The Active Pattern Continues With Heavy Rain, Some Severe

The upper level pattern we've been stuck in will continue over the next few days. A consistent "zonal flow" has set up over the middle of the country and brings ripples in the jetstream which track over the same areas day after day.

500mb chart early Sunday morning. West to east (zonal) flow with vorticity max moving into Great Lakes

At the time of this writing (Saturday evening), a shortwave trough is tracking north of the St. Louis area and has brought mainly brief spin up tornadoes to parts of the Metro-East and will drag a cold front through Southern Illinois overnight. The weak cold front will slide south and shift the storm axis south for Sunday also. That won't last long, as another vorticity maxima begins to shift the weak cold front north and brings more chances for showers and storms late Sunday into Monday.

500mb depicting where the max may track kicking of showers and a few elevated storms early Monday morning.

Showers and storms overnight Sunday into Monday are not anticipated to pose a severe weather threat thanks to the lifting warm front still draped to the south resulting in a northeast wind with temperatures and dewpoints slightly lower. How long the rain lingers around Monday may pose a few forecasting challenges. Attention then will shift to the strong trough which now appears will become a cutoff low as it digs out of the Plains.

500mb depicting cutoff low centered over SW Missouri late Monday/early Tuesday

As the cutoff low moves out of the Plains, it will pull a surface warm front north of Southern Illinois Monday. With some surface instability and a strengthening wind field Monday evening and into Tuesday morning, I don't think we can rule out the potential for severe weather. At this time, I feel that heavy rainfall may be a bigger concern as PWats approach 1.8-2 by Monday evening.

Tuesday afternoon may also bring a chance for storms. It's too early to pinpoint the details, but severe weather potential will be monitored.