2013–14 North American winter

2013–14 North American winter

A temperature map of the frigid conditions in the United States on January 2–4, 2014
Astronomical winter	December 21 – March 20
Meteorological winter	December 1 – February 28

The 2013–14 North American winter refers to winter in North America as it occurred across the North American continent from late 2013 through early 2014. While there is no well-agreed-upon date used to indicate the start of winter in the Northern Hemisphere, there are two definitions of winter which may be used. Based on the astronomical definition, winter begins at the winter solstice, which in 2013 occurred on December 21, and ends at the March equinox, which in 2014 occurred on March 20.^[1] Based on the meteorological definition, the first day of winter is December 1 and the last day February 28.^[2] Both definitions involve a period of approximately three months, with some variability.

Seasonal forecasts

Temperature Outlook

Precipitation Outlook

On November 21, 2013, the National Oceanic and Atmospheric Administration's Climate Prediction Center issued its U.S. Winter Outlook. Sea surface temperatures had been near average since spring 2012, and forecasters expected these conditions to continue through winter 2013–14, with neither El Niño nor La Niña conditions expected to affect the season's climate. In the outlook, little rainfall was anticipated in the Southwestern United States, and the development of drought was expected in the Southeastern United States. Below-average levels of precipitation and below-average temperatures were expected in the Alaskan panhandle. Below-average temperatures were also favored in the Northern Plains, while above-average temperatures were favored in New England, the South-Central, Southeastern, and Southwestern United States, and western Alaska. The remainder of the country fell into the outlook's "equal chance" category, with an equal chance of above-average, below-average, and near-average temperatures and/or precipitation.^[3]

Events

October storm complex

The first winter storm of the season, a significant system, was forecast by the National Weather Service, which issued a Blizzard Warning on October 3 preceding the storm.^[4] The storm occurred as an early season blizzard, and, according to the Weather Prediction Center, was an event of a magnitude unseen for the past decade.^[5] Many locations in Colorado, Nebraska, Montana, Wyoming, North Dakota, and South Dakota received near or over 10 inches (25 cm) of snow. Some areas in South Dakota received nearly 4 feet (1.2 m) of snow, with Silver City receiving 47 inches (120 cm). In many locations, there were high winds of over 50 miles per hour (80 km/h), with some locations reporting winds of nearly hurricane force, being 74 miles per hour (119 km/h).^[6]

December cold wave

On December 1, 2013, the weakening of the polar vortex led to the beginning of an abnormally cold trend in the Eastern and Central United States.^[7] On December 6, the continued deterioration of the polar vortex led to the jet stream pushing southward, bringing record cold temperatures across the Eastern U.S. During the cold wave, which extended from December 6–10, over 150 daily precipitation records^[8] and close to 100 daily snowfall records were broken across the northeastern, southeastern and south central United States.^[9] Numerous airline flights were canceled and there were reports of power outages.^{[10][11][12][13]}

Early December winter storm

On December 2, a Pacific storm system entered the Western United States, and it spread heavy rain and snow from the Pacific coast to the Rocky Mountains. As the storm continued to move east, high snow totals fell in its wake. Maximum reported snowfall totals in this area were found to have occurred in Idaho, Wyoming, and Montana, where 30 inches (76 cm) or greater were reported. High winds were widespread as well, with multiple locations in the mountainous regions of the western US reporting winds of greater than 60 miles per hour (97 km/h). As reported by the National Weather Service's Weather Prediction Center, the surface low reached its peak strength at approximately 6:00 UTC on December 3 while it was over western Wyoming, where a central pressure of 994 hectopascals (994 mbar; 29.4 inHg) was observed.^[14]

Mid-December ice storm

The ice storm over the Central United States on December 21

On December 19, a strong cold front moved southward across much of the Great Plains. By daybreak on December 20, temperatures in many parts of Oklahoma had dropped into to mostly between 10 and 30 °F (−12 and −1 °C).^[15] However, despite the freezing temperatures, the depth of the cold air was rather shallow, with a depth of generally no more than 1,500 feet (460 m). As a result of the shallow depth of the front, once the front reached parts of the higher terrain in northwestern Arkansas, the front stalled, leaving areas just ahead of the front significantly colder than areas behind it.^[16] While temperatures in much of the Plains remained at or below freezing, an upper low was forming over the Southwestern United States. As the low pushed eastward and northeastward across parts of eastern New Mexico and West Texas,^[17] it interacted with moisture over the Southern Plains; there was an unusually high amount of moisture across the area for December, and the low drew much of it over the cold air-mass near the surface.^[16] With the moisture in place, light rain began to fall in some locations prior to sunset. The rain persisted and spread from southwest to northeast overnight, with moderate rain beginning to fall across much of Southwest, Central, and northeastern Oklahoma and Southeast Kansas.^[17] By late morning on December 21, much of the rain had ended in Southwest and Central Oklahoma, where many areas had received over 0.25 inches (0.64 cm) of ice accumulation with some locations receiving over 0.50 inches (1.3 cm) or even, in localized areas, 0.75 inches (1.9 cm) of ice; isolated power outages occurred, and multiple trees and tree limbs were broken and/or pulled down by the weight of the ice.^[15] Heavy icing continued along the Interstate 44 corridor and parts of Osage County in Oklahoma; in these areas, there were reports of 0.50–0.75 inches (1.3–1.9 cm) of ice, and in southeastern Oklahoma and extreme northwestern Arkansas, there were lesser reports of 0.25–0.50 inches (0.64–1.27 cm) of ice.^[16] Additional ice totals occurred in Southeast Kansas, where there were isolated locations which received ice accumulations of as high as 0.75 inches (1.9 cm).^[17]

Early 2014 cold wave

2014 began on an active note, with a major winter storm affecting much of the United States. Between 6 and 12 inches (150 and 300 mm) of snow fell across a wide area spreading from central Missouri across Illinois and Indiana to Lower Michigan. Snowfall totals of near 18 inches (460 mm) were recorded across northern Indiana, and additional accumulations occurred downwind from the major Great Lakes. This storm was accompanied by some of the coldest temperatures to affect the Central and Eastern United States in 20 years. Upper flow which was meridional all the way up to the Arctic Circle provided a direct path for cold air advection to occur southward to the United States. The average temperature of the contiguous United States was 17.9 °F (−7.8 °C), the coldest day since January 12–13, 1997 and the 40th-coldest day in the United States since 1900. During the event, wind chills dropped as low as the -60s °F (-50s °C) across the Northern High Plains. The event was short-lived, with the portion of the polar vortex that had traveled across the Great Lakes lifting northeastward into Quebec soon after.^[18]

Late January winter storm

Early on January 27, a cold front crossed into the Gulf of Mexico, with temperatures ahead of the front in Texas and Louisiana in the 60s °F (10s °C) dropping to below freezing only one day later. As this occurred, a southern stream upper-level trough translated in an eastward direction across northern parts of Mexico. This also coincided with the backing of low-level winds along the western Gulf Coast. Relatively warm and humid air overrode the colder air near the surface, resulting in precipitation falling in Texas, Louisiana, and parts of the Southeastern U.S. as a mixture of rain, freezing rain, and snow. Late in the day, a broad northern stream upper-level trough containing a trough axis was located over the Central and Eastern United States, and the storm began to develop as this trough axis, initially reaching from the Upper Midwest to the northern Rocky Mountains, sharpened and moved in a southeastward direction during the following 24-hour period. This activity coincided with the movement of additional cold air at the surface. Many areas experiencing liquid precipitation falling at the surface saw rain switch over to freezing rain by 12:00 UTC January 28 as temperatures dropped. A mixture of frozen to partly frozen precipitation spread eastward over the following period into the early hours of January 29, impacting much of the Deep South. Widespread ice accumulations in excess of .25 inches (6.4 mm) occurred as a result of the event. As the southern stream trough axis weakened while it moved eastward across the western Gulf of Mexico, a northern stream trough amplified as it headed toward the Southeastern U.S. Overrunning wintry precipitation affected the area as a weak surface low traveled along the front and crossed into the Atlantic.^[19]

Mid-February winter storm

A winter storm on February 13

Late-March winter storm

Late on March 25, a winter storm emerged off the coast of the Southeastern United States and began to undergo explosive intensification, becoming a meteorological bomb by March 26. Powered by moisture coming from the Gulf of Mexico, the storm quickly became an unusually powerful nor'easter four times the size of Hurricane Sandy, and reached a maximum low pressure of 954 mbar (28.2 inHg; 95.4 kPa).^[20] The system produced powerful sustained winds up to 89 mph (143 km/h), and wind gusts up to 119 mph (192 km/h), with unofficial amounts reaching 129 mph (208 km/h). After making landfall on Nova Scotia, the system weakened to a 960 mbar (28 inHg; 96 kPa) nor'easter on March 27, before weakening further to a 975 mbar (28.8 inHg; 97.5 kPa) storm on March 28. On March 29, the system deteriorated into a weak winter storm over Greenland, where it would remain for the next few days while slowly dissipating.

See also

• Global storm activity of 2010
• Early 2014 North American cold wave
• November 2014 North American cold wave
• Cold wave
• Polar vortex
• Winter storm

References

 This article incorporates public domain material from websites or documents of the National Weather Service.

External links

• 2013 Storm Summaries from the Weather Prediction Center
• 2014 Storm Summaries from the Weather Prediction Center
• Major Winter Weather Events during the 2013-2014 Cold Season (WPC)