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

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FXUS64 KEWX 041735
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1235 PM CDT Sat Jul 4 2020

.AVIATION...
VFR skies have broken out across South Central Texas with little to
no cloud cover. This should continue through the afternoon and
evening hours. Overnight, some ceilings may develop across the
Coastal Plains, but any MVFR ceilings should stay to the south and
east of the terminals. With the upper ridge breaking down on Sunday
high resolution models now show very isolated showers and
thunderstorms possible Sunday afternoon. Because of the low
confidence and sparse spatial distribution of the activity have no
included mention in the TAFs at this time other than to include a
BKN040 at AUS/SAT tomorrow afternoon to indicate possibly increased
cumulus activity. Winds will continue to be southerly, generally
around 10 knots.


&&

.PREV DISCUSSION... /ISSUED 632 AM CDT Sat Jul 4 2020/

AVIATION...
MVFR/IFR ceilings came in from the SE a few hours ago and are now
mainly affecting areas east of I-35 in the coastal plains and into the
Bexar County taf sites SAT/SSF. Kind of messy looking on satellite
as the deck has broken up a bit near SAT. Unsure if more low cloud
over Wilson County will successfully make it to SAT/SSF again so
because of the lower confidence will be putting in a Tempo group of
BKN at SAT/SSF. Some of these decks are just missing AUS to the east
and by the trajectory looks to mainly stay that way so kept AUS at
VFR through the forecast period. DRT will also see VFR for the next
24 hours. Light to moderate S/SE winds will prevail.

PREV DISCUSSION... /ISSUED 321 AM CDT Sat Jul 4 2020/

SHORT TERM (Today through Sunday)...
The weather pattern across the U.S. consists of an upper trof over
the Pacific NW and a large upper level ridge with axis from the
desert SW up into the Dakotas and MN. To the east of us there is
troffing over the NE U.S. and a developing 500mb weakness over the
northern Gulf coast. At the surface, WPC is plotting a stationary
surface boundary/front over northern OK, snaking its way down into
the southeast and the FL Panhandle.

With the upper ridge centered to our west, we will continue with
mainly hot and dry in the short term. Still a chance for some
morning clouds this morning and again on Sunday morning but they
should be fairly short lived and not affect our expected hot
afternoon temperatures.  Many areas will reach at or near 100 today
although it looks like places like AUS/SAT/ATT will be just shy of
any record highs.  Mostly sunny skies in the afternoon are expected
today with only a light to moderate southerly wind. The afternoon
mixing will continue to give us some relief in the form of some
lower dewpoints, keeping the heat indices at a non-advisory level.

That weak frontal boundary over OK may help to induce some
convection well to our N/NW late tonight into Sunday.  May be just
enough to get some thicker mid-high clouds headed our way on the
heels of mid-upper level northern winds around the upper high.
Shaved a degree or two off the highs on Sunday for that reason...but
doubt anybody will feel the difference.

LONG TERM (Sunday Night through Friday)...
Unsettled weather over the lower Mississippi along with the high
amplitude ridge over the Rockies and high plains will leave a
meridional flow pattern aloft from the Central Plains into South
Texas from late Sunday through early Tuesday. A weak shortwave
depicted by model consensus near the CO/KS border Sunday drifts
southeast toward the Red River Sunday night into Monday. The SWd or
SEwd drift of this feature is in dispute among the past several runs
of the GFS/ECM, and the more popular solution is for the feature to
pull eastward toward the upper low over Louisiana and giving Central
TX only a glancing blow of mid level moisture and instability late
Monday into Tuesday. The GFS trends are thus shifting toward a better
rain chance day being over the eastern counties of South Central TX
Tuesday. Differential heating from west to east could generate a
small burst of late afternoon or early evening convection either day,
but with 700 mb and 300 mb features not really matching up well with
the 500 mb pattern would suggest a poor chance for organized
convection.

By early Wednesday, mid to upper level ridging breaks out over the
northern Gulf coast and the Wrn US upper ridge leans forward to halt
the meridional winds aloft over the high plains. This should leave
South Central TX with near rain-free days Wednesday through Friday.
Broad upper ridging connects from west to east late in the week, and
this should lead to lower pwat values and probably heat index values
as well. Assuming this to be the case, made a subtle upward
adjustment to blended guidance high temps for late in the week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry             101  77 101  76  96 /   0   0  20  -   -
Austin Bergstrom Intl Airport  99  74  99  73  96 /   0   0  20  -   -
New Braunfels Muni Airport    100  73  99  73  97 /   0   0  -   -   -
Burnet Muni Airport            99  75  98  73  94 /   0   0  20  10  -
Del Rio Intl Airport          101  78 105  79 105 /   0   0   0  -    0
Georgetown Muni Airport       100  77  99  74  97 /   0   0  20  10  10
Hondo Muni Airport            100  71 102  73 101 /   0   0  -    0   0
San Marcos Muni Airport        98  73  99  75  97 /   0   0  -   -   -
La Grange - Fayette Regional   98  76  98  77  97 /   0  -   10  -   -
San Antonio Intl Airport       99  77 100  78  99 /   0   0  -   -   -
Stinson Muni Airport           99  74 101  76  98 /   0   0  -   -   -

&&

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

$$

Short-Term/Aviation...Treadway
Long-Term...EWilliams
Decision Support...YBVP



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