After a week of temperatures in the 70s and 80s last week, it was a rude awakening for Michigan this morning, as temperatures across all but the extreme southern portions of the state dropped below freezing. Tonight, far colder temperatures in the low to mid-20s are expected across the entire state, and frosts and freezes are also expected in all of Ohio, plus portions of Indiana, Kentucky, Wisconsin, West Virginia, Virginia, Pennsylvania, Delaware, North Carolina, Maryland, Washington D.C., and New Jersey. A hard freeze (temperatures below 28°F ) will cause widespread damage to flowering plants fooled into blooming by last week’s unprecedented “Summer in March” heat wave. Temperatures as hot as 90° hit Michigan last week, and the National Weather Service in Detroit called the “Summer in March” heat wave “perhaps the most anomalous weather event in Michigan since climate records began 130 years ago.”

Figure 1. Frost and freeze advisories (white colors) are posted today for all of Michigan and all of Ohio, plus portions of Indiana, Kentucky, Wisconsin, West Virginia, Virginia, Maryland, Pennsylvania, Delaware, North Carolina, Washington D.C., and New Jersey. Although freezing temperatures in the extreme Northeast are also expected, the growing season there has not yet begun, since last week’s heat was not long-enough lived in that part of the country. Image taken from wunderground’s severe weather map.

Fruit trees at risk
Tonight’s hard freeze poses a significant danger to the region’s fruit industry, and growers of apples, pears, peaches, nectarines, plums, and cherries are gearing up to battle the freezing temperatures by operating large fans and propane heaters in orchards in an attempts to keep temperatures a few degrees warmer. While freezing temperatures for an extended period will not kill the trees, they will destroy the flowers and fragile buds that are needed to produce fruit later in the year. The situation this week is similar to what occurred in 2007. A warm spell in March that year was followed by cold temperatures in early April that were 10 – 20 degrees below average, bringing killing frosts and freezes to the Midwest and South that caused over $1 billion in agricultural damage, wiping out apple, peach, winter wheat and alfalfa crops. In an interview with citizensvoice.com, Ian Merwin, Ph.D., a horticulturist who specializes in tree fruit at Cornell University in Ithaca, N.Y., said, “I’m pretty sure this will be the earliest bloom, going back at least to the early 1900s. We are definitely in a very risky situation right now for the fruit crop in the whole Northeast.”

Jeff Masters