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

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FXUS64 KEWX 210808

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
308 AM CDT Mon Oct 21 2019

.SHORT TERM (Today through Tuesday)...
A line of showers and thunderstorms extends from northeast of Del Rio
to near Blanco to near Georgetown. After being slow to move earlier
tonight, the associated cold front has caught up to the convection
and is now helping the activity to propagate to the south/southeast.
Latest parameters on the mesoanalysis shows around 2000 J/kg of
MLCAPE and between 30-40 knots of bulk shear. This setup will allow
for continued strong to possibly isolated severe storms as the
activity progresses southeast overnight and into the morning hours.
The best helicity values will remain to our northeast which should
limit the threat for any isolated tornadoes. In addition, the main
upper forcing associated with the parent upper low remains well to
our north as well and therefore most of the activity will be driven
frontal dynamics. To summarize the expected trend overnight is a
continued movement of the line of showers and storms aided by the
available instability and shear in place. However, a lack of upper
dynamics and the best setup for severe parameters to our north, the
activity in our area should remain below severe limits for the most
part. Gusty winds will be main threat from the stronger cells with
speeds mostly in the 30-45 mph gust range. A brief stronger storm
could briefly reach severe limits with wind gusts again the main
threat. The better news is that the eastern majority of the CWA will
likely see beneficial rainfall with an average total between a third
and half an inch expected.

The bulk of the activity will be out of the CWA by the mid to late
morning hours. For the remainder of the day, skies will be clearing
as drier air filters into the area. Highs today will be in the upper
70s in the northeastern CWA to the upper 80s in the southwestern CWA.
In addition, very dry air will filter in behind the front with
afternoon humidity values west of Highway 281 dropping below 20
percent with Val Verde County dropping to near 10 percent. With the
beneficial rainfall expected for most of the CWA, the focus for any
fire weather conditions will be across the Rio Grande Plains where
little rain is expected. Although afternoon humidity values will be
near 10-15 percent in these locations, winds this afternoon will be
weakening to less than 10 mph. Therefore, only expecting elevated
fire weather conditions for the Rio Grande Plains due to the very dry
air in place.

For tonight, clear skies and light winds will lead to low
temperatures in the middle 40s to middle 50s. The dry weather will
continue into Tuesday with highs once again topping our in the upper
70s to middle 80s.


.LONG TERM (Tuesday Night through Sunday)...
South winds will return to the region by Wednesday ahead of our next
upper system. Temperatures will likely respond by increasing a degree
or two versus Tuesday. A strong upper trough axis will move through
the Central Plains and will bring the next strong front to the area
by the end of the work week. There remains varying differences
between the medium-range guidance with relation to the trough and
therefore the timing of the associated cold front and rainfall
chances. The GFS has been consistent with showing a more open and
therefore quicker trough axis with a frontal passage Thursday
afternoon. On the other end of the spectrum, the ECMWF and Canadian
close off the upper trough axis over New Mexico and therefore are
slower with the frontal passage shown on Thursday night. These
solutions would also have a better coverage and amount of rainfall
with the system. Will continue to stick closer to the blends for now
until a more confident forecast appears. As mentioned earlier, this
front is expected to be colder than today`s cold front. High
temperatures on Friday will likely be in the 60s with some locations
in the Hill Country potentially staying in the 50s. Lows on Saturday
will likely be in the 40s areawide and only a few degrees warmer on
Sunday morning. Highs on Saturday will be in lower 70s and a few
degrees warmer on Sunday.


Austin Camp Mabry              79  53  80  51  80 /  20   0   0   0   0
Austin Bergstrom Intl Airport  79  48  80  50  81 /  30   0   0   0   0
New Braunfels Muni Airport     80  50  80  51  81 /  40   0   0   0   0
Burnet Muni Airport            76  50  77  52  78 /  -    0   0   0   0
Del Rio Intl Airport           87  54  85  56  83 /   0   0   0   0   0
Georgetown Muni Airport        77  48  78  51  80 /  10   0   0   0   0
Hondo Muni Airport             86  50  85  52  85 /  20   0   0   0   0
San Marcos Muni Airport        79  50  80  51  81 /  40   0   0   0   0
La Grange - Fayette Regional   79  51  80  52  81 /  60   0   0   0   0
San Antonio Intl Airport       83  53  80  55  82 /  40   0   0   0   0
Stinson Muni Airport           84  54  81  55  83 /  50   0   0   0   0




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