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

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FXUS64 KEWX 300007
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
707 PM CDT Mon May 29 2017

.AVIATION...
A weak mid level impulse interacting with slightly stronger lower
level flow and deeper moisture may generate SHRA/TSRA along parts of
the Rio Grande into western Edwards Plateau overnight into Tuesday
morning according to some models. Have introduced VCSH mention at
KDRT. Otherwise, ISOLD SHRA/TSRA are possible along multiple surface
boundaries tonight, though mainly on Tuesday due to heating. No
impacts are currently expected at KAUS/KSAT/KSSF. VFR skies will
prevail tonight through Tuesday, except a period of MVFR CIGs late
tonight into mid morning is possible. Patchy BR and IFR/MVFR VSBYs
are possible early in the morning in areas where recent heavy rains
fell. Winds will be less than 7 KTs, except E/SE 7 to 14 KTs along
the Rio Grande.

&&

.PREV DISCUSSION... /ISSUED 556 PM CDT Mon May 29 2017/

UPDATE...
Made some adjustments to the Max T grid for today as southern areas
were warming about 5-8 degrees above the forecast. Also made tweaks
to the Min T grid to populate with the latest CONSshort and blended
hourly T through 12Z based off CONSshort model.

Will leave the PoP grid alone for now as we continue to monitor
outflow boundaries across the area but may need to trend these down
as it appears stability may be dominating the region. Will make that
decision after the 00Z KDRT balloon launch.

PREV DISCUSSION... /ISSUED 316 PM CDT Mon May 29 2017/

SHORT TERM (Tonight through Tuesday Night)...
The afternoon visible satellite imagery shows some clearing of the
low clouds has taken place across south central Texas. This along
with remnant outflow boundaries has been enough to allow isolated to
scattered convection to develop across the southern Edwards Plateau
and Rio Grande plains. Surface based CAPEs on the order of 2500-3000
J/Kg along with bulk shear vectors near 30kts could yield a strong
cell or two this afternoon. The models also suggest the western Hill
Country, including the Llano and Fredericksburg areas stand a little
better chance for some afternoon convection given a little better
instability. Given the slow storm movement, some locally heavy
rainfall can also be expected. Elsewhere, we can`t rule out a low
chance for some showers and storms, but given all the activity from
the overnight and morning hours, we`ll keep chances fairly low.

For tonight, most areas should stabilize with the loss of daytime
heating and we will only mention a 20% chance for rain across most
areas. The exception will be after midnight across the Rio Grande
plains where the latest models suggest some mid-level shortwaves will
move in late tonight. We have increased rain chances to around 40% to
account for recent model trends.

On Tuesday, we will mention a 20-40% chance for rainfall as daytime
heating along with outflow boundaries and continued mid-level
shortwaves will result in mainly afternoon and evening convection.

LONG TERM (Wednesday through Monday)...
Rainfall chances will trend upward on Wednesday and Thursday as the
medium range models continue to remain consistent in showing an
active southwest flow aloft traversing the area. Precipitable water
values climb into the 1.5-1.9" range and concerns will be on the
increase for locally heavy rainfall. Currently it appears areas west
of Highway 281 will have the best chance for locally heavy rains.
However, should a convective complex develop out west along the Rio
Grande and move east, we could see locally heavy rainfall across all
of south central Texas. Rain chances remain in the forecast through
the end of the work week into early next week. The models do show a
weak cold front could move in late Sunday or early Monday and help
increase our rain chances.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              69  85  70  84  69 /  20  30  20  50  60
Austin Bergstrom Intl Airport  67  85  69  84  69 /  20  30  20  50  60
New Braunfels Muni Airport     68  86  69  83  69 /  20  30  20  50  70
Burnet Muni Airport            66  83  67  82  67 /  20  20  20  50  60
Del Rio Intl Airport           69  84  70  83  69 /  40  30  40  60  60
Georgetown Muni Airport        65  84  68  83  68 /  20  20  20  50  60
Hondo Muni Airport             67  85  70  83  69 /  20  30  20  50  70
San Marcos Muni Airport        68  85  69  84  69 /  20  30  20  50  60
La Grange - Fayette Regional   67  86  70  85  71 /  20  30  20  50  60
San Antonio Intl Airport       69  85  70  83  70 /  20  30  20  50  70
Stinson Muni Airport           69  86  71  84  70 /  20  30  20  50  70

&&

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

$$

Mesoscale/Aviation...04
Synoptic/Grids...TB3
Public Service/Data Collection...YB



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