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Extreme Weather Whiplash: 106° in Iowa on the Heels of Record May Snows
beginning to sense a theme. Something something oh fuck the jet stream is on a rampage and fucking up the northern hemisphere
Does not compute! That must be what residents of Iowa and the Midwest have have been saying to themselves on Tuesday as a ferocious heat wave unprecedented in intensity for so early in the year sent temperatures soaring as high as 108°. Just two weeks ago, the deepest snowfall ever measured during any May of record buried a wide swath from Arkansas to Minnesota, with Iowa breaking its all-time snowfall record for May (13” accumulation at Osage on May 1 - 3.) And how's this for a definition of "Weather Whiplash": Sioux City, Iowa had their first-ever snowfall on record in the month of May on May 1 (1.4"
, but hit an astonishing 106° yesterday. Not only was this their hottest temperature ever measured in the month of May, but only two June days in recorded history have been hotter (June, 10, 1933: 107° and June 21, 1988: 108°.) On May 12th they registered 29°, and thus had a 77° rise over 56 hours (from 6 a.m. May 12 to 1:30 p.m May 14.)
...
Fires in Wisconsin and Minnesota
The intense heat was accompanied by strong winds, which fanned multiple fires in Minnesota and Wisconsin. One fire, near Gordon, Wisconsin, burned 8,700 acres, making it the largest fire in Wisconsin since the Cottonville fire on May 5, 2005, and the largest fire in Northern Wisconsin since the Oak Lake fire of April 22, 1980 (11418 acres.) The Gordon fire destroyed 47 structures, including 17 homes, and forced the evacuation of several dozen people. The fire was 90% contained Wednesday morning. At least 25 smaller wildfires were reported in Minnesota, and Governor Mark Dayton signed an emergency order on Tuesday to help the Minnesota Interagency Fire Center fight wildfires around the state.
Why the crazy extremes? Blame the jet stream
The position of the jet stream is a critical controller of weather regimes across the U.S., Europe, and Asia. Precipitation-bearing low pressure system ride along the axis of the jet, and the jet marks the boundary between cold, Canadian air to the north, and warm, subtropical air to the south. On average, the jet flows from west to east, but the jet often departs from average. The jet is continually rippling with U-shaped troughs of low pressure that allow cold air to spill southwards. The troughs are counterbalanced by upside-down-U-shaped ridges of high pressure that bring warm air northwards. When these ridges and troughs grow to unusually large amplitude, record extremes of both cold and heat occur adjacent to each other. Often times, the jet will have multiple extreme loops that result in unusual extremes over large portions of the Northern Hemisphere. That was the case Tuesday in Europe, where an unusually strong ridge of high pressure was present over Western Russia, with a companion strong trough of low pressure over the U.K. Moscow, Russia hit 29.7°C (85.5°F) on Tuesday, and several locations within the city rose to 31°C (88°F). According to weather records researcher Maximiliano Herrera, this has never happened in the first half of May before. At the same time, up to 3" of snow fell in the U.K. on Tuesday, a rare occurrence for mid-May. Could climate change be a factor in the extreme gyrations of the jet stream this year? It could, and I discussed some of the possible connections in my April 2013 post, Unusually cold spring in Europe and the Southeast U.S. due to the Arctic Oscillation.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2407
Figure 2. Monday afternoon's jet stream shows the pronounced ridge (upside-down U-shaped curve to the jet stream) over the Midwest U.S., which led to all-time record high temperatures for so early in the year. At the same time, a sharp trough of low pressure (U-shaped dip in the jet stream) was present over the East Coast, which allowed cold air from Canada to spill southwards and set record lows--for example, 44° at Tallahassee, Florida on May 14.
, but hit an astonishing 106° yesterday. Not only was this their hottest temperature ever measured in the month of May, but only two June days in recorded history have been hotter (June, 10, 1933: 107° and June 21, 1988: 108°.) On May 12th they registered 29°, and thus had a 77° rise over 56 hours (from 6 a.m. May 12 to 1:30 p.m May 14.)
...
Fires in Wisconsin and Minnesota
The intense heat was accompanied by strong winds, which fanned multiple fires in Minnesota and Wisconsin. One fire, near Gordon, Wisconsin, burned 8,700 acres, making it the largest fire in Wisconsin since the Cottonville fire on May 5, 2005, and the largest fire in Northern Wisconsin since the Oak Lake fire of April 22, 1980 (11418 acres.) The Gordon fire destroyed 47 structures, including 17 homes, and forced the evacuation of several dozen people. The fire was 90% contained Wednesday morning. At least 25 smaller wildfires were reported in Minnesota, and Governor Mark Dayton signed an emergency order on Tuesday to help the Minnesota Interagency Fire Center fight wildfires around the state.
Why the crazy extremes? Blame the jet stream
The position of the jet stream is a critical controller of weather regimes across the U.S., Europe, and Asia. Precipitation-bearing low pressure system ride along the axis of the jet, and the jet marks the boundary between cold, Canadian air to the north, and warm, subtropical air to the south. On average, the jet flows from west to east, but the jet often departs from average. The jet is continually rippling with U-shaped troughs of low pressure that allow cold air to spill southwards. The troughs are counterbalanced by upside-down-U-shaped ridges of high pressure that bring warm air northwards. When these ridges and troughs grow to unusually large amplitude, record extremes of both cold and heat occur adjacent to each other. Often times, the jet will have multiple extreme loops that result in unusual extremes over large portions of the Northern Hemisphere. That was the case Tuesday in Europe, where an unusually strong ridge of high pressure was present over Western Russia, with a companion strong trough of low pressure over the U.K. Moscow, Russia hit 29.7°C (85.5°F) on Tuesday, and several locations within the city rose to 31°C (88°F). According to weather records researcher Maximiliano Herrera, this has never happened in the first half of May before. At the same time, up to 3" of snow fell in the U.K. on Tuesday, a rare occurrence for mid-May. Could climate change be a factor in the extreme gyrations of the jet stream this year? It could, and I discussed some of the possible connections in my April 2013 post, Unusually cold spring in Europe and the Southeast U.S. due to the Arctic Oscillation.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2407
Figure 2. Monday afternoon's jet stream shows the pronounced ridge (upside-down U-shaped curve to the jet stream) over the Midwest U.S., which led to all-time record high temperatures for so early in the year. At the same time, a sharp trough of low pressure (U-shaped dip in the jet stream) was present over the East Coast, which allowed cold air from Canada to spill southwards and set record lows--for example, 44° at Tallahassee, Florida on May 14.
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