Friday, December 07, 2012

Remember Dec 2004's Dramatic Shift? Super Mild to Super Cold

2004 is far enough from back in time to where most of us now need some event from that time to jog our memory. So when I talk about December of 2004's weather, unless you were caught in a snowstorm or knew someone who gave birth that month back then, you're probably asking me "What is so special about December of 2004"?

This month marked the beginning of the snowiest winter in Cleveland history! The event that jogs my mind from this month was that I mowed my lawn on December 4th that year. December 2004 featured a VERY slow start to the winter. Hardly any snow through the 10th. Guess what happened after that?

35 inches of snow through the end of the year!!!

How about the temperatures from that month?  Here is the first and second week. Notice the warmth across the country:

Now watch what happened from the 15th through Christmas. Look at the deep cold across the east and Ohio.

I'm not saying this will happen this year but what I am saying is that the pattern has, in the recent past, performed a complete 180 degree flip. So those of you wondering where the snow is?  Its coming....just a matter of time!

Thursday, December 06, 2012

US Snowcover 2012 vs Last 5 Years

One element of our weather that has been lost in the aether somewhat (as we track the cold air over Canada) is the lack of snowcover across the country.

So  far, as of December 5th, the US was covered in only 7.2% snowcover compared to last year when the snowcover was at 32%

Below is each snowcover map for the US going back to 2008. Given the pattern ahead, I think this years number will go up!

Monday, December 03, 2012

Are December Highs in the 50s and 60s Happening More in Cleveland?

The 8day forecast has been calling for a few strong surges of warm air followed by strong cold fronts over the last 2 weeks. While we ignore the colder intrusions, we relish and remember more vividly the unseasonable temperatures. After all taking your jacket off in December is more memorable than shoveling a few inches of snow.

It is these type of extremes that brings out the Recency Effect in all of its glory. I wrote a post on Facebook last week on this effect. Here is what I said:

"...We succumb to the cognitive bias called the "recency effect". That is, we the tendency to weigh recent events (warmer temps in December) more important than earlier or past events because they are more fresh in our minds."
Are these 50 and 60 degree high temperatures for early December all that unusual? I dug through ALL of the high temperature records for early December since 1912 and plotted what I found in 20 year increments. (Each year would have been a mess!) The first chart is the number of days with highs in the 50s and 60s for the FIRST week of December. The second chart is the number of days with highs in the 50s and 60s for the SECOND week of December.

Notice that the 50 degree trend has varied much. The 60 degree trend is up a bit but not by much.

Days in the 50s and 60s from DEC1st thru 7th          

This second chart shows the second week of December. It stands to reason the number of days would be smaller especially SINCE 1992! In fact, we haven't have a daytime high above 60 AFTER DECEMBER 8TH in over 20 years!

Are 50s and 60 degree high temperatures in early December all that unusual, The quick answer is...NOT REALLY. If I have a chance tomorrow, I will try to plot the number of days for each year. It'll be messy...