What happened to spring?
As I write this it is Thursday morning the temperature outside is 27 degrees, a heavy frost and freeze occurred overnight, there is talk of snow in the forecast for the weekend and another heavy frost and freeze is expected on Saturday morning. This one could even effect urban areas and damage tender plants, shrubs and even blossoms on the flowering trees. It鈥檚 hard to believe it鈥檚 the second week of May and not the second week of March.
Frost occurs when the temperature gets down to the freezing mark or below and the vegetation gets covered with a layer of white ice crystals. A more damaging freeze occurs when temperatures fall into the mid and upper twenties and stay below freezing for a number of hours. In addition to the the frost, the plant also freezes and this usually kills the plant.
Location plays a key role and areas that are in the open and especially those in valley bottoms suffer most as cold air is heavier and likes to sink to the lowest spots. Deep woods and areas adjacent to our homes are usually a little warmer and sometimes can weather a cold night. Frost and freezes occur when skies are clear, winds are calm and usually a fair weather high pressure system is over the area.
Our cold air this past week and for the past six weeks has come out of the Arctic. All winter long the dome of cold air that builds up in the Arctic region stayed in Alaska and did not move southward. This was the result of the jet stream blocking any southward movement. After a number of very warm winters, Alaska had a very cold winter while we enjoyed another mild one with little in the way of cold and snow.
Washington, D.C. had less than an inch of snow, their normal is 18 inches. Philadelphia usually gets 23 inches; their total was just 0.3 of an inch. Boston got 16 inches, while its normal is 43. Pittsburgh received a total snowfall of 22 inches, while their average for winter season is 48.
The culprit in Alaska was the warming of the oceans caused by the continued warming of the planet. This allowed for the jet stream pattern to emerge and stay put until early April. After almost a year of above normal temperatures in Southwestern Pennsylvania, April was some four degrees below average, and a few days this past week saw the departure of 20 degrees below average.
For early May, we should be in the low 70s. It may surprise you to know that since all the cold air left the Arctic and is hovering over our area temperatures in Alaska are in the 60s and Fairbanks is expecting readings in the 70s on Mother鈥檚 Day and into the early part of the week.
The other aspect of our weather of late is the amount of rainy dreary days. We just can鈥檛 get a few nice days in a row. We had 22 days with rain in April and so far only one day in May without rain. The forecast for the wet and cold weather has been accurate and looking ahead, we do see a return to more normal May weather as the cold air dissipates and the wet pattern turns a bit more on the dry side. However, this will take another week or so before it settles in.
On any day in May, the Uniontown area can experience temperatures below freezing. On May 30, 1930, it was 32 degrees in the city and even colder in the outlying areas. Better days are coming.