Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
1125 am CST sun Nov 29 2015
IFR/MVFR conditions continue across the region and will slowly
improve to all MVFR after 20z . Lowest ceilings/visibilities will be in areas
of light rain that continue to move northeast across the area.
After sunset ceilings will begin to trend down. Current thinking is
that the I-35 sites will become LIFR 03z-05z. Kdrt will see IFR
conditions develop 10z-12z. All LIFR/IFR ceilings should gradually
improve to MVFR after 16z Monday. Clouds may lift enough after 18z
Monday to see VFR conditions especially across the west. Light
northerly winds will prevail this afternoon at 5-10 knots. After
sunset northerly winds will decrease to 3-5 knots. Kdrt will
likely see a light east wind develop after 06z and I-35 sites
after 20z Monday.
Previous discussion... /issued 523 am CST sun Nov 29 2015/
Aviation discussion...for 12z taf period...
another poor flying day today as thick cloud cover will persist
over the next 24 hours. Low level moisture is rich and wont be
changing much until our next frontal system can clear things
out...which wont be for the next few days. So we can expect MVFR
br and IFR ceilings to prevail through the period.
Previous discussion... /issued 420 am CST sun Nov 29 2015/
Short term (today through monday)...
an upper level trough currently over the Great Basin moves east
into the central and northern plains on Monday while an upper
level ridge remains over central Mexico into the Gulf of Mexico.
Surface ridging lingers across south central Texas through Monday.
A southwesterly flow brings the remains of former eastern Pacific
tropical cyclone Sandra across Texas today. Weak isentropic lift
keeps the light rain showers or drizzle going today...then shifts
to eastern areas tonight into Monday. Enhanced lift and moisture
from the remains of Sandra will bring bands of light to moderate
showers to The Hill Country into central Texas. Expect most areas
to have only a few hundredths of an inch of rain while those under
the bands may have a quarter to half inch of rain. Cannot rule out
an isolated lightning strike or two over central Texas. Isentropic
lift maintains cloudy conditions most areas and have gone on the
cool side of guidance during the daytime hours with only a few
degrees of warming expected. However...some clearing allows for a
better warmup on Monday across the Rio Grande. Only a few degrees
of cooling are expected tonight under cloudy skies.
Long term (monday night through saturday)...
the plains upper low opens up and moves across the Great Lakes
into southeastern Canada and New England by Thursday. An upper
level trough currently well off the Pacific northwest near 140w
almost fills as is moves onshore and then reintensifies as it
drops to the southeast across The Rockies Tuesday into Wednesday
and Texas Wednesday night into early Thursday. Pressure falls in
the plains ahead the next trough allows a southeasterly flow to
return above the surface and somewhat deeper moisture back into
our area. Isentropic lift strengthens leading to isolated to
scattered rain showers Monday night through Wednesday. The front
drifts back to near the Texas coast to focus a band of moderate
showers near the coastal plains. Rain is not expected over the
Edwards Plateau due to less moisture and minimal lift there.
Another cold front and reinforcing surface high pressure move into
south central Texas on Wednesday. The colder drier air is deeper
behind this front and ends the rains from north to south Wednesday
into Wednesday evening. Total rainfall amounts of less than one
inch are expected from Monday night through Wednesday evening with
most areas having less than one quarter inch. Dry surface to middle
level ridging keeps rain out of the forecast Thursday through
Saturday...although the ridge moves off to the east on Saturday
allowing for some moisture return. Have continued to go on the
cooler side of guidance for high temperatures due to clouds most
days and cold advection Wednesday into Thursday. A freeze is
expected in some Hill Country spots Friday morning. Just beyond
this forecast...another upper level trough moves to the east
across Texas (per ecmwf) or northeastern Mexico/deep south Texas
(per gfs) bringing slight chances for showers next Saturday night
Preliminary point temps/pops...
Austin Camp Mabry 47 44 56 48 56 / 80 40 30 30 30
Austin Bergstrom international Airport 48 43 55 47 56 / 70 40 30 30 30
New Braunfels Muni Airport 49 46 56 49 57 / 60 20 20 30 40
Burnet Muni Airport 45 42 56 44 55 / 90 20 20 10 20
del Rio International Airport 54 46 60 50 62 / 30 - - - 10
Georgetown Muni Airport 47 42 55 45 55 / 90 40 30 20 20
Hondo Muni Airport 49 46 59 51 59 / 50 20 10 20 20
San Marcos Muni Airport 49 45 54 48 56 / 70 30 30 30 30
La Grange - Fayette regional 50 47 55 51 57 / 70 40 30 40 40
San Antonio International Airport 50 47 59 51 58 / 60 20 20 30 30
Stinson Muni Airport 51 48 58 52 58 / 50 20 20 30 40
public service/data collection...Treadway