An Arctic cold front will move into the area tonight into Wednesday bringing some of the coldest air of the season for the rest of the week and the weekend. Instead of a short-lived cold snap it appears this episode of cold air will last at least at least two weeks, perhaps longer.
The normal monthly temperature for November is around 58º or 60º. Highs this week will sink in the 30s with overnight lows in the 20s. Temperatures will consistently run around 20º degrees below normal.
Cold air is not unusual for November. The record low for Fayetteville – in the month of November is 4º, On average, Northwest Arkansas does, in fact see .02″ of snow in November, too. The record low for Fort Smith is 8º degrees set back in 1976. Normally, the River Valley records about a trace of snow in the month of November.
This is a look at Monday’s temperatures in Arkansas which show 60s.
This is a look at Thursday’s temperatures which show morning lows in the 20s. Nice the extent of the purple and blue colors. The cold air will be widespread and generally anywhere east of the Continental Divide all the way to the Atlantic coast.
However, this sudden surge of cold air will feel like a shock to the system since temperature on Sunday and Monday were as high as the 70s. The drop will be dramatic; especially in the mornings.
This map from the Climate Prediction Center shows November 17th – 23rd and the below normal temperatures that will take place across much of the United States.
It’s important to note that the polar low (popularized by the national media, last year as the “polar vortex”) is not new or unusual. It typically resides to our north and does not move south into America. Nor will it this year. It wobbles around the northern hemisphere following a trough ridge pattern. As branches of the low rotate around the center, colder than normal air is displaced to the south.
This image is from the National Weather Service – Chicago and talks about what the Polar Vortex is and isn’t.
This large amplitude wobble is due to the remnants of Typhoon Nuri in the Pacific. We call these “teleconnections”. In fact, one of the tools we use in forecasting is to identify a trough over Japan because typically that leads to colder than normal temperatures in the eastern United States in the coming 7-10 days. A Typhoon in the pacific moving towards the poles will lead to much colder than normal temperatures which is what it happening this week.
Here’s a look at the high the jet stream pattern that has been altered by Typhoon Nuri. While warmer than normal temperatures move north into Alaska, colder than normal temperatures will move south into Arkansas.
As for local highs, expect upper 30s in Northwest Arkansas and around 40 for the River Valley. Lows will be in the 20s. There is some potential for rain/snow this upcoming weekend on Saturday and Sunday. With lows in the upper 20s and highs in the upper 30s, it’s unlikely that anything would stick and cause widespread travel problems at this point. The timing and the temperature will be critical as to whether or not travel is affected, but early indications point to more of a novelty.
This image shows temperature plot between the different computer models for the next week with the model average the white line with the square. The trend is down and will continue to stay down.
A 2nd surge of cold, Arctic air will move in late weekend into next week. Forecasts beyond day 7 tend to be mediocre at best, somewhat of a guess at worst. We’ll need to watch next week for the potential of more winter precipitation.
Get the coats ready and the fireplaces cleaned. Ready or not, a little bit of winter is coming.
-Garrett
