November Climatology for the Tennessee Valley

As we often do at the beginning of a new month, we look back at some of the stats for the previous month. After having a wet first 2/3 or so of summer, drought conditions rapidly started developing as we made our way into September and then have significantly increased in seriousness as we progressed through October. Many locations only got 10% to 25% of their normal rainfall during the month of October. At our viewing area’s local climate reporting station located at the Northwest Alabama Regional Airport in Muscle Shoals, just over 1/3 of an inch of rain was recorded for the entire month! October is usually one of our driest months here in the Tennessee Valley, but we do usually average over 3 inches of rain in total. This has put us from being near or a bit above average for the year when we went in to summer, to having a running rainfall deficit of almost 9 inches below normal for the year now. Significant rainfall is needed soon!

We are cautiously optimistic that there may be a bit of improvement as we head deeper into November. Even in drought years, the weather pattern often begins to get more active as we head through the month. The normal rainfall for the month usually averages around 4.15″. However, in some drought seasons we can be much drier. In the 2016 drought, we stayed completely dry until the last two days of the month! In other times, we can sometimes see big rainfall amounts and flooding with storm systems, as we can during any time of the year. As you would expect, our temperatures continue to get cooler as we head through the month. Yes, we can still be warm this time of year. Our monthly record was 89 degrees set in 2016, but the monthly average is around 63-64 degrees, with us starting around 69 as an average high at the beginning of the month and having an average high of only 57 as we end the month! Our average monthly morning low is 41 degrees, but we do usually see our first frost and light freeze either the last week of October or first week of November (as we have this year), and we’ve gotten as cold as 2 degrees in November, back in 1950! We usually average only trace amounts of snow as a long term average, but there can be accumulating snow this time of year. The Muscle Shoals reporting station set a record of 5.5 inches of snow back in November 1929.

Of significant note is that November begins our tornado season that runs from November through May here in the Tennessee Valley. Outside of the spring months of March, April, and May, the month of November has historically often been the next most active month for tornadoes in our region. In fact, prior to the 2011 Super Outbreak, November was statistically the most active month of the YEAR for tornadoes in the state of Alabama when looking at the 1950-current numbers back when we were in the early to mid 2000s! That uptick in tornado activity continues through December, January, and February before really ramping up for the spring. Tornadoes are sometimes a problem here during the fall and winter because the jet stream gets more active in the cooler months and storm systems get sent out across our area. Those storm systems then sometimes interact with warm, humid, unstable air that gets drawn north from the Gulf of Mexico. Because of our proximity to the Gulf compared to states farther north, it is easier for us to still get that unstable air, even during the heart of fall and winter. It should be noted that while many of our tornado events this time of year come from “small” spin-up tornadoes in lower instability events, THAT IS NOT ALWAYS THE CASE. On record, we have SEVERAL strong (EF2 or greater) tornadoes on record in our area for the month of November, and a few of them have been violent EF4 intensity. While we have not officially had an EF5 rated tornado in these cooler months in our explicit area, it HAS happened in other parts of the South, the Mississippi Valley, and the Ohio Valley during the fall and winter. There is nothing other than random chance that has prevented us from having a tornado that intense to happen this time of year so far. Tornadoes in the fall and winter months can be just as intense and dangerous as they sometimes are in the middle of March and April!

The good news is that, historically speaking, tropical activity in the Atlantic basin is usually sharply on the downhill swing in November. The Atlantic hurricane season even officially ends at the end of this month. Despite that, there certainly CAN occasionally be tropical systems or even hurricanes in the month of November. Very occasionally, they can even last into December or beyond like in the 2005 hurricane season. However, once we start moving into November, the southward moving jet stream and increasing number of southward moving cold fronts make it much harder for any tropical system to make landfall in the United States. It isn’t completely impossible, but we usually start shifting the focus more toward the western Caribbean, the Bahamas, and the open Atlantic.

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