THE ELEPHANT IN THE ROOM..
As most of you know, I'm the elephant in the room that loves winter. Forecasting a big snowstorm is one of my favorite challenges and I'm always a bit sad when the last flakes fall. Since this last winter was pathetically bad with an anemic 15" of snow in Cedar Rapids, I'm hoping for better things in 2017-18.
To that point, I was pleased to see the latest winter temperature forecast (December-February) offered by the CFS model. It showed significant cold across much of the country with the core centered over the Plains and Midwest.
With winter still safely on the horizon things can certainly change. However, based on projected sea surface temperatures, a weak Modoki El Nino, an easterly QBO (Quasi-Biennial Oscillation), and a solar minimum there are reasons for early optimism. If you bring the cold the snow will follow!
And for those interested, summer cold is coming this weekend. The jet stream flow aloft looks like this today. That will make for a very warm humid Thursday.
By the middle of next week the flow has morphed into this. That my friends does not look like late June.
Such a pattern will usher in unseasonably cool air that will thin out the swimming pools all around the Midwest. Here's the 5 day temperature departures at 5000 ft. June 23rd-June 28th.
On Monday, the EURO has highs in the 60s over many parts of the upper Midwest, at least 15 degrees below normal.
As the cool air enters the central U.S. late Thursday and Thursday night it will encounter a very warm moist air mass. Instability will be significant and strong thunderstorms are likely to develop towards evening over Minnesota and far northern Iowa. From there they sweep southeast and quickly grow upscale into a squall line. Strong winds and some hail are likely the end result. Here's the line of storms the 3kNAM shows at midnight.
SPC has my entire area under a slight risk of severe weather Thursday evening
Once the front clears the change to cool weather is on. I expect to see at least 5 consecutive days with highs in the range of 70-75. That's not easy to do at this time of year. The natural air conditioning will put some extra change in the rainy day fund. Roll weather...TS