Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Austin/San Antonio Texas
1148 am CST Tue Dec 12 2017
VFR conditions are expected throughout the taf period as strong north-NE
10-15 knot winds will continue this afternoon at the I-35 taf sites
with gusts to 20-25 knots possible for the next few hours. Winds will
gradually subside this afternoon as the pressure gradient relaxes
and high pressure moves into the area. Winds tonight will be nearly
calm, but patchy fog is not expected as dew point depressions should
be too high. Winds will become southwesterly at the I-35 sites (and
southeast at drt) tomorrow around 10 knots ahead of a pre-frontal trough.
Previous discussion... /issued 544 am CST Tue Dec 12 2017/
Aviation... /12z tafs/
Surface ridging behind this morning's weak cold front could send
sustained winds to near 15 knots over central Texas with some afternoon
gusts over 20 knots possible. Most of the winds should sustain closer
to 10 to 12 knots and relax in the late afternoon. Light winds should
trend more from the west in the evening hours with light and variable
winds expected at drt/ssf. No low or mid level cigs are expected
through the period.
Previous discussion... /issued 306 am CST Tue Dec 12 2017/
Short term (today through wednesday)...
an upper level trough moving across the Great Lakes and Mississippi
into Ohio valleys will drag a cold front across our area early this
morning. No rain is expected as pws near 1/4 inch are well below
normal. A fairly tight pressure gradient and some mixing from aloft
generate locally breezy conditions this morning into early afternoon.
Cold advection will drop high temperatures to near to slightly below
normal today. As a surface high settles in and winds aloft decrease,
winds subside rapidly by sunset and become light this evening into
overnight. Some cirrus passing overhead should not hamper efficient
radiational cooling and below normal low temperatures are expected
tonight. Surface high drifts off to the south on Wednesday turning
winds to southwesterly with highs around normal levels as weak upper
level ridging builds north from Mexico.
Long term (wednesday night through monday)...
an upper level shortwave rotates through the larger eastern states
upper level trough Thursday forcing another cold front across our
area. Again, no rain is expected as the airmass remains drier than
normal, though pws are a little higher, around 1/2 inch. Locally
breezy conditions are possible due to fairly tight pressure gradient.
Slightly above normal temperatures on Thursday turn near to slightly
below normal on Friday as weak cold advection continues. Southerly
winds return with warm advection raising temperatures to above normal
Saturday. Models remain inconsistent for Saturday night into Sunday,
though European model (ecmwf) and GFS show some quantitative precipitation forecast for our area, but for different
reasons. The European model (ecmwf) has an upper level trough moving out of Mexico
while the GFS has an upper level trough moving across the plains.
Have introduced slight chance pops for areas east of I-35 for
Saturday night into Sunday.
Preliminary point temps/pops...
Austin Camp Mabry 63 37 67 44 65 / 0 0 0 0 0
Austin Bergstrom Intl Airport 63 35 65 41 65 / 0 0 0 0 0
New Braunfels Muni Airport 64 36 65 42 66 / 0 0 0 0 0
Burnet Muni Airport 60 35 67 40 61 / 0 0 0 0 0
del Rio Intl Airport 66 38 66 42 67 / 0 0 0 0 0
Georgetown Muni Airport 61 35 67 42 63 / 0 0 0 0 0
Hondo Muni Airport 68 36 66 41 69 / 0 0 0 0 0
San Marcos Muni Airport 63 36 65 42 66 / 0 0 0 0 0
La Grange - Fayette regional 63 36 64 42 65 / 0 0 0 - -
San Antonio Intl Airport 65 38 65 44 67 / 0 0 0 0 0
Stinson Muni Airport 66 38 65 44 68 / 0 0 0 0 0