U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 150038 
Storm Prediction Center ac 150036 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0736 PM CDT Tue Aug 14 2018 

Valid 150100z - 151200z 

..there is a marginal risk of severe thunderstorms across parts of 
central Oklahoma...northern Colorado...eastern Wyoming and 
south-central Arizona... 

Marginally severe thunderstorms will be possible for a few more 
hours across central Oklahoma, northern Colorado, eastern Wyoming 
and south-central Arizona. 

..central Oklahoma... 
Latest radar imagery shows a cluster of strong to severe 
thunderstorms in and around the Oklahoma City Metro. This cluster of 
storms is located near a maximum of instability with the rap 
analyzing a pocket of moderate instability in central Oklahoma with 
MLCAPE values in the 2500 to 3000 j/kg range. In addition, Oklahoma 
City WSR-88D vwp shows 0-6km shear of 35 kt with gradually veering 
winds with height in the lowest 3 km above ground level. This 
environment should support an isolated severe threat for a couple 
more hours this evening. Although isolated supercells will be 
possible, the more viable threat will be from multicells that 
organize into short line segments. The cells could produce 
marginally severe wind gusts and hail but the threat is expected to 
diminish during the mid evening as instability drops across the 
region. The severe threat area appears too small and the temporal 
nature will be too brief to add a slight risk area at this time. 

..central and northern High Plains... 
The latest radar imagery shows a couple of strong thunderstorms 
across eastern Wyoming early this evening. These storms are located 
along a corridor of instability extending from western Nebraska into 
eastern and northern Wyoming where the rap is estimating MLCAPE 
values in the 1000 to 1200 j/kg range. In addition, regional WSR-88D 
vwps show 0-6 km shear around 40 kt. This combined with steep 
mid-level lapse rates will be sufficient for storm rotation and 
isolated large hail within the stronger isolated cores. A wind 
damage threat will also be possible over the next hour but the 
threat should become more isolated as instability weakens with time. 
Further south, a cluster of strong thunderstorms is located along 
the Front Range. This area is located in a weaker regime of 
instability but there still could be enough deep-layer shear for a 
marginal severe threat for another hour or two. 

..south-central Arizona... 
The latest radar imagery shows a broken line of strong thunderstorms 
located from just north of the Phoenix Metro extending southeastward 
to near the New Mexico state line. These storms are on the northern 
edge of a pocket of moderate instability with the rap showing MLCAPE 
values in the 2000 to 2500 j/kg range. As the storms move 
south-southwestward into the stronger instability, a marginal wind 
damage threat will be possible with the multicells that temporarily 
increase in intensity. 

.Broyles.. 08/15/2018 


Mesoscale Discussion

acus11 kwns 150101 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 150100 

Mesoscale discussion 1290 
National Weather Service Storm Prediction Center Norman OK 
0800 PM CDT Tue Aug 14 2018 

Areas affected...parts of southern/central Arizona 

Concerning...severe potential...watch unlikely 

Valid 150100z - 150230z 

Probability of watch issuance...5 percent 

Summary...isolated damaging gusts could occur through late evening. 
However, the threat should remain too marginal for watch issuance. 

Discussion...stronger thunderstorms have developed off both the 
Mogollon Rim and higher terrain of Southeast Arizona this evening. 
Ahead of this convection, the 00z tus sounding sampled weak 
mid-level buoyancy atop steep low-level lapse rates, yielding around 
1500 j/kg of dcape. As these cells and their related outflow advance 
west/southwest into lower elevations, deep/well-mixed boundary layer 
profiles will support some stronger gusts through late evening. 
Nonetheless, weak/unorganized deep-layer wind profiles should limit 
overall storm organization, precluding watch issuance. 

.Picca/grams.. 08/15/2018 

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


Latitude...Lon 32350977 31921075 31911144 32331280 33361326 34111325 
34411301 34761247 34801206 34261138 33291015 32820944