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

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FXUS64 KEWX 191742

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1242 PM CDT Mon Oct 19 2020

Current obs show that the front has stalled and will not impact any
sites. Persistent southeast flow will continue through this TAF
forecast period and keep dewpoints elevated. Southeast winds relax
overnight and expect widespread MVFR/IFR ceilings to build in
starting 05Z. Not much support from the high res guidance or MOS
guidance on fog return but some patchy ground fog isn`t out the
question, not expecting this to impact any sites given the low
confidence. Stratus deck clears late Tuesday morning and VFR ceilings
will prevail through the rest of the period.


.PREV DISCUSSION... /ISSUED 742 AM CDT Mon Oct 19 2020/

Rerunning the grids to include patchy fog for southeastern areas
based off of observations. Rest of the forecast looks to be on track.
Still some uncertainty with where the front will end up stalling but
confidence is increasing that this boundary won`t make it to the
Austin Metro, but rather hang up along the Hill Country.

PREV DISCUSSION... /ISSUED 712 AM CDT Mon Oct 19 2020/

/12Z TAFS/
Expect MVFR for the I-35 terminals and KDRT through at least 18Z this
afternoon. The shallow cold front across the Hill Country is forecast
to push just a little to the south this morning before stalls or
dissipates. No expecting the front to move over KAUS or KSAT/KSSF
with southeasterly winds staying through the forecast period. Clouds
will scatter for VFR cigs this afternoon through this evening across
all area sites. MVFR and even IFR cigs are expected overnight as
increased moisture returns across the area. Have added patchy fog
for areas southeast of the I-35 terminals for the overnight hours as
models suggest lower visibilities. This area may need to be monitored
closely for any expansion of fog in later updates.

PREV DISCUSSION... /ISSUED 318 AM CDT Mon Oct 19 2020/

SHORT TERM (Today through Tuesday)...
A shallow frontal boundary is literally across the northern border
of our county warning forecast area and the southern county warning
forecast area of San Angelo. The consensus is that the frontal
boundary is forecast to stall over that area for most of today
before it washes out. Wait, it is not that easy. Let`s tell the
whole story. There are some HiRes models such as the ARW and NMM
that bring the boundary 15 to 20 miles to the south of the current
location. Then, we have the RAP, HRRR and the Texas Tech WRF pushing
the boundary to the south around 5 miles from current position
before winds shift back to the southeast. Therefore, those over the
Hill Country area have a better chance for the cooler airmass to
knock at their doors. It is still a challenging forecast as far as
temperatures go since most models show highs in the low to mid 80s
across the Hill Country while others show mid 60s to lower 70s. With
these differences in place, we are using the ensemble approach once
again to come up with today`s high temperatures.

Now, if you are in the San Antonio area, we have a moderate to high
confidence that the cold front is not pushing through with southerly
winds staying all day and highs in the upper 80s.

There is a slight chance for showers along and east of Highway 77
late this morning into this afternoon ahead and over the warm sector
of the frontal boundary. Can`t rule out a thunderstorm or two across
the far southeast portion of Lavaca county and vicinity, where higher
moisture and instability reside (kept thunderstorms out of the
forecast due to the small coverage and low probability area).

Increased moisture returns Monday night into Tuesday as southerly
flow dominates the area with dewpoints in the lower 70s across the
Coastal Plains and to the southeast and south of Interstate 35. With
this type of set up in place, decided to add patchy fog across those
areas for the Tuesday morning commute. Tuesday`s highs are expected
to reach the mid to upper 80s across the Hill Country and areas
along the I-35 corridor to the lower 90s across the Rio Grande.

LONG TERM (Tuesday Night through Sunday)...
A weak upper level trough will remain over central/south Texas
through the mid to late portion of this week. This feature along with
daytime heating and a continued supply of low-level moisture will
result in a low chance for afternoon convection near the coastal
plains. Some of the medium range models are showing the possibility
of some early morning showers across the Hill Country and Edwards
Plateau through mid-week. This is likely due to the presence of the
nocturnal low-level jet. For now, our confidence is not high enough
to warrant a mention of showers in the forecast, but we will continue
to monitor subsequent model runs. Otherwise, temperatures look to
remain above normal for much of this week. Highs will generally range
from the lower 80s to lower 90s, with lows in the mid 60s to near 70.

The next feature of interest during this forecast package will be a
cold front set to move in as early as Friday evening. We will see a
brief cool down behind this front with highs on Saturday in the lower
70s to mid 80s along with lows in the mid 50s to lower 60s. Southerly
flow in the low-levels returns quickly by early Sunday and this will
lead to warmer temperatures along with an increase in moisture.


Austin Camp Mabry              70  86  69  86  67 /  10  10   0  -    0
Austin Bergstrom Intl Airport  69  87  68  86  67 /  10  10   0  -    0
New Braunfels Muni Airport     72  89  69  89  69 /  10  20   0  -    0
Burnet Muni Airport            68  84  67  84  66 /  10  10   0   0   0
Del Rio Intl Airport           72  89  69  89  70 /  -   -    0   0   0
Georgetown Muni Airport        69  86  67  86  66 /  10  10   0  -    0
Hondo Muni Airport             70  90  67  89  67 /  -   10   0  -    0
San Marcos Muni Airport        69  87  67  87  67 /  10  20   0  -    0
La Grange - Fayette Regional   72  88  69  88  68 /  10  -    0  10   0
San Antonio Intl Airport       72  87  69  87  69 /  10  20  -   -    0
Stinson Muni Airport           71  87  69  87  69 /  10  20   0  -   -




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