ACTIVE STORM TRACK SETTING OVERHEAD

A rather active week across the Upper Midwest is taking shape with a stagnant pattern leading to round after round of potentially heavy rain with severe weather mixed in. Plentiful moisture is sitting underneath a conveyor belt of disturbances which will likely parade along the northern edge of the heat dome this week.

Overall confidence day to day in terms of rainfall, severe weather and a flash flooding threat is low given the subtle nature of some of the storm chances, however we are looking at a chance for showers and storms pretty much every day through Saturday.

Monday's storm chances appear to favor areas along/east of the Mississippi River based on the European Ensemble. Monday looks like one of the lower-potential days based on some of the trends we are seeing today.

Tuesday on the European Ensemble also is favoring areas mainly along/east of the Mississippi River with the heaviest threat to the east. A few shorter-range models have increased chances overhead. I think Tuesday personally looks a little more on the active side for our region. Once more of the higher-resolution models get in range, hopefully we can start getting some higher confidence here.

Wednesday is looking like a nocturnal threat for the region with the source of storms to the west before pushing into our area later in the evening/overnight. Again, confidence is rather low day to day, so keep an eye on the forecast for changing severe weather probabilities as these will likely fluctuate pretty significantly and quickly.

Models are really honing in on Thursday as well as one of the more active days for our area. Again, overall confidence is somewhat limited but this signal is one of the better ones in the ensemble forecasts. This appears to favor more evening/overnight convection instead of afternoon storms, but we will watch trends closely.

Convective models struggle in this regime, so anticipate some rather quickly-adjusting severe weather forecasts over the next few days. Instability will be plentiful, and upper air support will allow mature thunderstorms to develop, but the timing and placement of the strongest storms will likely be adjusted daily. General confidence is high in above to well-above-normal rainfall over the next week through the corn belt. This pattern generally also favors more nocturnal thunderstorm complexes especially east of I-35.

The GEFS 7-day precipitation anomaly forecast above has 300-500% of normal precipitation right over our area. A lot is pointing to a rather active week.

Warm air aloft, known as the cap, may also prevent storm initiation daily until the evening/overnight hours.

This type of pattern is one of the weak points of meteorology and our forecast computer's abilities.

We know the ingredients are there. Pattern recognition gives us additional confidence in the overall threat this week. But nailing down specifics is very difficult. The moisture content of the atmosphere is forecast to be on the higher side, about the 90th percentil almost all week, a strong indicator of potential for heavy rain and flash flooding.

The officialt forecast from the Weather Prediction Center has a wide area of 1.5" to 2.0" across the region through Friday, generally favoring along/south of I-80 for the heaviest rain potentially pushing 3"+. I would again reiterate confidence is quite low in exact amounts and placement of the heaviest rain, but the potential is certainly there.

-Meteorologist Nick Stewart