U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 060730 
Storm Prediction Center ac 060729 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0229 am CDT Monday Jul 06 2015 

Valid 081200z - 091200z 

..there is a marginal risk of severe thunderstorms Wednesday afternoon and evening 
across parts of the middle Mississippi Valley... 

Thunderstorms capable of producing a few potentially damaging wind 
gusts or...perhaps...an isolated tornado or two may not be out of 
the question on Wednesday across portions of the middle Mississippi 
Valley. Otherwise...severe weather potential across much of the 
nation appears generally negligible. 

Seasonably high moisture content air is generally forecast to remain 
confined to areas along and south of a surface frontal zone 
advancing to the southeast of the stronger middle-latitude westerlies 
..which will remain near and north of the Canadian/U.S. Border 
through this forecast period. While the front may advance off 
northern Atlantic coastal areas...it is expected to remain 
quasi-stationary while weakening across the Ohio Valley into the 
Central Plains. 

Modest middle-level subtropical ridging is forecast to continue 
expanding westward across the Gulf Coast region...with flow 
transitioning to broadly anticyclonic on its periphery...from 
portions of the southern/Central Plains through the Ohio Valley and 
middle/North Atlantic coast. However...at least one convectively 
generated or enhanced perturbation emerging from the south Central 
Plains appears likely to be embedded within this regime...and may 
remain fairly well-defined while crossing the middle Mississippi 
Valley...before becoming increasingly sheared to the east northeast. 

Farther west...a significant middle/upper closed low...associated with 
a weak southern branch of middle-latitude westerlies and the 
subtropical jet...may begin slowly developing inland across the 
California coast. 

..middle Mississippi Valley... 
The potential strength of the convectively generated or enhanced 
perturbation emerging from the south Central Plains remains unclear. 
However...the flow field accompanying it may be strong and sheared 
enough to enhance convective potential along the remnant frontal 
zone. The best chance for this seems to exist across parts of east 
central Missouri and central/southern Illinois...into adjacent areas 
of Indiana...during the peak afternoon heating of a moist boundary 
layer characterized by 70f+ surface dew points. One or two storms 
with supercell structures capable of producing relative brief/weak 
tornadoes may not be out of the question. 

.Kerr.. 07/06/2015