138
FXUS64 KEWX 211733
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1233 PM CDT Sat Sep 21 2024

...New AVIATION...

.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...
(18Z TAFS)
Issued at 1227 PM CDT Sat Sep 21 2024

Expect remaining MVFR to lift and thin to VFR by 20Z at all sites.
South to Southeasterly flow will persist at all sites through the
forecast period, with gusts to 20-22 KT at times for KAUS and KDRT
this afternoon. Look for CIGS to develop and fall starting around
06-09Z, with MVFR CIGS expected at all locations from 09-15Z. There
may be some BCFG from 10-15Z, but that is not expected to impact
operations. CIGS will lift but be very slow to become SCT on Sunday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              75  96  74  93 /   0   0  10  10
Austin Bergstrom Intl Airport  73  95  73  93 /   0   0   0  10
New Braunfels Muni Airport     74  96  73  95 /   0   0   0  10
Burnet Muni Airport            73  92  71  87 /   0   0  20  20
Del Rio Intl Airport           79  95  76  91 /  10   0  30  40
Georgetown Muni Airport        73  94  73  90 /   0   0  10  10
Hondo Muni Airport             74  94  72  93 /   0   0  10  10
San Marcos Muni Airport        73  94  71  93 /   0   0   0  10
La Grange - Fayette Regional   73  94  72  93 /   0   0   0  10
San Antonio Intl Airport       76  94  75  93 /   0   0  10  10
Stinson Muni Airport           76  95  74  96 /   0   0   0  10

&&

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

$$

Short-Term...Zeitler
Long-Term...MMM
Aviation...Zeitler