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

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550
FXUS64 KEWX 251711
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1111 AM CST Wed Nov 25 2020

.AVIATION...

Winds are generally out of the N to NNE behind a cold front late this
morning and should remain at or below 10 knots the rest of today.
Clear skies at the terminals will prevail through this evening, and
winds will become light and variable or perhaps even calm. Some MVFR
cigs will develop south of the area overnight, and at this time are
not expected to reach the terminals, however brief periods of
category restrictions are not out of the question and have left a
SCT015-018 group to hint at this possibility. Winds will become
southerly during the day Thursday (southeasterly at DRT), remaining
light.



&&

PREV DISCUSSION... /ISSUED 326 AM CST Wed Nov 25 2020/

SHORT TERM
Cold front surging toward the Coastal Plains will exit our area by
sunrise taking any showers away. Breezy conditions this morning as
surface high pressure builds into our area slackens this afternoon
as surface high settles over our area. Cooler, though still above
normal high temperatures are expected today. A dry airmass filters
into our area with relative humidities falling into the teens and
20s this afternoon. However, winds will be less than 10 mph at the
time of lowest humidities keeping fire weather conditions slightly
elevated. Light winds, lower dewpoints, and clear skies will allow
for efficient radiational cooling tonight with chilly, slightly
below normal low temperatures expected. Surface high drifts off to
the east on Thanksgiving Day as pressures fall in the Plains ahead
of an upper level trough approaching the Four Corners region.
Southerly flow returns with increasing moisture and above normal
high temperatures.

LONG TERM
Overnight Thursday into Friday morning an upper level shortwave will
approach the region from the west. This feature will drive a strong
cold front into South-Central Texas by Friday morning. As this
boundary pushed into the area, thunderstorms will be possible with
even a potential for an isolated strong to severe storm. Chances for
these isolated strong storms will be greater over South-Eastern Texas
but 1000-1200 J/kg of MUCAPE, moderate mid level lapse rates (7.0
C/km), and 40 kt 0-6km shear could produce a strong cell or two.
Upper level support will come from shortwaves out ahead of the main
trough axis. The greatest threat would be sub-severe hail, at best
pea-size hail. The potential for any wind threats will depend on if
any storms will be surface based, which is uncertain at this time.
Regardless, this begins a period of better chances for rain areawide.

The front slows Friday afternoon as it moves over the Coastal Plains.
As the upper level low and trough axis swing over the state,
favorable widespread upper level support for ascent will bring likely
chances for showers and storms overnight Friday and most of Saturday.
Although it is not a polar airmass that will be moving in, big cool
down of temperatures will be in store with this Canadian airmass.
Highs on Saturday, given the chances for rain and cloud cover, will
only climb to the mid 50s for the Hill Country and low to mid 60s for
areas elsewhere.

Not only are there widespread likely chances for precip, the QPF
totals through Sunday look very promising. Global models indicating
that 1-3 inches is possible for the eastern half of the CWA. Western
areas still could see 1/4 to 1 inch of rainfall. Important to note
that WPC has our eastern CWA in a marginal risk for excessive
rainfall on day 3.

Skies clear by Sunday and much drier atmospheric column will be
overhead. This will allow for very efficient cooling Sunday night
and Monday night. Also, northerly flow looks to persist until
Tuesday as an elongated surface high remains in place along the
leeward side of the rockies and the upper level low that initially
brought us the front deepens to a mature-looking mid-latitude cyclone
over the northeast. Surface high eventually slides eastward turning
winds back out of the southeast and temperatures stabilize near
normal mid next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              71  45  78  60  67 /   0   0   0  30  70
Austin Bergstrom Intl Airport  72  39  78  60  68 /   0   0   0  30  70
New Braunfels Muni Airport     75  45  77  62  73 /   0   0   0  20  70
Burnet Muni Airport            69  43  76  54  63 /   0   0   0  20  60
Del Rio Intl Airport           78  49  79  57  71 /   0   0   0   0  40
Georgetown Muni Airport        69  42  77  57  65 /   0   0   0  20  60
Hondo Muni Airport             80  45  77  59  74 /   0   0   0  10  60
San Marcos Muni Airport        74  42  78  60  70 /   0   0   0  30  70
La Grange - Fayette Regional   72  44  80  64  73 /   0   0   0  40  70
San Antonio Intl Airport       76  48  77  62  71 /   0   0   0  20  70
Stinson Muni Airport           77  48  77  62  73 /   0   0   0  20  70

&&

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

$$

Short-Term/Aviation...KCW
Long-Term...Brady
Decision Support...YBVP



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