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

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FXUS64 KEWX 191128

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
628 AM CDT Sat Oct 19 2019

MVFR/IFR ceilings are in place across most of the area with DRT one
of the lone airports around with VFR conditions. These restrictions
will be slow to improve with VFR likely not back in place until 17z.
Otherwise, light winds can be expected today becoming more
northwesterly as a weak front arrives to the area.


.PREV DISCUSSION... /ISSUED 424 AM CDT Sat Oct 19 2019/

SHORT TERM (Today through Sunday)...
Shallow low level moisture and mostly light winds is producing some
light fog and low cloudiness over central and eastern counties this
morning. The moisture and cloud cover should be last through 15-17Z,
and then a rapid warm-up is expected by mid afternoon. A flat zonal
pattern aloft and a fast Srn Plains shortwave moving north of the
forecast area this morning will leave most of South Central TX seeing
light SW winds this morning shifting to W/NW winds this afternoon.
The weak front will not reach the SE counties this afternoon, but
should rather slip into the area with light and variable or light NE
winds by late this evening. The mostly west winds in the daytime
should add some downsloping to push high temps today to within a
degree or two of records.

The nighttime winds should pool low level moisture over the Coastal
Prairies and lead to some low clouds and weak instability late
tonight. Finer resolution models depict some convective activity east
of SAT along I-10, but expect just a few light showers as the
convergence area expected is expected be short-lived before south
winds return for late Sunday morning. Low clouds should spread inland
quickly Sunday with a few light sprinkles suggested by various
models to go as far west as the Hill Country. Am not confident this
moist layer doesn`t mix out to fast to produce the falling moisture,
but will consider the slightly cooler NAM high temperatures as a
result. Still, well above normal temps and abundant afternoon
sunshine remains in the forecast for Sunday. A few deeper showers or
isolated thunderstorms are depicted over eastern counties, but this
seems to be dependent on the model runs that develop a weak tropical
system over the Pacific coast of Mexico in the next 24 hours or so.
Any development noted could lead to more clouds, moisture, rain, and
lower high temps, as the 700 mb level winds connects well to this
region Sunday.

LONG TERM (Sunday Night through Friday)...
Sunday evening, the next trough to arrive into the Central US is much
larger with a vigorous upper low forecast to form over SD/NE by 06Z
Monday. By this time the upper trough extends south to SW TX and a
sharp front takes shape over West Central TX with the leading edge of
the front pushing into the Srn Edwards Plateau. Outflows ahead of
this system could generate some scattered convection as far south as
Hwy 90 west of San Antonio, but expect most of the rain chances to
hold off until after midnight as the cold front contrast continues
to sharpen. Deterministic models are inconsistent in developing a
tropical disturbance near the Pacific coast of Mexico, and this
continues to lead to a fairly wide variety of QPF depictions along
the front over South TX.

By 12Z Monday, the front should be draped over the central counties
and moving more progressively southward. Model trends have slowed the
frontal timing slightly over the past days worth of runs. Temps
behind the front aren`t drastic, and would expect to see a gradient
of mid 50s to near 70 from north to south. While high chances of rain
are expected over SE counties just after daybreak, good clearing is
expected to spread N to S during the day and leading to a near
seasonal warm-up for afternoon highs. Late night timing of the front
and trough should lead to a minimal threat for strong storms, but a
Marginal Risk extends from near Temple northeastward on the
overnight SPC Day 2 outlook.

Dry air and lighter winds Tuesday and Wednesday mornings should
bring cooler than normal min temps before the surface return flow
kicks in fully during the day Wednesday. Moisture return is expected
for morning low clouds by Thursday. Another high amplitude pattern
develops late Thursday into Friday with a cold front suggested to be
a bit stronger than the one early Monday. The model agreements were
better on timing yesterday than they were today, so am inclined to
lean more on consistency of forecast than the changing trends. This
leaves the GFS as an outlier is the 00Z run brought a partial fropa
in during the day Thursday, followed by a delayed stronger fropa
Friday. Prefer to consider no fropa Thursday and the strong fropa
to arrive with convection late Thursday night. Well below normal
temps should follow and linger through next weekend.


Austin Camp Mabry              92  66  91  67  79 /   0  -   20  60  30
Austin Bergstrom Intl Airport  92  62  91  66  79 /   0  10  20  60  40
New Braunfels Muni Airport     92  64  91  67  81 /   0  10  20  60  40
Burnet Muni Airport            88  60  89  62  77 /   0  -   20  60  20
Del Rio Intl Airport           93  63  93  66  85 /   0  -   -   20   0
Georgetown Muni Airport        90  60  91  63  78 /   0  -   20  60  20
Hondo Muni Airport             94  65  93  67  84 /   0  -   20  50  20
San Marcos Muni Airport        92  64  91  66  81 /   0  10  20  60  40
La Grange - Fayette Regional   90  68  90  68  81 /  -   20  20  60  60
San Antonio Intl Airport       92  67  90  68  82 /   0  10  20  60  30
Stinson Muni Airport           94  68  91  69  84 /   0  10  20  50  40




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