A major change in the forecast pattern is underway for the second half of this week. During the past weeks – and months – we have been fully entrenched in a dry, warmer-than-normal forecast pattern. Now, as we move forward through the weekend, we still see temperatures staying normal or even some above normal, but we will see our first significant moisture over a multi-day stretch in a long time.

We have a significant front working out of the Plains at midweek, and it will move over the Eastern Corn Belt this week through Oct. 6. There will be the initial front, and then a second wave moving through.

The first wave on Oct. 4 will have smaller rain totals with it – a few hundredths to one-third of an inch – with 70 percent coverage. However, we think that moisture chances are much higher and rain is actually likely region-wide on Oct. 5.

That day, a secondary wave rides up the old frontal boundary, coming out of the Missouri Valley area and moving northeast. This will bring good moisture to the entire region. In fact, area coverage will push 90 percent with rain totals of at least one-quarter to three-quarters of an inch. There is a threat of thunderstorms overnight on Oct. 5 into the first half of Oct. 6. If realized, that would add even more to the top end of the range of rain potential.

There is a question mark revolving around how long the rain will linger. Some models again are stringing the rains out to include all of Friday. We are not there, yet. We think this front sweeps through strong and has a good clearing line behind it. We may not see that until early Friday morning, but we think we see it.

This front does not look like one that wants to linger, unless it is stalling and dying over the region. It does not fit that description at the moment. Rain totals combined for the two-wave system will be well more than an inch.

We should see some drying weather for the balance of Friday and Oct. 7, although we admit that clouds will be a formidable foe for those days and may limit outright drying. A better way to put it may be “no new precipitation” those days.

A secondary front arrives on Oct. 8 bringing another quarter-inch to half-inch over about 75 percent of the region. This, combined with the rain for the second part of this week, will lead to our first significant slowing in harvest progress across the Eastern Corn Belt, as cumulative rain totals will be 1-1.5 inches over at least 60 percent of the area.

We expect a multi-day delay in harvest over about 80 percent of the region. However, behind the Sunday system, we do string together dry days Oct. 9 through at least Oct. 12, so even a multi-day delay will not last an exceptionally long period.

The map shows potential cumulative rain totals through Oct. 8, which would include both of the aforementioned systems.

To finish out our forecast period, we see strong, upper-level high pressure in control through early Oct. 14, keeping sunshine, blue sky and good drying over the entire Eastern Corn Belt. Later on Oct. 14-15, we have a system moving in from the Western Corn Belt that can trigger a few hundredths to perhaps a quarter-inch of rain. A much more impressive storm complex works toward us for Oct. 16.

This system has strong low pressure and ample moisture circulating with it. It could bring one-half to 1.5 inches of rain over 80 percent of the area east of the Mississippi River. However, this is far out in the extended period, and we have plenty of time to see the system modify or even change course. But it is a system we need to watch.

Overall, temperatures through the rest of the two-week window, right on through mid-October look to be normal to above normal. We do not see any significant below normal temperatures headed our way.

Even dramatic moves behind fronts only return our temperatures to seasonal levels, and they do not produce any kind of cold snap. Normal first frost dates for the region dance around Oct. 10. We do not see any significant frost threat until well after that date at this time.

Ryan Martin is Chief Meteorologist for Hoosier Ag Today, a licensed Commodity Trader and the Farmer Origination Specialist for Louis Dreyfus Company’s Claypool Indiana Soybean Crush Plant. The views and opinions expressed in the column are those of the author and not necessarily those of Farm World.

THIS MAP SHOWS potential cumulative rain totals through Oct. 8, which would include multiple rain systems.