U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 030108 
Storm Prediction Center ac 030107 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0807 PM CDT sun Aug 02 2015 

Valid 030100z - 031200z 

..there is an enh risk of severe thunderstorms across parts of southeast 
Wisconsin...northeast Illinois...northern Indiana...Northwest 
Ohio...and Southern Lower Michigan... 

..there is a slight risk of severe thunderstorms from the Great Lakes region westward 
into Nebraska... 

..there is a marginal risk of severe thunderstorms surrounding the slight risk 
area...from the Great Lakes westward across the Central Plains... 

Severe storms are expected to continue across the Great Lakes region 
through evening with damaging winds and large hail...and perhaps an 
isolated tornado. A few severe storms will also continue through 
this evening from the Great Lakes convection southwestward across 
northern Illinois...southern Iowa...northern Missouri...and into 
eastern Nebraska. 

..sern WI/northestern Illinois eastward across lower Michigan/northwestern Ohio... 
A well-organized line of storms continues advancing southeastward across the 
lower Michigan vicinity at this time...near/ahead of an advancing surface cold 
front. Objective analyses and evening DTX /Detroit Michigan/ radiosonde observation reveal 
moderate instability/steep middle-level lapse rates across the 
region...which should allow storms to continue spreading southeastward 
through the evening hours. While some weakening of convection is 
forecast into the overnight hours...moderately strong southwesterly/westerly flow 
through the lower and middle troposphere will help to maintain 
convective organization...and attendant risks for damaging winds and 
hail...and possibly a tornado near a rotating comma head or updraft. 

..ern Nebraska eastward across southern Iowa/northern MO/northern Illinois... 
Isolated thunderstorms continue in vicinity of the slowly advancing cold 
front from eastern Nebraska eastward across the southern Iowa/northern MO vicinity...and 
should develop/spread eastward into parts of northern Illinois over the next few 
hours. Extreme instability is indicated across the area -- per both 
evening radiosonde observations and objective analysis...which will fuel ongoing 
storm maintenance...and potential for additional storm development 
across this region over the next several hours. Along with the 
highly favorable thermodynamic environment...moderate/weakly veering 
flow with height will sustain organized/rotating updrafts -- and 
associated risk for large hail...locally damaging winds...and a 
tornado or two as the overall convective area spreads east-southeastward/southeastward 
into the overnight hours before gradually weakening. 

.Goss.. 08/03/2015 

Mesoscale Discussion

acus11 kwns 030420 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 030419 

Mesoscale discussion 1593 
National Weather Service Storm Prediction Center Norman OK 
1119 PM CDT sun Aug 02 2015 

Areas affected...parts of northern Illinois...northern ind...Northern Ohio and Southern Lower Michigan 

Concerning...Severe Thunderstorm Watch 463...465... 

Valid 030419z - 030545z 

The severe weather threat for Severe Thunderstorm Watch 

Summary...the severe wind/hail threat is expected to gradually 
diminish with a lingering line of storms overspreading the region 
through 05-07z. A new watch is not currently anticipated for 
Northern Ohio...but trends will continue to be monitored for this 

Discussion...the leading edge of conglomerate convective outflow 
continues to advance southward through southern portions of the 
Great Lakes region at up to 30 knots. Lift along this feature has 
remained sufficient to support renewed vigorous thunderstorm 
development... but lightning and radar data suggest general 
intensity trends are on the downward swing. Stronger middle/upper 
forcing for ascent associated with the vigorous short wave impulse 
pivoting through the upper Great Lakes region appears likely to 
begin turning eastward toward southern Ontario/Quebec shortly. As 
this occurs...40-50 knots westerly Lower/Middle tropospheric wind fields 
currently present across the southern Great Lakes region should 
begin to weaken. Coupled with continued boundary layer cooling 
within a narrowing pre-convective line instability axis...severe 
weather potential with lingering convection is expected to diminish 
through the 05-07z time. 

.Kerr.. 08/03/2015 

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


Latitude...Lon 41388692 41298457 41558375 41778168 42158083 42078037 
41338090 40888276 40398594 40598822 41548904 41388692