The main purpose of this ongoing blog will be to track planetary 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).😉
Main Topic: Early May Record Scoreboard Update And Climatological Review
It’s time once again for our monthly climatological review. Here on this site we present monthly summaries near the 7th of each month, and each is available if you want to go back through my Extreme Temperature Diary archive. This report will be added to our climate summary and record scoreboard category on this site for these posts where you can check out reviews and statistics from prior months:
I’m repeating my mantra from prior months:
April 2021 got ranked by the National Center for Environmental Information as an above average April, temperature wise, for the lower 48 states, coming in as the 85th warmest or 43rd coldest since records began being kept in 1895:
The Northeast and Southwest had the warmest relative conditions. The south-central states did see below average temperatures.
Here are my two U.S. Daily Record Scoreboards updated through 5/07/2021 (data compiled from the following NCEI site):
DHMX= Daily High Max Reports. DLMN= Daily Low Min Reports. DHMN= Daily High Min Reports. DLMX=Daily Low Max Reports.
For these data sets all monthly ratios of > 10 to 1 DHMX to DLMN or > 10 to 1 DLMN to DHMX are in bold type. The rankings are for the lower 48 states with the warmest ranking since 1895 of average temperatures being 126 and 1 being the coldest as of 2021. Blue colors represent cold months and red warm. Those months and years with counts close to a 1 to 1 ratio of highs to lows are colored black. Boldly colored months, such as January 2020, have ratios of more than 10 to 1 daily record highs to lows or lows to highs, and are either historically hot or cold, most of which have made news.
April 2021 had approximately an 26-17 ratio of record DHMX to DLMN individual record counts, so the color I used for this month was red on the top chart.
April 2021 had approximately a 4-3 ratio of record DHMN to DLMX individual record counts, so the color I used for this month was red on the bottom chart.
Due to climate change we are seeing less blue colors on these Record Scoreboards with time, and April 2021 was typical for this trend.
As stated, the ranking for April 2021 was 85, which was colored red. I color rankings +10 or -10 from the average ranking of 63 black, indicating that these are near average temperature wise. Record statistics matched up well with the ranking of 85 for April 2021.
As shown on both charts, we can see that May 2021 has gotten off to a warm start, but we are seeing indications that this month will see some cold conditions in the Midwest and Northeast starting in mid May, bringing down overall averages.
Here is much more detailed April 2021 U.S. climatology as complied by NOAA:
Assessing the U.S. Climate in April 2021
April was dry and mild across much of the contiguous U.S.; Preliminary data suggest April had the fewest tornadoes in almost three decades
During April, the average temperature of the contiguous United States was 51.9°F, 0.9°F above the 20th-century average. This ranked in the middle third of the 127-year period of record. The year-to-date (January-April) average contiguous U.S. temperature was 40.7°F, 1.6°F above average, ranking in the warmest third of the record. The April precipitation total for the contiguous U.S. was 2.03 inches, 0.49 inch below average, and ranked as the 14th-driest April in the 127-year period of record. This was the driest April since 1989. The year-to-date precipitation total was 8.63 inches, 0.85 inch below average and ranked in the driest third of the January-April record.
The preliminary count of 73 tornadoes reported in April was the lowest April total since 53 tornadoes were reported in 1992 and was also nearly half of the April 1991-2010 average of 155 tornadoes.
This monthly summary from NOAA National Centers for Environmental Information is part of the suite of climate services NOAA provides to government, business, academia and the public to support informed decision-making.
- Temperatures were above average across much of the West Coast, Southwest, Northeast, Great Lakes and parts of southern Texas and Florida. Maine ranked fifth warmest on record for April.
- A large portion of the southern Plains and Gulf Coast states experienced below-average temperatures, as did portions of the northern and central Rockies, northern and central Plains and the Tennessee Valley.
- The Alaska April temperature was 23.6°F, 0.3°F above the long-term average, ranking in the middle third of the 97-year period of record. In general, the interior portions of the state were cooler than average, while the Aleutians experienced above-average temperatures for the month.
- Despite the mild average, large temperature swings were seen throughout the month as records were set for both coldest temperatures seen so late and warmest temperatures seen so early in the season across portions of Alaska.
- Bering Sea ice cover for April was 80 percent of average and the highest for April since 2016.
- A majority of the Lower 48 experienced below-average precipitation during April with four states across the West ranking among their 10-driest Aprils on record. Oregon ranked third driest while California ranked fifth driest on record for April. Precipitation was above average across portions of the northwest Great Lakes, New England, Midwest, southern Plains and Gulf Coast.
- April is climatologically either the driest or second-driest month of the year across Alaska. For April 2021, precipitation received was above average for the state as a whole. Fairbanks saw significant April snowfall with more than 16 inches reported for the month — its second-highest April total on record.
- According to the April 27 U.S. Drought Monitor report, 48.4 percent of the contiguous U.S. was in drought, up nearly 4.5 percent since the end of March. Drought conditions intensified and/or expanded across the eastern Great Lakes, Northeast, northern Rockies, northern Plains and the West Coast. Drought intensity and/or severity lessened across portions of the Upper Mississippi Valley, southern Plains and central Rockies.
- Temperatures were above average over much of the West, northern Plains, Great Lakes, Northeast and Southeast. Maine ranked fifth warmest on record for the first four months of the year. Below-average temperatures were primarily found across portions of the southern Plains.
- The Alaska January-April temperature was 11.1°F, 0.8°F above the long-term average and ranked in the middle third of the record. Temperatures were below average across portions of the Southeast Interior, Northeast Gulf and Cook Inlet regions and above average over much of the Bristol Bay and Aleutian regions.
- Below-average precipitation extended from the West Coast to the northern Plains and from the southwestern Great Lakes to the Northeast, and across southern Texas. North Dakota ranked driest for this four-month period while Montana and Connecticut ranked seventh and ninth driest, respectively. Above-average precipitation was limited to portions of the central Plains, northwest Great Lakes, central Gulf Coast and parts of the Southeast.
- Precipitation across Alaska for the January-April period ranked in the wettest third of the 97-year record.
For more detailed climate information, check out our comprehensive April 2021 U.S. Climate report scheduled for release on May 12, 2021.
Here is some more international April climatology:
Here is more climate and weather news from Friday:
(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. The most noteworthy items will be listed first.)
Now here are some of today’s articles and notes on the horrid COVID-19 pandemic:
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Guy Walton “The Climate Guy”