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

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FXUS64 KEWX 152326 AAA

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
626 PM CDT Sat Jun 15 2019

Subtropical ridge remains just west of the area and this will allow
for the continuation of overnight stratus with MVFR ceilings then
breaking out to VFR 15Z-16Z. The chance for some convection to move
into the KDRT vicinity will remain in place this evening and again
Sunday evening. Have included the mention of VCTS 02Z-05Z. Models
are indicating isolated convection across the east after 18Z Sunday.
Then there is the potential for convection from the north to travel
south and impact the I-35 terminals tomorrow evening into the
overnight. With uncertain timing have gone with VCTS. Southerly flow
will continue with winds around 10 knots overnight and 10-20 knots
with gusts to near 25 knots after 16Z through sunset.


.PREV DISCUSSION... /ISSUED 300 PM CDT Sat Jun 15 2019/

SHORT TERM (Tonight through Sunday Night)...
Breezy southerly winds will maintain humid conditions through the
short term forecast as Gulf moisture remains entrenched across the
region. Early afternoon surface analysis showed a surface low
centered southeast of Amarillo with an attendant dryline stretching
towards the Davis Mountains and a cold front pushing into the Texas
Panhandle. While a few showers may continue to skirt Lavaca, Fayette,
and Lee Counties as the sea breeze mixes inland, best chances for
rain this evening will remain across Val Verde County. Visible
satellite imagery is showing cumulus beginning to develop across the
Trans Pecos with a secondary area of development noted across the
Sierra Madres/higher terrain of Mexico. SPC Mesoanalysis places over
5000 J/kg across Val Verde County earlier this afternoon and this
greater instability should encourage better maintenance of any
thunderstorm activity that attempts to move off the dryline or higher
terrain later this afternoon and this evening. Steep lapse rates in
excess of 8 C/km and surface dew point depressions close to 25
degrees will encourage a gusty wind threat and the potential for some
large hail should these thunderstorms reach the county. Otherwise,
expect a dry, but humid evening across South Central Texas.

There is a signal for some of the convection that develops along the
dryline this evening to grow upscale into a larger thunderstorm
complex. While a dry forecast is expected overnight, storm motion
vectors indicate that should a complex like this develop, it may make
a run for the Central Texas counties overnight and will have to watch
for this (low probability) potential. Another round of streamer
showers looks to spread into the Coastal Plains closer to sunrise
with morning lows in the upper 60s to mid 70s.

Sunday looks to be a fairly similar day to today with highs in the
upper 80s in the Hill Country to near 100 in the Rio Grande Plains.
However, slightly more shower coverage is expected across the Coastal
Plains as even deeper Gulf moisture arrives (forecast precipitable
water values in excess of 2 inches). The dryline may allow for
another round of storms to make it to Val Verde County Sunday
evening, but any residual boundaries left over from tonight`s storms
across West Central Texas will also need to be watched as potential
areas for convective initiation. Afternoon water vapor imagery shows
a compact shortwave churning across New Mexico and as this feature
slides into the Southern Plains Sunday night, forcing for ascent
along the Northwest Texas frontal boundary as well as any residual
outflow will need to be watched for thunderstorm development. High
resolution guidance attempts to develop another thunderstorm complex
across West Central Texas with storm motion vectors again indicating
the potential for this activity to reach South Central Texas should
a strong enough cold pool develop. The main differences between
tonight and tomorrow night appear to be the presence of these surface
boundaries and lift from the Southern Plains shortwave and have
increased rain chances Sunday night north of the Highway 90 corridor
in response. Gusty winds are expected to be the primary threat with
anything that moves into the region, but a large hail threat also
cannot be ruled out in the Hill Country should isolated thunderstorms
be able to develop during the late afternoon/early evening hours as
weak height falls move across West Central Texas ahead of the

LONG TERM (Monday through Saturday)...
As the shortwave trough over the Southern Plains begins to slide
east of the region, rain chances appear to be more diurnally driven
and will slide east of a Kerrville-San Antonio line Monday and into
the Coastal Plains on Tuesday. Heat builds into the region even more
behind the departing shortwave with highs rising to the mid 90s to
the low 100s by Wednesday as the 850 MB thermal ridge strengthens.
This thermal ridge appears to be strongest on Thursday with 850 MB
temperatures 25-30 degrees C across the region and consequently,
Thursday appears to be the hottest day of the upcoming week. With
Gulf moisture remaining in place, this will help contribute to heat
index values in the 102-110 degree range and Heat Advisories will
probably be needed at some point during the middle of the upcoming
week. Heat will linger through the end of the week with low rain
chances creeping back into the Coastal Plains by the end of the
forecast as the sea breeze becomes more active.


Austin Camp Mabry              76  91  74  92  75 /  10  30  30  30  10
Austin Bergstrom Intl Airport  75  91  74  92  74 /  20  30  30  30  10
New Braunfels Muni Airport     74  91  73  93  74 /  10  20  30  30  -
Burnet Muni Airport            74  90  72  91  73 /  10  20  30  30  20
Del Rio Intl Airport           74  95  74  97  76 /  10  10  20  -   -
Georgetown Muni Airport        75  92  73  92  74 /  10  30  30  40  20
Hondo Muni Airport             74  95  74  97  75 /  10  10  20  10  -
San Marcos Muni Airport        74  93  73  92  74 /  10  30  30  30  10
La Grange - Fayette Regional   77  92  75  92  76 /  20  50  30  50  -
San Antonio Intl Airport       75  93  74  94  75 /  10  20  30  20  -
Stinson Muni Airport           76  93  74  95  75 /  10  10  30  20  -




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