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

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FXUS64 KEWX 121154
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
654 AM CDT Wed Aug 12 2020

.UPDATE...
Please see the 12Z aviation forecast discussion below.

&&

.AVIATION...
Low clouds continue to develop slowly across the region this morning.
Based on current trends, we will mention MVFR cigs along I-35 this
morning, but will opt to go with TEMPO groups through 15Z. Otherwise,
no significant changes to the forecast have been made, with some
gusty south to southeast winds in store from late morning through the
evening hours. Low clouds are likely to develop again early Thursday
morning, but given recent trends, clouds may once again be slow to
thicken and will not mention in the forecast at this time.

&&

.PREV DISCUSSION... /ISSUED 330 AM CDT Wed Aug 12 2020/

SHORT TERM (Today through Thursday)...
The main concern in the short term portion of the forecast will be
centered on the increasing temperatures. It will be hot again today
as the subtropical ridge axis in the mid and upper levels, along
with a stout low-level thermal ridge remain the dominant weather
feature of interest. Trends over the last couple of days show low-
level moisture has not been able to not mix out quite as efficiently
for areas along and east of I-35. Thus, we have seen afternoon
dewpoints trend upward during the peak heating hours. The latest
model guidance does show some higher dewpoints remaining intact
today. With afternoon temperatures expected to remain persistent or
even increase slightly, we will likely meet Heat Advisory levels for
areas along and east of the I-35/I-37 corridor. We will issue a Heat
Advisory for the above mentioned areas from 1 PM - 7 PM today. It
will be hot again tomorrow and we may very well need another Heat
Advisory for portions of south central Texas. Otherwise, it looks
too stable aloft to support any rain chances across the region and
we will keep the forecast dry through Thursday.

LONG TERM (Thursday Night through Tuesday)...
Subtropical Ridge remains centered over southern Arizona/New Mexico
through Friday, then gradually shifts to the Four Corners and builds
north into the Great Basin this weekend, all the while extending over
Texas. Strong subsidence under the Ridge and below seasonal normal
moisture levels (PWs) make for no rain over most areas. An inverted
trough passing well south of our area across Mexico brings a slight
increase in moisture to near seasonal levels to the Coastal Plains
this weekend. This may allow the seabreeze to generate a few showers
and thunderstorms across Lavaca and possibly nearby counties during
the afternoon hours. Well above normal temperatures continue. A few
spots along and east of I-35 may briefly flirt with advisory levels
with both high temperatures and heat index values.

The portion of the Ridge over Texas weakens as upper level troughing
develops over the eastern states Monday and Tuesday. This may allow
a surface boundary or weak mid level impulses to move across our
area. Will maintain the low chances of showers and thunderstorms as
these features provide the upward forcing needed on slightly deeper
moisture. With the increased cloud cover and rain, high temperatures
may cool 2 or 3 degrees on Monday and even more on Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry             105  78 105  77 104 /   0   0   0   0   0
Austin Bergstrom Intl Airport 102  77 102  75 102 /   0   0   0   0   0
New Braunfels Muni Airport    104  77 104  74 103 /   0   0   0   0   0
Burnet Muni Airport           100  75 102  75 103 /   0   0   0   0   0
Del Rio Intl Airport          104  78 105  78 106 /   0   0   0   0   0
Georgetown Muni Airport       101  77 103  77 102 /   0   0   0   0   0
Hondo Muni Airport            102  76 104  75 105 /   0   0   0   0   0
San Marcos Muni Airport       101  77 102  74 103 /   0   0   0   0   0
La Grange - Fayette Regional  101  78 102  76 102 /   0   0   0   0   0
San Antonio Intl Airport      101  78 103  76 103 /   0   0   0   0   0
Stinson Muni Airport          102  77 102  75 102 /   0   0   0   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening for
Atascosa-Bastrop-Bexar-Caldwell-Comal-De Witt-Fayette-Gonzales-
Guadalupe-Hays-Karnes-Lavaca-Lee-Travis-Williamson-Wilson.

&&

$$

Short-Term/Aviation...Platt
Long-Term...04


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