Mid-May Cold Wave Could Bring Frost

By , AccuWeather.com Senior Meteorologist
May 7, 2013; 10:00 AM ET
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This story, which was intended to be a first look, has been updated and replaced by a new story on the cold, frost and freeze.

There is a chance that yet another cold wave slated for the middle of May could have just the right conditions for frost in parts of the Midwest and Northeast.

The period for potential frost would span Sunday to Monday (May 12-13) over part of the Midwest and would settle eastward Monday to Tuesday (May 13-14).

The greatest concern would be for damage to blossoming fruit trees, vineyards, berry bushes and emerging tender growth as well as flowers and vegetable plants that home gardening enthusiasts may have put out.

Garden and home improvement centers that leave flats of vegetables and annual flowers outdoors will run the risk of losing them.

The frost and freezing temperatures are mostly likely to occur only during one night in most locations, but there may be some exceptions.

According to Expert Senior Meteorologist Brett Anderson, "Last May brought an atypical frost during an atypical spring."

There were several nights of below-freezing temperatures that took a heavy toll on fruit trees, berries and other tender plants.

Forecast Temperature Maps
Growing Season Outlook (Issued in March)
AccuWeather.com's 2013 Summer Forecast

Fortunately, the overall chilly weather this spring has much of this activity developing at a much slower pace compared to the incredible sprout-driven warmth from last spring.

"During this time of the year, it typically takes more than just a push of chilly air to produce favorable conditions for frost and when it occurs it is usually for just a single night," Anderson said.

The short nights limit the time for the air to cool down this time of the year.

Dry air, clear skies and light winds must coincide with a cold air mass for a frost.

This map shows a first look at the area at greatest risk for a frost or freeze. However, the actual area that may have near-freezing temperatures may be much smaller and highly localized. Keep checking your local AccuWeather.com forecast.

The center of high pressure producing the calm, clear conditions is aiming more for the central Plains to the Ohio Valley, while the coldest air will slice across the upper Great Lakes to northern New England.

A narrow swath of countryside may overlap both atmospheric conditions from Michigan to upstate New York, southward to parts of western and central Pennsylvania and West Virginia. It is possible that part of the central Appalachians have two nights of low temperatures teetering in the upper 20s to lower 30s. These areas have seen a significant amount of consumers purchasing vegetables and flowers.

The pattern will bring chilly daytime highs for the middle of May over the Upper Midwest to the Northeast, and in many cases, that chill will be accompanied by some cloud cover, wind and shower activity. A couple of wet snow showers are not out of the question.

However, it is the wind, clouds and moisture that may lower the threat for frost just a bit in the more typical northern areas. These locations experience freezing temperatures into the end of May, on average.

Farther south, the air may chill out under the cover of darkness, but any near-freezing temperatures could be limited to only a couple of hours.

Official temperatures and forecasts are made for a height at approximately six feet off the ground. Under clear and calm conditions at night, temperatures can be significantly lower at ground level.

Since there is a chance the chilly air could get together with clear and calm conditions in a portion of the Midwest and Northeast, AccuWeather.com will continue to monitor the potential for a mid-May frost and freeze.

In the meantime if have purchased annual flowers and vegetables, but not yet planted them, hold off until after this cold wave moves away during the middle of next week. If you have planted, be prepared to take preventive action, unless you live in an urban area.


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