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

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FXUS64 KEWX 091749

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1249 PM CDT Sun Aug 9 2020

Skies have gone VFR across South Central Texas with cloud streets of
cumulus mainly along and east of Interstate 35. Winds through the
afternoon will be gusty out of the south across the area, and
indications are that wind will not drop off much, at least into the
early overnight hours. Guess what, another round of MVFR ceilings
should build into the I-35 terminals (AUS/SAT/SSF) some time between
09z and 15z on Monday morning. The lower ceilings will be more
persistent at the San Antonio terminals and more intermittent at AUS.
Have not mentioned precipitation again in these TAFs as high
resolution models show the sea breeze more active to the east of the
TAF sites today. That said as we have seen the last few days there
is a very low chance of an isolated shower or thunderstorm making it
into the I-35 corridor late into the afternoon and evening hours.


.PREV DISCUSSION... /ISSUED 639 AM CDT Sun Aug 9 2020/

MVFR ceilings are moving in from the south and into portions of the
Hill Country and I-35 corridor. Will likely be going in and out of
SCT/BKN 1500 feet for the next few hours at SAT/SSF/AUS. Like
yesterday its possible the morning heating will create a stratocu
layer at DRT as well. MVFR should go away by 15-16Z, leading to VFR
through the afternoon with southerly winds getting gusty in the mid-
late PM hours. Guidance has the wind fairly strong through the
evening and into the first part of the overnight period as well. MVFR
repeat Monday morning. Did not mention any isolated convection as of
right now at SSF/SAT/AUS. Based on the past few days, late afternoon
and evening very isolated SH/TS is not out of the questions. Probs
too low for mention.


SHORT TERM (Today through Monday)...
The upper level pattern across the lower 48 includes a cut off low
off the CA coast, an upper ridge centered over north TX, and a
couple of short waves moving through the mid/upper MS Valley and the
far NE United States.  Our wx will continue to be dominated by our
close proximity upper ridge which isnt abnormally strong for this
time of year, but with the dry conditions over our region, is
allowing for very hot August temperatures.  With precipitable water
values forecast to hold steady near 1.5 inches, the end result is
some scattered clouds in the morning, becoming a cu field in the
afternoon, and then watching very isolated convection in the late
afternoon-early evening.  Main dilemma is whether or not to include
mention of these 10 pop chances in the text forecast. With a couple
of days of rouge SH/TS making it into the I-35 corridor, bumped pop
to 10 percent as far inland as I-35. Low Monday pop will be scaled
back and confined to a small area in the coastal plains. Will use
persistence for the temp forecast, most areas hitting near 100, mid
to upper 90s in the Hill Country. Can`t rule out a few spots hitting
our 108 HI criteria over the next 2 days, but should be isolated
enough that Heat Advisories should stay on the sideline. Dewpoints
have been mixing out fairly good by late afternoon which has been
helping the situation along with a decent southerly breeze.

LONG TERM (Monday Night through Saturday)...
High pressure in the mid and upper levels of the atmosphere will
remain anchored over the desert southwest into the Gulf Coast states
through the week. Initially, the center of this area of high pressure
will reside over northern Mexico. As the week progresses, the center
of the high pressure will build northward and strengthen over the
desert southwest. Late in the forecast period, we could see a
weakness in the ridge develop over the western Gulf of Mexico. This
could bring a slight uptick in convection, but for now we will opt to
keep shower and thunderstorm activity limited to the coastal plains. For
our region, a continuation of hot and dry weather is in store. We
will likely see some isolated, afternoon convection develop near the
coastal plains into the Highway 77 corridor, with the remainder of
the region expected to remain dry. Temperatures will continue to
remain above normal and with moisture levels near the surface
remaining slightly higher east of I-35, we could see a few locations
getting close to Heat Advisory criteria. Numerical guidance with
respect to temperatures seemed fairly reasonable. However, we did
make some minor tweaks upward in the forecast for the urban areas. We
have also been able to mix out dewpoints a little more efficiently
than the models suggest and have made downward adjustments to the
afternoon dewpoint temperatures mainly along and west of I-35.


Austin Camp Mabry             103  78 102  77 101 /  -    0   0   0   0
Austin Bergstrom Intl Airport 100  77 100  76 100 /  10   0   0   0  -
New Braunfels Muni Airport    102  77 102  75 100 /  -    0  -    0  -
Burnet Muni Airport            97  75  97  74  99 /   0   0   0   0   0
Del Rio Intl Airport          102  78 104  78 104 /   0   0   0   0   0
Georgetown Muni Airport        99  77 100  76 101 /  -    0   0   0   0
Hondo Muni Airport            101  75 102  75 102 /   0   0   0   0   0
San Marcos Muni Airport        99  76  99  75 100 /  -    0   0   0  -
La Grange - Fayette Regional   98  78  98  77  99 /  20  -   -    0  -
San Antonio Intl Airport      100  78 100  77 101 /  -    0   0   0  -
Stinson Muni Airport           98  77  99  77 101 /  -    0   0   0  -




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