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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Sunday
• 
• High: 90 °
• Low: 72 °
• Chance of T-Storms

• Monday
• 
• High: 86 °
• Low: 72 °
• T-Storms

• Tuesday
• 
• High: 84 °
• Low: 66 °
• T-Storms

• Wednesday
• 
• High: 86 °
• Low: 63 °
• Chance of T-Storms

• Thursday
• 
• High: 82 °
• Low: 61 °
• Clear

Area forecast discussion...updated 
National Weather Service St Louis MO 
1252 PM CDT sun may 19 2013 


Update... 
issued at 1251 PM CDT sun may 19 2013 


Morning activity that moved through Central/Northeast MO...west 
central Illinois has exited. Otherwise...warm front to continue slowly 
lifting north through forecast area this afternoon. Could still see some 
isolated storms early this afternoon over west central...southwestern 
Illinois...but dry elsewhere. High temperatures will depend on cloud cover and 
warm front...for now have highs in the upper 80s to low 90s. 


Byrd 
&& 


Short term...(through wednesday) 
issued at 253 am CDT sun may 19 2013 


Active weather pattern expected through Wednesday in response to 
a series of shortwaves moving across the region as an upper low/trough 
moves from the Central Plains to the upper Mississippi River valley. 
Several rounds of severe thunderstorms appear likely to occur...with 
the potential of large hail...damaging winds and tornadoes. 


Warm front is currently located to our southwest and linear 
convection from the plains continues to decay as it moves into 
western Missouri. Plenty of low level stratus and debris clouds from 
western convection cover the County Warning Area early this morning. 


Potential for a warm day with 850mb temperatures rising above 
+20c...but residual cloud cover and lifting warm front has ME 
cautious about going too warm. Have generally forecast highs in the 
middle to upper 80s...which is in line with latest MOS guidance. 
Short term model guidance continues to show isolated to scattered 
convection developing along and north of the advancing warm 
front...and likely some residual boundary pushing east from the 
decaying convection. 0-6km bulk shear and cape of 2000-3000 k/jg 
would support multicell development and the potential of some 
marginal severe hail reports if initiation occurs. Think this will 
mainly be along and east of the Mississippi River. 


Attention will once again turn to our west late this evening as 
severe convection is expected to develop across eastern Kansas and 
western Missouri...eventually developing into a line and moving east 
toward the western County Warning Area by late evening. Main threat with this 
convection would be damaging wind gusts. Line of convection will 
weaken as it moves further east toward the Mississippi River by 
early morning with loss of instability. 


Atmosphere should easily reset for Monday...with the potential for a 
major severe weather outbreak to occur across at least the western 
half of the County Warning Area during the afternoon and evening hours. 
Instabily/shear combination is supportive of supercells with large 
hail...damaging wind and tornadoes. 


Still some uncertainty regarding convective trends for Tuesday and 
Wednesday...but could see two more active days given position of the 
longwave trough to our northwest and approaching cold front. Once 
again...shear/instability combination supports supercells. 


Cold front should finally move through the County Warning Area by Wednesday 
night...ending the severe weather threat. 


Cvking 


Long term...(thursday through saturday) 
issued at 253 am CDT sun may 19 2013 


A reinforcing cold front will provide enough lift for at least a 
chance of showers and thunderstorms on Thursday. High pressure 
ridge in its wake should bring at least a couple dry days to the 
County Warning Area Friday and Saturday before return flow brings increased 
chances of thunderstorms back into the forecast for the latter 
half of the Memorial Day weekend. Temperatures will remain 
seasonal with highs in the 70s and lows in the 50s. 


Cvking 
&& 


Aviation...(for the 18z tafs through 18z Monday afternoon) 
issued at 1251 PM CDT sun may 19 2013 


With storms out of forecast area...have dry tafs for now with 
gusty southeast to south winds...before diminishing early this 
evening. Next round of activity to fire up over eastern Kansas/western 
MO and slide east overnight. Storms to reach kcou by 04z and KUIN 
by 05z...could see MVFR...high end IFR visibilities/ceilings with some of the 
storms. As for metropolitan area tafs...still not sure if storm complex will 
hold together...so for now kept vicinity ts after 09z. Storms to 
taper off from west to east by 12z Monday. 


Specifics for kstl...with storms out of forecast area...have dry tafs 
for now with gusty southeast to south winds...before diminishing 
by 03z Monday. Next round of activity to fire up over eastern 
Kansas/western MO and slide east overnight. Still not sure if storm 
complex will hold together and make it into metropolitan area...so for 
now kept vicinity ts after 09z. Storms to taper off by 12z 
Monday...with next round firing up by 21z Monday...so added thunderstorms in the vicinity 
mention during this period. South winds to persist through the 
rest of forecast period. 


Byrd 
&& 


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


$$ 
Weather forecast office lsx