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!

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!

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...

Will Early December Give Us More Milder Days?

This recent movie of the European Long Range forecast model tells the story into the first week of December as to why we are still going to feel colder temperatures. Notice the wave-like nature of the winds aloft in the video below. This would allow some milder days with a trend to colder temps into the heart of December. The stronger/flatter these troughs in the wind aloft in the middle/eastern half of the US, the longer the colder periods. We didn't have this type of aggressive troughiness in the east last year.

...something to watch as it develops!

Will We See the Lunar Eclipse in Northern Ohio?

The short answer is probably not. The long answer is...maybe, depending on where you are.


This eclipse is a bit different than other eclipses because of the position of the moon in relation to the shadow of the earth. This eclipse called a "Penumbra Eclipse" because the moon enters the Penumbra area of the Earth's shadow. The Penumbra is a region of the shadow that is not completely obsured from the rays of the sun. This lighter shadow is a result of the relative size of the Sun to the Earth. 

Due to the path of the moon around the earth, the best place to view this lunar eclipse will be in Asia and in western North America.  In northern Ohio, the eclipse will occur when the moon is almost below the horizon (one degree above) and only for a few minutes. Unless you live on a hilltop away from trees along the horizon, the chances of seeing it will be remote. The times for viewing in Cleveland are below.

December 21, 2010 was the last time we had a total lunar eclipse visible in northern Ohio. The next penumbral lunar eclipse will be next May the 25th.

The next Total Lunar Eclipse (moon passes directly into the earth's shadow) for northern Ohio will be APRIL 15, 2014. Good luck!

First Lake Effect Event Tonight & Saturday

Our first lake event of the 2012-13 winter season will commence tonight and Saturday. As much as we want lake effect forecast to be more cut and dry, each event is far from it due to the many factors that influence where and how much falls:

* Wind Direction
* Wind Speed (10-20 mph is preferrable)
* Temperature difference between the lake and the air about 5000 feet above the lake* Moisture content from the surface to 10,000 feet
* Elevation Changes
* Depth of the cold air

Most of these components will be present tonight and Saturday. The higher wind speeds (gusts to 35 mph) will reduce the amount of evaporation over the lake and probably the accumulations somewhat. Even with these gusty winds, we will still see some shovelable snow.

SNOWFALL FORECAST BY SATURDAY LATE AFTERNOON

When was our LATEST FIRST SNOW?

A few Facebook comments today asked what the latest first snowfall was in Cleveland?

1948-49  DEC 10TH
1985-86  DEC 2ND
1990-91  DEC 3RD
1994-95  DEC 10TH
2010-11  DEC 1ST

You can include these winters too:

1946-47
1923-24
1918-19


The daily snowfall records are a little hard to come by prior to the mid 1940s. Digging a little deeper, I found that the 1923-24 winter HAD NO SNOW UNTIL JANUARY!

The high temperature on January 1, 1924 was 28. We had 0.07" of precipitation. A strong cold front came through early January 1st. Here are the surface maps for Dec 31st and Jan 1st:

The temperatures behind the front were DEFINITELY cold enough for lake effect snow given the strong NW wind.

So the latest we EVER had measurable snowfall in Cleveland was more than likely JANUARY 1ST during the WINTER OF 1923-24!

COLDER Pattern shift ahead. Clipper Snow!

The pattern is starting to evolve into a colder one next week.

November has been running almost 5 degrees below average (3rd month in a row) even after this past weekend where the image of neighbors hanging Christmas decorations on their roof will forever be embedded in my mind. Full disclosure, I was on the roof staple gunning icicle lights too.

Remember The Greenland Block that drove Hurricane Sandy inland? That was providing us with some foreshadowing on the pattern that seems to be evolving late next week. That same Greenland Block is once again, establishing itself which will more than likely lead to below normal temperatures for Ohio.

For more evidence showing that last year's "not so cold and snowy" winter probably won't occur early this year, look at the pattern in early December from last year. Notice how the colder air wasn't even close to the US. The ridge of high pressure kept Alberta Clipper snows from developing. November was one of the warmest on record! Compare the map on the left to the one to its right. That is the forecast for late next week. Weak ridge in the middle of the country, stronger trough should equate to COLDER AIR for northern Ohio and MAYBE our first ALBERTA CLIPPER SNOW of the season!

November Snowfall: 1970s vs Present

Cleveland Plain Dealer - Shoreway Near East 55th

Those late 70s winter were brutal. I remember driving to Fairview Park Hospital for the birth of my sister in 1978 in my dad's 1977 Buick on the Ohio Turnpike. The snow was unlike anything I had EVER seen. The winds were unbearable. It was the poster child of a typical winter back in the late 1970s in northern Ohio.

After last winter, our perceptions have become twisted. We hadn't had a winter with little snow (38.5"; 62" is the average) and mild temperatures like 2011-2012 in a while. Using the National Climate Data Center temperature data for all of northeastern Ohio, the December-February period in the winters of 2001-02, 1997-98 (El Nino), 1982-83 (El Nino), 1948-49 & 1931-32 were the only winters milder than last.

So when I show an 8day forecast that features temperatures trending slooowly back to normal or slightly above into Thanksgiving week, we immediately think of last winter. We remember how lackluster the snow was. We try to paint a similar picture now since we've had little to no snow this month. I bet if I surveyed 1000 people on the street, most would say that this winter will be similar to last winter. The RECENCY EFFECT (our instinctive ability of placing too much significance on more recent experiences or events) is a very powerful cognitive bias.

How about those 1970s snowfalls specifically in November. Were they extraordinary? Here are the November snowtotals from 1975 to 1983. Surprisingly, nothing out of the ordinary.

What about the DECEMBER and JANUARY snowtotals that followed compared to our last 9 winters? It seems that DECEMBER-JANUARY snow totals since 2004 have outpaced the same months in the late 1970s and early 1980s.

What should we take from the numbers? NEVER fall victim to thinking that a snowless November will always lead to a winter will less than normal snowfall. It happens of course. It happened last year. It didn't happen during the 2004-05 season which ended up as the SNOWIEST WINTER EVER!

It didn't happen in the 1970s and it probably won't happen this year. Next post, I'll take a look at the temperatures for the same period.

What Are The Teleconnections Telling Us?

We Didn't See Much of This Last Winter

I don't want to harp too much about the connections between the oceans and atmosphere and their influence on our long range outlooks. As I mentioned earlier in the week, teleconnections like El Nino or La Nina or the North Atlantic Oscillation, which has received alot of media attention since Hurricane Sandy rarely provide a straight forword, hard-and-fast forecast commandment to follow. If they did, long range outlooks would be as easy as looking out the window and saying whether it was sunny or cloudy.

Last winter gave us a great laboratory environment by which to view the atmosphere, like a fly on a wall, react to several teleconnections abrupt shift to levels that feature a lack of arctic drivers. This was a wake up call for all of us after a few very cold winters in 2009 and 2010. As a scientist, it was nice to see the other end of the spectrum at work in nature. Let's look at the late 2011 teleconnection levels:

The North Atlantic Oscillation, The Arctic Oscillation and the Pacific North American Index (Click on the link here for a detailed description)

Each one is more influential on weather patterns in the winter. The more POSITIVE the NAO and AO; the more NEGATIVE the PNA, the "colder" pattern shuts down. Conversely, the more NEGATIVE the NAO and AO; the more POSITIVE the PNA, the "colder" pattern becomes stronger and stronger.

North Atlantic Oscillation/Arctic Oscillation/Pacific North American Index charts from late 2011. Notice the perpetual POSITIVE levels. The PNA forecast for December 2011 was barely in positive (colder) territory.

 Now compare late 2011 to late 2010 and late 2009. Notice the levels were opposite.

How are the levels currently as we approach Thanksgiving 2012? They are no where as "mild" as last year and not as "cold" as 2010 or 2009. The NAO and AO are showing signs of more frequent negative turns. Yet the PNA still shows the western ridge or warmth hasn't developed into something steady and strong which would ultimately drive a trough/colder pattern more in the east and Ohio.

I still do not think this winter will be a repeat of last winter. The index levels are reflect a pattern that features a higher frequency of colder air episodes. The wild card will be whether or not the WESTERN RIDGE strengthens and STAYS WEST. Keep an eye on the PNA INDEX. If this happens in December coincident with INCREASED SNOW COVER in CANADA along with a few other factors over the arctic and Siberia, expect more cold this winter than last.