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

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FXUS64 KEWX 260533
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1233 AM CDT Mon Jun 26 2017

.AVIATION...
No significant changes in the ongoing TAFs. There are isolated
showers in the northern part of our area that may move through AUS
over the next few hours. If any showers move over the airport, they
will not change flying category. We expect MVFR CIGs to develop
within the next couple of hours in Austin and San Antonio and by
around 12Z at DRT. CIGs should lift to VFR by around noon. There is a
chance for showers and thunderstorms during afternoon and evening
and we have included VCSH as timing is uncertain at this time.

&&

.PREV DISCUSSION... /ISSUED 1008 PM CDT Sun Jun 25 2017/

UPDATE...
Showers and thunderstorms have generally dissipated across the area
aside from some light stratiform rain over portions of Lee and
Fayette Counties that should dissipate over the next hour. Hi-res
models are generally in good agreement that additional convection
will not develop until possibly very late in the overnight hours
just before sunrise as some streamer showers and possibly a rogue
thunderstorm develops. Thus, we have removed rain chances over the
Rio Grande Plains for most of tonight and decreased to 20-30 POPs
elsewhere, only mentioning very isolated thunderstorms in the Coastal
Plains prior to 4 am. We have included 40 POPS for scattered shower
activity across most of the CWA from 4-10 am just in case remnant
outflow boundaries with nearly moist adiabatic lapse rates allow for
some early development, but only very isolated thunderstorms are
expected due to stability near the melting level.

Scattered showers and thunderstorms are expected across most of the
region by late tomorrow morning into the afternoon hours, with the
best chances for storm initiation in the Coastal Plains along outflow
boundaries and a possible sea breeze. Convection should also develop
over the Edwards Plateau and western Hill Country counties along an
outflow boundary expected to be near or northwest of our northwest-
most counties associated with a complex of storms expected to move
southeast tonight from the Texas panhandle. Depending on how far
southeast this activity makes it tonight, rain chances may need to be
increased later tomorrow afternoon and evening over much of the CWA
as additional shortwave forcing may help expand the coverage of
showers and thunderstorms along this particular outflow boundary.

PREV DISCUSSION... /ISSUED 254 PM CDT Sun Jun 25 2017/

SHORT TERM (Tonight through Monday Night)...
Convective focus today has been largely controlled by a sharp
moisture gradient where deeper tropical moisture is being held east
of I-35 by circulation around a TUTT low over the NW Gulf. Low level
winds are mainly E or NE which has limited moisture advection for the
counties far inland. This has led to some over-forecasting of
precipitation for the western half, especially from the models
attempting to develop an unstable NW flow pattern with storms forming
over the high plains and moving south. Tonight`s forecast initially
remains marked by shortwave ridging and no connection between the
tropical moisture and the monsoonal triggered convection to the
north. There is still small chance for a round of weakening storms to
arrive from the north late tonight, but a better low level moisture
advection pattern for daytime convection will set up as the effects
of the TUTT low retreat east. Monday night is suggested to be the
best opportunity for High Plains storms to move south into the area
given some mid-level dynamics dropping south. Nevertheless will
continue to undercut PoPs until synoptic scale models lose their
moist bias.

LONG TERM (Tuesday through Sunday)...
Tuesday looks to be the last day for all areas to see rain potential
with deterministic runs showing mid level ridging to cut off the NW
flow pattern Tuesday evening. Pooled moisture over the Coastal
Prairies a weakness in the upper ridge over the Gulf Coast will
continue into Friday, so isolated to scattered mainly daytime
convection will continue over the same counties that received the
bulk of rains over the past day-and-a-half. Mid-level ridging
continues to steadily build, with no rain and increasing heat indices
expected next weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              88  72  90  72  91 /  40  30  40  10  20
Austin Bergstrom Intl Airport  88  71  89  72  91 /  40  30  40  10  20
New Braunfels Muni Airport     88  71  89  72  90 /  40  30  40  10  20
Burnet Muni Airport            85  70  87  70  89 /  40  30  40  10  10
Del Rio Intl Airport           92  73  92  74  95 /  30  30  30  10  10
Georgetown Muni Airport        87  71  88  71  90 /  40  30  40  10  20
Hondo Muni Airport             90  71  91  71  93 /  40  30  40  10  10
San Marcos Muni Airport        88  71  89  72  90 /  40  30  40  10  20
La Grange - Fayette Regional   88  72  90  73  90 /  50  30  50  20  30
San Antonio Intl Airport       89  72  90  73  91 /  40  30  40  10  20
Stinson Muni Airport           89  73  90  73  91 /  40  30  40  10  20

&&

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

$$

Mesoscale/Aviation...05
Synoptic/Grids...04


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