Weather

Weather Year Review – North Carolina State Climatic Office


Wet or dry, Mother Nature was undecided in North Carolina last year.

While 2021 isn’t particularly extreme in the final chart of temperatures or precipitation, it is worth noting the strong seasonal variation between wet and dry weather and their effects, ranging from devastating floods to drought outbreaks of fire.

Year by numbers

The National Center for Environmental Information (NCEI) reports the statewide average temperature last year was 60.1°F0.5°F warmer than the average from 1991 to 2020 and ranks as Record of the 16th warmest year dating from 1895.

ONE cool february and a good start to the summer that has left us incomparable with the warmth of recent years, including warmest year record in 2019. However, 2021 is our seventh consecutive year of above-normal temperatures, and 19 of the past 21 years have been warmer than the historical average.

Locally, several observation sites have recorded their one of the ten warmest years. It was the 5th hottest year in Wilmingtontied to the 9th warmest at Charlotteand the 10th warmest at Hatteras.

Percentage map of normal rainfall in 2021
Percentage of normal precipitation for the calendar year 2021.

According to the NCEI, the statewide average rainfall is 47.33 inches 3.44 inches lower than the average from 1991 to 2020, making it 42nd dry year in the past 127 years. That broke our three-year streak of wetter-than-usual years, including wettest year on record from 2018 and ours wettest second from 2020. It was also our driest year since 2012.

Local rainfall chart showed more variation, reflecting that some areas received more rainfall and others started to dry out earlier. Driven by the wettest summer on record, Greenville had the 12th wettest year since 1914. Late summer rain from the remnants of Tropical Storm Fred spurred the 14th wettest year on record in Asheville.

Without much tropics contributing to their rainfall, the western Piedmont and Sandhills were the driest areas last year. Lumberton has the 19th dry year on record and the 20th driest year in Charlotte. Remarkable, Lincolntown ended the year 12.3 inches below normal, making it the 8th driest year there since 1958.

The seasons change

While those annual statistics are informative, they do not fully capture our pattern of irregular rainfall over the past year. Our last four seasons – from winter 2020-21 to late fall last November – alternate between wet and dry.

While we’ve seen such a seasonal oscillation before – in fact, it’s happened 15 times in a calendar year since 1895 – it has never occurred of such extreme magnitude. Like we saw last year. Each season in 2021 is 2.5 inches above or below average long-term rainfallwhich means that our wet seasons (winter and summer) are particularly wet and our dry seasons (spring and fall) particularly arid.

Graph showing seasonal precipitation departures from the long-term average in 2021
Seasonal precipitation departs from the historical average (1985-2020) in North Carolina in 2021.

A year begins in the middle of a wet winter despite the expected effects of our La Niña model. Multiple storm systems from the Gulf of Mexico have crossed the state, including in February is the wettest day 17 in profile. However, snow is mostly limited to one Small events throughout our northern counties at the end of January, and the Trio endured pair of ice storms in mid-February.

The beginning of March brought with it dry weather for several weeks that made them unwelcome for the rest of spring. By our end May 13 is the driest day record in which some areas received less than an inch of rain, nearly half the state was classified as drought, making this our most widespread drought since October 2019.

A new season brings an abrupt paradigm shift, with heavy rain in early june extinguish the driest areas of eastern North Carolina. Each summer month sees a tropical system affecting parts of the state: Claudette in June, Elsa in July, and the ruins of Fred in August. In some areas, this rain is a good thing. ONE wet week ends for Fred created near-record river peaks and devastating floods in the mountains that claimed the lives of six people.

A photo of road flooding in Transylvania County after Tropical Storm Fred
Flooded on US 64 in Transylvania County after Fred. (Picture taken by NC DOT)

While the tropics remain active during the peak of the season in September, and the Atlantic hurricane season ends with 21 named storms – 3rd most on record – end-of-season storms mostly made landfall in the Southeast United States. In North Carolina, a prolonged warm and dry pattern helped the drought re-emerge and trigger Autumn fire season there was a November fire on Pilot Mountain.

Our current drought peaked in mid-December, with more than half of the state being classified as a Severe Drought (D2) for the first time since July 1, 2008. Since then, rain and snow on The widespread area in January has brought some improvement, although rainfall and groundwater deficits since the fall have continued to cause drought in many areas.

A Dangerous Year Nationwide – What about NC?

Nationwide, NOAA confirmed 20 weather and climate disasters by 2021 with at least a billion dollars in damage. That number is second only to 2020, with 22 disasters. Last year’s events ranged from a deep freeze in February in the Southern Delta to a June heatwave and western wildfires to Hurricane Ida to a December tornado outbreak in the west of our country.

Aside from Tropical Storm Fred, North Carolina missed out on the worst of those. Even our extreme weather is relatively mild, with only 20 confirmed tornadoes – down from the 30-year average of 31.3 and well below the 47 tornadoes in 2019 and 48. tornado in 2020.

Map showing the locations of 20 confirmed tornadoes in North Carolina in 2021
Location, duration, and intensity of 20 confirmed tornadoes in North Carolina in 2021.

Several factors have helped us avoid the burden of these hazards:

  • The topography of the mountain range tends to weaken the cold fronts moving in from the west, even if it also removes their moisture. That means our dry spring and fall-promoting models effectively shielded us from inclement weather on the other side of the Appalachians.
  • The large scale model has spurred events like the western wildfires that have brought better weather to our part of the country. While June saw record heat in the Northwest below a towering peak, we cooler and more comfortable to the southeast along the downstream trench, or to the south in the jet stream. (The main consequence of that model for us is few days with poor air quality like smoke filtered from those distant fires.)
  • A little luck might as well have been on our side. For example, if Hurricane Ida moves even 100 miles east, it is likely to bring heavy rain to parts of the Mountains that are still recovering from Fred’s flooding just two weeks earlier.
  • The nearby waters – the Atlantic Ocean and the Gulf of Mexico – also produce some wet summers regulate our overall climate, so we tend to avoid the extremes of other parts of the country. At that time, most of North Carolina had annual temperature range just 70 to 80 degrees last year, from the coldest winter lows in the 20s to the hottest summer afternoons in the 90s. That’s a far cry from the more than 100-degree range observed across the Midwest.
A photo of the Bodie Đảo Island lighthouse
The Bodie Island Lighthouse is one of our coastal lighthouses. (Photo by Kurt Moses / National Park Service)

While it’s been a relatively unremarkable year overall, 2021 still offers some reasons to keep it in mind going forward.

For a, Fred’s flood was a historical event has the same magnitude as Frances and Ivan in 2004and it sets the bar for future hurricanes in the hardest hit areas like Haywood County.

The year-end deadlineincluding ours The driest November in 90 years, showing how dry conditions can occur in the fall, even after a wet summer. Upper flow meter Great marsh near Tar Heel in Robeson County spent most of November and December at record lows for that time of year, bottoming out below levels observed in Record drought since 2007.

Our final back and forth, changing with the dry and wet seasons leaving everyone from farmers to foresters to forecasters struggling to keep up with changing weather patterns. However, evidence suggests that extreme seasons like the one we saw in 2021 could become more common in the future – and that was one of many trends observed last year, both in North America and North America. Carolina and around the world.

Last year in perspective

Globally, 2021 is 6th warmest year recordaccording to the calculation of both NOAA and NASA. That high rank came even though that year was ended by consecutive La Niña eventsis characterized by cooler conditions over the equatorial Pacific that tend to lower global temperatures.

Even if still, 2021 is the warmest La Niña year on record, and as NOAA reportIt was the 45th year in a row – since 1977 – with global temperatures exceeding the 20th century average.

Digging deeper into our statewide statistics, the average minimum temperature for 2021 ranks as the warmest on record, after six consecutive years each setting or tightening the record. record for our lowest nighttime temperatures. The NCEI also notes that our average maximum temperature for 2021 ranks as the 21st warmest on record.

Global temperature ranking map for 2021
Global temperature charts for 2021, from NOAA NCEI.

While we didn’t feel as extreme as in other parts of the country last year, generally above-normal temperatures are still a cause for concern. Long-term exposure to high daytime and nighttime heat poses public health risks, especially in areas where cooling is not available, and elevated temperatures can pose a challenge. food for farmers.

Our seasonally variable precipitation in 2021 highlights another aspect of the changing climate that is expected to continue. As NC . Climate Science Report note, precipitation events are increasing in intensity, but the intervals between them are getting longer – meaning wetter days will be wetter and dry periods even drier.

That means our future climate could look like 2021. Hurricane systems — whether they’re ice storms, tropical storms, or just thunderstorms — will generate total polar precipitation. more assertive. Then, just a few weeks or months later, that humidity could be just a memory as drought blankets the state.

Be ready for such a variety of weather, because climate change will include more floods and more droughts, often in the same year.

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