U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 010720 
Storm Prediction Center ac 010719 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0219 am CDT Sat Aug 01 2015 

Valid 031200z - 041200z 

..there is a marginal risk of severe thunderstorms over a portion of the northestern 

..there is a marginal risk of severe thunderstorms over a portion of the Central 
Plains into the middle MS valley area... 

A few strong to severe storms will be possible over the northeast 
states and a portion of the Central Plains into the middle to upper 
Mississippi Valley. 


Embedded within base of an upper low circulation centered over southeastern 
Canada...a shortwave trough and attendant upper jet will continue 
through the Great Lakes region and into the northestern states accompanied 
by a cold front. Trailing portions of this boundary will stall over 
the Central Plains area. Models continue to indicate that a vorticity 
maximum currently over the eastern Pacific will undercut western U.S. Upper 
ridge and reach the Central High plains later Monday. 

..nern states... 

Modified cp air with upper 50s to low 60s f dewpoints will advect 
through pre-frontal warm sector and contribute to modest 500-1500 
j/kg MLCAPE as the boundary layer warms. A few thunderstorms may be 
ongoing along and ahead of cold front within warm conveyor belt over 
a portion of the northestern states. Additional storms are expected to 
develop along the front as the atmosphere destabilizes during the 
afternoon. This activity will be embedded within a belt of stronger 
deep-layer winds within the upper low circulation. The stronger 
storms will become capable of producing damaging wind and possibly 
some hail. Have introduced a marginal risk area for this 
update...but an upgrade to slight risk will probably be needed in 
later outlooks if data continue to indicate sufficient 
boundary-layer destabilization will occur to support a more robust 
severe threat. 

..cntrl plains into the middle-upper MS valley... 

Atmosphere is expected to become moderately unstable in vicinity of 
stalled boundary from the Central Plains into the middle MS valley area 
/most likely Nebraska into Iowa and northern MO/. This boundary will remain 
along southern fringe of modest middle-level winds...but sufficient veering 
will exist to support 30-40 knots effective shear. Thunderstorm 
initiation along the front during the afternoon remains uncertain 
due to weak forcing and presence of a cap. Greater confidence exists 
that storms will develop and become more widespread during the 
evening and overnight as the low level jet strengthens and augments 
convergence and isentropic ascent in vicinity of the front. The 
stronger storms may produce damaging wind and large hail. This area 
will continue to be monitored for a possible slight risk in later 

.Dial.. 08/01/2015