Thursday March 7th… Dear Diary. The main purpose of this ongoing post will be to track United States extreme or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉
Another Shoe Drops…The U.S. Had Its Wettest Winter On Record
Yesterday I wasn’t shocked but a little surprised to learn that the United States, once NCEI had compiled statistics, had its wettest winter in recorded history. That’s the top billing since 1895 when record keeping starts, so in a neutral climate with nothing changing a 1 in 124 chance for seeing a wettest or coldest or warmest winter. As John Upton notes:
Bob Henson of Weather Underground writes a deep dive describing the statistics of the winter of 2018/19, which I will quote (I’m just reposting Bob’s part about winter precipitation):
https://www.wunderground.com/cat6/Wettest-Winter-US-History?cm_ven=cat6-widget
The contiguous United States just slogged its way through the wettest winter and the second wettest February in more than a century of recordkeeping, according to analyses released Wednesday by NOAA’s National Centers for Environmental Information.
Across the three months of meteorological winter (December-February), the nationally averaged precipitation was 9.01”, just above the old record of 8.99” from 1997-98. That winter’s precipitation was goosed by a record-strong El Niño event, as was the case in 1982-83 (the fifth wettest winter on record) and 2015-16 (the fifteenth wettest). This past winter saw only borderline El Niño conditions, though.
This winter’s moisture was well distributed, with most of the nation wetter than average. Leading the pack were states east of the Rockies, where heavy snows and torrential rains fell time and again on the north and south sides of a persistent storm track from the Southern Plains to New England. Tennessee had its wettest winter on record, and 18 other states had top-ten wettest winters.
| Figure 1. Statewide rankings for average precipitation for December 2018–February 2019, as compared to each meteorological winter since records began in 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest month on record and 124 the wettest. Image credit: NOAA/NCEI. |
A soggy 12 months as well
The last 12 months have been the wettest March-to-February period on record, with a nationally averaged 35.67” of precipitation. Only two other 12-month periods at any time of year have been wetter: May-April 2015-16 (35.95”) and April-March 2015-16 (35.78”). The past year’s precipitation totals were pushed up not only by the record-wet winter but also by Hurricane Florence in September. One analysis ranked Florence as the nation’s second wettest storm of the past 70 years, behind only Hurricane Harvey of 2017.
On the plus side, drought concerns are at a low ebb across the contiguous United States. The weekly U.S. Drought Monitor report released on February 28 showed just 12% of the nation experiencing drought of any intensity (levels D1 to D4), the lowest extent since August 2017. A small pocket of northern New Mexico remained at extreme or exceptional drought (D3-D4), with less-intense drought still affecting much of the Great Basin.
Despite periods of intense drought in recent years, especially toward the Southwest—with the impacts worsened by rising temperatures—the overall trend over the last century has been toward wetter U.S. conditions. The 48-state annual precipitation average is now around 31” compared to 29” a century ago.
A month replete with snow and rain records
Last month wasn’t quite moist enough to rank as the wettest February on record. The nationally averaged total of 3.22” fell just behind the 3.32” from 1998. Still, it was a remarkable month for Northwest snowfall and mid-South rainfall. Echoing the rankings for winter as a whole, Tennessee had its wettest February on record, and 18 other states saw top-ten-wettest Februaries.
Figure 4. Statewide rankings for average precipitation for February 2019, as compared to each February since records began in 1895. Darker shades of green indicate higher rankings for moisture, with 1 denoting the driest month on record and 125 the wettest. Image credit: NOAA/NCEI. |
Colder-than-average conditions across the West and Midwest (see below) helped ensure that the unusually wet conditions led to prodigous snowfalls. At least 24 locations from California to Michigan had their snowiest February on record (see Figure 5). In Eau Claire, Wisconsin, the monthly total of 53.5” buried not only the previous February record (28.2” in 1936) but also the record for any month (35.3” in January 1929). The Midwest snowpack raises concerns for flooding across the region should the spring warmup arrive suddenly, especially if it’s accompanied by heavy rain.
Among the towns and cities with massive snowfall in February, as reported by weather.com’s Brian Donegan, were Omaha, Nebraska (46.1”, a February record), and Nome, Alaska (69.8”, second snowiest for any February).
| Figure 5. The locations plotted above had an all-time snowiest February in 2019. The underlying contours show the estimated February snowfall. Image credit: weather.com; data from NOAA/NWS. |
Last month also brought some very impressive rainfall records, triggered by several intense multiday downpours. Nashville, Tennessee, ended up with 13.47”, more than an inch above its longstanding February record of 12.37” from 1880. Tupelo, Mississippi, also had its wettest February, with 15.61”, but the record that it doused was set just last year (12.98” in 2018).
To sum up the U.S. was affected by some wild gyrations this last winter with the jet stream leading to many strong storm systems affecting the CONUS. That and associated heavy precipitation, even if it was in the form of snow, is yet one more marker of a more rapidly changing climate. So, we have yet another shoe to drop within one year besides Australia’s hottest summer on record.
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Here is more climate and weather data news from Thursday:
(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article.)
Here are some ETs from around the world:
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The Climate Guy