Summer Weather Here To Stay For The Week

A summer-like pattern, one where the jetstream stays north and an upper level ridge sets up over the middle of the country, will be the big weather story for the week of the 16th-22nd. At 500mb, a dominate ridge is centered over the Deep South which is pumping very warm and humid air north into the Ohio River Valley. Very little change in the overall airmass is expected this week resulting in overnight lows in the low 70's and afternoon high temperatures in the low 90's with heat index values pushing into the upper 90's thanks to dewpoints in the low 70's.

500mb map for Tuesday afternoon. Large ridge can be seen from Texas to Georgia to N. Illinois.

With this pattern taking hold, very little in the way of change is expected to occur over the rest of the week. With the jetstream running from the Pacific Northwest along the Canadian border into the Upper Great Lakes, the storm track will remain well north of Southern Illinois. Later in the week, the ridge will slowly start to moderate. This will lead to a challenging rain forecast as we expect afternoon showers and storms around the outer edges of the ridge.

500mb Friday map. 500mb flow adjusts to westerly. Outer edge of ridge draws east.

GFS picks up on precipitation on the outer rim of the ridge Friday

Exactly how the ridge moderates will be the key in forecasting shower and storm chances Thursday evening through Saturday. At this time, it's my belief that we'll be very close to the outer edge of the ridge which will lead to spotty, at best, chances for rain Thursday evening through Saturday.