Ag Weather Forum

As alluded to last week, the weather pattern is finally coming around to being favorable for producing bigger storm systems and good rainfall for the middle of the country.

In general, an upper-level ridge of high pressure has been dominant over the majority of the country the last couple of months, not allowing for storm systems to really move through the country. Some small ones have, but not ones that bring widespread heavy rain. That started to change this weekend as an upper-level trough of low pressure moved into the West, pushing the ridge to the East. Several more bursts of energy will replace the western trough into next week, keeping this general pattern in place.

That is the setup needed to generate large storms. The western trough provides the dynamics and the ridge, with its clockwise motion around it, brings up heat from the South and moisture from the Gulf of Mexico. The combination is usually good enough to produce a storm system with a large shield of rain and potential for severe thunderstorms.

While thunderstorms may indeed be severe, the storm systems are generally not ones that will result in large comma-shaped cloud signatures on satellite. A lot of the rain that comes from these systems will fall along fronts, more focused than the widespread shields from large storm centers.

But the middle of the country, which has seen very little rainfall during the last couple of months, will take what it can get. And it will have multiple systems from which to do so. I count five separate low-pressure centers that will move through the middle of the country between Oct. 29 and Nov. 6, a span of just nine days.

The setup will not change much during this time frame, giving each low the opportunity to create areas of thunderstorms and heavy rainfall. A zone of good rainfall is forecast from Texas up through Wisconsin where amounts are likely to be in the 1- to 3-inch range with locally higher amounts where several rounds of thunderstorms move through. Some moderately good rain up to an inch is forecast west and east of this zone.

To go along with the rainfall, there is some potential for a little bit of snow accumulating as well. Wyoming into western South Dakota is at risk of snow occurring Oct. 29-30 while an area from east-central Minnesota to the Upper Peninsula of Michigan could see snow falling early morning on Oct. 31. In general, the snow will not last long with warmer surface conditions and overall warm afternoons. Some snow can also not be ruled out on the systems that move through early- to mid-next week across northern areas as well.

Despite the risk of a little snow, the precipitation is great news for those in the middle of the country who are done with harvest and trying to build some soil moisture before winter sets in or get some moisture in the soils for applying fertilizers where soils have become too dry in which to do so.

What is less certain is the rainfall for areas that truly need it right now -- those that produce winter grains. Soft red winter wheat varieties that are grown in the Mississippi Valley through the Midwest are more likely to see good rainfall, a zone that is generally forecast to receive 0.75 to 1.5 inches, thus helping plants establish roots.

However, those that produce hard red winter wheat varieties in the southwestern Plains could end up on the edge of most of these five systems. Western Kansas, the Texas and Oklahoma Panhandles, and Colorado are forecast to generally see less than an inch and with how scattered rain is likely to be in this area, some areas could be left completely dry in the active pattern. That would not be a good thing, given that winter wheat conditions in these areas are not in a favorable spot. Good-to-excellent ratings are just 34% in Nebraska, 38% in Kansas, 21% in Oklahoma, and 30% in Texas. The rain will help, but probably not everywhere.

One of the troughs that move into the West will sweep through the country mid- to late-next week, shutting down the active pattern. But that may only be temporary. Models suggest the western trough and eastern ridge scenario may redevelop several days later, around Nov. 10-12, and could start the train back up again.

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John Baranick can be reached at john.baranick@dtn.com

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