Monday, April 9, 2012

A Freeze Later This Week May Damage Crops




Apr 9, 2012; 3:50 PM ET
An exceptionally warm March over the eastern half of the country has led to the early growth of trees and shrubs, early flower blossoms and an early start to the pollen season, especially across the Southeast. Farmers and gardeners have taken advantage of the early warmth by planting early.
However, the weather pattern for the early and middle part of April has changed to one that allows colder air to push into the eastern part of the nation again.
This will result in an a couple of unseasonably cold nights over the eastern part of the country later this week when a polar air mass settles in. Freezing temperatures and frost will be found into parts of the South as a result.
It looks as though the coldest time will span Wednesday night and Thursday morning, when freezing temperatures could be found as far south as Interstate 85 in Georgia and the Carolinas. Readings may dip into the 20s over the mountains and in parts of eastern Tennessee and Kentucky.
Freezes can still occur well into the South in April. In fact, both Atlanta and Charlotte have seen a freeze as late as April 25. Raleigh has experienced freezing temperatures as late as May 10. Montgomery, Ala. and Jackson, Miss. have recorded freezes in mid-April. So, it is certainly not unprecedented for freezes this time of the year into the South.
A damaging frost can occur even later. An official low temperature at or below freezing is not required for frost, since official temperature measurements are made at about 6 feet off the ground. Therefore, on a clear and calm night, the ground itself can be below freezing and frost may form.
Fortunately, the cold that is coming will not be too severe, and a hard freeze, where the ground freezes solid, is not anticipated since that would require lows in the middle 20s. So, only the plants most susceptible to the late cold, such as tomatoes, are likely to be affected. Some of the colorful spring flowers that have bloomed early, such as azaleas, are likely to experience a setback. Corn farmers that have gambled by planting early may see some damage from the cold.
Hardier plants, or those well advanced in their growing cycle, should be largely unaffected. While it will be a close call for peach growers in Georgia and South Carolina, their crop should emerge mostly unscathed and on track for a bumper crop. On the other hand, apple growers in North Carolina and Virginia may see more significant damage to their crop, some of which was already damaged by earlier freezes on blossoms that were out well earlier than usual.
It also looks as though the cold spell will be short-lived, with a warming trend starting Friday afternoon. Highs in the 80s should return by Sunday over most of the South with 70s into the Midwest and parts of the Northeast.
By Frank Strait, senior meteorolgist

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