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

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FXUS64 KEWX 181757

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1257 PM CDT Fri Oct 18 2019

See below for the 18z aviation discussion...


Currently VFR under clear skies and generally light winds across the
region (except for DRT where winds are a bit more elevated). These
conditions are expected to persist for the remainder of today and
into the early overnight period. Moisture return overnight will allow
for MVFR CIGs and some patchy fog to develop at AUS/SAT/SSF by
around 9z Saturday morning, with IFR CIGs likely developing at
SAT/SSF by 11z (with IFR CIGs also possible at AUS). There could also
be patchy light showers/drizzle in the vicinity of AUS/SAT/SSF
Saturday morning. CIGs and VSBYs are expected to improve to VFR by
around noon Saturday. Light and variable winds early Saturday morning
will become southwesterly by late morning. A cold front is expected
to move from northwest to southeast across the region on Saturday,
turning winds to northwesterly at DRT by late Saturday morning and at
AUS/SAT by late Saturday afternoon.


.PREV DISCUSSION... /ISSUED 1024 AM CDT Fri Oct 18 2019/

Quick update to account for temperature and sky cover trends across
the Rio Grade Plains where lingering cloud cover has slowed heating
this morning. Visible satellite trends show this deck eroding and
still expect a pleasant and mild day for the region with highs in the
low to mid 80s. Remainder of forecast is on track.

PREV DISCUSSION... /ISSUED 353 AM CDT Fri Oct 18 2019/

SHORT TERM (Today through Saturday)...
NE winds over the Coastal Prairies will limit warming slightly today
as the inversion left behind the compact departing upper low will not
fully mix out. Out west, areas along the Rio Grande should see highs
a few degrees warmer with better mixing from the westerlies above the
boundary layer. Tonight a fast moving shortwave trough moves into the
Red River valley and brings the return of southerly and boundary
layer winds across all areas. The surface pressure gradient is
expected to remain weak while higher surface dewpoints near the coast
surge northward into the Coastal Prairies. This could lead to some
low level saturation with patchy advection fog after midnight. A weak
Pacific style front arrives by the afternoon, and the mixing levels
and downsloping effects will translate to a more rapid warmup to near
attainable record highs for some locations.

LONG TERM (Saturday Night through Thursday)...
The Pacific front stalls late Saturday night over the Coastal
Prairies, and there should be a fair amount of moisture in the low
levels to generate some light radar echoes, whether it be light
sprinkles or drizzle. Progressive zonal flow aloft will enhance
return flow Sunday and the moisture surge will deepen quickly in the
low levels as a vigorous upper low digs into the Central and Northern
Plains by 00Z Monday. Low coverage and low confidence PoPs of mainly
showers are expected to be possible along and east of I-35 Sunday
afternoon, and high temps should again reach several degrees above

While the rapidly forming upper low well to the north of TX, the jet
stream wrapping south of it cuts into NW TX to OK, and develops a
rapidly sharpening cold front that is set to arrive late Sunday night
into Monday morning. The sharpening of the front occurs over NW TX
and a broken line of thunderstorms is expected to arrive into the
the Hill Country by late Sunday evening and into the SE corner of the
forecast area after daybreak Monday. Deterministic model depictions
are mostly in agreement, but the Nam appears to be coming in much
drier and a bit slower with the front. For this reason, will continue
to undercut likely PoPs to chance for all but the Coastal Prairies.
Late night timing usually limits the potential for severe weather,
but timing of activity in our northernmost counties late in the
evening could lead to a few strong storms.

Run to run trends on frontal strength look to be consistent over the
past several runs, with the front looking somewhat typical for mid
October. Seasonally mild and mostly clear weather is expected to last
into Wednesday night with clouds and humidity expected to return
Thursday morning. The warm and humid day Thursday should be short-
lived with another front arriving early Thursday evening. Run-to-run
tendencies might suggest this front may delay until later in the
night, but already the model agreement is above average on showing
another round of scattered convection with the front.

In the case of both fronts, there is a weak connection of mid-level
winds with an unstable Eastern Pacific Ocean. A change in this
tropical connection or a more mature development of a tropical
disturbance in this region could alter rain potential.

CLIMATE (Record Highs for Saturday Oct 19)...
AUS 93 (1993)
ATT 95 (1921)
SAT 92 (1993)
DRT 93 (1938)


Austin Camp Mabry              64  92  64  91  66 /   0   0  -   20  40
Austin Bergstrom Intl Airport  62  92  61  92  66 /   0   0  10  20  40
New Braunfels Muni Airport     62  92  63  91  65 /   0   0  -   20  40
Burnet Muni Airport            62  88  60  90  61 /   0   0   0  10  50
Del Rio Intl Airport           64  92  61  93  64 /   0   0   0   0  10
Georgetown Muni Airport        62  90  60  90  63 /   0   0   0  20  50
Hondo Muni Airport             64  94  63  93  67 /   0   0  -   10  30
San Marcos Muni Airport        62  92  62  91  65 /   0   0  -   20  40
La Grange - Fayette Regional   62  90  67  90  68 /   0   0  10  20  40
San Antonio Intl Airport       65  92  66  90  67 /   0   0  -   10  30
Stinson Muni Airport           65  94  66  92  69 /   0   0  -   20  30




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