U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 260542 
Storm Prediction Center ac 260540 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1240 am CDT Mon Aug 26 2019 

Valid 261200z - 271200z 

..there is an enhanced risk of severe thunderstorms from central 
Missouri southwestward into northeast Oklahoma... 

Severe thunderstorms are expected this afternoon through the evening 
from the middle Mississippi Valley region into eastern Kansas and 
Oklahoma. Large hail, severe gusts, and a few tornadoes are 
possible before the threat transitions to mainly a risk for severe 
gusts and wind damage tonight. 

..lower MO valley into OK... 
A mid-level trough over the upper Midwest today will evolve into a 
closed low near the Minnesota/Canada border by early Tuesday. A belt of 
strong westerly 500mb flow will overspread the lower MO valley 
during the day. A complicating factor for this forecast will 
involve an mesoscale convective system over the north-Central Plains which is forecast to 
move into the lower MO valley during the morning hours. Model 
guidance generally depicts this scenario with some severe risk 
perhaps ongoing early this morning before possibly waning with the 
mesoscale convective system dissipating over the lower MO valley. Renewed storm development 
is likely by late afternoon along a cold front forecast to move 
southeast across the central Great Plains and lower MO valley. The 
intersection of possible earlier-day outflow with the front may 
serve as a preferred storm initiation zone before additional storms 
develop along the southwest-northeast oriented boundary. The 
pre-convective airmass is forecast to become very unstable from 
central OK northeast into eastern Kansas and MO with MLCAPE ranging from 
3000-4000 j/kg. An initial window of opportunity (2 hours) may 
exist for a supercell risk capable of all hazards. Precipitable 
water around 2 inches and large cape, a wind profile strengthening 
from the low into the midlevels (40-50kt) and weakening in the high 
levels, and strong agreement of convection-allowing model guidance 
all suggest a relatively quick transition to a linear band of storms 
from northern MO zippering southwest into central OK during the 
evening. Wind damage from severe gusts will likely become most 
prevalent during the cellular to squall line transition (possible hp 
supercells) and the initial 1-3 hours afterwards during the evening. 
A gradual diminishing in storm intensity and potential severe 
coverage is expected by late evening into the overnight as storms 
move to the MS river and The Ark-la-tex. 

.Smith/Wendt.. 08/26/2019 


Mesoscale Discussion

acus11 kwns 260707 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 260706 

Mesoscale discussion 1862 
National Weather Service Storm Prediction Center Norman OK 
0206 am CDT Mon Aug 26 2019 

Areas affected...portions of eastern MO into west-central Illinois 

Concerning...severe potential...watch unlikely 

Valid 260706z - 260900z 

Probability of watch issuance...5 percent 

Summary...a brief/weak tornado will remain possible in the near 
term. Watch issuance is not expected at this time as the overall 
threat appears very isolated. 

Discussion...a small line of storms has recently strengthened across 
east-central MO in association with a remnant mesoscale convective vortex from prior 
convection located over far west-central Illinois at 07z. The vwp from 
klsx does show a gradually veering wind profile in the 0-3 km above ground level 
layer. Two weak circulations have been observed so far embedded 
within the line. The presence of around 125-200 m2/s2 of effective 
bulk shear suggests that transient circulations capable of producing 
a brief/weak tornado may continue for the next couple of hours. 
However, both modest instability and weak effective bulk shear will 
likely tend to limit a more organized severe threat across this 
region through the early morning hours. Therefore, watch issuance is 
not anticipated at this time. 

.Gleason/Edwards.. 08/26/2019 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 38369214 38909139 39429094 39739071 39789040 39639014 
39279011 39029017 38559041 38309109 38319166 38369214