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Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
637 PM CDT Fri Mar 23 2018

Aviation...//00z tafs//
strong onshore flow this afternoon has continued to feed moisture
into the region. Current VFR conditions will fall back to MVFR
around 05z-07z then IFR 10z-12z. Cigs will be slow to lift Saturday
and do not expect a return to VFR until 18z west and 22z east. Gusty
S/southeast winds through at least 03z will decrease to near 10 knots
overnight. At this time looks like the winds speeds will be less on
Saturday. S/southeast winds after 15z-16z should remain near 10 knots. Could
see a few sprinkles Saturday morning, but confidence is not great
and will not include in the forecast.


Previous discussion... /issued 324 PM CDT Fri Mar 23 2018/

Short term (tonight through Saturday night)...
low level moisture will steadily increase tonight through Saturday
night beneath a capping inversion. This will lead to increasing
cloud cover and warmer overnight lows. Can't rule out some patchy
drizzle or light rain Saturday morning along the southern Escarpment.
Winds on Saturday should be weaker than today as the pressure
gradient relaxes slightly.

Long term (sunday through friday)...
a strong capping inversion will remain in place Sunday and Monday
across central and eastern areas of the County Warning Area with continued warm and
mostly cloudy conditions as well as a slight chance of showers.
Farther west, the dry line Sunday afternoon and evening should become
active across west central Texas along with a few storms associated
with orographic lift up the serranias del burro. Can't rule out some
of these storms making into far northern and far western areas of the
County Warning Area late Sunday where cap erodes. Cape values are forecast to
increase to over 1500 j/kg along with deep layer shear values of 60
kts, and can't rule out a storm or two becoming strong to severe,
with hail and damaging straight-line winds the primary threat. The
day 3 marginal risk from Storm Prediction Center clips far northwest areas of the County Warning Area. A
mid level shortwave in the southwest flow aloft will aid in convection
chances Monday night into Tuesday and send the dry line further into
the southern Edwards Plateau and Rio Grande plains Monday afternoon
and evening and into The Hill Country Tuesday. This should allow for
better chances for showers and storms near and northwest of a del Rio
to Llano line late Monday as the cap erodes. Again instability and
shear values should be favorable for some strong to severe storms
northwest of this line and eventually extending eastward through
portions of the eastern Hill Country Tuesday.

Better chances for more widespread rainfall will come Tuesday night
through Wednesday night as a combination of a potent upper level low
to the west across northern Mexico opens and approaches, interacting
with a frontal boundary and deep moisture in place. There is still
significant uncertainty on frontal timing between GFS and European model (ecmwf) on
Wednesday as well as run to run consistency. 12z GFS is now quicker
and farther south with the front Wednesday with Post frontal
precipitation and cool temperatures over the region. However it does
appear showers and storms will be likely in general Tuesday night
through Wednesday night, possibly with more of a focus for pockets of
locally heavy rainfall if all ingredients come together, especially
with a slower frontal solution and the significantly anomalous high
precipitable waters forecast over the region.

Drier conditions and clearing skies are expected Thursday as the main
trough axis moves east. An upstream disturbance aloft is shown by
the GFS to move through west central Texas and into north central
Texas Thursday night into Friday, possibly clipping northern areas
of the County Warning Area. European model (ecmwf) has this signal as well, but slightly faster. At
this time will keep the Thursday night and Friday dry due to


Preliminary point temps/pops...
Austin Camp Mabry 65 83 67 85 67 / - 10 10 20 20
Austin Bergstrom Intl Airport 65 83 67 84 67 / - 10 10 20 20
New Braunfels Muni Airport 65 84 66 86 66 / 10 10 10 20 20
Burnet Muni Airport 64 85 66 84 66 / - - 10 20 20
del Rio Intl Airport 67 88 66 91 67 / 0 - 0 - 20
Georgetown Muni Airport 66 84 66 84 66 / - - 10 20 20
Hondo Muni Airport 66 85 66 89 66 / - 10 0 - 20
San Marcos Muni Airport 65 83 66 85 66 / 10 10 10 20 20
La Grange - Fayette regional 68 83 67 84 67 / - 10 - 20 20
San Antonio Intl Airport 67 84 66 86 67 / 10 10 10 20 20
Stinson Muni Airport 67 85 66 88 68 / - 10 - 10 20


Ewx watches/warnings/advisories...


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