U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 220050 
Storm Prediction Center ac 220048 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0748 PM CDT Thursday Aug 21 2014 

Valid 220100z - 221200z 

..there is a slight risk of severe thunderstorms across the Ohio Valley... 

cluster of strong/severe thunderstorms will move southeastward across 
northern Indiana toward the Ohio River late this evening. Damaging 
winds and perhaps some large hail are possible. 

..OH valley... 

WV imagery and longer radar loops depict middle-level vorticity over Southern 
Lower Michigan moving southeastward toward Western Lake Erie. Southwestern extension of 
associated short-wave trough appears to be partly responsible for 
upward growth to convection over northestern Illinois/northwestern Indiana late this 
afternoon. This activity has evolved into an mesoscale convective system over northern Indiana 
and should progress within modest northwesterly flow toward the Ohio River 
later this evening. Damaging winds and large hail are the primary 

..cntrl plains to middle MS valley... 

Strong heating contributed to high-based convection along dryline 
across the Texas Panhandle into northern Kansas. This isolated activity should 
spread slowly northeastward along the boundary into southeastern Nebraska this evening 
with a propensity to become elevated as boundary layer decouples. 
Weak warm advection will be focused across southeastern Nebraska into Iowa/northern Illinois 
overnight and this may be sufficient for isolated elevated storms 
during the overnight hours. However...large scale height rises and 
weak upward vertical velocity suggest this activity should remain sparse. Despite the 
moderate instability observed across this region 5 percent severe 
appears warranted for wind/hail. 

..lower Colorado River valley... 

Well defined middle-level circulation is progressing slowly eastward across 
the lower Colorado River valley. Considerable amount of convection 
developed in vicinity of this feature and overturning has now stabilized much 
of the region. A few robust storms may continue across Pima County 
but severe threat should remain minimal. 

.Darrow.. 08/22/2014 

Mesoscale Discussion

acus11 kwns 212244 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 212243 

Mesoscale discussion 1597 
National Weather Service Storm Prediction Center Norman OK 
0543 PM CDT Thursday Aug 21 2014 

Areas affected...central and northern Kansas into southern Nebraska 

Concerning...severe potential...watch unlikely 

Valid 212243z - 220045z 

Probability of watch issuance...20 percent 

Summary...scattered storms with gusty winds and hail are possible 
through evening but the threat should remain disorganized. 

Discussion...visible satellite shows a concentrated area of towering cumulus and 
a few thunderstorms from central into northern Kansas within a zone of enhanced 
convergence near the low pressure trough. Strong heating has eroded 
cin...and a strengthening southerly low-level jet bodes well for continued 
development this evening as cin will be slow to increase due to a 
rather deeply-mixed and moist boundary layer. 

This activity is beneath modest westerlies aloft...with cells 
generally expected to move slowly with a northeastward component. Localized 
severe wind and hail will be possible...but coverage perhaps too 
sparse for a watch. 

.Jewell/Thompson.. 08/21/2014 

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


Latitude...Lon 39109991 40169937 40799809 40939689 40659650 40229662 
39299807 38609952 38639982 38749990 39109991