Wed-Fri, July 13-16th Severe T'Storm Episode Update #4

(10:00PM - 7/14/21) Multiple disturbances will continue to move through the region through Friday, bringing periods of severe t'storm potential to portions of the state through Friday night.

Summary...
Multiple disturbances ejecting out of the Plains, will push eastward across the Midwest and Mid-Mississippi Valley through Friday. These disturbances will bring periods of severe t'storm potential to portions of the state through Friday night. Little to no change was needed with this update, as going forecasts are on track. Friday has now been included in this period, as severe potential is now possible for that day.

Forecast...
Tonight, July 14th...
After an initial complex of rain and t'storms brought isolated severe t'storms to Northern Illinois this afternoon, a new complex of rain and t'storms across Iowa is expected to move across Northern Illinois tonight. An isolated severe t'storm potential will exist with this activity, given a favorable severe t'storm environment is in place. This environment features moderate instability of 2,000-4,000J/KG, dew points in the mid 60's to mid 70's, good shear, good forcing, and  modest lapse rates of 5.0-7.0C. This environment will be supportive of upwards of a an isolated to widely scattered severe t'storm risk (levels 1-2) across Northern Illinois. Damaging winds and hail will be the severe weather threats, though an isolated tornado can't be ruled out.

Thursday Morning - Thursday Night, July 15th...
Areas of showers and t'storms will be ongoing across portions of Northern and Central Illinois Thursday morning. Regeneration and new development is then expected to occur Thursday afternoon across portions of Iowa, Missouri and Northern/Central Illinois. This activity is then expected to push eastward and across a large portion of Northern and Central Illinois, Thursday afternoon through Thursday night. This environment will feature moderate instability of 1,500-3,500J/KG, dew points in the mid 60's to mid 70's, good shear, good forcing, and  poor lapse rates of 5.0-6.0C. This environment will be supportive of upwards of a an isolated severe t'storm risk (level 1) across Northern Illinois. Damaging winds and hail will be the severe weather threats, though an isolated tornado can't be ruled out.

Friday Morning - Friday Night, July 16th...
Areas of showers and t'storms will be ongoing across portions of Central and Southern Illinois Friday morning. As another disturbance moves through, regeneration and new development of rain and t'storms is then expected to occur Friday afternoon across portions of Missouri and Southern Illinois. This activity is then expected to push eastward and across a large portion of Central and Southern Illinois, Friday afternoon through Friday night. This environment will feature moderate instability of 1,000-3,000J/KG, dew points in the mid 60's to mid 70's, good shear, good forcing, and  poor lapse rates of 5.0-6.0C. This environment will be supportive of upwards of a an isolated severe t'storm risk (level 1) across portions of Central and Southern Illinois. Damaging winds and hail will be the severe weather threats, though an isolated tornado can't be ruled out.

​Below are the severe t'storm forecasts for this event.

JP