This is a composite jet stream forecast for the week beginning February 9. A deep trough will bring cold and possibly snowy weather to the eastern US, while the El Niño-inspired jet stream over the Pacific Ocean is poised to deliver storms to the west coast. Forecast courtesy of NOAA.
The big weather news in January was the Great Atlantic Blizzard (GAB16), also known as Jonas (an unworthy name given it by The Weather Channel).
January also saw an unusual Atlantic Ocean hurricane, though the National Hurricane Center (NHC) may have been a little too aggressive with its designation.
NOAA issued its land and sea temperatures for December and calendar year 2015: A clean sweep of record warmth.
February is beginning with a bang in the US, as Weather System ROO (Return Of Omni, also called Winter Storm Kayla by the Weather Channel) does its best to imitate GAB16, but falls short by about half.
Looking forward, most locations in the Northern Hemisphere will begin warming by mid-month, albeit slowly. El Niño is beginning to ebb and the Pineapple Express, though it brought some drought relief to southern California, delivered most of its juice to the northern 2/3 of the US west coast. There is still a good chance that the next round of storms will hit farther south.
January Recap
GAB16: The Great Atlantic Blizzard of 2016 buried New York, Philadelphia, and Washington under more than two feet of snow. Areas just west of the big cities, where the lifting of air by elevation enhances the precipitation process, got over three feet.
We can blame this storm partly on El Niño, which has induced a low-latitude jet stream over the Pacific. After a few failed attempts, this jet pushed across the US, and when a sufficiently vigorous wave (trough) rippled through, everything came together: Warm, humid air from the Gulf of Mexico and later the Atlantic Ocean surged north and west; cold arctic air from Canada covered the northern states; the cold air next to warm is a state of high potential energy, and the approach of the trough set off a conversion of potential energy to kinetic energy (wind). The redistribution of the air masses involves lifting of the warm air, which causes precipitation because air cools as it rises and the moisture is wrung out.
Hurricane Alex: Out-of-season Hurricane Alex formed far out in the Atlantic Ocean on January 13. Its parentage was unusual but not unique. A mid-latitude storm had retained considerable strength during its journey across the ocean and eventually acquired some tropical characteristics. Though the NHC recognized Alex as a hurricane, Decoded Science believes it was a hybrid storm, with relatively modest input from the mechanism of tropical cyclones.
Hurricane Alex traveled over open ocean and never threatened any land other than the Azores. Graphic courtesy of NOAA.
Extra-tropical storms, a la GAB16, are fueled by adjacent warm and cold air masses.
Tropical cyclones eat energy locked in water vapor molecules and regurgitate wind. For this process to keep a cyclone going, the water must normally be 80 degrees Fahrenheit (80F) or higher.
The water in the eastern Atlantic along Alex’s path never exceeded 77F. Many storms use both energy conversion processes, and the designation of tropical, extra-tropical, or hybrid (sometimes called sub-tropical) is subjective. We’ll give NHC their prerogative in naming this storm, but it should have an asterisk.
December global temperatures: In mid-January, NOAA released its data for December and full-year 2015. All categories were new records for warmth. Land, sea , northern hemisphere, southern hemisphere, and combined.
Not only was 2015 the hottest year since 1880 (when reliable records begin), but the increase over the old record was also the biggest jump ever recorded.
January global land and sea temperatures have not been released yet; anyone betting on the cold side of normal is nuts. The over/under is a substantial increase and a new record.
Some of the warmth of 2015 can be attributed to El Niño. With Pacific waters beginning to cool and La Niña likely by late summer, 2016 will be an important year temperature-wise. A continued rapid increase would be ominous.
January tornadoes: There were 14 tornadoes reported in the United States in January. Though winter tornadoes are not numerous, neither are they rare. There is a correlation between winter tornado numbers and El Niño.
What’s Up For February?
The forecast for today, February 2, shows the effects of Weather Event ROO: Snow from the Rockies to the midwest and severe weather in the Mississippi Valley. Forecast courtesy of NOAA.
Weather System ROO: To start, there’s a large area of disturbed weather covering much of the central US today. Decoded Science calls it ROO for Return Of Omni, the weather pattern that was in place for most of December, bringing snow, flooding rains, record warmth, and tornadoes in various places.
ROO will not reproduce the unprecedented pre-Christmas warmth in the east, though temperatures will be ten to even twenty degrees above average.
The Rockies will get up to two feet of snow and the snow will extend through the plains to the midwest.
The warm, humid air being drawn into the Mississippi Valley ahead of the trough will create conditions conducive to violent weather, including tornadoes.
This round of Omni will be short-lived. A new jet stream pattern featuring a deep trough in the eastern US and a ridge in the west will temporarily bring an end to the Pineapple Express, but the powerful jet stream across the Pacific suggests a new onslaught of rainy weather for the west coast by the end of the month.
The sea surface temperature anomaly chart shows El Niño is still strong, though beginning to weaken. Graphic courtesy of NOAA.
The trough in the east will bring cold weather with the potential for snowstorms that will remind residents of last winter, but Decoded Science confidently forecasts a return to mild weather in the eastern US by the end of February as El Niño weakens a little but still dominates the weather patterns in much of the world.
Grudgingly Moving Towards Spring
As the sun gets higher in the sky each day, spring will inevitably be in evidence by the time of the next Weather Around The World on March 1.
Tell us what harbingers of spring you see where you live.
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