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

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000
FXUS64 KEWX 140519
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1219 AM CDT Sat Oct 14 2017

.AVIATION...
Another round of IFR ceilings and/or visibility restrictions is
likely overnight for the I35 sites with MVFR possible for DRT.
Ceilings are beginning to develop west of I-35 with fog developing
closer to the coast. Should see these two areas expand and converge
overnight. Will show 1 mile visibility for now and amend as necessary
for any possible dense fog. Restrictions will lift around 16-17z
with VFR expected for the remainder of the day. Otherwise, light
southerly flow will continue through the period.

&&

.PREV DISCUSSION... /ISSUED 848 PM CDT Fri Oct 13 2017/

UPDATE...
We have updated the forecast to re-trend hourly temperatures, dew
points and winds to account for recent observations. In addition, we
have expanded the mention of patchy fog a little farther westward
into the southern Rio Grande plains and farther northward along the
I-35 corridor into Williamson county. No other changes have been
made to the forecast at this time.

PREV DISCUSSION... /ISSUED 647 PM CDT Fri Oct 13 2017/

UPDATE...
See below for the 00z aviation discussion...

AVIATION...
Currently VFR at all terminals with a scattered cumulus field and
south/southeast winds across the region. VFR conditions should
continue for the remainder of the evening and into the early
overnight period. Low ceilings are expected to develop in the 10-11z
Saturday morning time frame at all terminals, dropping flight
categories to MVFR at AUS and DRT with SAT/SSF lowering further to
IFR. Visibilities will also likely lower to the 3-5 SM range at
AUS/SAT/SSF Saturday morning due to the development of fog.
CIGs/Vsbys should improve to MVFR by late Saturday morning at SAT/SSF
with all sites improving to VFR by early Saturday afternoon. Winds
will remain out of the south and generally in the 5-10 knot range at
the Interstate 35 sites. Winds at DRT will remain out of the
southeast with sustained winds picking up to or above 12 knots by
Saturday afternoon.

PREV DISCUSSION... /ISSUED 300 PM CDT Fri Oct 13 2017/

SHORT TERM (Tonight through Saturday Night)...

Above normal temperatures continue today and will again Saturday
before a larger drop occurs Sunday and into early next week. Patchy
areas of dense fog could occur both Saturday and Sunday mornings and
this hazard will need to be monitored for regarding any specific
advisories.

The entire region has warmed into the mid to upper 80s with even a
few spot 90F degree readings in the coastal plains under decent
amount of sun this afternoon. These values are running about 3-5
degrees above normal for this time of year. Overnight lows will also
be above normal with values only falling into the upper 60s to low
70s. Low clouds and fog are again expected to develop as they did
this morning across much of the region. Fog will likely be dense in
some locations across the coastal plains per NAM BUFR soundings and
hi-res output.

Saturday will be a near repeat of today with low clouds and fog in
the morning and then becoming sunny by the late morning into the
afternoon. Temperatures will once again reach into the mid to upper
80s and some spot low 90s will also be possible. Low clouds and fog
is again expected overnight Saturday into Sunday morning ahead of a
cold front that will sweep through the entire region. See long term
section for more details.

LONG TERM (Sunday through Friday)...

A decent cool-off is expected Sunday vs. the previous few days with
increasing rain chances (40-50%) Sunday morning as a fast moving cold
front shifts through the region. Gusty north winds, light to moderate
rain, and clouds through the day will keep temperatures down in the
70s. No hazards are expected with the cold front passage.

A long wave trough currently over the Pacific northwest is shifting
south and east while pulling cooler continental air southward from
the northern plains. The trough axis will pivot across the central
plains and the attendant cold front will move through the region
Sunday morning. Ahead of the front, moisture will pool across the
area and another round of low-clouds and fog will occur where the
front does not reach that morning. The front should be traversing
the Hill country near 7am and through Austin/San Antonio by 10am and
the rest of the region by 12-1pm. Given the good forward speed and
limited dynamics support with weak thermodynamic bouyancy, no
hazards are expected. While showers will be along and slightly
behind the front, no strong storms are expected and even thunder may
be hard to come by. Have made the main weather element wording chance
rain showers with slight chance thunder for this package. Winds will
gust upwards of 20-25 mph from the north through the day Sunday as
clouds hold on through the afternoon. High temperatures Sunday will
occur in the early to mid morning hours (mid to upper 70s) and likely
remain steady through the day without much warming.

Clouds will clear overnight into Monday and with dewpoints in the mid
30s to low 40s, temperatures will be able to fall to below normal
values for the first time in a while. Tuesday morning looks to be the
coolest morning thus far of the fall season with lows in the low 40s
for the Hill country and likely below 50F for the Austin area.

A slow warming trend will occur by mid-week and continue into the
late week as winds once again turn easterly and then south as
moisture returns to the region by next weekend like it is today and
tomorrow.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              70  77  54  75  51 /  10  40  -    0   0
Austin Bergstrom Intl Airport  70  78  54  75  48 /  -   40  -    0   0
New Braunfels Muni Airport     69  78  55  75  50 /  -   40  -    0   0
Burnet Muni Airport            67  72  50  72  47 /  20  50  -    0   0
Del Rio Intl Airport           69  76  57  74  52 /  10  40  -    0   0
Georgetown Muni Airport        69  75  51  74  47 /  10  40  -    0   0
Hondo Muni Airport             70  80  55  76  49 /  -   40  -    0   0
San Marcos Muni Airport        69  78  55  75  49 /  -   40  -    0   0
La Grange - Fayette Regional   70  81  56  75  50 /  -   20  -    0   0
San Antonio Intl Airport       70  79  56  76  52 /  -   40  -    0   0
Stinson Muni Airport           71  81  59  76  53 /  -   30  -    0   0

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Mesoscale/Aviation...Hampshire
Synoptic/Grids...17



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