Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
949 PM CDT Tuesday Oct 6 2015
latest water vapor image shows an upper low across the southwest
part of Arizona. Most models including medium-range solutions such
as the NAM...GFS...ecm...Canadian...sref and even the GFS
ensembles are in fair to good agreement on the upper low
movement/track for the next few days. The system is forecast to
track to the southeast and into northern Mexico late Wednesday
into Thursday. This will bring good chances for rain across much
of the west(rio grande plains). By Friday...the upper low is
expected to push to the southwest and into the eastern Pacific
waters. A cold front is now advertised for late Friday into
Saturday with little upper level support for showers or
thunderstorms. The area to see showers and isolated thunderstorms
is the Rio Grande plains. Storm rainfall totals of 1 to 3 inches
are possible across the Rio Grande plains with up to 5 inches over
few spots. Across the I-35 corridor...rainfall will be limited
with few locations getting up to one quarter inch but in general
expect one hundredth of an inch or less for the period.
Previous discussion... /issued 620 PM CDT Tuesday Oct 6 2015/
Update...00z aviation update below.
Aviation...VFR conditions through the taf period with scattered high
cirrus. Wind decreasing to less than 5 kts and becoming vrb after
sunset for Sat/aus then becoming east to southeast 5-8 kts Wednesday afternoon.
Wind at drt remaining southeast 5-7 kts overnight then increasing to
10-15 kts Wednesday afternoon.
Previous discussion... /issued 238 PM CDT Tuesday Oct 6 2015/
Short term (tonight through Wednesday night)...
shortwave ridging is in place across Texas this afternoon and is
overall limiting cloud cover. Also...temperatures are running
about 4-8 degrees warmer than at this time yesterday. While
shortwave ridging is over Texas at the present time a strong upper
level low is currently centered near the California/Arizona
border. Clear skies and light winds will still allow temperatures
to bottom out in the 60s despite the warmer day time temperatures.
Tomorrow...highs will be similar to today with partly cloudy
skies as the upper low nears the region. With somewhat increased
moisture Wednesday night...warmer temperatures are expected with
lows in the upper 60s to lower 70s.
Long term (thursday through tuesday)...
yesterday...the upper low was forecasted to make it as far east as
just south of The Big Bend area of Texas. However...models have
now shifted west and have the center of the low not even making
it to the same longitude of El Paso. Also...the cold front that
was expected to come south Thursday night is now delayed until
Saturday morning in the latest model runs. Unfortunately...what
this means is smaller rain chances for the most of the County Warning Area except
for the Rio Grande counties. This location...for now...will still
be in closer proximity to the low for dynamical upper support for
convection. Have lowered probability of precipitation for the rest of the County Warning Area some 20-30
percent. Without the frontal boundary coinciding with the peak
lift...the threat for heavy rain has also somewhat diminished.
However...the European model (ecmwf) is still showing some support for locally
heavy rainfall across the extreme western portions of the County Warning Area.
Will update the hazardous weather outlook to only keep the threat
of heavier rainfall to the western areas.
With the low not making it as far east....rain chances should end
a bit sooner and have rain ending in the forecast for much of the
area by Saturday morning. High pressure will return to Texas
beginning on Sunday...which will equate to drier conditions and
temperatures being above normal.
Preliminary point temps/pops...
Austin Camp Mabry 66 91 69 89 70 / 0 0 - 20 20
Austin Bergstrom international Airport 62 91 66 89 69 / 0 0 - 20 20
New Braunfels Muni Airport 65 91 69 89 69 / 0 0 - 30 20
Burnet Muni Airport 64 88 67 85 65 / 0 0 - 20 20
del Rio International Airport 68 90 72 81 68 / 0 0 20 70 60
Georgetown Muni Airport 63 89 66 89 67 / 0 0 - 20 20
Hondo Muni Airport 65 91 69 87 70 / 0 0 10 50 40
San Marcos Muni Airport 64 90 68 88 69 / 0 0 - 30 20
La Grange - Fayette regional 66 90 68 89 69 / 0 0 0 20 20
San Antonio International Airport 68 90 71 88 71 / 0 0 - 30 30
Stinson Muni Airport 68 92 70 89 71 / 0 0 10 40 30