Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
FXUS64 KEWX 311147
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
647 AM CDT TUE MAY 31 2016
.AVIATION... /12Z TAFS/
Rapid refresh models continue to struggle with the unstable
airmass over TX, each run attempting to break out new convection
in the first few hours. Given this poor performance, will revert
back to conventional late spring afternoon/early evening timing
with prob30s reflecting a breaking cap, as the 12z DRT sounding
suggests this could take some time today. The rest of the TAFs
continue to show routine lowering/raising of low cigs from VFR to
IFR and back in the early morning hours and mostly light winds.
Once organized convection develops over part of the area later
today...a more distinct forecast will be possible.
.PREV DISCUSSION... /ISSUED 357 AM CDT TUE MAY 31 2016/
SHORT TERM (Today through Wednesday)...
Early this morning, an upper level low centered over southwestern
Arizona is drifting south, a shortwave west of the Big Bend is
moving to the east, and a moist southeasterly lower level flow is
off the Gulf of Mexico. Radars show showers and thunderstorms west
of the Pecos River to the Big Bend and into Mexico and developing
over Rio Grande Plains. Expect these will move across Rio Grande
Plains and Edwards Plateau as other showers and thunderstorms
develop over those same areas as most hi-res models are showing.
The upper level low is forecast to move into northern Sonora state
of Mexico today and across northern Chihuahua state of Mexico on
Wednesday. Expect showers and thunderstorms to develop over
southwestern Texas and the Serranias del Burro of Mexico early
this afternoon, organize into an MCS by evening, and then move
across South Central Texas tonight. PWS rise with pockets near 2
inches with locally heavy rains possible. On Wednesday, a cold
front approaches from the north. Expect showers and thunderstorms
to develop along it and again over the Burros into southwestern
Texas around midday, then organize and move into South Central
Texas during the afternoon into evening. Locally heavy rains are
possible on Wednesday. Some models have slightly different timing
and location resulting in slight uncertainty on rainfall amounts.
Shear and instability are sufficient for isolated strong to severe
storms today through Wednesday.
LONG TERM (Wednesday Night through Monday)...
The upper level low moves into Texas on Thursday and then drifts
or meanders over mainly Central Texas Friday into Saturday. The
GFS shows it slowly pulling away Sunday into Monday, while the
ECMWF keeps it over our area Sunday into Monday. While yesterday`s
model runs kept the front north of our area, the latest runs bring
it slowly through our area late Thursday into Friday. With these
latest developments, periods of showers and thunderstorms are
expected with the threat for heavy rains continuing to increase,
and possibly continue into late week or even this weekend should
the system slow as the ECMWF indicate. In addition, there is a
potential for the system to attain warm core characteristics which
along with elevated or surface boundaries could lead to copious
mainly nighttime rainfall amounts. For now, rainfall amounts of 3
to 6 inches are expected across most areas with some totals up to
10 inches possible.
Due to recent heavy rains making soils saturated in many places,
the potential for new or renewed flooding is high over the next
few days. Flash flood watches will likely be needed over the next
few days, possibly as early as tonight. In addition, some rivers
and streams may rise again out of banks or in flood.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 86 70 82 68 80 / 40 50 70 70 70
Austin Bergstrom Intl Airport 86 70 82 68 79 / 40 50 70 70 70
New Braunfels Muni Airport 86 70 82 68 80 / 40 50 70 70 70
Burnet Muni Airport 84 67 79 66 78 / 40 60 70 70 70
Del Rio Intl Airport 89 71 85 68 83 / 50 60 70 70 60
Georgetown Muni Airport 85 68 81 67 78 / 40 50 70 70 70
Hondo Muni Airport 86 70 83 67 81 / 50 60 70 70 70
San Marcos Muni Airport 85 70 81 67 79 / 40 50 70 70 70
La Grange - Fayette Regional 87 71 83 70 81 / 30 30 70 60 70
San Antonio Intl Airport 86 71 82 69 80 / 50 50 70 70 70
Stinson Muni Airport 87 72 83 70 81 / 50 50 70 70 70