336
FXUS64 KEWX 210830
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
330 AM CDT Sat Sep 21 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today through Sunday)
Issued at 300 AM CDT Sat Sep 21 2024

Low clouds are increasing across the eastern part of South Central
Texas as of 230 AM CDT. Also, there is a deck of mid level clouds
covering the western part of Bexar County that has been around for
several hours. Latest nighttime microphysics images are showing some
low clouds developing underneath with San Antonio International
Airport reporting broken ceiling at 1800 feet. The low level cloud
coverage is forecast to remain and expand across most areas through
at least 10am - 11am time frame. Overnight lows are forecast to
range from the lower 70s across the Hill Country to upper 70s across
the Rio Grande and Coastal Plains areas. One more thing, patchy to
areas of fog are possible around dawn to about 8-9 am over the
Coastal Plains especially over portions of Wilson, Karnes, Gonzales,
DeWitt, Lavaca and Fayette Counties.

Clouds begin to break late this morning giving way to partly cloudy
and mostly sunny skies this afternoon. Highs are forecast to be a
few degrees cooler than those on Friday, however, above climate
normal values ranging from the upper 80s across the Hill Country to
upper 90s along the I-35 corridor and the Coastal Plains.

A dry airmass is forecast to push across the eastern part of South
Central Texas throughout the day as pwats values come around 1.2 to
1.3 inches and 1000mb - 500mb RH layer at 36 to 38 percent based on
the GFS solution. Hires models such as HRRR,NAM 3KM and RRFS also
concur. Therefore, the local area should see very limited shower
activity if any with 5 to 10 percent chance between U.S. Highway 83
and U.S. HIghway 281 mainly mid to late afternoon.

Clouds return during the evening hours and continue developing and
spreading through Sunday. An upper level low pressure system is
forecast to move across the four corners region today and into the
Central Plains by Sunday. A southwest flow aloft is forecast to stay
in control over the Rio Grande while a moist southerly wind flow is
forecast to prevail late tonight into Sunday morning. This setup
could send a few showers across the Rio Grande and parts of the
southern Edwards Plateau overnight and Sunday morning. As the day
progresses and we enter into the Sunday afternoon period, slight
chances for showers are in place for the Coastal Plains and even a
shower or two with an isolated thunderstorm is possible over Val
Verde County and vicinity as the upper level low pushes to the
northeast over the Central Plains while sending a cold front that
extends from northeast Texas southwestward to the western part of
the state. Sunday`s highs still above climate normal ranging from
the upper 80s to mid 90s.

&&

.LONG TERM...
(Sunday night through Friday)
Issued at 300 AM CDT Sat Sep 21 2024

The upper level low currently over the desert southwest will
eventually weaken into an upper trough axis and move east into the
central plains states early next week. As the trough axis moves east,
a cold front is expected to move southward early Monday and should be
near a Rocksprings to Llano line around sunrise Monday. With some
weak lift and low-level forcing along the front, rain chances will be
in the forecast late Sunday into Monday across the southern Edwards
and Hill Country. The latest guidance has trended a little stronger
with the frontal boundary and rain chances have trended upward across
the southern Edwards Plateau. The front is expected to gradually
slide southward during the daytime hours on Monday. The models are
fairly reluctant to develop much in the way of convection during the
afternoon hours along the front and rain chances still look to remain
favored over the Hill Country. In addition, some isolated afternoon
convection may develop over the coastal plains as the sea breeze
moves inland. Temperatures will trend downward slightly for most of
the region, with the most notable drop in the Hill Country and
southern Edwards Plateau. On Tuesday, a reinforcing shot of upper
level energy is expected to drop southward out of the southern
Rockies and help reinforce the upper level trough. The models differ
with the speed and strength of this upper level energy, so there will
be some uncertainty in the forecast. For now, we will keep rain
chances in the forecast for most of south central Texas, with the
focus for better rain chances still favored for areas generally west
of I-35. We will also need to maintain an eye on the northwestern
Caribbean or southern Gulf of Mexico as the last few NHC outlooks
maintain an increasing probability for tropical development in the
mentioned region.

Uncertainty continues through the remainder of the forecast as much
will depend on the development of an upper level trough or perhaps a
closed low over the southern U.S. plains and the expected tropical
system in the Gulf of Mexico. For now, we will keep some low rain
chances in the forecast for most of the region along with near to
slightly above normal temperatures.

&&

.AVIATION...
(06Z TAFS)
Issued at 1154 PM CDT Fri Sep 20 2024

There are a few low clouds around KSAT and KSSF with way more mid
level clouds overhead and to the west of terminals as of 05Z. Still
expecting low clouds to develop overnight (07z-08z) across the San
Antonio sites and around 09z at KDRT and 12z over KAUS. MVFR cigs
stay to about 15z-16z time frame and then to VFR conditions through
the evening. Southeast winds 10 knots or less are forecast overnight
through mid Saturday morning then picking up from 10 to 15 knots with
gusts up to 21 knots especially across KDRT in the afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              98  74  96  73 /   0   0   0  10
Austin Bergstrom Intl Airport  97  73  95  72 /   0   0   0   0
New Braunfels Muni Airport     98  74  97  73 /   0   0  10   0
Burnet Muni Airport            95  72  93  70 /   0   0   0  10
Del Rio Intl Airport           96  78  94  76 /  10   0  10  30
Georgetown Muni Airport        95  72  93  72 /   0   0   0  10
Hondo Muni Airport             95  74  93  72 /   0   0   0  10
San Marcos Muni Airport        96  72  95  70 /   0   0  10   0
La Grange - Fayette Regional   95  72  94  72 /   0   0  10   0
San Antonio Intl Airport       96  75  94  74 /   0   0  10  10
Stinson Muni Airport           97  76  96  75 /   0   0   0   0

&&

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

$$

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