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Area forecast discussion 
National Weather Service Austin/San Antonio Texas
131 PM CDT Sat Jul 4 2015

Aviation... /18z taf update/
the coastal prairies convection has so far steered clear of I-35
taf sites to the east where higher precipitable water values persist. Hrrr runs
show decreasing potential for cells to reach the I-35 terminals
with each run...so will conitnue to exclude mention of convection
in the forecasts. The rest of the taf considerations are simply a
reflection of persistence on winds and ceilings. IFR ceilings should still
be possible near daybreak...but the visibilities should continue to trend
drier with no br mentioned in todays tafs.

&&

Previous discussion... /issued 643 am CDT Sat Jul 4 2015/

Aviation...
we start with MVFR ceilings at all terminals this morning. Expect them
to lower to IFR in Austin and San Antonio within the next couple
of hours. VFR will return by around noon. There is a slight chance
for thunderstorms and rain in Austin and San Antonio this afternoon...but
probability is too low to include in tafs. Ceilings will lower again
tonight.

Previous discussion... /issued 350 am CDT Sat Jul 4 2015/

Short term (today through sunday)...
an upper level trough is currently moving to the east across the
southeastern plains with a weakness in the subtropical ridge over
south central Texas today. A lower to middle level ridge extends from
the western Atlantic west across the Gulf Coast states maintaining
a moist southerly lower level flow with precipitable waters of 1.5 to 1.9 inches.
The surface pressure gradient is sufficiently weak to allow for a
seabreeze. The weakness aloft and seabreeze will lift the moisture
to generate isolated showers and thunderstorms later this morning
into this afternoon. Cannot rule out a locally heavy downpour near
the coastal plains where moisture is deepest and a gusty downdraft
wind. Have left out probability of precipitation for the Austin and San Antonio areas as
any showers and thunderstorms likely dissipate before reaching
them. However...have slight chance probability of precipitation southwest of San Antonio
along I-35 as slightly deeper moisture is there. Expect showers
and thunderstorms to dissipate by sunset. The weakness aloft moves
off to the east on Sunday as the subtropical ridge over northern
Mexico builds a little to the east drying the airmass slightly
from above. The seabreeze may generate isolated showers and
thunderstorms across areas near the coastal plains on Sunday
afternoon where precipitable waters near 1.7 inches remain.

Long term (sunday night through friday)...
a middle to upper level trough moving east across The Rockies into
the Southern Plains erodes the subtropical ridge back into Mexico
by Monday. The southern end of the trough lingers over western
Texas Monday through Tuesday night as noted in the European model (ecmwf)...Gem and
NAM bringing slightly deeper moisture to our western areas while
the GFS keeps the trough north with a drier airmass. Have favored
the model consensus and slight chances for showers/thunderstorms
across the Edwards Plateau to lower Pecos Valley. Earlier runs of
some models showed quantitative precipitation forecast further east across The Hill Country.
However...will leave out for now as Gulf of Mexico ridge caps the
airmass further east. The southern end of the trough lifts north
by Wednesday as subtropical ridges over Mexico and Gulf of Mexico
begin a process of building over Texas which continues through
next weekend. Underneath the building ridge...subsidence and a
drying airmass will prevent rain. A slow warming trend is
expected as lower level thicknesses increase. However...residual
soil moisture should continue to keep 100s out of the forecast.

&&

Preliminary point temps/pops...
Austin Camp Mabry 92 76 92 76 92 / 10 - 10 - -
Austin Bergstrom international Airport 91 74 91 76 92 / 10 - 10 - -
New Braunfels Muni Airport 91 74 90 75 91 / 10 - 10 - -
Burnet Muni Airport 90 74 90 75 91 / 10 - 10 - -
del Rio International Airport 93 76 93 76 95 / 10 - 10 0 -
Georgetown Muni Airport 91 75 90 76 91 / 10 - 10 - -
Hondo Muni Airport 91 74 90 75 92 / 10 - 10 0 -
San Marcos Muni Airport 91 75 90 76 92 / 10 - 10 - -
La Grange - Fayette regional 92 75 91 77 91 / 20 - 20 - -
San Antonio International Airport 91 76 91 76 92 / 10 - 10 0 -
Stinson Muni Airport 92 76 91 76 92 / 10 - 10 0 -

&&

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

$$

Mesoscale/aviation...Oaks
synoptic/grids...tb3
public service/data collection...LH

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