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: U.S. Average Temperature Fall Forecast (It Will Be Warm.)
Dear Diary. Today is the last day of boreal or meteorological summer, so once again as we do on this blog, it is time to make a forecast for this coming season. Summer 2023 got off to a relatively average season temperature wise across the lower 48 states in June but got progressively hotter as the season rolled along. Today, Heatwave Conoco, the fourth major heatwave of the season, ended today, just as boreal summer was ending. Rest In Peace but good riddance Heatwave Conoco 8/18/23-8/31/23. As most of my readers know, I started naming major heatwaves after oil companies this year.
A couple of days ago I promised to let my followers know if there would be another major heatwave setting up during September. I’ll be incorporating that information into this post. Thankfully, I’m seeing no signs that this “fantasy” past 240 hour will verify, but summer temperatures should linger for most of the month:
At the very start of fall, it’s time for me to make another attempt at a forecast for average seasonal temperatures in the U.S. This forecast will be very broad and not specific for any one state comprising the continental United States (or lower 48 states).
So how did the forecast work out for Summer 2023? Here is a link to the post for that forecast:
By September 8th the National Center for Environmental Information will finish their climatological assessment for Summer 2023, so our verification is not complete as of August 31st. Let’s do fill in ranking numbers with 1 being the coldest and 129 warmest for a verification for months during 2023, which have already been assessed (129 would be warmest for 2023.):
Here are my two cents for a broad, rough forecast for the U.S. for Fall 2023, which I guarantee to be cooler than this past summer, of course, as the amount of daylight decreases across the Northern Hemisphere. First, I like to look at water temperature anomalies surrounding North America just before the start of a season to get a sense of how much potential anomalous heat can be added to the atmosphere across the continent. Here is what we see:
The entire continent of North America is surrounded by above average temperature waters, the warmest at the start of a season that I have ever witnessed. The El Niño that started in the spring is intensifying and is pegged to become strong this fall. Frankly, I don’t see any good reason why the U.S. will have a bellow average fall looking at sea surface temperatures. It should be quite warm unless we get an unusual jet stream pattern sometime from October on.
Speaking of the upper air patterns and the jet stream, looking at ensembles, it should be warm across most of the 48 states through the middle of the month with a chance for a major CAT3 heatwave going into the second week of September:
The above temperature chart is anything but “fall-like” and could be mistaken for a July chart at first glance. Certainly, when I was a teenager during the cooler decade of the 1970s, I didn’t see any temperature regimes like this going into mid-September. Another major CAT3 heatwave is likely, especially from the Southwest into the south-central states before mid-September.
Well, the jokes on me. I think that I was reading too much into trends during the advent of the last two strong El Niño patterns. My Summer 2023 forecast was too cool. As global atmospheric temperatures were responding to the start of the last two strong El Niño’s in the past, across the United States we saw fairly chilly conditions. Here is my write up on that:
Here is the National Weather Service forecast for Fall 2023:
The National Weather Service fall forecast looks very reasonable to me. During Summer 2023 it was hotter than average across the periphery of the U.S. and near average in the heartland, and this trend may continue into the fall. Interestingly over the long term, we also see this same temperature pattern:
Why? This probably has a lot to do with North American geography in relation to icy Hudson Bay, affecting jet stream patterns. Once we lose seasonal ice across Hudson Bay and the Arctic, gulp, the north-central U.S. will fall in line with the rest of America’s warming trend, which may only be one or two decades from occurring.
Last, we can get another clue looking at prior National Center for Environmental Information ranking and temperature record count data. For this I like to drag out my “Record Scoreboard” (updated through 8/31/2023):
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 129 and 1 being the coldest as of 2023. 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 red-, blue-, or purple-colored months, such as January 2020 and June 2021, have ratios of >10 to 1 daily record highs to lows or <1 to 10 daily record highs to lows, and are either historically hot or cold, most of which have made news. All-time record hot or cold ranked months are highlighted in purple.
Notice that August 2023 will see a better that 10-1 ratio of DHMX to DLMN record reports, so it likely will be one of a historic top ten hottest Augusts since NCEI rankings began in 1895. July-September 2022 saw three consecutive months of a greater than 10-1 ratio for the first time in the NCEI database and was the hottest three-month July-September period in recorded U.S. history. I’m thinking that the period from August-October 2023 might be similar.
I’m predicting that all three months of Fall 2023 will be above average with November being the most likely month to see temperatures closer to average. Here is the link to avg. rankings per year for the lower 48 states since 1895:
https://www.ncdc.noaa.gov/cag/national/rankings
Not all seasons in the near future will see above average temperatures, but seasonal forecasters are beginning to ”chuck it,” discounting colder than average scenarios due to carbon pollution.
Here are all seasons ranked for the last decade:
The last time we had a near average fall season was in 2019. An average ranking on the above chart would be 64.5 as of 2023.
Here is my bottom-line forecast for Fall 2023:
“I think that this fall will be ranked well above average. I’m going to forecast that Fall 2023 ranking will be around 110 + or – 10, with above average confidence given all of the factors on this post.“
My forecast for Spring 2023 of a ranking of 100 was 16 rankings too warm since we saw a ranking of 84 for that season and partially led me down the garden path of predicting a rather cool summer. We will see how well my forecast ranking of near 70 for Summer 2023 worked out in a few days.
As of 2023 the top ranking for any month or season would be 129 since climatological rankings for the United States started in the year 1895. Carbon pollution is definitely making below average seasons rarer. As stated, I’m going to guess that Fall 2023 gets ranked around 110 + or – 10, and with above average confidence given all of the factors in this post.
Here are more notes on Idalia and the tropics, which I’ll be adding to as Thursday rolls along (Newest items are listed first.):
Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks, as well as any extreme precipitation reports:
Here is more climate and weather 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. The most noteworthy items will be listed first.)