Meteorological autumn

posted in: Michigan Weather Forecast, Slim | 10

And Now onto Fall

Where did summer go? Next week we not only flip the calendar to September we also slip into meteorological autumn. I know there are some people that do not like the warmer temperature and high humidity of summer and look forward toward the fall season.  Well, I am a weather enthusiast so while I preferer the warmer months of the year I am interested in all types of weather. Before my sister passed away, we would go down to Fort Myers in the winter for a few weeks to get out of the cold and snow for a while. And even after she passed, we still would go down for a week or two. We did not go last year, and I have not decided if we will go this year or not. Anyway it is now time to look at both some average and record or both September and meteorological autumn.

September

In September at Grand Rapids the 30 year mean is 63.5 and the 15 year mean is 64.2. The average  30 year high/low 78.6/58.3 on the 1st dropping to 68.0/47.6 by the 30th the 15 year average high/low starts out at 79.1/58.6 and drops down to 68.4/48.6 by the 30th so Grand Rapids drops over 10° over the 30 days.  The warmest mean for any September is 69.0 in 1931. In that September there was a “heat wave” that lasted 6 days with 5 days in a row of 90 or better with two of the days at 94, one at 93 and two at 92. The coldest mean was 56.2 in 1918. That September had 9 days that highs stayed in the 50’s. The highest temperature recorded at GR in September is 99 set on September 2nd the coldest low on 27 was set on September 27, 1991 during that cold snap lows of 31 and 32 were also recorded. The wettest September was in 1986 when 11.85” fell and the driest was in 1979 when just a trace was reported.

Meteorological autumn

For meteorological autumn (September, October and November) the mew 30 year mean is 51.6 and the 15 year mean is 52.1. The average amount of precipitation is 10.53 for 30 years and 10.92 for 15 years. The 30-year average autumn snow fall is 7.4” but the new 15 year average is now down to 5.2” The most snow to fall in any October was 7.4” in 1967 and the most in any November was 31.0” in 2014. 2014 has the most snow fall for any autumn with 31.0” other snowy falls are 1951 with 26.9, 1991 with 25.6 and 1989 with 25.2. In 1907 no snow was reported in the fall season 1984, The autumns in 1948,1946 and 1931 only had a trace in the fall season. The warmest fall season was in 1931 with a mean of 57.5 in 1931 and the coldest was 45.8 in 1976. The most snow is 31.0” set in 2014 the least amount of snow is a trace in several years. The most days of 90 or better is 7 set in 1931 there were 6 days of 90 or better in 2017. The record hottest days in autumn are 98 on September 2nd 1913, it reached 97 on September 1st 1953 and that same 97 the next year on September 7th 1954. In more recent times readings of 96 and 95 and 94 were recorded in the 2017 heat wave. The record low for autumn was a bone chilling -10 on November 24th, 1950, there was also a -9 on the 23rd of that November. The low has dropped below +10 in 13 past autumns that last time it has happened was November 19th 1986.

We will not sit back and see how meteorological autumn will play out for 2021.

Slim

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Mr. Negative
Mr. Negative

And now…7 months of shovels/snowblowers. Life in the Southern Arctic.

Andy W
Andy W

Just another 90 degree day in GR!! What a heat wave!!!

Barry in Zeeland
Barry in Zeeland

Thanks Slim! Yesterday was the 5th day of the last 6 over 90 here. Today will prob be another one. Already dew points as high as 82 in Michigan, that’s just ridiculous. For generally only happening 1 or 2 times a decade, today makes about the 4th or 5th time just this month.

INDY
INDY

Bill Steffen said yesterday this will be the hottest weekend of summer crazy how it’s the last of weekend of August but whoe’s complaining not me …INDY

Mark (East Lansing)
Mark (East Lansing)

Summer has flown by, but it hasn’t been boring. Good storms this season along significant rain events and extended periods of above average temps (NOAA defines them as heat waves).

Man, I cannot wait until the temps return to normal and the humidity is gone. The windows on the outside of the house are soaked each morning.

MichaelV

Hard to believe we are talking about autumn already with the heat and humidity in place, for myself, I am looking forward to cooler temps and breathable air to come around.