908 
fxus64 kewx 201745 
afdewx 


Area forecast discussion 
National Weather Service Austin/San Antonio Texas 
1245 PM CDT Wednesday Aug 20 2008 


Aviation... 
the sky will remain chaotic through 02z with ceilings varying from 
MVFR to VFR. Clusters of showers and thunderstorms will develop and 
move east across the area. After 02z shower activity will become 
isolated and skies mostly VFR. By 09z IFR-MVFR ceilings will develop 
along the Escarpment and spread across all of south central Texas. 
All IFR ceilings will lift to MVFR levels by 15z and begin to 
scattered out around 17z. The weak surface gradient and the storm 
system center lifting north out of Texas will result in light 
winds varying from northwest to southwest to south. 


&& 


Previous discussion... /issued 1050 am CDT Wednesday Aug 20 2008/ 


Update... 
late this morning the middle/upper level low pressure system was centered 
over northeast Texas...with the latest spoke of instability moving 
into East Texas and western Louisiana. Drt/crp 12z soundings still 
indicated precipitable waters  in excess of 2 inches with convective trigger temperatures 
in the upper 80s. Thus still expect showers and thunderstorms to 
develop in the heat of the afternoon with the threat of locally heavy 
rainfall mainly along and east of the I-35 corridor. 


Previous discussion... /issued 639 am CDT Wednesday Aug 20 2008/ 


Aviation... 
areas of IFR/MVFR ceilings and patchy MVFR visibilities will lift to VFR by 
late morning, then become scattered during the afternoon. MVFR/IFR ceilings 
will redevelop late tonight. Isolated rain showers/thunderstorms and rain this morning will 
increase to scattered rain showers/thunderstorms and rain this afternoon, then decrease to isolated 
tonight. Small hail is possible in thunderstorms and rain. Winds will be variable at 
10 kts or less, except wind gusts to 30 kts are possible in and 
near thunderstorms and rain. 


Previous discussion... /issued 338 am CDT Wednesday Aug 20 2008/ 


Discussion... 
the upper level low centered across the Red River valley will 
enable good chances for rain across much of south central Texas 
today. The very juicy airmass (with precipitable waters  ranging from 1.5-2") which 
has remained across the region over the past few days will persist 
a little longer. This coupled with the already wet grounds from 
previous rainfall will continue the threat for heavy rains...which 
may lead to localized flash flooding...through tonight. Afternoon 
temperatures today will once again be in the middle to upper 80s 
across most of the region. 


Rain chances will decrease from west to east over the next 24 hours 
as the upper low ejects to the northeast. Despite drier conditions 
expected for the next several days...lingering moisture will provide 
enough instability to spark some daytime convection across the 
coastal plains through the weekend. 


Temperatures through the end of the week and into the weekend will 
generally be at or a few degrees below middle to late August normals 
due to lingering cloud cover as well as better evaporation from 
damp grounds. Some early morning patchy fog is expected along and 
southeast of the I-35 corridor through the next few mornings. 
Gfs(x) numbers have been fairly consistent from run-to-run and are 
in good agreement with other models. Thus...stayed close to gfs(x) 
numbers through much of the forecast period. 


&& 


Preliminary point temps/pops... 
Austin Camp Mabry 88 72 92 74 94 / 50 20 20 10 20 
Austin Bergstrom international Airport 88 70 93 72 94 / 50 20 20 10 20 
del Rio International Airport 93 74 96 76 96 / 10 - 10 10 10 
San Antonio International Airport 89 73 92 75 92 / 40 10 20 10 20 


&& 


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


$$ 


13/06