Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
1141 am CST sun Dec 8 2013
upper level trough will continue to progress east today. This will
allow for clearing line to move west to east across the area. Far
eastern areas will not likely see much clearing before sunset. VFR
conditions will prevail at kdrt through the forecast period with
light east and southeast winds 5 to 10 knots. The I-35 terminals
are currently reporting MVFR ceilings and visibilities. As
clearing moves slowly east will see MVFR conditions improve to VFR
20z-22z. Winds will be southeast at 3 to 7 knots. Overnight
expecting VFR conditions with light and variable winds. After 15z
Monday will see low level moisture returning with MVFR ceilings
expected after 15z with northerly winds 7 to 10 knots.
Previous discussion... /issued 1016 am CST sun Dec 8 2013/
at 10 am there were still a few locations below freezing across
the eastern Hill Country and across our northern counties...north
of Highway 71. These areas should climb above freezing by 11 am
ending the threat of light ice on bridges an overpasses. Latest
model solutions are trending to a later return of light precipitation on
Monday so have removed the mention of light freezing precipitation from
the forecast for Monday morning across our far northern counties.
There still is a chance that light freezing rain/drizzle will
return late Monday night through Tuesday morning...north and east
of a line from Tow to Boerne to Dime Box. This includes the
Austin metropolitan area.
Previous discussion... /issued 603 am CST sun Dec 8 2013/
have allowed Winter Weather Advisory to expire.
the band of drizzle/light rain has moved out of the area. No
additional precipitation is expected this morning...but patchy ice
from the freezing rain and freezing drizzle overnight will continue
early this morning until temperatures begin to warm. Most of the
region will warm to above freezing before 10 am. Updated zones
have been sent.
Previous discussion... /issued 538 am CST sun Dec 8 2013/
I-35 terminals are still socked in with clouds but things are
starting to improve. Over the past few hours both Sat/ssf have
improved to VFR while aus is still holding on to MVFR. Satellite
shows skies are clear out in drt except for some high cirrus. Over
the next few hours aus will go VFR as clearing line approaches
from the west. Have clouds scattering out along the I-35 taf sites
around 20z. This VFR will then continue at all sites for about
24-30 hours before more cool high pressure comes into the region
Monday afternoon and we go through yet another overrunning
situation with developing ceilings Monday afternoon and evening.
At both the aus/Sat 30 hour taf sites...indicated this trend. Winds
will be light today as surface ridge sits over the area but will see a
general trend of winds veering to the south before the return to a
north-NE direction by Monday afternoon.
Previous discussion... /issued 401 am CST sun Dec 8 2013/
Short term (today through monday)...
a swath of precipitation which generated freezing drizzle
overnight is slowly moving eastward across the coastal plains and
will continue to move eastward through the early morning hours.
Due to the continuing potential for freezing drizzle...will leave
the current Winter Weather Advisory in effect until 12z. Water
vapor imagery shows very dry air in the middle-levels moving into the
region. The drier air and westerly winds aloft mixing down will
cause skies to clear from west to east today. The return of
sunshine and surface ridging will help chip away at the cold surface
airmass...with temperatures warming into the middle 40s across our
far northestern zones...and into the low 50s across western portions of
the region. Lows Monday morning will be warmer than we've had the
last few nights...with freezing temperatures mostly limited to The
Hill Country and adjacent areas.
Isentropic lift will increase late tonight and into Monday as an
upper level trough approaches. Sunday night will be mostly
dry...but chances for precipitation will begin to increase Monday
morning. There is a very brief window of opportunity for light
freezing rain Monday morning across our northestern zones. However...freezing
temperatures will be spotty...and overall chances for any precipitation
early Monday morning are low. Chances for precipitation will increase
throughout the day on Monday...but by then temperatures will be too
warm to support wintry precipitation. Due to the isentropic nature of the
rain...quantitative precipitation forecast amounts will average only a few hundredths of an inch.
Long term (monday night through saturday)...
a reinforcing cold front will move into the region Monday
night...allowing slightly colder lows to settle in Tuesday morning.
Low temperatures Tuesday morning will fall to near or below
freezing across the northern half of the County Warning Area. Given that chances
for drizzle/light rain will continue into Monday night...there
will be another opportunity for light freezing rain/drizzle. The
current forecast includes freezing precipitation across the
Austin metropolitan and adjacent ares...with temperatures across the San
Antonio metropolitan area remaining just above freezing. The chance for
precipitation will exit to our east Tuesday morning with dry ridging
building into the region. Temperatures on Tuesday will reach the
low to middle 40s across northestern areas...to near 50 across the Rio
Cold air advection and light winds Tuesday night will enable
another widespread freeze Wednesday morning. Moisture will begin
to increase across the region during the middle of the week ahead
of the next upper trough. The moisture will enable a slow warming
trend during the latter half of the week...but temperatures will
nonetheless remain below average for middle December. Chances for
rain will re-enter the forecast Thursday night and linger through
Friday night as an upper level low moves across the area.
Temperatures will still be chilly...but too warm to support
Preliminary point temps/pops...
Austin Camp Mabry 45 34 44 31 45 / - - 20 20 10
Austin Bergstrom international Airport 44 31 43 29 44 / - - 20 20 10
New Braunfels Muni Airport 48 35 46 33 45 / - - 20 20 10
Burnet Muni Airport 44 31 41 26 43 / - - 20 20 -
del Rio International Airport 52 36 54 35 51 / 0 0 10 10 -
Georgetown Muni Airport 43 30 42 28 43 / - - 20 20 10
Hondo Muni Airport 51 35 51 34 50 / - - 20 10 -
San Marcos Muni Airport 47 34 45 32 44 / - - 20 20 10
La Grange - Fayette regional 44 39 48 36 46 / 10 10 30 20 10
San Antonio International Airport 50 37 47 34 47 / - - 20 20 -
Stinson Muni Airport 50 38 49 34 49 / - - 20 20 -
public service/data collection...32