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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Friday
• 
• High: 68 °
• Low: 46 °
• Clear

• Saturday
• 
• High: 73 °
• Low: 55 °
• Chance of T-Storms

• Sunday
• 
• High: 75 °
• Low: 61 °
• Chance of T-Storms

• Monday
• 
• High: 84 °
• Low: 61 °
• Chance of T-Storms

• Tuesday
• 
• High: 88 °
• Low: 63 °
• Partly Cloudy

Area forecast discussion...updated 
National Weather Service St Louis MO 
1253 PM CDT Friday may 24 2013 


Update... 
issued at 1252 PM CDT Friday may 24 2013 


Going forecast still looking good for this afternoon. 


Truett 


&& 


Short term...(through late this afternoon) 
issued at 315 am CDT Friday may 24 2013 


The elongated surface high currently stretching through the Upper- 
Middle MS valley will continue to dominate the sensible weather as 
it slowly moves eastward. This system will continue to bring below 
average temperatures...but unlike yesterday...today there will be 
abundant sunshine resulting in warmer temperatures. 


Glass 


Long term...(tonight through wednesday) 
issued at 315 am CDT Friday may 24 2013 


The upper air pattern will undergo progression and deamplification 
over the weekend into Monday resulting in an extended period of 
unsettled weather for parts of the County Warning Area. The plains upper ridge 
will progress eastward into the MS valley today and then flatten 
beginning tonight as a series of weak short waves top the ridge and 
spill northeastward within the weak west-northwest flow aloft on the downstream side. 
The biggest problem is the models show a fair amount of spread in 
the timing/position of these waves tonight through Monday. The low 
level warm air advection regime will get underway tonight in the wake of the 
retreating surface high/low level anticyclone...however moisture 
return looks to be delayed a bit until Saturday. With this in 
mind...I have to believe the European model (ecmwf) is a bit aggressive with quantitative precipitation forecast 
early on. However by midday Saturday...an intensifying warm air advection regime 
and southwesterly low level jet should accelerate the moisture transport and ascent 
across the area interacting with the migratory short waves... 
resulting in multiple waves of showers and thunderstorms from 
Saturday into Monday. The highest threat area looks like the 
northern third to half of the County Warning Area. Finally on Tuesday the warm 
front lifts north of the area as the upper ridge builds from the 
lower MS valley into the eastern U.S. Bringing much warmer 
temperatures and lesser precipitation chances until late next 
week. 


Glass 


&& 


Aviation...(for the 18z tafs through 18z Saturday afternoon) 
issued at 1252 PM CDT Friday may 24 2013 


Surface ridge axis extending from east WI to southeast MO will continue to 
slide east this afternoon and tonight. This will mean that VFR 
conditions will prevail through 06z...with clouds limited to a bit 
of cirrus and east-southeast surface winds primarily at or below 10 kts. Attention 
then turns to threat of nocturnal convection. There seems to be 
some consensus in the latest short range that Theta-E advection on 
nose of low level jet will be well to our north...causing the 
development and centroid of the mesoscale convective system to track across Iowa and then 
either advect or attempt to develop a bit south into north sections of 
the County Warning Area during the predawn hours. Based on this trend have 
introduced thunderstorms in the vicinity in uin by 12z..but elsewhere have held off 
mentioning thunder at this time as solutions are literally all over the 
place with convective trends during the day on Saturday. Details 
for Saturday should become a bit more clear once tonights 
convective trends become established. 


Specifics for kstl...VFR conditions will prevail through 15z 
Saturday...with NE winds at or below 8 kts this afternoon becoming 
easterly tonight and southeast on Saturday. Should see an increase in middle 
and high level clouds late tonight and Saturday morning as cloud 
debris streams downstream from Iowa/north MO convection...but these 
should be at or above 10kft. 


Truett 


&& 


Lsx watches/warnings/advisories... 
MO...none. 
Illinois...none. 
&& 


$$ 


Weather forecast office lsx