Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 101212
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
612 AM CST Sat Dec 10 2016
MVFR CIGs slowly lower today across most areas. CIGs drop to IFR
late this afternoon and evening as -RADZ with MVFR VSBYS develops
with periods of LIFR CIGs and LIFR/IFR VSBYs overnight into
Sunday morning. CIGs slowly lift as -RADZ shifts off to the east
by midday Sunday. Have kept mention of -RADZ out of KDRT as
forcing is much weaker there. S to SE winds 5 to 10 KTS prevail,
except winds more VRBL closer to the Coastal Plains.
.PREV DISCUSSION... /ISSUED 359 AM CST Sat Dec 10 2016/
SHORT TERM (Today through Sunday)...
A fairly large temperature gradient is present across South
Central Texas tonight as low clouds continue to move N-NE as SW to
NE oriented isentropic descent is developing over the region.
Temperatures are warming a few degrees once the cloud deck moves
overhead with gradual warming thereafter, which has allowed areas
south of the Highway 90 corridor to warm up into the lower 40s.
Temperatures are generally in the lower to mid 30s north of the
leading edge of the cloud deck. Although some lower lying spots
in the Hill Country may experience another hour at or below
freezing, all sites should be back above freezing by sunrise as
most sites have already seen their low temperature for tonight.
The cloud deck and weak warm air advection responsible for our
slowly warming temperatures overnight will persist today as winds
become southeasterly by late afternoon, but the clouds will only
allow highs to warm up into the lower 50s. This pattern continues
Saturday night into Sunday morning to keep temperatures steady
in the lower 50s. However, a weak shortwave/lee trough coming off
of the Rockies will provide weak PVA tonight that will interact
with a strengthening LLJ and relatively moist environment to
cause isolated shower activity mainly along and east of Highway
281. The showers will end from west to east Sunday morning with
skies gradually clearing Sunday afternoon and winds veering to the
southwest to allow temperatures to warm up into the upper 60s to
lower 70s back above normal for the first time in over a week.
LONG TERM (Sunday Night through Friday)...
A very weak front will push through the region around sunrise on
Monday, but this will really just cause a weak northerly wind
shift as dry southwest flow persists aloft. Thus, highs on Monday
will remain in the upper 60s to lower 70s, with some mid 70s
possible west of San Antonio just south of the Escarpment where
some downsloping warming may occur. Very weak ridging in an
otherwise zonal flow pattern aloft allows for very pleasant, more
fall-like days on Tuesday and Wednesday with highs in the upper
60s to lower 70s and lows in the upper 40s to mid 50s. Models have
moved into better agreement with a cold frontal passage Wednesday
evening. However, this should only cool temperatures about 5-10
degrees back to around seasonal normals as high pressure behind it
is not very impressive and the low pressure system associated with
it occludes as it ejects east over Quebec and Ontario. An upper
level trough digging into California should amplify the flow aloft
and break the zonal pattern, causing temperatures and moisture to
increase quickly Friday and Saturday ahead of a stronger cold front
that should pass through sometime next weekend. In collaboration
with surrounding offices, we increased temperatures and dew points
for the second half of next week well above model guidance to
better reflect this pattern and the ensemble mean trends.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 53 51 70 53 70 / - 20 10 - -
Austin Bergstrom Intl Airport 54 52 70 54 70 / 10 20 10 - -
New Braunfels Muni Airport 52 51 69 54 72 / 10 20 10 - -
Burnet Muni Airport 51 49 69 48 68 / - 20 10 0 -
Del Rio Intl Airport 54 45 67 45 74 / - 10 0 0 0
Georgetown Muni Airport 52 49 70 50 68 / - 20 10 - -
Hondo Muni Airport 52 48 68 49 75 / 10 10 10 0 -
San Marcos Muni Airport 53 51 70 54 71 / 10 20 10 - -
La Grange - Fayette Regional 55 52 72 60 70 / 10 30 20 10 10
San Antonio Intl Airport 52 51 69 53 73 / 10 20 10 - -
Stinson Muni Airport 53 51 69 54 74 / 10 20 10 - -