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Area forecast discussion
National Weather Service Austin/San Antonio Texas
312 PM CST sun Nov 19 2017

Short term (tonight through Monday night)...
pleasant and cool late Fall weather conditions are in place across
south central Texas as temperatures have only climbed into the 60s
with mostly clear skies and NE 5-10 mph winds under high pressure.
Patchy high clouds associated with the right entrance region of a jet
streak aloft and weak midlevel shortwave west of Big Bend are moving
into central Texas. This cloud cover should increase to some extent
as the shortwave pushes into south central Texas overnight, but this
should only have a small effect on low temperatures overnight. Winds
tonight will generally be light and variable and skies will be mostly
clear especially for spots along and east of I-35, so our forecast
low temperatures range from the mid 30s in The Hill Country and low-
lying spots along the I-35 corridor to lower 40s elsewhere. This
forecast is bit cooler than model guidance which tends to struggle
on nights with more efficient radiational cooling, but the high
clouds should be enough to prevent spots from falling below freezing
as supported by even the lowest ensemble members in the MOS guidance.

High temperatures will increase a few degrees tomorrow as southerly
flow returns and scattered high clouds associated with the shortwave
remain and weak west-east isentropic ascent overspreads the region. A very
isolated shower may occur in our southeastern-most counties
associated with this large-scale lift, but nearly all models keep
this activity well south and east of the region. Low temperatures on
Monday night into Tuesday morning will be several degrees warmer than
tonight in the upper 40s and low 50s as scattered to broken low
clouds develop over the region. A few hi-res models suggest that
patchy fog may be possible as well, but this will most likely depend
on the coverage and timing of low cloud development.


Long term (tuesday through sunday)...
dry weather will generally continue for at least the next week and a
half. A stronger shortwave will dig into East Texas on Tuesday
afternoon and evening to allow another cold front to move through the
region. Dry southwest flow behind a pre-frontal surface trough just
ahead of the front should allow temperatures to warm up into the mid
to upper 70s on Tuesday afternoon. Although we will have decent west-SW
to east-NE oriented isentropic ascent across the region, moisture return
aloft will be limited and the best dynamics from the shortwave will
be east of the region. The GFS does bring some very isolated shower
activity into our eastern-most counties Tuesday night into Wednesday
morning, but this does not seem consistent with isentropic descent
at midlevels so we have left this out of the forecast. Wednesday will
be another cool fall day under high pressure and northerly flow
similar to today before we warm back up above normal for Thursday
through Saturday as southerly flow returns. Another front is expected
next Saturday evening, but its effect on temperatures will most
likely be very weak as high pressure aloft continues to build over
Mexico and slide east towards Texas for last week of November.


Preliminary point temps/pops...
Austin Camp Mabry 41 67 50 76 49 / 0 - - - -
Austin Bergstrom Intl Airport 36 67 49 76 49 / 0 - - - -
New Braunfels Muni Airport 40 67 49 76 49 / 0 - - - -
Burnet Muni Airport 39 64 46 73 45 / 0 - - - -
del Rio Intl Airport 42 68 45 78 47 / 0 0 0 0 0
Georgetown Muni Airport 38 65 49 74 47 / 0 - - - -
Hondo Muni Airport 39 68 47 78 48 / 0 - 0 0 -
San Marcos Muni Airport 39 66 49 77 49 / 0 - - - -
La Grange - Fayette regional 40 68 51 75 51 / 0 - - - 10
San Antonio Intl Airport 40 68 51 76 51 / 0 - - 0 -
Stinson Muni Airport 42 68 50 77 51 / 0 - - 0 -


Ewx watches/warnings/advisories...


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