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

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FXUS64 KEWX 251200
AFDEWX

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

.AVIATION...
At the I-35 sites, VFR FEW035-080 and northerly winds of 10 to 15 KTs
with a gusts to 25 KTs this morning. Skies become SKC as winds
decrease to less than 7 KTs this afternoon, then VRBL less than 4 KTs
tonight. MVFR SCT010-020 returns on southerly winds of 4 to 7 KTs on
Thursday. At KDRT, SKC as northerly winds around 6 KTs become
southeasterly later this afternoon. MVFR SCT010-015 returns tonight.
The NAM is the only model showing a potential of CIGs at all sites
and for now, will not mention.

&&

.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              72  46  76  61  67 /   0   0  -   30  70
Austin Bergstrom Intl Airport  72  43  77  60  68 /   0   0  -   30  70
New Braunfels Muni Airport     77  48  79  63  73 /   0   0  -   30  70
Burnet Muni Airport            69  45  76  55  63 /   0   0  -   20  60
Del Rio Intl Airport           77  49  78  56  71 /   0   0   0  -   40
Georgetown Muni Airport        69  44  75  57  65 /   0   0  -   30  60
Hondo Muni Airport             80  46  79  59  74 /   0   0  -   10  60
San Marcos Muni Airport        74  44  78  60  70 /   0   0  -   30  70
La Grange - Fayette Regional   74  46  80  64  73 /   0   0  -   40  70
San Antonio Intl Airport       76  49  77  63  71 /   0   0  -   30  70
Stinson Muni Airport           77  48  77  63  73 /   0   0  -   20  70

&&

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

$$

Short-Term/Aviation...04
Long-Term...EWilliams


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