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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Monday
• 
• High: 77 °
• Low: 48 °
• Partly Cloudy

• Tuesday
• 
• High: 77 °
• Low: 52 °
• Clear

• Wednesday
• 
• High: 82 °
• Low: 63 °
• Clear

• Thursday
• 
• High: 88 °
• Low: 72 °
• Partly Cloudy

• Friday
• 
• High: 91 °
• Low: 72 °
• Partly Cloudy

Area forecast discussion...updated aviation 
National Weather Service St Louis MO 
1142 am CDT Monday may 21 2012 


Short term... 
issued at 319 am CDT Monday may 21 2012 
(today and tuesday) 


Cold front continues to drift through southeast Missouri and 
southern Illinois. The wind has shifted to the northwest through 
most of the area but the true moisture/temperature gradient is just 
getting into the stl metropolitan area and parts of southwest Illinois at 
this time. Should see cold/dry advection continue to push southeast 
with dewpoints dropping into the 50s along an Ellington-Salem Illinois 
line by 12z-13z. High pressure will build into the area behind the 
front today and dominate our weather through Tuesday. Temperatures 
will be near seasonal averages with highs in the low to middle 70s 
today and middle to upper 70s Tuesday. Expect below average lows in 
the upper 40s to middle 50s. 


Carney 


&& 


Long term... 
issued at 319 am CDT Monday may 21 2012 
(wednesday through sunday) 


Enjoy the mild Spring weather while it lasts...southwest flow 
develops Wednesday and temperatures will climb back into the 80s. 
Medium range models have been pretty consistent in building a 
July-like 5900+ meter 500mb ridge over the middle-Mississippi Valley 
starting Thursday and peaking over the weekend. GFS tries to drop 
a front into northeast Missouri and west central Illinois on 
Friday...but given the strength of the upper ridge I think the 
European model (ecmwf) solution is more likely. GFS and European model (ecmwf) are showing 850mb 
temperatures of 20-22c which mix down to 90-95f at the surface. Think MOS 
guidance is being overly influenced by climatology so have bumped temperatures 
up 3-5 degrees over mex numbers through Sunday. 


Carney 


&& 


Aviation... 
issued at 1103 am CDT Monday may 21 2012 


Ridge of high pressure extending from eastern Minnesota northwestern WI SW through 
eastern Kansas will move southeastward through MO and Illinois this forecast period. Low 
level moisture and cloudiness over portions of northern and central Illinois 
will spread S-southwestward into the stl metropolitan area this afternoon with scattered 
cumulus clouds around 4000 feet rising to 5000 feet late this afternoon. 
Cloud coverage could briefly go broken in stl and cps this afternoon 
although the better coverage should remain east of stl. Most of the 
cumulus field should dissipate early this evening with loss of 
daytime heating. Northerly surface winds will continue this afternoon gusty at 
times...then weaken this evening and becoming light late tgt with the 
surface ridge axis right over uin and cou around 12z Tuesday. The surface wind 
will become southeasterly in uin and cou late Tuesday morning as the surface ridge 
axis moves east of this area although still relatively light. 


Specifics for kstl...cumulus field will develop in stl due to 
diurnal heating and as low level moisture and cloudiness advects 
S-southwestward into stl this afternoon from central Illinois. The coverage should be 
mainly scattered although could briefly go broken this afternoon. Cloud 
heights will be around 3500-4000 feet early this afternoon rising to around 
5000 feet late this afternoon. These clouds should dissipate this evening 
with loss of daytime heating. North-northwesterly surface winds will continue this 
afternoon possibly a little gusty at times...then weaken this evening and 
become light by late tgt. Northerly surface wind on Tuesday only increasing to 
7-8 kts with surface ridge axis moving over stl Tuesday afternoon. 


Gks 


&& 


Preliminary point temps/pops... 
St Louis 74 54 79 58 / 0 0 0 0 
Quincy 72 49 78 55 / 0 0 0 0 
Columbia 73 49 79 57 / 0 0 0 0 
Jefferson City 74 49 79 57 / 0 0 0 0 
Salem 72 50 76 53 / 5 0 0 0 
Farmington 73 47 78 52 / 5 0 0 0 


&& 


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


$$ 


Weather forecast office lsx