Below are maps that illustrate the surface weather conditions leading up to and including the Easter weekend 2007 freeze. Due to the unseasonable warmth before Easter and cooler than normal conditions during Easter, many crops were adversely affected. Further down this page are maps illustrating the crop losses by county.
Climatological Synopsis
by Joshua Hemperly
A very strong cold front moved through North Carolina on April 4, 2007. This surface cold front was indicative of a very strong upper level jet over the Eastern U.S. and especially over North Carolina. A 500 mb upper level low over the great lakes and associated jet streak over NC brought arctic Canadian air into region. This pattern persisted and caused the Easter weekend frost due to severe cold advection into the area. At the surface, lows over the North Atlantic and Canada created Northerly/ Northeasterly flow. On April 7, 2007, the closed 500 mb upper level low remained while the jet streak over North Carolina was still intense with jet streaks of 85 knots at 500 mb over parts of North Carolina. On April 11, 2007, the upper level jet decayed and upper level flow shifted to Westerly/Southwesterly as an upper air disturbance from the Atlantic approached. Eventually, a strong surface low over the central plains built into the Southeast region and changed the winds to Southeasterly.
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This map displays the departure from normal of maximum temperatures preceeding the Easter freeze period (March 1-April 4, 2007). The mostly positive values and warm colors show how the maximum temperatures for the entire state were above normal during this period. This early warmth encouraged early plant germination.
This map displays the departure from normal of maximum temperatures during the Easter freeze period (April 5-11, 2007). The cool colors and negative values show how the maximum temperature for the entire state was below normal during this period.
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This map displays the departure from normal of minimum temperatures preceeding the Easter freeze period (March 1-April 4, 2007). The mostly positive values and warm colors show how the minimum temperatures for the entire state were above normal during this period. This early warmth caused the plants to begin germination early, which were then killed off by the Easter freeze.
This map displays the departure from normal of minimum temperatures during the Easter freeze period (April 5-11, 2007). The cool colors and negative values show how the minimum temperature for the entire state was below normal during this period.
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This map depicts the accumulated departure from normal of base 50 degrees Fahrenheit Growing Degree Days during the period before freeze (March 1-April 4, 2007). This quantity is important to agricultural calculations and the mostly positive values and warm colors on this map denote the accrued heat for the region leading up to the Easter freeze.
This image shows the accumulated departure from normal of base 50 degrees Fahrenheit Growing Degree Days during the Easter freeze period (April 5-11, 2007). This quantity is important to agricultural calculations and the entirely negative values and cool colors on this map denote the accrued cold spell during this freeze.
Agricultural Impact
Due to the unseasonable warmth preceeding Easter weekend, many crops began germinating early. The unseasonable cold period during Easter weekend damaged many crops in the region. The NC Department of Agriculture and Consumer Services estimates crop losses at $112 million [7] in North Carolina.
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Additional Resources and Information:
- NC Department of Agriculture information about crop losses [7]
- NC Cooperative Extension Service 2007 Easter Freeze Information [10]
- NWS Raleigh, NC, data analysis [11]
- NOAA Technical Report on the Easter Freeze [12]
Maps, analysis, and data manipulation performed by Meteorologists Joshua Hemperly, Sherri Pugh, Ryan Boyles, and Mark Brooks.