Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 302045

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
345 PM CDT Thu Mar 30 2017

.SHORT TERM (Tonight through Friday Night)...
A beautiful spring day with sunny skies has settled in across South
Central Texas under northwest flow aloft and weak westerly 5-10 mph
winds and relatively high pressure at the surface. Temperatures have
warmed up into the mid to upper 70s across the region with some lower
80s still anticipated in the Rio Grande Plains and along the I-35
corridor with some weak downsloping effects. Clear skies are expected
tonight, but warm air advection overnight will allow for lows tonight
to be a bit warmer than last night generally in the mid 50s. The
upper level ridge will move through South Central Texas tomorrow,
allowing for clear skies and highs in the mid to upper 80s. However,
some lower 90s expected along the Rio Grande Plains as temperatures
approaching 20 deg/C at 850 mb should mix down dry adiabatically to
the surface. Southerly winds are expected to increase dramatically
tomorrow afternoon to 10-20 mph with stronger gusts to 25-30 mph.
These winds coupled with minimum relative humidities in the lower
20s in the Rio Grande Plains and southern Edwards Plateau and some
teens in Val Verde County will lead to elevated fire weather
conditions in those areas tomorrow afternoon. Low clouds will return
overnight Friday into Saturday morning to keep lows up in the 60s.


.LONG TERM (Saturday through Thursday)...
The main weather impact of the next seven days continues to be this
weekend`s slow-moving storm system that should bring some wetting
rainfall and possibly some severe thunderstorms to the region.
Models generally continue to indicate that the upper level trough
digging south from the Four Corners into the Mexican state of
Chihuahua by Saturday evening will be positively tilted and
relatively slow moving as it weakens. This would suggest that the
potential for more widespread showers and thunderstorms on Saturday
is lower, which model trends generally reflect aside from the GFS.
However, the potential for a shortwave rotating around the broad
trough into south Texas, upper-level divergence associated with a N-S
oriented jet streak to our west, shear values in excess of 40 knots,
and CAPE values in excess of 2000 J/kg continue to suggest the
potential for strong to severe thunderstorms is there for Saturday
afternoon and evening. The biggest question mark will be whether lift
will be focused along a N-S oriented dryline or in a broader area of
NW-SE oriented isentropic ascent. Relatively weak midlevel dynamics
and surface cyclogenesis would favor the latter scenario which
decreases our severe threat somewhat for Saturday afternoon.

Therefore, the most likely scenario at the current moment is for
light streamer showers along the Escarpment Saturday morning with
some scattered strong to marginally severe thunderstorms across most
of the region as the atmosphere destabilizes. We may have a brief
lull Saturday evening before widespread showers and thunderstorms
develop as the surface cold front approaches the region and the
trough to our west finally begins to eject into Coahuila. Some models
suggest storms will develop in the Rio Grande Plains overnight
before merging into a squall line that moves through the region
Sunday morning with the synoptic cold front. Given the shear and
instability present, strong to severe thunderstorms with this line
will be possible. Showers and elevated thunderstorms may last into
Sunday afternoon and early evening as a deepening upper trough that
is becoming more negatively tilted moves through the region before
ending by late Sunday. Rainfall amounts should average around an
inch, but some locally higher totals of 2-3 inches will be possible
particularly along and east of Interstate 35. The greatest threat of
locally heavy rainfall capable of producing flash flooding still
appears to be well east of our area.

Pleasant dry spring weather returns for the first half of next week
as southwest flow aloft returns with highs in the 80s and lows in the
50s and lower 60s. A weak front moving through the region late
Tuesday into Wednesday will cause a slight chance of showers and
thunderstorms over our easternmost counties. Otherwise, the second
half of next week looks dry with cooler temperatures a bit closer to
seasonal normals with highs in the upper 70s to lower 80s.


Austin Camp Mabry              57  87  65  81  65 /   0   0  -   40  60
Austin Bergstrom Intl Airport  54  87  63  81  65 /   0   0  -   40  60
New Braunfels Muni Airport     53  87  64  82  65 /   0   0  -   40  50
Burnet Muni Airport            55  85  63  78  62 /   0   0  -   40  50
Del Rio Intl Airport           55  91  65  87  61 /   0   0  10  10  50
Georgetown Muni Airport        55  86  63  79  63 /   0   0  -   40  60
Hondo Muni Airport             52  89  64  85  64 /   0   0  -   30  50
San Marcos Muni Airport        53  86  63  81  66 /   0   0  -   40  50
La Grange - Fayette Regional   55  86  64  82  67 /   0   0  -   30  60
San Antonio Intl Airport       56  88  65  83  66 /   0   0  -   30  50
Stinson Muni Airport           54  88  66  83  67 /   0   0  -   30  50




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