605
FXUS64 KEWX 201709 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1209 PM CDT Fri Sep 20 2024

...New AVIATION (18Z TAFS)...

.SHORT TERM...
(Today through Saturday)
Issued at 242 AM CDT Fri Sep 20 2024

The typical overnight clouds are developing across the Coastal
Plains and then moving toward the north into the I-35 corridor, the
escarpment and over areas to the southwest of San Antonio. This
trend is forecast to continue through mid Friday morning. Otherwise,
lows are forecast to range from the lower 70s across the Hill
Country to upper 70s along the Rio Grande. Dewpoint temperatures are
elevated across the Coastal Plains and areas to the east and
southeast of Interstate 35, where patchy to areas of fog can`t be
ruled out between dawn and the early morning commute.

The low clouds are forecast to lift and dissipate for the most part
of South Central Texas mid to late morning with the exception of the
Rio Grande, where low clouds linger for several more hours. Today`s
highs are likely to reach the lower to mid 90s across the Hill
Country and upper 90 along the I-35 and portions of the Coastal
Plains. Heat index values are likely to be elevated ranging from 103
to 107 this afternoon. A few places could get into the 108 to 109
for an hour or two especially across the far southeast counties of
the local area (Karnes, Gonzales, DeWitt and Lavaca).

Overall weather conditions are expected to be hot and dry with
slight chances for showers and even a thunderstorm or two over areas
to the south, southwest and west of San Antonio mid to late
afternoon. The reason of these chances of precipitation is the
position of a mid level low pressure system to the southwest of the
Rio Grande. The influence of this feature over the local area is
enough for isolated showers and maybe a storm. Any activity that
develops should come to an end early evening.

Clouds start to build across the local area on Friday night through
Saturday morning with overnight lows in the 70s. Clouds linger
through late Saturday morning before partly cloudy skies dominate
the region. As far as high temperatures on Saturday, there are
forecast to be above normal climate values but a few degrees cooler
than Friday. The reason for this is that the upper level ridge over
the local area weakens a bit and flatten as an upper level short
wave moves from the four corners region into the Central Plains.
Going with a rain-free forecast for Saturday but can`t rule out an
isolated shower or two across the southern Edwards Plateau mid to
late afternoon.

&&

.LONG TERM...
(Saturday night through Thursday)
Issued at 242 AM CDT Fri Sep 20 2024

Late this weekend into early next week, the subtropical ridge axis
begins to weaken as an upper level low moves out of the Rockies into
the central plains states. A trough axis associated with this upper
low will gradually move across the northern half of Texas and may aid
in some isolated convection across portions of south central Texas on
Sunday and Monday. For Sunday, we will keep rain chances limited to a
small portion of northwestern Val Verde county. In addition, we could
see an isolated shower or storm develop over the coastal plains as
the sea breeze moves inland. Rain chances may slide a little farther
southward into the southern Edwards Plateau and western Hill Country
on Monday. A weak cold front is expected to gradually push into the
region on Monday, with only a slight cooling trend in store for the
southern Edwards Plateau and Hill Country. The front may gradually
work southward to near the Highway 90 corridor late in the day. The
medium range models are reluctant to show much in the way of rain
chances for the I-35 corridor on Monday as most of the mid and upper
level support remains to our north.

The forecast for Tuesday through Thursday remains uncertain as the
operational GFS and ECMWF both show differing solutions with regard
to the mid and upper level flow pattern across the CONUS. For now, we
will keep some low rain chances in the forecast on Tuesday and
Wednesday for areas mainly along and west of the I-35 corridor. Much
of the forecast will also depend on possible tropical activity in the
Northwestern Caribbean Sea and Southeastern Gulf of Mexico. For now,
we will show a slight cooling trend as we could see continued north
winds in the lower levels. However, temperatures are still expected
to remain a little above climatological normals for this time of
year.

&&

.AVIATION...
(18Z TAFS)
Issued at 1203 PM CDT Fri Sep 20 2024

Wash, rinse, repeat. Basically a carbon copy of the past couple of
mornings with MVFR ceilings developing around 09Z at SAT and SSF and
around 12Z at DRT. We should see rapid improvement after 15-17Z at
all sites, with AUS looking to remain VFR at this time. Winds will
generally be out of the ESE at 5-10 kts but could be a bit stronger
at DRT, upwards of 10-15 kts after 17Z Saturday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              75  97  73  96 /   0   0   0   0
Austin Bergstrom Intl Airport  74  97  71  95 /   0   0   0   0
New Braunfels Muni Airport     74  98  73  97 /   0   0   0   0
Burnet Muni Airport            73  94  71  92 /   0   0   0   0
Del Rio Intl Airport           79  96  78  95 /  10  10  10  10
Georgetown Muni Airport        73  96  71  94 /   0   0   0   0
Hondo Muni Airport             74  94  72  94 /  10  10   0   0
San Marcos Muni Airport        73  96  70  95 /   0   0   0  10
La Grange - Fayette Regional   74  95  72  94 /   0   0   0  10
San Antonio Intl Airport       76  95  74  94 /   0  10   0   0
Stinson Muni Airport           76  97  75  96 /  10  10   0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Short-Term...17
Long-Term...Platt
Aviation...MMM