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A look back at September rainfall and a look ahead at October climatology in the Tennessee Valley.

Rainfall for the month of September came in very near normal for the climate reporting site for our area at the Northwest Alabama Regional Airport in Muscle Shoals. Rainfall for the month was measured at 3.62", putting it 0.07" above normal. This helped go toward a deficit this year of -1.81 inches of rainfall. We usually average 41.14" so far by now, and we have received 39.33"

Not everyone across the Tennessee Valley was so lucky though. Areas generally along and east of Highway 43 in southern Tennessee and northern Alabama received 2 to 4 inches of rain for the month, or more, but there were some spots across the area below that mark, and a few even near or below an inch. This has caused an expanding rainfall deficit across the area over the past 30 days, with many locations only getting about half or so of the rain they usually see in September. Drier weather is to be expected this time of year, but we have to be careful. We are very close to being back in drought conditions across much of southern middle Tennessee and north Alabama.

So, now we are into October. That means we have a new month to look ahead to weather-wise, and one of the best first ways to do that is to look at climatology for the area to see what we can "normally" expect for the month ahead.

Even though fall officially started in September, October is a definite month of changes across the area in the temperature department. We start seeing stronger cold fronts swing down from Canada this time of year, and this brings big weather changes. The average high for the month overall comes in at 74 degrees, with that starting around 79 at the beginning of the month and below 70 by the time we make it to Halloween. It can certainly still get hot this late into the year on occasion though. 2019 is big proof of that, giving us our monthly record high of 100 degrees! With the cold fronts that swing through the area, that means overnight lows start taking the downhill tumble as well. Our monthly average low comes in right at 50, but that starts in the mid 50s at the beginning of the month, and we average in the 40s as early as October 15th. By Halloween, our average morning low is 45 degrees. We usually also average or first frost and freeze by the last week of the month. That means it is no surprise that we occasionally get cold in October. Our monthly record low, set in 1917, is 23 degrees!

October also averages as the driest month of the year (which isn't good news in the short term) with the area averaging only 3.43" of precipitation. That doesn't mean that we can't occasionally get a tropical system or a cold front and associated thunderstorms that can bring much more than that. It just doesn't happen as often. And while none of that is NORMALLY in the form of wintry precipitation, we can and occasionally have had that come in the form of snow flurries flying as early as Halloween!

We do still have to vigilantly watch the tropics in the month of October, but things often start trending downward the deeper we go into the month. Systems that develop out in the eastern and central Atlantic usually recurve in the open waters away from land. We do have to carefully watch the western Caribbean for development. There can occasionally be intense hurricanes that develop here (Wilma in 2005 for example) that curve northeastward and come across Florida or Cuba, and through the Bahamas before moving out into the open Atlantic or occasionally near the East Coast. However, we can occasionally see trouble in the Gulf of Mexico as well. Hurricane Opal in 1995, Category 5 Hurricane Michael in 2018, and Tropical Storm Olga in 2019 are all examples of impactful tropical systems making landfall on the northern Gulf Coast in the month of October.

While October isn't known to be overly busy in terms of severe weather, it sometimes does happen, and our tornado count starts ticking up a little bit in October before we get into the larger uphill swing that happens in November. As the mid-latitude westerlies get more active and cold fronts come down, this can occasionally mean that we have the ingredients necessary for severe storms and even tornadoes. Occasionally, those can even be strong tornadoes. Wayne and Hardin Counties of Tennessee were hit by an F3 tornado that killed 24 people way back on October 14, 1909. There were also other F2 tornadoes in Hardin and Wayne Counties that day, as well as Lawrence County, Alabama. Another example, two F3 tornadoes touched down in the Shoals of northwest Alabama on October 25, 1967. One F3 tornado took a 15 mile long path through eastern Colbert County. Another F3 tornado that day struck the north side of downtown Florence, Alabama very close to the Seven Points areas and just north of the UNA campus location. Fortunately, neither tornadoes were deadly, despite being rated on the upper half of the intensity scale and striking populated areas. October can be thought of as the beginning of the fall/winter portion of our long tornado season that runs from October/November until the early part of June.

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