Area forecast discussion
National Weather Service Austin/San Antonio Texas
632 am CDT sun may 19 2013
Aviation...
a moist southerly flow will maintain MVFR ceilings over the I-35
corridor terminals until late morning when drier air from aloft
will mix down and lift ceilings to VFR cloudiness. MVFR ceilings will
redevelop along the I-35 corridor terminals after midnight. I-35
corridor terminal winds south to southeast 10 to 15 kts until late
morning becoming south 15 to 25 kts. South to southeast winds will
lessen after dark to 10 to 15 kts. Kdrt terminal VFR clouds at or above 10
thousand agl, kdrt terminal winds southeast 10 to 15 kts.
&&
Previous discussion... /issued 423 am CDT sun may 19 2013/
Short term (today through monday)...
above normal heat will continue today through Monday. The leading
shortwave as part of a troughing pattern over the western half of the
US has trended deeper and ehnanced the middle-level dry slot over West
Texas. This trend does not appear to show much impact on the weather
over south central Texas. However...a weak shortwave passing over
the northern Mexico toward the Rio Grande would go unnoticed if
not for an isolated batch of storms that formed over the higher
terrain. The feature appears weak enough to leave unaccounted for
in the forecast at this time...but will monitor for a possible
update to a slight chance of rain for this morning over western
counties.
Model forecast temperatures in the dry layer to the west are
consistent with those of Saturday...so will continue with more
triple digits near the Rio Grande and near persistence highs in
the low-middle 90s for the I-35 corridor. With low level moisture
being reduced in part from the dry slot...probability of precipitation are left as silent
10s for this evening. Aloft...the tap to the Pacific tropics is
only temporarily broken...and some middle to high level moisture
should become established over the dry-line in time for isolated
convection to be possible again for Monday afternoon and evening.
Meanwhile...daytime temperatures should continue to moderate
slowly in the zonal pattern aloft.
Long term (monday night through saturday)...
Monday night convection is left as an evening event for now...but
the approach of the upper trough into northwest Texas could present some
added lift to extend the chance of rain into The Hill Country and
connect with the higher chance of rain for Tuesday into Tuesday
night. The dry slot could become a factor...given the shallow base
of the upper trough...so the probability of precipitation are mostly low chance to reflect
continued poor confidence. This forecast period shows the only
pattern that models show a good chance of organized convection and
a possible weak front to provide a focus. Better rain chances and
dynamics aloft favor better rain chances over East Texas and tapering
off to slight chance probability of precipitation over our western counties. With not a
great signal on diurnal timing of this system...we would only
suggest that these storms could approach severe levels and could
produce isolated heavy downpours of 1 to 2 inches. Run-to-run
model trends have not been favorable for a good rain event. The
extended forecast for Wednesday into next weekend is also
pessimistic in terms of rain chance. Models continue to trend
toward a building upper ridge over Texas with decreasing amounts of
moisture over Texas...and more above normal temperatures.
&&
Preliminary point temps/pops...
Austin Camp Mabry 93 73 93 74 93 / 10 10 10 10 20
Austin Bergstrom international Airport 92 72 91 72 91 / 10 10 10 10 20
New Braunfels Muni Airport 93 72 93 72 93 / 10 10 10 10 20
Burnet Muni Airport 91 71 91 70 90 / 10 10 10 10 20
del Rio International Airport 101 73 101 74 99 / 10 10 20 20 10
Georgetown Muni Airport 89 71 90 70 90 / 10 10 10 10 20
Hondo Muni Airport 97 72 97 72 96 / 10 10 10 10 20
San Marcos Muni Airport 91 72 90 73 91 / 10 10 10 10 20
La Grange - Fayette regional 91 73 91 76 92 / 10 10 - - 20
San Antonio International Airport 94 74 93 74 94 / 10 10 10 10 20
Stinson Muni Airport 95 73 94 74 93 / 10 10 10 10 20
&&
Ewx watches/warnings/advisories...
none.
&&
$$
Mesoscale/aviation...02
synoptic/grids...18
