along and west of the US
Highway 281 corridor. Precipitable water values in forecast
soundings from the GFS approach 2 inches by Monday morning so
there will be the possibility of locally heavy rainfall from the
activity tomorrow afternoon. With those same soundings showing
limited cape and fairly weak shear the main threat from these
storms will be gusty winds in addition to the heavy rainfall.
Afternoon highs will "cool" a bit for Monday due to the increased
cloud cover. Heat index values will still reach up to around the
Long term (monday night through saturday)...
as the lower Mississippi Valley trough moves west across the state
Monday night rain chances will continue. The South Florida trough
will approach the state late in the day on Tuesday. The
combination of the lift caused by both of these disturbances,
daytime heating, residual boundaries, and daytime heating will
lead to increased coverage of showers and thunderstorms across
south central Texas on Tuesday. Again with precipitable water values around 2
inches brief locally heavy rainfall will be possible. Gusty
thunderstorm winds and lightning will remain The Hazards from the
stronger thunderstorms. Highs Tuesday will be at or below normal
across the area, in the lower 90s, thanks to the cloud cover and
precipitation. The NAM and European model (ecmwf) show a focus for showers and
storms across our western counties Tuesday night into Wednesday as
the low moves across the Rio Grande plains. Wednesday will bring
another decent shot of rain as the low slowly moves west and
moisture remains across south central Texas.
From here the long term models diverge. The GFS has weak ridging
across the area Thursday and Friday, keeping the trough across the
Midwest farther north. The European model (ecmwf) has the South Florida trough
hanging around northern Mexico which maintains the weakness in the
ridge. This allows not only for sea breeze each day, but isolated
showers and storms across most areas Thursday, and east of I-35
Friday and Saturday. As the European model (ecmwf) has been consistent with the
weakness in the ridge, and moisture should remain pooled over
south central Texas will side with it and continue slight chances
for precipitation through Saturday before finally drying US out.
Temperatures have not been at or below normal since early June,
and this chance of precipitation is our most solid chance since
early June as well.
Preliminary point temps/pops...
Austin Camp Mabry 101 78 99 76 94 / - 10 40 40 60
Austin Bergstrom Intl Airport 100 76 98 75 93 / - 10 40 40 60
New Braunfels Muni Airport 101 76 99 76 93 / 0 10 30 40 60
Burnet Muni Airport 99 76 96 74 92 / 0 10 30 40 50
del Rio Intl Airport 103 80 101 80 96 / 0 0 10 20 50
Georgetown Muni Airport 100 78 97 75 93 / - 10 40 40 50
Hondo Muni Airport 101 76 100 76 93 / 0 0 10 30 60
San Marcos Muni Airport 100 77 98 74 92 / - 10 40 40 60
La Grange - Fayette regional 100 77 97 76 93 / 10 10 40 40 60
San Antonio Intl Airport 99 78 98 77 92 / 0 - 30 40 60
Stinson Muni Airport 102 78 100 78 95 / 0 - 30 30 60
public service/data collection...30