187 
fxus64 kewx 282348 
afdewx 


Area forecast discussion 
National Weather Service Austin/San Antonio Texas 
648 PM CDT Thursday Aug 28 2008 


Aviation... 
little change for the next 24 hours as deep tropical moisture 
remains in place over S central Texas. Isolated-scattered evening rain showers/thunderstorms and rain 
will diminish around sunset and only isolated rain showers/thunderstorms and rain will continue 
overnight near the Rio Grande where deeper moisture exists. 
Generally VFR conditions this evening will become MVFR ceilings over 
much of the area after 08z with ceilings occasionally dipping to IFR 
between 09z and 13z. Patchy MVFR visibilities in br are also possible around 
sunrise. Friday will be similar to today with isolated-scattered afternoon 
convection firing across much of the area with daytime heating. 


&& 


Previous discussion... /issued 346 PM CDT Thursday Aug 28 2008/ 


Discussion... 
precipitable waters  have increased as forecast to over 2 inches across most of 
our area...and the result is scattered daytime heating-triggered 
showers and thunderstorms. Look for the current round of 
convection to spread north into the evening hours across the 
remainder of south central Texas...then decrease in coverage and 
intensity with the loss of heating. Rainfall amounts will 
generally be a quarter inch or less...although spotty totals up to 
two inches are possible with the stronger storms. Showers may 
persist all night over our western-most counties in closer 
proximity to lift associated with the upper low over northern 
Mexico. The 12z model solutions offered no significant changes to 
the ongoing forecast through the weekend...with the forecast 
beyond Sunday highly dependent on the track of what will then be 
Hurricane Gustav. The 12z European model (ecmwf) and Canadian models showed 
excellent run-to-run consistency bringing Gustav into central 
Louisiana late Monday or early Tuesday. The forecast track of 
Gustav from these two medium range models agrees with the current 
NHC track. This adds-up for increasing confidence on the forecast 
for what will likely be major Hurricane Gustav prior to landfall. 
However...some uncertainty remains and there is some potential for 
Gustav to make a bit of a westward turn prior to landfall with the 
forecast position/strength of the upper high to the north as the 
key to forecasting Gustav's movement. 


The 12z gfsmos offered reasonable and consistent guidance compared 
to previous runs and given the current airmass in place...so our 
numbers will be very close. 


&& 


Preliminary point temps/pops... 
Austin Camp Mabry 75 93 74 95 74 / 10 20 20 20 20 
Austin Bergstrom international Airport 72 93 70 95 71 / 10 20 20 20 20 
del Rio International Airport 74 88 72 87 71 / 60 60 60 50 50 
San Antonio International Airport 76 92 74 92 73 / 20 20 30 20 20 


&& 


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


$$ 


13/01