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Area forecast discussion
National Weather Service Austin/San Antonio Texas
548 am CST Sat Nov 18 2017

Aviation... /12z tafs/

Morning low clouds and patchy fog have not lowered to levels earlier
predicted as the low level jet has held up and prevented surface
winds from decoupling all the way. Some spotty IFR cigs and vsbys
will remain possible from drt to Sat/ssf, but prevailing MVFR cigs
and VFR vsbys should be more common. Strong fropa is expected over
northern counties later this morning, but will show a more gradual
shifting of winds by the time the front interacts with daytime mixing
when passing through the area taf sites. Some shifty winds could thus
go out of tolerance at times mainly in the 16z to 19z timeframe.
After 19z, north winds should begin to become more uniform with gust
over 30 knots possible. The strong gusts should ease up by around
02z.

&&

Previous discussion... /issued 319 am CST Sat Nov 18 2017/

Short term (today through sunday)...
low clouds have developed across much of the County Warning Area overnight and these
clouds should continue to expand through the rest of the overnight
period. Could also see some patchy fog by morning in some areas as
current dewpoint depressions are around 0-4 degrees. Current water
vapor imagery shows a longwave trough moving through the Central
Plains. This system is sending a cold front south with its current
location in the Texas Panhandle and northwestern Oklahoma. This front
will continue to move south this morning and should begin to enter
the northern counties around 10am and then push through the entire
area by 3 PM.

The main story today behind the front will be the breezy northerly
winds this afternoon. Winds should be sustained around 15-25 mph with
higher gusts. The northern counties may see a brief period of
sustained winds near advisory criteria of 25 mph, but duration and
averaged speeds should allow for not needing a Wind Advisory today.
However, if wind speeds are a bit higher than currently forecasted,
an advisory could be needed. Highs today will be in the 70s and 80s
with the peak temperature likely occurring just before the passage
of the cold front. The front is expected to be a dry one and there is
no mention of precip in the forecast. For tonight, wind speeds will
begin to slacken but will likely remain in the 5-15 mph range. Lows
will reach into the upper 30s for The Hill Country and 40s elsewhere.
Sunday should see partly cloudy skies and temperatures remaining in
the 60s across the area.

Long term (sunday night through friday)...
for Sunday night, wind speeds will generally be at or below 5 mph and
with mostly clear skies we should see a better radiational cooling
environment versus Saturday night. Low temperatures will drop into
the middle 30s for The Hill Country and the upper 30s to lower 40s
for the rest of the area. After the cold start to the morning, highs
will return to the middle 60s to near 70 degrees with the return of
southerly flow. The southerly flow will only last until Tuesday
afternoon as another trough axis is expected to move into the plains
in the afternoon hours and will send another cold front into the
region.

Previous forecasts had some rain with this system but models
continue to come in drier and have removed all mention of rain out of
the forecast for the entire area. High temperatures will cool back
off into the 60s on Wednesday with low temperatures on Thanksgiving
in the upper 30s to middle 40s. Highs on Thanksgiving are currently
forecasted to be in the middle 60s to near 70 degrees with the higher
values in the western County Warning Area. This should be our coolest Thanksgiving
since 2014 as 2015 and 2016 saw high temps in the 70s. Weak
southerly flow returns on Friday with highs likely responding several
degrees warmer. Another cold front looks likely just beyond this
forecast period.

&&

Preliminary point temps/pops...
Austin Camp Mabry 80 46 63 43 66 / - 0 0 0 0
Austin Bergstrom Intl Airport 82 44 63 37 67 / - 0 0 0 0
New Braunfels Muni Airport 84 44 64 39 67 / - 0 0 0 -
Burnet Muni Airport 74 41 60 39 64 / 0 0 0 0 0
del Rio Intl Airport 79 45 63 42 67 / 0 0 0 0 0
Georgetown Muni Airport 77 43 62 41 65 / - 0 0 0 0
Hondo Muni Airport 84 41 65 41 68 / 0 0 0 0 -
San Marcos Muni Airport 84 45 64 41 67 / - 0 0 0 -
La Grange - Fayette regional 83 45 63 42 68 / 10 0 0 0 -
San Antonio Intl Airport 84 45 65 42 68 / - 0 0 0 -
Stinson Muni Airport 84 47 65 43 69 / - 0 0 0 -

&&

Ewx watches/warnings/advisories...
none.
&&

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