What Is An Average Thanksgiving?
When you think of an "average Thanksgiving", images of a typical America Holiday may spring to mind. Moist turkey, gross cranberry sauce (sorry, not my favorite), and yelling relatives. Mmmmm, the yelling relatives.
However, being a meteorologist, when I think of the average Thanksgiving, temperatures spring to mind. Using Weather Underground's extensive historical archive, I have managed to bring back the temperature record for each Thanksgiving from 1950 to present. I have managed to give two numbers for each Thanksgiving...average national high temperature and average national low temperature. Granted, these numbers are not scientific for a number of reasons (the observation density has increased over the years, how valuable is an average national temp, etc...), but they are still fun to look at...especially after a hefty Thanksgiving dinner.
The dark blue line is the average national high temperature for each Thanksgiving, while the pink line is the average national low temperature.
There are a couple notes that jumped out at me when I looked at this graph for the first time. First, there was a definite period of cool Thanksgivings from about 1976-1990. These cooler Thanksgivings were bookended by periods of warm Thanksgivings.
By this measure, the warmest Thanksgiving since 1950 was November 26, 1998. This year had a national average high of 61 degrees. The warmest temperature on that day occurred in Santee, CA when the Southern Californian city hit 87 degrees. Just to round it out, the coldest maximum temperature on that day was on top of Mt. Washington, NH at 24 degrees.
What was the "coldest" Thanksgiving over the past 60+ years? Well, there is actually a tie. 1993 and 2002 tied with an average low of 25 degrees. If you dig even deeper into these two Thanksgivings, an interesting pattern emerges. In 1993, over 70 cities reported a low temperature below 0 degrees. The coldest of these temperatures was recored in Laramie, WY when the city hit -25 degrees. Initially, I expected the 2002 dataset to mirror this cold outbreak with a smililar number of cities below 0 degrees. However, only two weather stations reported sub-zero temperatures (Mt. Washington at -11 degrees, Saranac Lake, NY at -9 degrees).
Now, normally it would take a huge task to compare the temperatures regionally between these two years. But, Weather Underground has just made that difficult task extremely easy. GO ON THIS JOURNEY WITH ME. Weather Underground has recently released its newest version of WunderMap. The newest WunderMap allows you to, very easily, go back in time. So, you can go back to Thursday, November 28, 2002 and click forward hour-by-hour to see how the temperatures change. IT IS AWESOME! All you have to do is click on the link above and then click on "Adjust Time" near the bottom-middle of WunderMap. Then click the "Hour" buttons.
What you will see is that there was a hefty amount of cold air in the Northeast that prevented many areas of New England from warming past 20 degrees. Further, afternoon temperatures in the 30s and 40s were observed well into the Southeast. This means that the eastern half of the country struggled to reach 40 degrees in the warmest spots. But, remember, we were investigating the coldest temperatures. If you go back a few hours to see what the morning temperatures were, you will see nearly the entire country in the 10s, 20s, and 30s.
Thanksgiving 2002 minimum temperatures.
Now, compare that with Thanksgiving 1993 and you will see where all the subzero temperatures were recorded that year. Temperatures below 0 degrees were recorded from the hills of Oregon through the Rockies.
Thanksgiving 1993 minimum temperatures.
The only reason 2002 tied 1993 was because temperatures in the Southeast 1993 were quite warm, offsetting the cold temperatures in the West. One can imagine the classic setup of a very deep low pressure trough over the West and a strong high pressure ridge in the East, bringing warm air into the Southeast.
Anyway, I could literally do this all day, but I will leave the WunderMap investigation to you.
What to expect this Thanksgiving
Well, one look at the above forecast would lead someone to believe that this Thanksgiving should be one of the warmer ones. Unseasonably warm temperatures are expected well north into the Great Lakes. The warmest temperatures are anticipated in Texas where some cities will be in the 80s.
I want to bring one more thing to your attention. Chicago's forecast high this Thanksgiving is in the mid-60s with a chance of rain. But, just one day later, Chicago is expected to struggle to reach 40 degrees. Over 20 degrees of cooling in 24 hours! This is only one example as much of the Upper Midwest will experience this cool down as a strong low pressure trough blasts through the region. Welcome to late Autumn.
Anyway, enjoy the food everybody!