The cold blast of air continues to be the main theme in the weather for today and the rest of the week. It will be cold enough tonight that some patchy frost might form, but it is not a guarantee. The threat is great enough that the National Weather Service has issued a FROST ADVISORY for effective tonight into Thursday morning for Ashland, Price, Taylor, Clark, Jackson, Juneau, Adams, Wood, Portage, Waushara, Marathon and Lincoln counties.
The northeastern part of the area might not have any frost because there will be some lake effect cloudiness and some wind continuing out of the northwest. Some of the clouds might even hang around the Wausau area later tonight and thus I am forecasting a low of 34 in town. Even though I do not expect an official frost in the city, I am not going to leave any vulnerable plants outside. If we don’t have an official frost in Wausau tonight, it will likely happen Thursday night into Friday morning. We should have clear skies and light winds on Thursday night. Low in the northwoods will likely drop into the 20s. In Wausau I am forecasting 31. It will likely be the effective end of the growing season and it would break a record in Wausau. The record low on Friday is 32, set back in 1916. It is interesting to note that there was quite a wicked cold spell back in 1916 (besides just the record low on the 16th of September). In September of 1916 there was a record cold high temperature of 44 on the 15th, a record cold high temperature of 38 on the 16th (Yikes!), a record low of 32 on the 16th, a record low of 28 on the 17th, and a record low of 28 on the 18th. So if you don’t like the weather today, just be glad that you did not have to suffer through 1916. On the flip side, it was quite hot during this time of year in 1939. During September of 1939 we had record high temps in the 90s for 4 days in a row! It was 92 on the 13th, 94 on the 14th, 93 on the 15th, and 92 on the 16th
If we do get a frost in Wausau on Friday morning, it would be about 2 weeks earlier than normal. Check out this graphic to see when the first frost usually happens. For most of our area, it usually occurs between the 20th and the 26th of September. Wausau used to fall closer to this date range, but in the last couple of decades the city has grown enough to impact the date of the first frost. The Urban heat island effect is likely what makes Wausau’s first frost now occur around October 1st.
If we do have a frost on Friday then we will also have a longer time to experience official “Indian Summer”. The first frost is of course one criteria in the definition of Indian Summer. For the full definition of Indian Summer we use here at StormTrak 9, check this past blog post.
Have a good Wednesday! Meteorologist Justin Loew.
This post was written by jloew on September 14, 2011