U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus02 kwns 311726 
Storm Prediction Center ac 311725 

Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1225 PM CDT Friday Oct 31 2014 

Valid 011200z - 021200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms will be possible across parts of the Great 
Basin and Rocky Mountain states...as well as parts northeast South 
Carolina...central and eastern North Carolina and the middle-Atlantic 

A highly amplified middle- and upper-level flow pattern will prevail 
through day 2 across the lower 48 states...as a deep trough over the 
eastern states moves to the Atlantic Seaboard by 12z Sunday...while 
a central U.S. Ridge shifts slowly eastward. In the west..a split-flow 
regime is expected to develop across western North America with the 
Pacific trough...in the southern branch...advancing slowly eastward 
across the interior west. 

..northeast SC/central and eastern NC to coastal mid-Atlantic... 
A rather substantial increase in upward vertical motion is expected 
from 12z Saturday into the afternoon across northestern SC and central/eastern 
portions of NC as a deepening...closed low and attendant strong 
shortwave trough move through the base of the parent eastern U.S. 
Longwave trough. This combined with low-level moistening/ 
destabilization and frontogenesis while a surface low develops eastward 
from northestern SC suggests the likelihood for convection Saturday morning 
and afternoon. Cold midlevel temperatures /-24 to -26 c at 500 mb/ 
will result in steep lapse rates for buoyancy /though weak/ to 
become sufficient for low-topped thunderstorms. Weak instability /MUCAPE 
at or below 100 j/kg/ will limit the severe weather threat...though small 
hail may occur with the stronger updrafts. 

..Great Basin to rockies... 
Steepening lapse rates associated with the western U.S. Trough will 
support afternoon development of showers and embedded/isolated thunderstorms 
across portions of the interior west and rockies. The greatest 
convective coverage should occur as forcing for ascent attendant to 
a strong lead shortwave trough and attendant cold front advance from 
Nevada through Utah to the northern rockies. The risk for severe weather 
remains minimal due to the lack of appreciable cape. 

.Peters.. 10/31/2014