Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
1237 PM CST Friday Feb 12 2016
VFR conditions are expected through late tonight across area
sites. A weak cool front is pushing across the Interstate 35
corridor based on current observation and expected to continue to move
across the coastal plains counties this afternoon. Hires models
and medium-range guidance suggest for the boundary to stall
between the Escarpment and the coastal plains. If this
verify (boundary stalls along or to the north of
I-35 corridor)...southerly flow is expected to dominate overnight
into Saturday morning with patchy to areas of fog developing
across the coastal plains and the I-35 corridor. Area forecast
soundings and time-height maps suggest the developing of stratus
around 11z/12z time frame period with MVFR/IFR ceilings/vbsys along
the I-35 terminals to about 17z/18z Saturday. Across kdrt...MVFR
ceilings are expected around 14z through 16z Saturday with VFR
conditions returning afterward. Clouds are forecast to linger
around for much of the afternoon along the I-35 sites as well as a
low cloud deck around 025 to 035 kft.
Previous discussion... /issued 908 am CST Friday Feb 12 2016/
have allowed the dense fog advisory to expire as of 9 am.
Visibility has improved across most areas of the Texas coastal
plains although a few areas of fog between 1/2 and 2 miles remain
from Pleasanton to Gonzales and La Grange. This fog will continue
to lift over the next hour or so. The low clouds over the coastal
plains will also dissipate leading to a mostly sunny afternoon.
Previous discussion... /issued 546 am CST Friday Feb 12 2016/
VFR conditions were being reported across all the taf sites this
morning. With higher dewpoints and increasing low level moisture
could see a brief period of some MVFR visibilities at kaus. Have
included a tempo group to account for this between 13z and 15z.
Current thinking is that fog will remain out of the other I-35
terminals. After 15z VFR conditions will prevail through early
Saturday morning when we expect to see MVFR ceilings develop between
09z-11z at the I-35 sites. Winds will become east/NE at 5-10 knots
after 16z then more northerly overnight and into Saturday
morning. Could once again see some fog especially at kaus around
Previous discussion... /issued 417 am CST Friday Feb 12 2016/
Short term (today through saturday)...
Overview...despite a weak cold front passage this afternoon -
near to above normal temperatures will remain in place. More
clouds and cooler conditions are expected Saturday with continued
Synoptic 500 mb pattern over the Continental U.S. This morning per water vapor and
rap analysis reveals a longwave trough over eastern Continental U.S. Arcing northwest
back into the north Central Plains. A 500 mb ridge is in place across
the Desert Southwest and this is placing Texas in weak northwest 500 mb flow
with noted shaper shortwave over the middle MS valley. This feature
alongside a strong Canadian surface high pressure system will send a
weak front into the region this afternoon. H925 temperatures ranged 24-18c
west to east yesterday that allowed for near record heat. Values
will range around 23-15c today so maximum highs are not expected to
reach yesterdays values. Still - above normal and quite pleasant
conditions are expected as humidity remains low.
For Saturday...expect more clouds in the morning across a good
portion of the region that will slowly erode through the afternoon.
Clouds will dissipate quickest in the SW and central areas. Based on
some implied weak isentropic lift over-top of the weak front that
stalls over the region...low-lvl moisture may become trapped under
an inversion and be tougher to clear out in NE areas through the
afternoon. Due to this and the cooler h925 temperatures...surface
temperatures may not reach 70f towards the Austin area while San
Antonio and points SW will warm up more.
Long term (sunday through next thursday)...
Other than some light drizzle and low-end light rain chances for
portions of Sunday and early Monday for eastern locations...a dry
week is expected. Temperatures will recover into next week and
remain above normal in the middle 70s to low 80s.
More clouds are expected to develop late Saturday into Sunday
morning and this low-level saturation could lead to patchy areas
of light rain and drizzle. Little to no accumulation is expected
and dry conditions will continue through the next week.
The western Continental U.S. Ridge will break down slightly Sunday into Monday due
to a stronger 500 mb shortwave digging south across the Central Plains.
Most models have trended farther north with the better lift and
dynamics associated with this piece of energy with minimal rain
chances for this region. If the track of this system shifts south
then additional rain chances will need to be added to NE
locations. For now have gone with low-end /20%/ light rain chances
for far eastern locations but best precipitation location will be
towards east/North Texas. There could be some possibility of
thunderstorms just North/East of our area towards Waco and Houston
Monday morning given 100-300 j/kg MUCAPE. However - feel risk is
to low to include for our region given ingredient disconnect here.
A stronger front moves through Monday afternoon but no true cold
air resides behind it.
For Tuesday-Thursday - expect sunny skies with above normal temperatures
and continued worsening fire weather conditions. While no red flag
criteria is expected to be met at this point...fuels will
continue to dry out and the energy release component values will
likely continue to climb.
Preliminary point temps/pops...
Austin Camp Mabry 50 68 54 74 55 / 0 - 10 10 10
Austin Bergstrom international Airport 45 68 52 74 53 / 0 - 10 10 10
New Braunfels Muni Airport 47 71 53 76 53 / 0 - 10 10 -
Burnet Muni Airport 45 66 52 72 50 / 0 0 10 10 -
del Rio International Airport 50 77 53 78 48 / 0 0 - 0 0
Georgetown Muni Airport 45 65 52 73 53 / 0 0 10 10 10
Hondo Muni Airport 46 75 52 77 48 / 0 0 - - 0
San Marcos Muni Airport 47 69 53 74 53 / 0 - 10 10 10
La Grange - Fayette regional 51 68 53 75 58 / - 10 10 10 10
San Antonio International Airport 49 72 54 75 53 / 0 0 10 10 -
Stinson Muni Airport 49 74 54 77 52 / 0 0 - 10 0
public service/data collection...LH