Summer in March peaks in U.S. and Canada; record late snow in Oregon

A spring heat wave like no other in U.S. and Canadian history peaked in intensity yesterday, during its tenth day. Since record keeping began in the late 1800s, there have never been so many temperature records broken for spring warmth in a one-week period--and the margins by which some of the records were broken yesterday were truly astonishing. Wunderground's weather historian, Christopher C. Burt, commented to me yesterday, "it's almost like science fiction at this point." A few of the more remarkable records from yesterday:

Pellston, MI: record high broken by 32°F
Pellston, Michigan in the Northern Lower Peninsula is called "Michigan's Icebox", since it frequently records the coldest temperatures in the state, and in the entire nation. But the past five days, Pellston has set five consecutive records for hottest March day. Yesterday's 85° reading broke the previous record for the date (53° in 2007) by a ridiculous 32°, and was an absurd 48°F above average.

Low temperatures beat the previous record high for the date at two stations
The low temperature at Marquette, Michigan was 52° yesterday, which was 3° warmer than the previous record high for the date! The low at Mt. Washington, NH yesterday (44°) also beat the previous record high for the date (43°.)

Canadian cities break all-time April record for warmth in March
Not only was yesterday the warmest March day in recorded history for many of Canada's major cities, it was also warmer than any April day at St. John, New Brunswick. The city hit 25.4°C (78°F.) Not only did this crush the record high for March (previous record: 17.5°C), it is well above any temperature ever measured in April (extreme April temperature on record: 22.8°C.) Halifax, Nova Scotia hit 25.8°C yesterday, beating their all-time March record of 25.6°, and falling just short of their all-time April record of 26.3°C, set on April 30, 2004. As of 1 pm today, Halifax was at 27°C, beating their all-time April record. Other major cities in Canada that set all-time warmest March records yesterday included Ottawa (27.4°C), Montreal (25.8°C), Windsor (27.8°C), Hamilton (25.6°C), London (26.4°C), and Fredericton (27.1°C).


Figure 1. The intensity and scope of Summer in March is clearly visible in this data from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite. The map depicts temperatures on March 8 - 15, 2012, compared to the average of the same eight day period of March from 2000-2011. Areas with warmer than average temperatures are shown in red; near-normal temperatures are white; and areas that were cooler than the 2000-2011 base period are blue. These land surface temperatures are distinct from the air temperatures that meteorological stations typically measure, and indicate how hot the surface of the Earth in a particular location would feel to the touch. From a satellite vantage point, the “surface” includes a number of materials that capture and retain heat, such as sand in the desert, the dark roof of a building, or the pavement of a road. As a result, daytime land surface temperature are usually much higher than air temperatures—something that anyone who has walked barefoot across a parking lot on a summer afternoon knows instinctively. Image credit: NASA Earth Observatory.

Summer in March warmth crushes records in Michigan
Yesterday, nearly every major airport in Michigan's Lower Peninsula broke the record they set the previous day for their hottest March temperature, including Detroit (84°), Flint (86°F, just 2° below their all-time April record), Saginaw (87°F, just 2° below their all-time April record), Grand Rapids (87°), Muskegon (82°), Lansing (86°), Alpena (87°), Gaylord (83°, which was 26° above the average high for the date), Pellston (85°), Houghton Lake (85°), and Traverse City (87°, which was which was 45°F above the average high for the date, and was the fifth consecutive day they tied or broke their record for hottest March temperature, and just 3° below their record high temperature of 90° for April.) In Michigan's Upper Peninsula, Sault Ste. Marie's 83° (26° above the average high for the date) crushed the previous March record by 8°, and was only 2° shy of the warmest temperature ever measured in April. Cities in states neighboring Michigan that broke all-time March records for warmth yesterday included:

Indiana:
Fort Wayne (87°) and South Bend (86°)

Ohio:
Columbus (85°), Toledo (85°), Cleveland (83°), and Mansfield (82°)

Wisconsin:
Milwaukee (84°), Madison (83°), and Green Bay (82°). The NWS office in Madison notes that in July of 2009, Madison only had seven days of 80 degree temperatures, and the highest temperature for the whole month was 82. This March, Madison has had five days of 80 degree temperatures, with a high temperature for the month of 83. Prior to this year, there had been only five March 80°F+ days in Madison's history, going back to 1869.

Record March warmth continues in the Northeast U.S.
For the second consecutive day, temperatures across much of Vermont, New Hampshire, and Maine yesterday were the warmest on record for so early in the year. Hottest March temperatures on record occurred at Bangor, Maine (83°F), Houlton, Maine (79°F), Caribou, Maine (75°), Mount Washington, New Hampshire (54°F), and Buffalo, NY (82°).


Figure 2. The jet stream pattern features a large, southwards dipping bulge over the Western U.S., creating a trough of low pressure with cold and snow, and a large, northwards looping bulge over the Central U.S., creating a record-strength ridge of high pressure. The Western U.S. trough has cut off into a "cut-off low" that is slowly drifting eastwards.

Remarkable late-season snow storm on West Coast
The convoluted jet stream pattern that brought Summer in March conditions to the Eastern U.S. and Canada is also bringing record snows to Oregon. Eugene, Oregon picked up 7.5 inches of snow yesterday, the largest snowstorm this late in the year on record. The previous record was a 7.6" snow storm on March 5 - 7, 1951. Snow amounts as high as 32" have been recorded in the Oregon Cascades over the past few days. A loop in the jet stream has created a large upper-level ridge of high pressure that is stuck in place over the Eastern U.S., and large upper-level trough of low pressure over the Western U.S. Since the jet stream acts as the boundary between cold air to the north and warm air to the south, and the large loop in the jet places its axis far to the north of the eastern U.S., summer-like warmth has developed over the eastern half of the U.S. Conversely, colder than average temperatures have developed over the western third of the U.S. behind the southwards-dipping loop of the jet stream. This jet stream pattern was too extreme to be stable, and the big loop over the Western U.S. has broken off to form a giant eddy. The resulting area of low pressure is known as a "cut-off low", because it is cut off from the jet stream. The cut-off low is drifting slowly eastwards, and will bring an end to "Summer in March" over the Eastern half of the U.S. by Friday.

Jeff Masters