Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 230445
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1045 PM CST Sun Jan 22 2017
06Z Aviation Update Below.
VFR conditions under clear skies through the TAF period. NW winds
have subsided and will remain 5 kts or less overnight through mid
morning Monday. A S to SW wind 5-10 kts will develop 16-18Z at
SAT/AUS and SE at DRT.
.PREV DISCUSSION... /ISSUED 839 PM CST Sun Jan 22 2017/
Winds have continued to decrease as the pressure gradient loosens and
the boundary layer decouples. Most places have less than 10 mph. Have
updated the zone forecast to remove the evening strong winds.
Otherwise, the forecast looks good.
PREV DISCUSSION... /ISSUED 624 PM CST Sun Jan 22 2017/
Strong low pressure area continues to move away from the region and
the pressure gradient is loosening. Winds have decreased below
advisory criteria and we have allowed the winds advisory to expire.
There may still be a few gusts to around 30 mph until shortly after
sunset. Wind speeds will continue to decrease this evening.
PREV DISCUSSION... /ISSUED 336 PM CST Sun Jan 22 2017/
SHORT TERM (Tonight through Monday Night)...
A Wind Advisory and Red Flag Warning remains in effect for all of
South Central Texas through 6 PM this evening. W-NW winds sustained
at 25-35 mph with widespread 40-50 mph gusts (and a few in the 51-53
mph range late this morning at SAT and DRT) are finally beginning to
decrease with gusts generally staying below 45 mph. Winds at 925 mb
have been slowly decreasing and are currently around 35 knots based
on aircraft soundings at AUS and area radars at KGRK, KEWX, and KDRT.
In addition, dew points appear to be recovering a bit out in the Rio
Grande Plains to get relative humidity values up towards 20 percent,
suggesting subsidence is decreasing in those areas. The decrease in
winds aloft combined with a weakening isallobaric component as the
pressure gradient decreases indicates hi-res model trends showing
weakening winds is on track. Sustained winds should remain above 25
mph with gusts above 40 mph through 5-6 PM before the decoupling
begins to help winds rapidly decrease below 10 mph by mid-evening.
Northwest flow behind the potent mid-to-upper level disturbance over
the southeast U.S. will quickly transition to ridging aloft for
Monday. This will allow for relatively calm winds and clear skies
that will cause low temperatures to be much cooler tonight in the
upper 30s over the Hill Country to mid 40s in the Coastal Plains.
Southwest winds at 5-10 mph quickly return with warm air advection at
850-925 mb supporting high temperatures in the lower 70s for our
northern counties to upper 70s and lower 80s in the Rio Grande
Plains. Forecast guidance was increased about 3 degrees to get these
temperatures as it has has been undershooting temperatures during
this abnormally warm period. The warmer temperatures over our
southwestern counties will allow for elevated fire weather concerns
due to minimum RH values decreasing to around 20 percent, but winds
should be weak enough to mitigate any major fire weather concerns.
LONG TERM (Tuesday through Sunday)...
Temperatures increase further on Tuesday with highs in the upper 70s
to mid 80s over the Rio Grande Plains as a pre-frontal trough and
dry cold front approach the region. Relative humidity values will be
in the 20-30 percent range on Tuesday once again, but the strongest
S-SW winds at 10-15 mph should be along and east of I-35/I-37 where
RH values will be a bit higher. The areas with the lowest RH values
in the Rio Grande Plains should have winds below 10 mph. Nevertheless,
have mentioned elevated fire weather conditions for Tuesday given
uncertainties in the timing of surface features as 10-15 mph winds
with RH values below 30 percent could cause major concerns. Winds
become northerly on Wednesday behind the front at 10-15 mph with
minimum RH values remaining below 25 percent in the Rio Grande Plains
to support elevated fire weather conditions there.
Temperatures will gradually fall behind the front Wednesday through
Saturday, with highs generally remaining in the upper 50s and 60s
and lows in the 30s and lower 40s. A light freeze is possible in the
Hill Country for Thursday and Friday morning, but the current forecast
keeps everyone just above freezing. A mid-to-upper level trough
digging through the Central Plains into NE Texas will help cause a
slight chance of showers on Friday evening into Saturday, but rain
amounts should remain below a tenth of an inch. Seasonal temperatures
look to continue into next weekend and beyond as both the GFS and
ECMWF depict weak northwest flow aloft between a ridge in the west
and trough in the east with a cutoff low over Baja California.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 69 45 75 52 80 / 0 0 0 0 -
Austin Bergstrom Intl Airport 68 42 74 49 80 / 0 0 0 0 -
New Braunfels Muni Airport 72 43 75 49 80 / 0 0 0 0 0
Burnet Muni Airport 66 42 74 50 77 / 0 0 0 0 -
Del Rio Intl Airport 72 41 78 49 80 / 0 0 0 0 0
Georgetown Muni Airport 68 42 73 51 78 / 0 0 0 0 -
Hondo Muni Airport 73 42 78 47 83 / 0 0 0 0 0
San Marcos Muni Airport 68 43 75 48 80 / 0 0 0 0 0
La Grange - Fayette Regional 70 44 73 52 80 / 0 0 0 0 -
San Antonio Intl Airport 72 45 77 51 81 / 0 0 0 0 0
Stinson Muni Airport 73 42 77 50 82 / 0 0 0 0 0
Public Service/Data Collection...33