Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 191152 AAA
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
552 AM CST Sun Feb 19 2017
.AVIATION.../12Z TAF CYCLE/
IFR to MVFR conditions are ongoing across the region as ample
moisture streams in from the southeast. -DZ will also be possible
across KAUS/KSAT/KSSF sites through the mid morning to late morning
hours. Visibilities may also reduce to 3-4SM at times through 15Z but
will return to P6SM thereafter. IFR conditions should improve
through 15-17Z but MVFR ceilings should stick around through much of
the morning and into early afternoon. Some cloud breaks will be
possible by mid to late afternoon across the far south but may be
tough to come by at TAF sites themselves. VCSH will be possible
towards KAUS through the mid afternoon and this trend for TAF
inclusion will need to be watched.
By early to mid-evening, widespread SHRA and TSRA should develop
near KSAT/KSSF/KAUS and persist through the overnight and into Monday
morning. Depending on heavy rain placement, IFR to LIFR conditions
will be possible at times as visibilities sporadically jump up and
down along with ceilings. SHRA and TSRA will slowly clear to the east
after 12-15Z Monday morning.
.PREV DISCUSSION... /ISSUED 437 AM CST Sun Feb 19 2017/
SHORT TERM (Today through Monday)...
Very active weather expected today into Washington`s Birthday
(Monday). An upper level trough over Arizona into Sonora state of
Mexico is moving to the east with a moist lower to mid level flow
over South Central Texas. Isentropic lift will produce isolated to
widely scattered showers this morning into early afternoon.
The upper level trough moves into New Mexico to Chihuahua state of
Mexico this afternoon encouraging larger scale lift to develop.
Forecast soundings for late this afternoon into evening show MUCAPEs
of 1K to 2.4K J/KG and 0-6 KM shear of near 50 KTs across much of
our area with the highest values along the I-35 corridor. Some mixing
of the airmass is expected, especially southwest of San Antonio
allowing for some breaks in the clouds in that area to realize some
of that instability. Isolated thunderstorms will develop in that area
and race to the northeast along to just east of I-35. Some of these
could become strong to marginally severe with large hail and strong
winds the main threats.
Stronger lift occurs tonight as the trough moves into Western Texas
to south of the Big Bend. Showers and thunderstorms become more
numerous across our area tonight with the greatest coverage along and
east of Highway 281. Storms may organize into line segments with
damaging winds and isolated large hail the main threats. An airmass
with PWs near seasonal maximums at 1.6 inches and flow allowing for
training indicates at least a marginal risk of locally heavy rains
along and east of Highway 281 with the greatest threat from near the
Coastal Plains to along the Highway 77 corridor.
The upper level trough slows down on Monday as it loses contact with
a northern stream upper trough. Expect some showers and thunderstorms
on Monday morning with possibly some locally heavy rains lingering
near the Coastal Plains to the Highway 77 corridor. Drier air will
filter into our area during the afternoon with some showers and
thunderstorms east of I-35.
Rainfall totals along and east of Highway 281 will average 1 to 2
inches with isolated amounts of 5 inches possible where training
occurs. This may cause some flooding. West of Highway 281, less than
an inch is expected.
Clouds and rain will keep high temperatures lower today and Monday,
but, still well above normal.
LONG TERM (Monday Night through Saturday)...
The upper level trough moves east of our area by Tuesday with upper
level ridging building from northwestern Mexico into Texas late
Tuesday into Wednesday. An upper level trough moving through the
Central Rockies will allow for lower level flow from off the Mexican
Plateau increasing high temperatures again midweek. The trough moves
out into the Central Plains by early Friday pushing a weak cold front
across the area. Due a much drier airmass from a couple of days of
upper level ridging and flow off the Plateau, no rains are expected.
Temperatures will fall a little, but remain above normal for Friday
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 77 61 74 54 78 / 30 90 50 - -
Austin Bergstrom Intl Airport 78 62 74 53 78 / 30 90 50 - -
New Braunfels Muni Airport 79 62 75 53 80 / 30 90 50 - -
Burnet Muni Airport 74 57 73 49 77 / 30 70 40 - -
Del Rio Intl Airport 78 55 79 49 81 / 20 50 10 0 0
Georgetown Muni Airport 76 60 73 52 77 / 30 90 40 - -
Hondo Muni Airport 82 60 78 49 81 / 30 70 40 - 0
San Marcos Muni Airport 77 62 74 53 78 / 30 90 50 - -
La Grange - Fayette Regional 79 63 72 56 76 / 30 100 60 10 10
San Antonio Intl Airport 80 62 76 53 79 / 30 90 40 - -
Stinson Muni Airport 81 62 77 54 81 / 30 90 40 - -