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

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FXUS64 KEWX 160122 AAA

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
822 PM CDT Tue Oct 15 2019

Please see the 00Z aviation forecast discussion below.


The main concern over the next several hours will be isolated to
scattered convection impacting the I-35 terminals. KSAT and KSSF will
likely see some TEMPO TS over the next couple of hours, with AUS only
expected to see some light showers. Convection still looks like a
good bet for the overnight hours as a strong cold front moves in from
the north.


.PREV DISCUSSION... /ISSUED 255 PM CDT Tue Oct 15 2019/

SHORT TERM (Tonight through Wednesday Night)...
Surface analysis this afternoon shows a strong cold front making
progress into the Permian Basin with an attendant pre-frontal trough
stretching from DFW towards Rocksprings. A veering wind profile in
response to the frontal system`s approach has allowed for lower
clouds to scatter over the Rio Grande Plains, Interstate 35 counties,
and Coastal Plains as some drier/warmer air advects off the Mexican
Plateau. Nearly full insolation in these areas is contributing to
temperatures in the upper 80s to mid 90s as of 2 PM. Farther north, a
shortwave tough dropping across central New Mexico is pulling a
steady mid- level stream of Pacific moisture across the Edwards
Plateau and Hill Country and this has resulted in persistent cloud
cover, cooler temperatures/lower instability, and periods of light

As the frontal system continues to drop south through the remainder
of the afternoon and evening hours and the New Mexico shortwave
reaches Far West Texas, the aforementioned cloud cover continues to
result in divergent solutions amongst high resolution guidance with
respect to thunderstorm initiation. The pre-frontal trough will
continue to sag deeper into the region through the afternoon before
being overtaken by the cold front. Limited stability across the
eastern Hill Country and northern Edwards Plateau due to cloud cover
will initially help limit convection along this boundary. However,
ample heating across the remainder of the region should allow for a
few thunderstorms to develop both along and ahead of the trough as
it drops farther south into the southern Edwards Plateau and Hill
Country. The KEWX radar has already shown isolated showers attempting
to develop across Williamson, Lee, and Burnet Counties and expect
daytime heating to continue to force this type of activity within an
abnormally moist environment. The veered wind profile has also
resulted in a rather pronounced steepening of low level lapse rates
per SPC Mesoanalysis, with values in excess of 7.5 C/km across most
of the region. This will help enhance updraft acceleration with
effective bulk shear values in excess of 40 knots promoting
thunderstorm organization and a few thunderstorms this afternoon and
evening may become strong to possibly severe. The threat for damaging
wind, large hail, and brief heavy rain will be isolated... but the
potential for these hazards will exist through the evening hours.

As stronger forcing from the cold front coupled with increasing
height falls ahead of the New Mexico shortwave reach the Hill Country
closer to 9-10 PM this evening, expect scattered to numerous
thunderstorms to spread along the frontal boundary. The front will
continue to make quick progress south, reaching the Interstate 35
corridor closer to 12-1 AM and clearing the entire region by 4-5 AM.
Cold pool interactions may result in some acceleration of the frontal
timing and earlier than listed arrival times are possible. Areal
rainfall averages are generally expected to be under one inch with
tonight`s rain but high atmospheric moisture in place (precipitable
water values in excess of 1.8 inches) will mean localized 2 to 4 inch
amounts will remain possible. This is really only expected to
provide much-needed drought relief, but high rain rates may result in
minor or nuisance flooding concerns in localized spots.

Rain will linger into Wednesday morning, gradually shifting south as
the post frontal layer deepens. A break in rainfall will be possible
by Wednesday afternoon as cooler and breezy conditions spread across
South Central Texas behind the front. Highs on Thursday are only
expected to top out in the upper 60s to low 70s with breezy northerly
winds gusting into the 20-30 MPH range at times. As the shortwave
trough over New Mexico drops south across the Trans Pecos on
Wednesday and eventually closes off, increasing forcing for ascent
will allow for another round of scattered showers and thunderstorms
to develop near the Rio Grande on Wednesday night. Cooler conditions
will linger across the region as this happens with lows in the upper
40s to mid 50s.

LONG TERM (Thursday through Tuesday)...
The closed low over the Trans Pecos translates east across the
region on Thursday, opening up again as it reaches the northern Gulf
Coast. Strong dynamic forcing within the base of this low will mean
the scattered showers and thunderstorms that develop Wednesday night
persist and translate west to east across the region during the day
Thursday with mild highs in the low to mid 70s. A drier and warmer
trend is expected Friday through the weekend with highs rebounding
into the 80s and rain chances relegated to the Coastal Plains. A weak
surface low in the western Gulf of Mexico is expected to remain well
south of the region through the weekend as it lifts towards the
Mississippi River, but may back surface winds enough locally to keep
rain chances shunted south of the region until Sunday. A longwave
trough sweeping across the Central Plains on Sunday is expected to
send another cold front across South Central Texas by Monday,
providing another chance for widespread showers and thunderstorms
with cooler and drier conditions settling in on Tuesday.


Austin Camp Mabry              62  69  54  74  57 /  60  10  -   20  -
Austin Bergstrom Intl Airport  62  68  50  74  55 /  70  20  -   20  -
New Braunfels Muni Airport     62  69  53  73  56 /  80  30  10  30  -
Burnet Muni Airport            59  69  50  73  54 /  40  -   -   10   0
Del Rio Intl Airport           65  72  57  77  59 /  70  40  40  20   0
Georgetown Muni Airport        59  69  49  74  54 /  50  -    0  10   0
Hondo Muni Airport             64  70  54  76  58 /  80  40  20  40  -
San Marcos Muni Airport        62  68  52  73  55 /  80  20  -   30  -
La Grange - Fayette Regional   64  70  53  74  57 /  70  20  -   20  10
San Antonio Intl Airport       64  69  55  73  59 /  80  40  10  40  -
Stinson Muni Airport           65  70  56  73  59 /  90  40  10  40  -




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