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fxus64 ksjt 212315 
afdsjt 


Area forecast discussion 
National Weather Service San Angelo Texas 
615 PM CDT Thursday Aug 21 2008 


Update... 


Made a quick update to the going forecast to increase probability of precipitation to 30 
percent across the south...and to expand the 20 percent probability of precipitation north. 


&& 


Discussion... 


Scattered thunderstorms have been ongoing mainly south of Highway 
87 this afternoon. Storms have merged over extreme southwest Irion 
and northern Crockett counties and are likely producing very heavy 
rain along with some hail. The activity is drifting to the south 
and southwest. Other isolated storms developed to the northwest of 
San Angelo. This activity should begin to dissipate as the sun 
sets this evening. I removed probability of precipitation from the forecast after 06z.&& 


Previous discussion... /issued 609 PM CDT Thursday Aug 21 2008/ 


Discussion... 
see below 


Aviation... 
expect VFR conditions to prevail across west central terminals 
through the next 24 hours. Isolated showers and thunderstorms 
will continue through early evening but will dissipate quickly 
after sunset over the southern half of the area...have included 
thunderstorms in the vicinity for ksoa for the next several hours. Otherwise...light south 
and southeast winds should continue...at mainly less than 10 
knots. There will be a chance of afternoon thunderstorms over the 
southeast terminals on Friday...have included a mention at the 
kjct and kbbd sites. 


Previous discussion... /issued 237 PM CDT Thursday Aug 21 2008/ 


Short term... 
WV imagery indicating upper level low lifted rapidly to the north 
from northeast Texas to the upper Mississippi Valley during the 
past 24 hours. A weak upper level trough axis remains across west 
central Texas...with some increase of middle and upper level 
moisture. Widely scattered thunderstorms have developed between Waco and 
Junction due to some moisture convergence and sbcapes of 3000 to 
3500 j/kg. Will go with slight chance probability of precipitation across the Northwest Hill 
country and northern Edwards Plateau tonight. Going with a dry 
forecast Friday and Friday night...with highs Friday in the middle 
90s. 


Long term... 
the models are indicating an upper shear axis developing from 
northern Mexico across central Texas this weekend into early next 
week. The GFS has much more quantitative precipitation forecast with this system than the NAM. The 
European model (ecmwf) is in the middle of the Road with the quantitative precipitation forecast. Looks like the 
GFS is having some convective feedback problems. However...will go 
with chance probability of precipitation across mainly the I-10 corridor and Heartland Saturday 
and Sunday...with slight chance probability of precipitation elsewhere. Going with slight chance 
probability of precipitation Monday across much of the County warning forecast area. A week upper level west- 
northwest flow pattern for Tuesday through Friday...resulting in 
a dry forecast. Highs will be mainly in the middle 90s for Tuesday 
through Friday. 


&& 


Preliminary point temps/pops... 
Abilene 69 95 72 91 70 / 10 10 10 10 20 
San Angelo 70 95 71 91 68 / 20 10 10 20 20 
Junction 69 91 71 88 69 / 30 20 10 30 30 


&& 


Sjt watches/warnings/advisories... 
none. 
&& 


$$ 


Lacy