U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 221944 
Storm Prediction Center ac 221943 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0243 PM CDT Wed may 22 2019 

Valid 222000z - 231200z 

..there is a moderate risk of severe thunderstorms from northeast 
OK into central MO... 

Severe thunderstorms are forecast this afternoon into evening from 
Oklahoma into Missouri and central Illinois. Tornadoes, 
large/damaging hail and severe gusts all are possible. 

..20z update... 

Note: severe probabilities are being increased along the I-44 
corridor across OK. 

Latest satellite imagery depicts a subtle but potentially 
significant mid-level short-wave trough ejecting across the Texas South 
Plains within an otherwise rising height field. It is becoming 
increasingly clear this feature will play an important role in the 
evolution of deep convection across OK over the next few hours. 

High-precipitable water air mass has surged northwest into OK with lower 70s surface 
dew points across much of the central/eastern parts of the state. 
Strong heating along the western fringe of this air mass appears to 
be instrumental in recent thunderstorm development over Tillman 
County OK. 1813z Arcadia (ne okc metro) sounding exhibited minimal 
inhibition and reflected the approaching short wave at mid levels. 
Based on recent radar/satellite trends, latest thinking is ongoing 
storms in southwest OK will continue to mature and lift northeast 
along the I-44 corridor. The potential for very large hail and 
tornadoes will be noted with this activity as it spreads downstream. 

.Darrow.. 05/22/2019 

Previous discussion... /issued 1126 am CDT Wed may 22 2019/ 

..OK to Illinois... 
Given latest model guidance and observational trends, have opted to 
upgrade to MDT risk along a narrow corridor from northeast OK into 
central MO. Consensus continues to grow in model guidance that 
several discrete supercells will develop along this corridor this 
afternoon and evening, as low-level moisture streams northward and 
shear profiles rapidly strengthen. The primary negative indicator 
of a more significant severe weather event involves the large scale 
pattern, and the large midlevel height rises that are occurring 
throughout the plains. However, latest water vapor loop and model 
guidance suggest very subtle shortwave troughs embedded in the upper 
flow, with one currently over southwest OK. This feature would 
arrive into the risk area around peak heating, potentially helping 
initiation. Forecast soundings suggest an environment favorable for 
strong tornadoes and very large hail and if discrete supercells can 

It is unclear how far southwest the development will occur into 
central OK. Several 12z cam solutions suggest 1-2 storms near okc 
that could be severe if they develop, with a conditional risk of 
significant tornadoes and hail. However, confidence in persistent 
thunderstorms that far southwest is lower than farther northeast. 

Storms that form over central MO will spread eastward into 
central/northern Illinois during the evening, with the continued risk of 
supercells capable of large hail, damaging winds, and a few 
tornadoes. It is unclear how rich the low-level moisture will be 
ahead of the storms, but shear profiles will be quite favorable in 
this area. 


Mesoscale Discussion

acus11 kwns 222006 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 222006 

Mesoscale discussion 0734 
National Weather Service Storm Prediction Center Norman OK 
0306 PM CDT Wed may 22 2019 

Areas affected...northeast Oklahoma...southeast Kansas...southwest 
Missouri...and northwest Arkansas 

Concerning...severe potential...watch likely 

Valid 222006z - 222200z 

Probability of watch issuance...95 percent 

Summary...supercells capable of large hail, damaging winds, and 
tornadoes -- a few of which may be strong -- are expected. A Tornado 
Watch is likely. 

Discussion...visible satellite shows boundary layer cumulus 
developing over portions of northeast Oklahoma, southeast Kansas, 
northwest Arkansas, and southwest Missouri, as low-level moisture 
advects northward across the region. Surface dew points in the low 
70s f are overspreading the region, ahead of a stalled cold front. 
Along the front, elevated convection has developed and is moving 
parallel to the boundary. With continued diabatic heating and 
low-level moisture advection, further destabilization can be 
expected, with MLCAPE values of 3000-4000 j/kg developing by late 

Given these thermodynamic conditions, convective initiation is 
expected within the next 1-2 hours. Convection along the front may 
eventually root into the boundary layer, and additional storms may 
develop in the warm sector, particularly in southern parts of the 
mesoscale discussion area. As storms develop, effective bulk shear of 50-55 kt will 
help organize the convection into supercell structures. With 
effective srh exceeding 200 m^2/s^2, tornadoes -- a few of which 
could be strong -- are possible, along with the threat for large 
hail and damaging winds. A Tornado Watch will likely be issued 
within the next hour. 

.Karstens/Hart.. 05/22/2019 

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


Latitude...Lon 35669518 35659603 36079676 37159695 38339563 38879401 
38249256 36809326 36129422 35669518