Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Austin/San Antonio Texas
1131 am CST Sat Feb 13 2016
Update...18z aviation update below.
Aviation...MVFR stratus along and southeast of a Uva-Sat-aus
line will continue to gradually erode over the next hour with VFR
cumulus thereafter through the afternoon and early evening. Southeast to S
wind 8-12 kts developing through the afternoon.
IFR ceilings will re-develop with stratus along aus-Sat line
around 06z tonight and expand west overnight through The Hill
Country and into the Rio Grande plains...with IFR to LIFR ceilings
at drt possible by 12z.
Previous discussion... /issued 858 am CST Sat Feb 13 2016/
dense fog has developed farther west and is slower to dissipate
than we previously anticipated. Have expanded and extended the
dense fog advisory. It now includes all of the southern counties
to Maverick...but only the southern half of Maverick will have
dense fog. Have extended the time until 11 am. Expect visibility
will improve by that time.
Previous discussion... /issued 539 am CST Sat Feb 13 2016/
weak boundary remains in place along or just to the east of I-35
this morning. This has allowed for drier air to filter into the
region and currently all the taf sites are VFR. Just to the east
and south of the boundary moisture remains and stratus and fog
have developed and currently are progressing north. Have included
some MVFR/IFR ceilings for ksat/kssf. Will have to watch kaus as some
of the lower clouds could move across the terminal after 13z. Should
see a return to VFR conditions at all sites after 16z. Will see
light northerly winds become southeast after 17z at 10-15 knots. Tighter
gradient along the Rio Grande will allow for southeast winds near 15
knots with gusts to 20 knots after 18z. Winds overnight become
southerly near 10 knots. Expect to see MVFR ceilings develop at the
I-35 terminals after 06z. Kdrt not likely to see low clouds until
near 12z when MVFR ceilings develop. After 09z may see some light
drizzle and fog but have not included at this time due to
uncertainties in timing and location.
Previous discussion... /issued 439 am CST Sat Feb 13 2016/
Short term (today through sunday)...
Overview...main focus will center on early morning dense fog chances
near the coastal plains till 9am and the low-end (20%) rain chances
for Sunday morning.
Light patchy fog as developed across the inner coastal plains as
expected with dense fog being observed along the coast. Hrrr
extrapolation along with NAM/GFS/rap bufr soundings suggest these
kind of visibilities (1/2-1/4 mile) may occur over the eastern
tier of coastal plain counties through 9am. Will continue to
monitor if a dense fog advisory is needed but so far observations
have shown more of a stratus deck vs. Fog. This is likely due to
some of the low-level dry air mixing in near the stalled frontal
The fog and low stratus will slowly shift inland through middle-morning
while slowly eroding. Deeper low-level moisture will be funneled
along and east of the I-35 corridor with the increasing southeast
flow and this will allow for clouds to linger in the east through
the afternoon. Bufr soundings and GFS/ec model output of h925
temperatures suggests that despite the clouds, locations should
be climb into the 69-72f range across the NE section of the
region. Warmer readings are expected across central and SW
locations given the drier conditions and more sun.
Slightly deeper 500 mb troughing will shift over Texas late tonight into
Sunday that will subtlely enhance upper level divergence over the
shallow moist southeast flow. Light patchy drizzle could be possible over
central and eastern areas Sunday morning but little to no
accumulation is expected. While more clouds are expected
Sunday...highs should be warmer than today given the warmer start
Sunday morning and continued h925 temperatures in the 21-15c range west
Long term (monday through next friday)...
Only highlight in the long term will a low-end (20%) rain chance
Monday morning with the passage of a Pacific cold front but
again...no significant accumulations are expected. Well above normal
temperatures and dry weather are expected through the remainder of
Continental U.S. Pattern on Monday per the GFS/ec will feature a strengthening
yet displaced 500 mb shortwave over North Texas that will likely mean
negligible rain coverage and amounts for the region. Upper-level
divergence will increase late Sunday night but low columnar moisture
in concert with limited instability will keep rain coverage low. The
stronger dynamics and elevated to even some surface based
instability will remain north and east of the region. The Pacific
front will move through Monday afternoon with no Canadian air
associated with it.
Tuesday-Friday...Texas will be well displaced from the polar jet
stream to the north in addition to an inactive southern branch. Low-
level southeast and middle-level southwest flow will dominate as the
pattern transitions from weak 500 mb troughing to a 500 mb ridge pattern.
Middle 70s to low 80s and dry conditions are expected for the rest of
the week with morning clouds returning Thursday and Friday with
quick mix out to sunny skies each afternoon.
Preliminary point temps/pops...
Austin Camp Mabry 73 56 74 55 76 / 0 - 10 10 10
Austin Bergstrom international Airport 72 53 74 52 75 / 0 - 10 10 10
New Braunfels Muni Airport 74 53 76 52 78 / 0 - 10 10 10
Burnet Muni Airport 71 52 73 49 74 / 0 - 10 10 -
del Rio International Airport 79 52 77 49 80 / 0 0 - - 0
Georgetown Muni Airport 70 54 73 53 74 / 0 - 10 10 10
Hondo Muni Airport 77 52 77 47 79 / 0 0 10 10 -
San Marcos Muni Airport 73 54 75 53 76 / 0 - 10 10 10
La Grange - Fayette regional 72 55 74 57 76 / - - 20 20 10
San Antonio International Airport 74 54 75 52 77 / 0 - 10 10 -
Stinson Muni Airport 75 54 77 52 79 / 0 - 10 10 10
public service/data collection...LH