U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 191256 
Storm Prediction Center ac 191255 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0755 am CDT sun Aug 19 2018 

Valid 191300z - 201200z 

..there is a slight risk of severe thunderstorms Ozarks vicinity... 

a conditional threat for a few tornadoes and damaging winds may be 
realized across the Ozarks region during the late afternoon and 

..MO/southeast Kansas to The Ark-la-tex... 
Complex, low confidence forecast with a wide range of plausible 
forecast scenarios ranging from negligible severe to multiple 
tornadic supercells in the late afternoon and evening. The most 
prudent risk categorization appears to be a conditional slight and 
expansion of the marginal with refinements likely in shorter-term 

A broad convective swath is ongoing across central/southeast Kansas and 
the body of OK. An mesoscale convective vortex is apparent over central OK in the stratiform 
rain region and it is this feature that will likely track northeast 
towards Kansas City as its absorbed into the broader shortwave 
trough over the central Great Plains. Most cams do adequately 
resolve this ongoing activity and suggest that the leading 
convective cluster will weaken through midday. 

While extensive cloud debris and ongoing overturning will 
undoubtedly slow daytime destabilization, at least modest surface 
heating should occur in the wake of this morning's convection and 
may yield a moderately unstable air mass across eastern OK into far 
southeast Kansas. Models are consistent in suggesting amplification of 
the shortwave trough and associated cyclogenesis, but have 
pronounced variation in the degree and timing at which this occurs. 
The NAM appears to be most bullish in low-level mass response and 
has impressively large hodographs with 0-3 srh of 300-600 m2/s2 by 
00z. Other models suggest a more muted/delayed response. Even so, 
the hrrr for example has consistently simulated several supercells 
across southeast Kansas/northeast OK into southwest MO and northwest Arkansas. 
South of this corridor, increasingly weaker tropospheric flow and 
correspondingly smaller hodographs should tend to favor more 
multicell clustering with damaging winds the predominant hazard. 

Have expanded marginal risk for tonight as enlarged low-level 
hodographs and a low probability tornado/damaging wind threat may 
persist into northern MO east of the surface cyclone in the Kansas 
City/northwest MO vicinity. 

.Grams/Broyles.. 08/19/2018 


Mesoscale Discussion

acus11 kwns 182334 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 182334 

Mesoscale discussion 1321 
National Weather Service Storm Prediction Center Norman OK 
0634 PM CDT Sat Aug 18 2018 

Areas affected...the southern High Plains 

Concerning...severe potential...watch possible 

Valid 182334z - 190130z 

Probability of watch issuance...60 percent 

Summary...storms are expected to continue developing southeastward 
toward the OK/Texas Panhandle region, with an overall increase in 
coverage through evening. A few storms may produce severe wind or 

Discussion...scattered storms currently exist from western Kansas into 
northeast nm, ahead of a weak cold front and shortwave trough aloft. 
The area is characterized by a moderately unstable air mass with 
modest lapse rates aloft, and weakly veering winds with height. 
Storm Mode has been mixed through early evening, but a more linear 
structure has formed over northeast nm, which will be entering into 
the western panhandles shortly. Other slow-moving cells persist over 
western KS, with isolated severe hail cores noted on radar. 

As the shortwave trough continues to shift southeast, lift will be 
maintained over the region. Visible satellite imagery shows a 
substantial cumulus field over the Texas/OK panhandles, indicative of little 
if any inhibition and likely supportive of continued storm 
formation/sustenance. As such, a watch will be considered. 

.Jewell/Thompson.. 08/18/2018 

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


Latitude...Lon 35850475 36790370 37670274 38360237 38660204 38490155 
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