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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Thursday
• 
• High: 90 °
• Low: 70 °
• Chance of a Thunderstorm

• Friday
• 
• High: 91 °
• Low: 73 °
• Chance of a Thunderstorm

• Saturday
• 
• High: 93 °
• Low: 72 °
• Chance of a Thunderstorm

• Sunday
• 
• High: 93 °
• Low: 73 °
• Partly Cloudy

• Monday
• 
• High: 93 °
• Low: 77 °
• Partly Cloudy

Area forecast discussion 
National Weather Service St Louis MO 
318 am CDT Thursday Jun 20 2013 


Short term...(through late this afternoon) 
issued at 317 am CDT Thursday Jun 20 2013 


Early this morning...a ridge-runner shortwave is located just west of 
the MS river and has been kicking up clouds as a result. Weaker 
upper level disturbances exist further upstream in northern Kansas and 
Nebraska closer to the current location of the upper level ridge 
axis. At the surface...hi pressure centered over the eastern Great Lakes region 
continues to have a wide influence and resulting in a light southeast flow. 
Mostly clear skies Grace much of the forecast area with temperatures in the 60s. 


Upper level ridge over the plains will strengthen and amplify today 
and therefore make it much more difficult for any additional upper 
level disturbances to successfully cross through. One such is located 
over in eastern Colorado at this time and is looking increasingly likely it will be 
stuck on the plains as a result...which would discount the 00z NAM 
forecast which has this feature making a run on eastern MO late this afternoon. 
Closer to home...the shortwave over eastern MO is expected to very 
slowly ooze eastward today...and should still be over southwestern Illinois this 
afternoon. The environment will be again geared towards Ordinary 
cells with weak shear...no cinh...and modest cape generally less 
than 1000 j/kg. The only focus to really key in on is the 
ridge-runner shortwave which will provide some source of lift and 
might be enough Sans a decent surface boundary to kick off isolated 
shra/tsra. Will need to monitor for potential of /sunrise surprise/ 
through middle morning but looking doubtful. At this time...and until a 
better source of lift presents itself...can only justify no more 
than slight chances in this setup and centered on the afternoon hours. 


H850 temperatures expected to be about 1-2c higher than persistence with 
similar sunshine and more southerly oriented winds...and should translate 
to about a 2-4f increase from maximum temperatures on Wednesday...or maximum temperatures 
in the 85-90f range. 


Tes 


Long term...(thursday through next wednesday) 
issued at 340 PM CDT Wednesday Jun 19 2013 


(thursday through saturday) 


Forecast area to remain in warm sector on Thursday. As for precipitation 
chances will depend on how far east the remnants of an mesoscale convective system over Kansas 
makes it as it drifts east towards central MO by midday Thursday. 
For now have chance probability of precipitation over Central/Northeast MO...with slight 
chances further east. Otherwise...warming trend to continue with 
highs in the middle 80s to around 90. 


Thursday night...low level jet and frontal boundary focus activity 
just to our north over Iowa...not sure how far south southern edge 
may be...so kept slight chance/chance probability of precipitation in our far northern 
counties after 06z Friday. Mild conditions to persist with lows only 
dipping into the upper 60s. 


Models continue to show corfidi vectors pointing to a 
southeasterly/southerly trajectory for any complex that develops to 
our north...so could see dying mesoscale convective system move into forecast area on 
Friday. For now have best chances over far northern portions of 
County Warning Area...with silent slight chance probability of precipitation further south. Highs will be in 
the upper 80s to low 90s. 


Could see a repeat of this Friday night and Saturday...but with 
remnants a bit further east on Saturday...so have silent slight 
chance probability of precipitation during the day on Saturday. Lows Friday night will be in 
the low 70s and highs on Saturday in the low 90s. 


(Saturday night through wednesday) 


Upper level ridge builds in a bit more for the last half of the 
weekend with activity shifting a bit further north. But hot and 
humid conditions to persist with highs on Sunday in the low 90s. 


Then upper level ridge to flatten a bit for the beginning of the 
work week...then next weather system approaches area by Wednesday. 
But confidence is low on how far south and east activity will make 
it so kept silent slight chance probability of precipitation for rest of forecast period for 
portions of the forecast period. Otherwise...highs will remain in 
the upper 80s to low 90s and lows in the low 70s. 


Byrd 


&& 


Aviation...(for the 06z tafs through 06z Thursday night) 
issued at 1136 PM CDT Wednesday Jun 19 2013 


No major changes in earlier thinking...with western periphery of 
surface ridge continuing VFR conditions across our area for the rest 
of tonight and into at least Thursday morning. 00z NAM is focusing 
on convective cluster firing across Kansas overnight which generates 
an mesoscale convective vortex that in turn works into our area and ignites additional 
convection during the late morning and afternoon. This is a 
fairly major change from earlier solutions...and is also a much 
more robust solution than the 00z GFS which hints at a threat of 
convection that will be much more hit and miss. Because of this 
considerable uncertainty will stick with diurnally driven cumulus field 
for now...and let middle shift monitor convective trends overnight to 
ascertain whether the addition of thunderstorms and rain is warranted in later 
forecasts. 


Specifics for kstl... 


Generally clear skies expected overnight...giving way to fair 
weather cumulus at or above 3kft by late Thursday morning and into the 
afternoon. As mentioned above...will need to keep an eye on 
convection potential Thursday afternoon but at this time it appears 
any coverage will be very spotty...so threat in vicinity of terminal 
will be very low. Light east winds tonight will veer to the south 
by late Thursday morning...with speeds increasing to around 8 kts or 
so. 


Truett 


&& 


Preliminary point temps/pops... 
Saint Louis 90 70 93 71 / 20 10 20 10 
Quincy 88 68 89 70 / 20 20 20 10 
Columbia 89 69 91 70 / 20 10 20 10 
Jefferson City 90 69 91 70 / 20 10 30 10 
Salem 87 67 89 70 / 20 10 10 10 
Farmington 88 66 89 68 / 20 20 10 10 


&& 


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


$$ 


Weather forecast office lsx