It feels like it has been more than a year since we have seen a quieter weather pattern across the major growing areas of the United States. Every week seems to bring about the same story: It is wet. I do not see a reason to stray from that now but add to it.
A suddenly persistent trough in the Eastern Pacific should continue to bring storm systems through the west, where 90-day precipitation deficits in northern California had been running 20-40% of normal. Storms through the end of March should at least ease concerns over snowpack in the Sierras and irrigation supplies, though will not completely reverse the dry trend. The DTN forecast through the end of the month contains about 6-10 inches of liquid equivalent for the snowpack in the Sierras with another 1-2 inches of rainfall through the Central Valley.
Farther east, from the Southern and Central Plains through the Delta and Midwest it is the same old song we have been singing for the past several months. The storm track continues through the region and storms pulling in Pacific moisture from the trough in the west and combining it with Gulf of Mexico moisture will continue to lead to moderate-to-heavy precipitation events through the end of the month. This includes moderate-to-heavy snow on the northern side of the precipitation bands from the Central Plains through the Upper Midwest.
But now that average temperatures are increasing, we will see more of a risk for severe weather, particularly from the Southern Plains through the Delta and southern Midwest. It is not unusual to see severe weather in this part of the country for this time of year. However, the repeated storm track indicates that we could see the same areas get hit over and over again with stronger storms.
And did I mention rainfall? The DTN forecast through the end of March shows widespread 2-6 inches of liquid from the eastern Plains eastward with an elongated bullseye along the Ohio River. However, thunderstorm activity is not handled well by the forecast models. Model depiction tends to spread precipitation out instead of concentrating it like we see in actual storm activity. With this in mind, an indicated swath around 6 inches of rain along the Ohio River on the U.S. forecast model could be much higher than that. Indeed, the remainder of this month will continue to delay necessary fieldwork activities.
The only areas "escaping" the storm track are the southwestern and northwestern High Plains where downslope winds off the Rocky Mountains will cause drier conditions than the upslope variety in the central High Plains that should increase precipitation. Windy conditions and brief cold shots will follow the departing storms through this region, however, so most of these areas will still see effects from the storms. For instance, temperatures behind the system this week will plummet well below normal across the Plains for March 20-21. Daytime highs may not escape the middle 20s Fahrenheit on Friday with low temperatures in the single digits from Nebraska northward.
In South America, showers have been on the increase during the last week across much of Argentina and some periods of showers will continue through March 19 before a noticeably drier trend sets up for the following several days. Late-planted corn and soybeans had seen a marked drop in soil moisture prior to last week's rains and some damage may have been the result. The timely showers are likely to have been beneficial, but will need to continue into April, even if unorganized, as double-crop soybeans will not mature until then.
In Brazil, it was very dry over the last week over southern and central growing areas which has allowed the soybean harvest and planting of second-crop corn to near completion off to the north. Showers have since returned and should be highly beneficial for the developing new crop. The exception will be over the far south, which has seen rainfall deficits of 20-50% of normal during the last 60 days. Damage has been reported to both full-season corn and soybeans. Showers will be much more limited in this region over the next week, which could further damage the crop prospects.
John Baranick can be reached at email@example.com
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