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

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426
FXUS64 KEWX 200422 AAA
AFDEWX

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1022 PM CST Thu Jan 19 2017

.AVIATION...
/06Z/ TAFS
Similar aviation weather conditions are expected overnight and Friday as
previous aviation forecast discussion stated. That said, VFR
conditions are expected across area sites through much of the
overnight hours. Patchy to areas of fog are already ongoing across
the coastal plains and areas east of I-35 corridor. This condition
will persist overnight through Friday morning. Winds are light and
variable and expected to remain that way through Friday morning under
clear skies. This combination could have an impact mainly for KSSF
and maybe KSAT by daybreak as vbsys could end up being IFR/LIFR and
even VLIFR due to clear skies, light winds and soil moisture content.
Will be monitoring closely the weather observations through the
overnight hours for any changes/amendment. Low clouds/radiational fog
will lift by mid morning to allow VFR conditions across area
terminals throughout the day and Friday evening. West to southwest
winds will prevail on Friday while averaging from 5 to 10 knots.

&&

.PREV DISCUSSION... /ISSUED 550 PM CST Thu Jan 19 2017/

AVIATION...
/00Z TAFS/
VFR conditions are expected across area sites through the overnight
hours. Patchy to areas of fog are expected to form overnight across
the coastal plains and along and east of I-35 corridor. Winds will
become light and variable overnight under clear skies and this
combination could have an impact mainly for KSAT and KSSF as vbsys
could end up lower than forecast. Will be monitoring closely the
weather observations for any changes. Low clouds/radiational fog will
lift by mid morning to allow VFR conditions across area terminals.
West to southwest winds will prevail on Friday and averaging from 5
to 10 knots.

PREV DISCUSSION... /ISSUED 238 PM CST Thu Jan 19 2017/

SHORT TERM (Tonight through Friday Night)...
Cloud cover remains in place across the eastern counties and
therefore is keeping temperatures steady in the upper 50s and lower
60s while the remainder of the area has warmed into the upper 60s.
These clouds should continue to slowly erode so temperatures should
be able to warm a few more degrees while surface heating remains. For
tonight, winds will be light but with somewhat of a westerly
component to the wind think any patchy fog will be confined to the
eastern counties. However, with the light winds and clearing skies
there could be the risk of some patchy dense fog by tomorrow morning.
Lows tonight will bottom out in the 40s and 50s across the area.

A weak disturbance will move through South Texas tomorrow and will
bring lift for some isolated to scattered showers and possibly a
storm to areas mainly south of our CWA. Model data suggest that one
or two storms could clip our southeastern counties tomorrow afternoon
with the best chances shifting to the extreme eastern counties
tomorrow evening. Overall, the chances of rain will be low given the
low PW values less than an inch for the most part. Highs tomorrow
will top out in the middle to upper 70s with lows tomorrow night back
into the 40s and 50s.

LONG TERM (Saturday through Thursday)...
On Saturday, a strong upper low pressure system will be approaching
Texas and will bring with a potent punch of winds beginning late
Saturday night and into Sunday afternoon. Before then, strong upper
lift will allow rising motions to take place in the mid-levels of the
atmosphere, but moisture levels should be low enough to prevent a
large amount of precip formation. Will continue to carry a 20 PoP in
the northern zones where the lift will be strongest.

By Saturday night, west winds will be occurring with speeds expected
to be in the 20 to 30 mph range across the western CWA. By sunrise,
west and northwest winds will have overspread the region with speeds
possibly in the 30-35 MPH sustained range with higher gusts in the
western counties and weakening to the 20 MPH range in the eastern
counties. By the early afternoon hours, the 25 to 35 MPH sustained
winds are likely to be encompassing much if not all of the CWA.
Speeds will quickly diminish around sunset with the loss of daytime
heating and mixing. This wind event will be driven primarily by the
mixing down of very strong winds in the atmosphere on the backside of
the upper low pressure system and with the expected wind speeds a
wind advisory will likely be needed for Sunday. The focus then shifts
to the possibility of critical fire weather conditions. Humidity
values will drop to near or slightly below 20 percent across the Rio
Grande Plains in the afternoon and near critical fire weather
conditions will be expected. Critical conditions will be possible
depending on how much fine fuels can dry out in the next few days
with the ample sunshine and above normal temperatures. The most
likely places for critical conditions will be in Maverick, Zavala,
and Dimmit counties which have not received as much rain as the rest
of the area.

Temperatures on Monday morning will be slightly cooler with the
northwest winds in place and should bottom out in the 40s across much
of the area. South winds will return by the afternoon hours and will
begin a warm up trend through Tuesday. On Wednesday we should see a
cold front move through the region as a large trough encompasses
much of the western Conus. This front could have enough a push to
allow low temperatures to drop back into the 30s for portions of the
area by Thursday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              52  77  52  74  51 /   0  10  10  10  10
Austin Bergstrom Intl Airport  50  77  51  75  51 /   0  10  10  10  10
New Braunfels Muni Airport     51  76  53  76  50 /   0  10  10  -   10
Burnet Muni Airport            48  74  48  73  48 /   0  -   -   20  10
Del Rio Intl Airport           45  76  49  77  52 /   0   0   0  10  -
Georgetown Muni Airport        49  75  49  73  50 /   0  10  10  20  10
Hondo Muni Airport             49  79  49  79  49 /   0   0   0  -   -
San Marcos Muni Airport        50  77  52  75  50 /   0  10  10  10  10
La Grange - Fayette Regional   55  76  56  75  52 /   0  10  20  10  10
San Antonio Intl Airport       53  78  53  77  52 /   0  10  -   -   10
Stinson Muni Airport           51  78  53  78  52 /   0  10  -   -   -

&&

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

$$

Mesoscale/Aviation...17
Synoptic/Grids...05
AVIATION (......
Public Service/Data Collection...33



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