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Area forecast discussion
National Weather Service Austin/San Antonio Texas
936 am CDT sun Mar 26 2017

Morning update...
made some minor adjustments to the hourly T/TD grids to match with
latest obs trends. Also, made some edits to the morning sky grids
through the rest of the morning as well.

Latest hi-res runs continue to keep south central Texas quiet this
afternoon and evening. Latest rap forecast soundings continue to
show weak capping holding this afternoon preventing surface parcels
from realizing a very unstable environment aloft. Previous forecast
of a very low confidence opportunity for isolated strong storms
continues to look good. Based off rap soundings, if anything does
develop, the window of opportunity would be 21-00z.



&&

Previous discussion... /issued 644 am CDT sun Mar 26 2017/

Aviation...
low clouds and visibility are spreading across the region and will
continue until late morning. Cigs will be MVFR/IFR at all area
airports through that time. VFR conditions should prevail through
the afternoon and evening. Low clouds and fog will develop again
overnight and through Monday morning.

Previous discussion... /issued 445 am CDT sun Mar 26 2017/

Short term (today through monday)...
a moist southerly lower level flow has returned bringing low stratus
and patchy fog to our area in response to falling surface pressures
across the plains ahead of an upper level trough moving to the east
over the central/southern rockies. The stratus and fog mixes out by
midday. Forecast soundings show a very unstable airmass with MLCAPES
around 2000 j/kg and strong shear around 50 kts. A strong cap may
persist inhibiting convective development, however, solar heating and
a left exit region of a compact upper level jet as the trough moves
across the plains could break it allowing for isolated storms that
would rapidly become strong to severe late this afternoon into
evening. Large hail and damaging winds are the main threats. The most
favored area is north of a Llano to Lago Vista to Lexington line
where moisture convergence will be the strongest. The cap reasserts
itself later this evening into overnight with loss of heating. The
trough moves further to the east on Monday toward the Mississippi
Valley causing a weak cold front to drift into The Hill Country and
central Texas by midday and stall across our area. Lack of upper
level dynamics and a strong cap should inhibit any convective
development. Above normal temperatures are expected in the short
term.

Long term (monday night through saturday)...
another upper level trough moves toward The Four Corners region
Monday night shifting the front back north of our area. Upward
forcing begins across the Rio Grande plains and Hill Country with
showers and thunderstorms developing there on Tuesday as the trough
moves across The Rockies. The showers and thunderstorms spread east
across the remainder of south central Texas Tuesday night into
Wednesday morning as the upper level trough moves out into the High
Plains. CAPES of 1000 to 2000 j/kg and 30 to 50 kts of shear are
forecast making strong to severe storms possible with large hail,
damaging winds, and isolated tornadoes all possible. Storm Prediction Center has
indicated a slight risk of severe storms for The Hill Country and
Edwards Plateau with a marginal risk for most of the remainder of
south central Texas. Precipitable waters around 1.5 inches are forecast along and
east of I-35 with locally heavy rainfall possible across that area. A
Pacific front/dryline and a dry mid level slot will end the rains
from west to east midday to afternoon on Wednesday. Then, a shortwave
rotates through the base of the trough while interacting with the
front/dryline over areas mainly along and east I-35 to produce
showers and thunderstorms later Wednesday night into Thursday morning
to midday. Fair weather is expected on Friday. Yet another upper level
trough is set to move across the Southern Plains and Texas next
weekend bringing additional rounds of showers and thunderstorms.
Above normal temperatures will continue in the long term.

Fire weather...

&&

Preliminary point temps/pops...
Austin Camp Mabry 87 67 86 67 84 / - 10 10 - 20
Austin Bergstrom Intl Airport 87 65 86 66 85 / - 10 10 - 20
New Braunfels Muni Airport 87 65 87 66 85 / - - 10 - 20
Burnet Muni Airport 86 62 84 63 80 / 10 10 - - 20
del Rio Intl Airport 92 60 90 67 88 / 0 - 0 - 20
Georgetown Muni Airport 85 65 85 65 83 / 10 10 - - 20
Hondo Muni Airport 90 63 89 66 86 / 0 - - - 20
San Marcos Muni Airport 87 65 87 66 85 / - 10 10 - 20
La Grange - Fayette regional 86 68 86 68 85 / 0 10 10 - 10
San Antonio Intl Airport 88 65 89 67 84 / - - - - 20
Stinson Muni Airport 89 65 89 67 85 / - - - - 10

&&

Ewx watches/warnings/advisories...
none.
&&

$$

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