Scientific Forecaster Discussion
fxus64 kewx 180515
Area forecast discussion
National Weather Service Austin/San Antonio Texas
1215 am CDT Wed Sep 18 2019
VFR conditions are currently prevailing at the taf sites with light
easterly flow. There is a chance for some MVFR ceilings for aus and
will mention it there. There is a smaller chance for the San Antonio
sites and will keep things VFR for now and amend as necessary.
Otherwise, we could see some scattered showers tomorrow afternoon
with heating for the i35 sites with no activity expected in the night
Previous discussion... /issued 239 PM CDT Tue Sep 17 2019/
Short term (tonight through Wednesday night)...
tropical storm Imelda made landfall near Freeport earlier this
afternoon. Scattered showers in the outer rain bands have wrapped
into eastern areas of the County Warning Area. Additional isolated showers and
thunderstorms could form through the remainder of the afternoon and
early evening, closer to the I-35 corridor, near the edge of the
tropical moisture plume and differential heating boundary. After
sunset convective activity is expected to diminish inland across
south-central Texas, and contract toward the center of Imelda and
within bands to the east and south of the center.
South-central Texas will remain on the "drier" side of the system on
Wednesday, with the center of Imelda remaining east of the County Warning Area. We
have trended pops slightly downward for Wednesday across the I-35
corridor for Wednesday. However, with diurnal heating Wednesday we
should still see the development of scattered showers and a few
thunderstorms in outer bands across eastern areas of the County Warning Area.
Long term (thursday through tuesday)...
Thursday actually looks to be the best opportunity for rainfall
for some central areas of the County Warning Area. As the remnants of Imelda open up
to the northeast of the County Warning Area it appears instability on the southwest
side of the system could interact with the tropical airmass and result
in some heavier convective feeder bands developing in an area of low
level moisture convergence over the region in the afternoon and
evening. Where these potential bands develop is highly uncertain, but
should they develop there could be some locally heavy rainfall,
given the tropical airmass, that could potentially lead to isolated
pockets of minor flooding.
A deeper southerly fetch develops across south-central Texas on
Friday as the remnants of Imelda pull move north of Texas. Lingering
moisture in the area could result in streamer showers across eastern
areas of the County Warning Area in the morning, working inland along the sea-breeze
in the afternoon. Weak, flat ridging builds over the area during the
weekend into early next week, with convective chances gradually
diminishing and limited to only isolated showers across the eastern
zones. Disagreements in global models with respect to the upper
level pattern develop into the middle of next week.
Preliminary point temps/pops...
Austin Camp Mabry 75 94 76 92 75 / 30 60 50 50 10
Austin Bergstrom Intl Airport 73 93 74 92 73 / 40 60 50 50 10
New Braunfels Muni Airport 73 94 74 92 73 / 30 60 50 50 10
Burnet Muni Airport 71 91 73 91 72 / 20 60 50 40 10
del Rio Intl Airport 77 101 77 98 76 / - 10 10 10 -
Georgetown Muni Airport 72 92 73 92 73 / 30 60 50 50 10
Hondo Muni Airport 75 99 76 97 74 / - 30 30 20 10
San Marcos Muni Airport 73 94 73 92 73 / 30 60 50 50 10
La Grange - Fayette regional 74 93 75 91 73 / 50 70 50 50 -
San Antonio Intl Airport 76 96 77 94 76 / 20 50 40 40 10
Stinson Muni Airport 77 96 77 94 76 / 20 50 40 40 10