© 2019 Terry Swails

MAKE NO MISTAKE ABOUT IT....

August 31, 2018

Make no mistake about it. The signs are there for all to see. The Midwest is entering an unusually wet pattern that raises concerns about excessive rains and flooding for some the next 7-14 days. Let's dig in.

 

We'll start with the MJO. By following the dotted green lines you can see the long range forecast of the EURO MJO it's projected to spend much of the next 3 weeks in phases 1 and 2. Both have a September correlation to above normal precipitation across the central Midwest.

The trend is highly supported by ensembles of the EURO (an average of 51 members). Notice how the 500mb jet stream flow is directed around the Bermuda high which is displaced over the Ohio Valley.

That's significant because it directs deep tropical moisture into the Midwest for an extended period of time. It also allows late season warmth to set up shop. The northern edge of the warm, humid, unstable air is layed out over the Midwest. As disturbances rotate out of the W/SW along the boundary, clusters of thunderstorms should be regular visitors. The pattern known as the ring of fire is much more common in June than September but is commonly known for producing heavy rain.

The EURO ensemble which goes out 15 days have big rainfall numbers centered on the Midwest where we've seen heavy rain the past 2 weeks. That raises a red flag when it comes to potential short term flash flooding and long term river flooding.

Assuming the EURO ensembles are latching onto the pattern long term, and I think it has the right idea, the wet weather is likely to be with us into early fall. The EURO weekly ensemble mean has this for 46 day rain totals (ending October 15th). Remember this is the average of 51 solutions. Some have substantially higher amounts.

The control weeklies are heavier with 8-14" totals centered on Iowa between now and October 15.

Here's something for you fans of the white gold. The EURO weekly control has an early start to winter in the Rockies and northern Plains. This is snowfall that is shown falling between September 28th and October 2nd. Daddy likes that!

For those wondering about the holiday weekend. It does have some trouble spots but it's still too early to time and predict the placement of thunderstorm complexes. Just know the chances are there for occasional periods of rain. Along with that, warm muggy conditions are expected. The last big weekend of summer will have the appropriate feel. Roll weather and have a terrific Labor Day everyone...TS 

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