Christopher C. Burt is the author of 'Extreme Weather; A Guide and Record Book'. He studied meteorology at the Univ. of Wisconsin-Madison.
By: Christopher C. Burt , 20:20 GMT le 27 janvier 2012
Wild January Temperature Swings in the U.S.A. and Canada and Record Chinooks (but not this January). BREAKING NEWS: -79°F in Alaska on January 28th?
Scroll to bottom of blog for Jim River breaking news.
The month of January is looking like it may be one of the top five warmest for the contiguous United States. Aside for one good arctic outbreak during the week of January 14-20 it has been a mild month with several Chinook wind events affecting Montana and other western mountain states. Here are some historical examples of the most intense Chinook events to have occurred in the U.S. and Canada.
Chinook winds (named after a Native American tribe in the Pacific Northwest where the phenomena was first observed by French explorers) occur during the winter months when Pacific storms moving inland come against the Rocky Mountains and, as the storm winds flow down the eastern slopes, they are heated adiabatically and dry out.
A simple graphic illustrating the cause of Chinook wind events.
The region most prone to these winds in North America is the area around Lethbridge in southern Alberta thanks to the topography in the mountains to the west of the area where passes and valleys help funnel the down-sloping effect of the Chinooks.
A map of the Canadian province of Alberta showing the region most affected by Chinook events. The yellow area sees 1-5 Chinook days a year, the orange area 5-10, and the red area 10 or more. Map from The Atlas of Canada.
Pincher Creek (about 50 miles west of Lethbridge) once recorded a temperature rise of 40°F (22°C) in one hour (from -2°F/-19°C to 38°F/3°C) during a Chinook on January 27, 1962. In Lethbridge winds as high as 106 mph (171 km/h) were measured during a Chinook on November 17, 1962. Mid-winter temperatures as high as 75°F (24°C) have been recorded in Alberta during Chinook events, as was the case at Claresholm in February 1992. This is close to the warmest temperature ever measured during a winter month anywhere in Canada.
A (perhaps apocryphal) story relates how on January 11, 1983 during the construction on Calgary’s Petro-Canada Center carpenters on the 45th floor, about 460 feet (145m) above the street, worked in their shirt sleeves as a warm Chinook brought 55°F/12°C temperatures (as measured by the crane operator). Cold air, however, was still trapped at street level where the temperature stood at -4°F/-20°C.
A Chinook arch cloud forms over Calgary, Alberta on the evening of January 6, 2003. The formation is caused by a wave-like wind flow over the mountains to the west. On this day Calgary recorded its warmest January temperature on record: 64°F/18°C. Photo from Wikipedia, photographer undisclosed.
In the United States, Montana is most susceptible to Chinooks. The most extreme example of which was when the temperature rose 103°F in 24 hours (from -54°F to 49°F) at Loma, Montana on January 14-15, 1972. The greatest 24-hour temperature change ever recorded on earth. Some other extreme examples include an 83°F rise in 12 hours at Granville, North Dakota on February 21, 1918 and a 47° rise in Great Falls, Montana in seven minutes on January 11, 1980! When the temperature rose 80° in 15 hours at Kipp, Montana on December 1, 1896 the dry wind apparently melted and evaporated a 30” snow pack in a single day.
The Famous Black Hills, South Dakota Temperature Antics
The Black Hills of western South Dakota can have a strange effect on Chinooks because of the hills unique location topography. The mountains sit isolated on the northern Great Plains and are often subject to Chinook winds. The warm winds sometimes just blow over ridges and leave cold air trapped in the valleys below. The fight between the dense cold air and light warm air causes the two to slosh back and forth from valley to hilltop, sometimes repeatedly during the course of a day causing wild temperature variations. The most famous example of this occurred on January 22, 1943. Spearfish saw its temperature warm from -4°F at 7:30 a.m. to 45°F at 7:32 a.m., a 45-degree rise in just two minutes during the morning of January 22nd. By 9:00 a.m. the temperature had risen gradually to 54°F when it suddenly dropped again to -4°F over the next 27 minutes. Dressing for the day must have been problematic for Spearfish’s residents. Rapid City suffered the same effect a few hours later as evidenced by the thermograph trace below.
The town of Lead, up in the hills, experienced such a shocking change in temperature that plate-glass windows cracked. At one point, the town of Deadwood, in a canyon 600 feet lower than Lead but only one and a half miles away, had a temperature of -16° at the same time that it was 52° in Lead. Wind gusts of 40–50 mph were whipping through the region. Motorists found it difficult to drive as their windshields would instantly frost over as they drove from a warm pocket to a cold one.
In Rapid City a thermograph trace captured the temperature swings on January 22, 1943. Graphic from ‘Extreme Weather: A Guide and Record Book’.
Temperature Swings this January (2012)
Nothing as dramatic as the Chinook events listed above has yet occurred this January although there have been several mild Chinook events from Alberta to Colorado and across the western Great Plains. In Livingston, Montana (windiest town in America) the wind has gusted to over 70 mph on five days so far this month (as of January 26) and over 50 mph on 17 days. Sheridan, Wyoming reached 67°F on January 5th close to its warmest January temperature on record (which was 70° on Jan. 9, 1953 and again on Jan. 15, 1974). By January 16th the arctic outbreak mentioned in my opening paragraph brought the temperature down to -20°F and -20°F again on Jan. 19th before rebounding to 56° by January 25th. Minot, North Dakota saw an all-time January high of 61°F on January 5 (accompanied by Chinook winds gusting to 47 mph). This smashed the previous January high of 59° set way back on January 28, 1906. Denver, Colorado saw its temperature rise from 2°F on January 17th to 61°F on January 19th.
Not associated with a Chinook but worthy of note was the amazing warm-up at Saranac Lake in the Adirondacks of northern New York state. The temperature rose 68°F in 36 hours on January 16-17 from -27°F to 41°F.
Also, Fairbanks, Alaska saw its temperature rise 62°F on January 9-10 from -41°F to 21°F. It has been one of the coldest months in some years for portions of Alaska.
-79°F in Alaska on January 28th?
Breaking news is a report from Alaska that a reading of -79°F (-61.2°C) has just been reported from Jim River, Alaska on January 28th. This would represent a tie for the 2nd coldest temperature ever measured in the U.S. if verified. I have a query in to the state climatologist, Peter Olsson, for confirmation. If true, the only colder or as cold readings on record for Alaska (and thus the USA) would be -80°F at Prospect Creek, -79° at Circle. I think this figure is suspicious since the daily maximum was reported as -68°F and thus the coldest daily maximum ever recorded in North America. According to the daily summary from WSO Fairbanks the coldest temperature on Jan. 28 at any COOP site has just been -63° at a few sites. UPDATE: Peter Olsson has just emailed me (Jan. 29) saying that the reading from Jim River has a chance of being authentic. The site is apparently nearby Prospect Creek which holds the offical lowest temperature ever recorded in Alaska (-80°F) and that this area is known to be the coldest region in the state so far as absolute minimum temperatures are concerned. The site went off-line yesterday and this could be because of the extreme cold which can play havoc with communications.
New Update on Jim River -79°F Temperature Report
This figure has been disallowed by the Alaska State Climatologist, Dr.Peter Olsson. The figure was apparently a result of low battery failure at a personal weather station at the site. The Davis Vantage Pro2 instrument apparently used at Jim River D.O.T. is not considered reliable for readings lower than -40°F/C°.
Christopher C. Burt
KUDOS: To Peter Olsson, Alaska State Climatologist for information concerning the purported -79° at Jim River
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